Okay, I've got a lot of exposure with UTEC and have tuned other standalones like SDS. I've come to a place where I'm stumped and need some ideas though.

I jumped on the "modded stockers" bandwagon a while back and have had fun with them. However, I can't seem to get these things to idle correctly. On one of the WRX's, when the rpms come back down - say after blipping the throttle or just pushing the clutch in while coming to a stop, it'll hesitate and stumble but won't usually die out. On the other one, the same thing happens but will usually stumble and then DIE out.

Anybody seen this? The idle is fine with both it's just the stumbling/hunting issus after pressing the clutch back in or blipping the throttle.


Vehicle mods:

Car #1 - UTEC (4.2C), Garrett GT3271, modded stockers, 3" intake with integrated MAF hosuing, and various other bolt-ons

Car #2 - UTEC(4.2C), Garrett GT3276, modded stockers, 3" intake with integrated MAF housing, and various other bolt-ons


OLF param's:

I've tried 390/720, 420/720, 470/720, etc, etc and little affects the stumbling hunting issue and/or just straight cutting off at idle.


Some things I've noticed: both car's AFRs hunt around between 13:1 and 20:1. Car #1 above doesn't hunt as bad as car #2 though. When the stumbling/die out events occur the AFR's go very rich. Car #1 will just stumble and jump back out of it where number #2 seems to go too rich and doesn't recover most of the time.

Who knows about this? Suggestions?

TIA,

Todd

Reset the stock ECU. It will zero out the fuel trims and it will relearn for the change in weather. I dont know where you are located, but I had a similar problem with mine so I examined the fuel trims, it was adding fuel like CRAZY. I reset it and it was instantly better.

Reset the stock ECU. It will zero out the fuel trims and it will relearn for the change in weather. I dont know where you are located, but I had a similar problem with mine so I examined the fuel trims, it was adding fuel like CRAZY. I reset it and it was instantly better.


Both have been reset. Car #1 about 20 times. Car #2 has been reset once. Seems logical though but doesn't help much on these two.

3" intake with integrated MAF

So this intake came with its own MAF sensor? What brand is the sensor?

So this intake came with its own MAF sensor? What brand is the sensor?


Oops, I should edit that. I meant MAF housing :o

Do you have a way to check STFT and LTFT? If you can get those close to zero and you still have trouble then try and bump the idle up 150-200rpm. Just for kicks you should try the stock airbox, specifically the corrugated hose after the box.

I will suggest that you use something bigger than 720. How did you come up with that value? Did you have them flow tested at operating pressure? I ask because I guessing you're talking about modded top feeds. My modified side feeds I ended up at 850. What does your 0% column in your fuel map look like? I would guess that your LTFT is out of whack.

Do you have a way to check STFT and LTFT? If you can get those close to zero and you still have trouble then try and bump the idle up 150-200rpm. Just for kicks you should try the stock airbox, specifically the corrugated hose after the box.

STFT and LTFT - not at this time. Probably would help so maybe this will be next on the "to get list".

As for the OE airbox, we thought this through. Our intake has four vac posts just like the stock intake tube. All reroute just like stock.

This is just odd :confused:

I will suggest that you use something bigger than 720. How did you come up with that value? Did you have them flow tested at operating pressure? I ask because I guessing you're talking about modded top feeds. My modified side feeds I ended up at 850. What does your 0% column in your fuel map look like? I would guess that your LTFT is out of whack.


It's because we're using a 3" MAF housing primarily. Taking it to 720 got them close to the overall map to 11:1 in the upper rpms range. It made it easy to tune the rest of the map.

0% has 4 from 0rpms to 2000rpms.

Do they both have the same intake? The only time I have seen that same problem is with an intake that was, uh, problematic to say the least. Double check that it is not the MAF setup that is causing the problem.

In the worst case of this that I have seen the car ran fine with STi pinks, but when the customer switched to the modded stockers the stumble began. The logical starting point was the injectors, but the solution was found in the MAF housing. I have no idea if this is your problem here or not, but try switching the intakes, or putting on a different one.

Do they both have the same intake? The only time I have seen that same problem is with an intake that was, uh, problematic to say the least. Double check that it is not the MAF setup that is causing the problem.

In the worst case of this that I have seen the car ran fine with STi pinks, but when the customer switched to the modded stockers the stumble began. The logical starting point was the injectors, but the solution was found in the MAF housing. I have no idea if this is your problem here or not, but try switching the intakes, or putting on a different one.

Interesting. The only difference between the two is the type of metal and the angle. One is straight made from SS and the other is made from aluminum. The SS one is 3" and completely straight. The other is aluminum, 3" and has a 45 deg bend. The MAF housing designs are identical on both except the fact that one is aluminum where the other is SS. They both seal extrely well with the o-ring on the MAF sensor.

What does your LTFT look like?

What does your LTFT look like?


Like I said above above, I don't have a way of checking it but may get it this week.

The injectors don't flow like 750/850s at idle. Or even cruise. Closer to 550s. Not sure if its a pulse width problem, or if its the spray pattern (I think spray pattern), but you gotta give them more juice at lower RPMs.

If its hunting, its lean - so the car starts adding fuel, and ends up overcompensating... you go mad rich, and the car pukes. With a 3" maf, thats going to offset the larger injectors almost perfectly at idle. Try just turning on the car with the stock numbers, see what happens, I think you'll be surprised.

I have seen this, you need 0% fuel modification. It's what DarthChicken says, the modders flow a little strange.

You will have to monitor the LT/ST fuel trims to work out exactly what is going on.

It's a fine line. I usually live with the idle issues while I'm doing the WOT tuning based on the UTEC injector size. I then adjust the UTEC stock size and 0% fuel to get it to idle and rev up correctly. Don't touch the UTEC injector size when doing this.

The injectors don't flow like 750/850s at idle. Or even cruise. Closer to 550s. Not sure if its a pulse width problem, or if its the spray pattern (I think spray pattern), but you gotta give them more juice at lower RPMs.

If its hunting, its lean - so the car starts adding fuel, and ends up overcompensating... you go mad rich, and the car pukes. With a 3" maf, thats going to offset the larger injectors almost perfectly at idle. Try just turning on the car with the stock numbers, see what happens, I think you'll be surprised.


I think this may be it! Can't wait to give this a shot today. I'll go 420/550 to start. I can imagine that the upper 60-100 columns will need a lot of fuel augmentation.

I'll let you guys know.

DarthChicken made my day! I loaded car #2 with 420/550, reset the ECU and let it warm up. One up to temp, I revved and blipped the throttle, little hestitation and the motor did not come close to dying this time. The AFR doesn't seem to load up nearly as bad now when returning to idle. Whe i get back to the shop tonight, I try lowering the the values to 420/530 or so and see if that helps smooth it out a little more.

I kinda had an advantage here, I use stock modified injectors in my car, with a Perrin BigMAF to pass DEQ when the time comes :)

DarthChicken made my day! I loaded car #2 with 420/550, reset the ECU and let it warm up. One up to temp, I revved and blipped the throttle, little hestitation and the motor did not come close to dying this time. The AFR doesn't seem to load up nearly as bad now when returning to idle. Whe i get back to the shop tonight, I try lowering the the values to 420/530 or so and see if that helps smooth it out a little more.

What you have found is that you need about 110cc spacing between the two settings. Instead of running 420/530 try 610/720, that way you won't have to retune the open loop map.

What you have found is that you need about 110cc spacing between the two settings. Instead of running 420/530 try 610/720, that way you won't have to retune the open loop map.


Good point. I'll give that a try as well and see what's the outcome - much appreciated guys. Got to hate it sometimes when things are too black and white :D

I kinda had an advantage here, I use stock modified injectors in my car, with a Perrin BigMAF to pass DEQ when the time comes :)

Cool man. I don't care either way as it works. Couple of questions:

1.) What's your MAF housing size?

2.) What's your UTEC injector sizing both xxx/xxx?

3.) How much add/delete fuel do you have in your map?

My example won't work for you - I can only bring you this far. I don't have a utec anymore, and when I did I used it over a JDM ECU that was reflashed. For emissions, I swapped in my US ECU, got the utec close on cruise, ran it through emissions and yanked it back out.

Sorry

My example won't work for you - I can only bring you this far. I don't have a utec anymore, and when I did I used it over a JDM ECU that was reflashed. For emissions, I swapped in my US ECU, got the utec close on cruise, ran it through emissions and yanked it back out.

Sorry


Argh, just looked at your sig. You've got a Hydra. Thanks anyway man :D

I am going to be putting modded stockers in as well, I have a second set just waiting to go in but I want to get a pump first...anyway when you first put them in and reset the ECU should you initially run them at the default 420/420 numbers and check idle? Or what should you initially set them to to make it easiest to tune them? What if you plugged them in as 720/720, what would that do?

420/720 provided that you are running the stock MAF. Get LTFT right in cruise and idle and you will get less hesitation. Work your way up from there. I think that you're going to end up with a bigger number than 720 even with the top feeds.

I am having the exact same problems as tmarcel except I have stock maf housing. This after a tune at txs (and a retune), most of my problems were caused by a faulty bpv spring, but i still have this idle/stall throttle blip problem. Txs set my scaling 520/810, My STFT is exactly -.8 all day at idle. Anyway, I figured I'd latch onto to Tmarcel's problem rather than start a new thread.

I am having the exact same problems as tmarcel except I have stock maf housing. This after a tune at txs (and a retune), most of my problems were caused by a faulty bpv spring, but i still have this idle/stall throttle blip problem. Txs set my scaling 520/810, My STFT is exactly -.8 all day at idle. Anyway, I figured I'd latch onto to Tmarcel's problem rather than start a new thread.

sharko, I forgot about your problem too as we had conversed through PM's about this issue not long ago. Anyhow, I got sick of the issue and decided to ask for help here on the idle prob's. As you see above, I simply took the advice by given by DC using 420/550 and it got way better. Now I'll just need to play a litlle more with it to perfect it. This is only on one of the cars though and will have to get around to the other one once it's back together.

Unfortunately for you, you already spent cash on a tune so by screwing with the scaling figures you'll throw off the entire map. I will mention that I enlisted "Turboxs Pete's" help through PM's and he said that it looked like I was on the right track.

Unfortunately for you, you already spent cash on a tune so by screwing with the scaling figures you'll throw off the entire map.

...thats exactly what I'm worried about. Why are there so many people without these problems, that have scaling like; 420/740 or 420/820, etc... Also, if this is my problem, wonder why turboxs chose the scaling that they did w/ my car. Would this also make my crossover hard to tune? I have nagged turboxs about this multiple times since my tune, kinda sick of bothering them all the time(they def. spent plenty of time w/ my car).

Okay, crap I'm pissed. I spoke to soon. I just spent the last three hours and a 1/4 tank of gas mostly trying to get the idle issue corrected. For what ever reason, the 420/550 settings were fine yesterday. However, I ddn't really drive it or rev it high enough to let the rpms fall back to idle.

Today, it's running rich as hell with those settings and is smoking unburnt fuel just idleing. I also tried everything from 300/500, 420/420, 600/800, well you get the idea? I couldn't evn get the car to hold an idle without it stalling after a rev or between shifts. No vac leaks, the intake is designed just like the stock one with the MAF housing right before the filter.

I'm once again stumped and am beginning to think that they're not going to ever work.

So, once again, anybody have any more suggestions? Turboxs Pete care to get involved yet? Really need to get this taken care of by tomorrow at the latest.

TM


Edit: I haven't even hooked the LM1 WB up yet on the current car I'm working on as I was just utilizing the UTEC OE WB capture as a ref for idle. When I saw the unburnt fuel earlier at idle, I thought that it might be a bad front O2 sensor. However, it still reads the data through UTEC. If the O2 sensor wasn't working properly, would UTEC still be able to use that data?

I know this may seem redundant, or obvious...but does the car have an atmospheric BOV? If so maybe it is venting all the way down to idle RPM after throttle let off and causing bad enough stumble to stall? I know when I had adjusted mine, I went a bit too low and it would stumble coming off the throttle and revs would drop close to stall, even with mild revs to 2-3k...tightened up the spring a bit and voila, no more stumble. Maybe just another link to take out of the picture.

I know this may seem redundant, or obvious...but does the car have an atmospheric BOV? If so maybe it is venting all the way down to idle RPM after throttle let off and causing bad enough stumble to stall? I know when I had adjusted mine, I went a bit too low and it would stumble coming off the throttle and revs would drop close to stall, even with mild revs to 2-3k...tightened up the spring a bit and voila, no more stumble. Maybe just another link to take out of the picture.

This was contributing to my problem. But, since been fixed and I still have the problem, just less pronouced. I have tried every hardware solution I can think of, except swapping injectors. I do believe Tmarcel has covered the bov issue as well.

Alrighty guys, having a new front O2 sensor overnighted for car #2. Based on past experience, this may be the source for the idle issue of smoking unburnt fuel. I believe that the sensor is ****'d. Once it's in I should know more tomorrow.

BTW, I'm just really surprised that all of the proclaimed UTEC "experts" don't have anything else to add to this issue. For that matter, even TXS to chime in :confused:

I have seen this, you need 0% fuel modification. It's what DarthChicken says, the modders flow a little strange.

You will have to monitor the LT/ST fuel trims to work out exactly what is going on.

It's a fine line. I usually live with the idle issues while I'm doing the WOT tuning based on the UTEC injector size. I then adjust the UTEC stock size and 0% fuel to get it to idle and rev up correctly. Don't touch the UTEC injector size when doing this.

Did you try something like this?

http://www.mickandsarah.com/wrx/scaled-map.jpg

This was from a car with modded injectors. The WOT run's were perfect with the scaling but as you can see the rest of the map required much more tuning. Notice the 0% MAF modification.

This car also had the issue when you blip the throttle it would die. In this case it was far too rich at idea. I tried many different stocjj size settings. In the end I just set it back to the default size and used MAF modification to resolve the issue.

This car has been running for over 6 months without issue.

Maybe this is not the same issue as you have. Just an idea.

What I will say is if it worked one day and then not the next your issue maybe machanical, not SW. Do all the injectors flow the same? Are their any leaks around the injectors? <- I've seen this before when the 0 rings were damaged during installation. What about leaks in the intake track?

Just ideas.

Are you logging the fuel trims yet? Viewing LT and ST trims are the only way to see what the ECU is doing in respect to idle compensation. Just looking at AFR is not going to tell you is the ECU is adding or removing fuel. LT trim should be within +-7%.

Another tip is setup the UTEC fueling so the ecu is removing fuel using the LT fuel trim. I have seen that the ecu is much more able to control idle when it is forced to remove fuel rather than add fuel to correct lean AFR's

BTW, I'm just really surprised that all of the proclaimed UTEC "experts" don't have anything else to add to this issue. For that matter, even TXS to chime in :confused:

Well, I think most of them told you that you need a way to check fuel trims.
With out being able to do this you really can't properly tune the closed loop opperation.

Thanks, Mick. I believe I used -4 in the 250-1250 cells using 420/550 yesterday. It was still the same. I truly believe that the fornt O2 is fubar'd though. Once the new one is in tomorrow I'll go from there. As for leaks, I've checked multiple time around the injectors seats and fuel rails. Absolutley snug and clean fitting.

When this car came to me, the car ran fine FWIW with a basic TXS stage 4 kit. I pulled everything back out, and refitted with our GT32 kit (Up-pipe,DP, turbo, oil lines, etc etc). During that time, I also modded the supplied OE blue injectors per the customers request since his STI pinks aren't up for the job. I've done injector swaps many times now so I know they're done correctly.

There are no vac leaks on the intake. TXS already confirmed that our MAF is placed properly. I modeled it after the stock inake tube.

So Mick, on the fuel map from above, what are your stock injector and scaled injector numbers?

Thanks,

Todd

Here's a fuzzy pic of the MAF location.

http://img146.exs.cx/img146/8784/maf6jq.jpg \

Pic of Intake length.

http://img146.exs.cx/img146/6567/filter8xv.jpg

Pic of inlet beginning at turbo.

http://img146.exs.cx/img146/6246/turboinlet2yv.jpg

Well, I think most of them told you that you need a way to check fuel trims.
With out being able to do this you really can't properly tune the closed loop opperation.

Hey man, that wasn't meant to be a bash just trying to get folks to take a another stab at this. Everything so far has been helpful :) I've never had an issue with the ST/LT fuel trims before so I was just trying to do what's worked in the past. I could probably get my hands on an OBDII reader by tomorrow morning though. Looks like it may be necessary in this case.

So Mick, on the fuel map from above, what are your stock injector and scaled injector numbers?

Thanks,

Todd

I did not note down the scaling numbers, very bad of me as I am usually so an&l in respect to documentation. As I remember it I used 480 and 690. But don't quote me on it. Those numbers would explain the addition of fuel low down and the removal of fuel higher up

I did not note down the scaling numbers, very bad of me as I am usually so an&l in respect to documentation. As I remember it I used 480 and 690. But don't quote me on it. Those numbers would explain the addition of fuel low down and the removal of fuel higher up


Thanks, Mick. After installing the new O2 sensor tomorrow morning, I'll try those numbers. I'll probably start at the 420/550 numbers again and then try the numbers that you used. I should have an OBDII reader in hand as well. Having to pull or add big numbers to the rest of the map doesn't bother me - it's just the damn idle :lol:

TM

I'm relieved to see that I'm not the only one with this problem. I didn't have much luck corresponding w/TXS. I am not using modded injectors but 785cc Ultimate Racing inj. I found that 420/550 seemed to be the point where it stops stumbling so much, so I was surprised to find that is the exact number that others noted previously. The thing is, my car doesn't stumble on deceleration, but usually after the car has reached idle and then I accelerate. For instance I come to a stop sign, stop, then proceed. My utec log maps show a severe drop in ignition timing..as low as 4-6 degrees. I never have problems with this above 1800-2000 rpms. I currently have the utec at 420/600, but I actually had to add a ton of gas in the idle column to ease the stumble. I've tried everything from -6 to +6. The latter seems to help the most for right now. Unfortunately I don't have means at the moment to check fuel trims. When the version 4.1 came out I was able to scale it out to over 700. Last summer I finally upgraded to the latest 4.2. Now I just have lots of gas added in the idle and large negative correction values under load. :(

Are you guys "starting" your tuning with an "off the shelf" Txs stage 4 map? If you are you must remember that those maps are based off of 550cc injectors, not the stock wrx's 420cc's.
I also use the modded injectors w/vf34, fmic, etc. Scaling IIRC is set at 550/810, with +3 added globally, I'll check later to confirm, but I do not have any stalling issues, idle dips to 680rpms on hard decel then levels out at 720rpms. The cars always starts immeadiatly and idles perfect even when it was 18deg. a couple of days ago.
The only issue I havn't had time to fix is transition from ECU to UTEC at part throttle. I'll be happy to send you the map and parameters if you want to experiment.

Yeah, I started out with that map. It has been scaled and corrected 5 ways 'till sunday since. I would be interested in viewing your map just to see how my car would react to it on a cold start. If you like you can send it to res192vu@verizon.net
Thanks
Matt

Hey guys, we never got it straightened out. It's been said that the MAF position in the intake may not be far enough away from the turbo and/or it needs to be lengthened. I'm not too sure about that theory but the customer is going to try a mock piece of pipe where the cone filter would sit and try a few revs and see if it works. When I created the intake, I modeled it after the stock intake as far as MAF placement. The only difference is length after the MAF. The stock one is about 8" longer.

Car #2 is now with the customer and had Phil (Element) road tune it. That didn't resolve the idle though. He also had TXS take a look to no avail. They both thought that the intake length might be the issue. I even had this problem with a VF23 about a year ago with the stock intake so I don't know. I'm just not having good success with these modded injectors. We'll see what happens by lengthing the intake for future reference.

Todd

Maybee it could be a bad mod job? Were the injectors cleaned and flow-tested after modification?

I would like to add that I am using an Injen CAI that was hacked to a short ram...I have had it on the car longer than most of my mods and never previously had problems with it. Along with that, my injectors aren't even modded and it seems I am having similar problems to what the others noted abv.

Maybee it could be a bad mod job? Were the injectors cleaned and flow-tested after modification?

I suppose anything is possible. I was very careful when I cut the caps off with a fine rotary cutting disk. They were not flow tested or cleaned. I don't see this as the source of the problem though. There's no longer any holes to get clogged so...

Okay car #2 tested an extention in front of the MAF to lengthen it but is still stalling and/or stumling when returning to idle. There's no vac leaks, nada. I am recommending that he find some OE blue injectors (or pinks) and swap them back in. Switch UTEC to another map position and enter in the equivelant values in scaling/stock injectors settings. I bet that the issue will be resolved. I don't know though, if he wants to keep the modded stockers then he'll have to do a reflash or something because it doesn't look like UTEC is going to cut it for his particular car. Or get large UR injectors or something and hope UTEC will be fine.

Okay car #2 tested an extention in front of the MAF to lengthen it but is still stalling and/or stumling when returning to idle. There's no vac leaks, nada. I am recommending that he find some OE blue injectors (or pinks) and swap them back in. Switch UTEC to another map position and enter in the equivelant values in scaling/stock injectors settings. I bet that the issue will be resolved. I don't know though, if he wants to keep the modded stockers then he'll have to do a reflash or something because it doesn't look like UTEC is going to cut it for his particular car. Or get large UR injectors or something and hope UTEC will be fine.
Why would utec have a problem controlling some injectors and not others that all have the same specs other than flow rate? Have you tried swapping known good coilpacks into either one of these cars. Fatray had this problem (no high load problems) and solved it by replacing the coilpacks. This was after he removed the intake manifold multiple times to check for vaccum leaks.

I suppose anything is possible. I was very careful when I cut the caps off with a fine rotary cutting disk. They were not flow tested or cleaned. I don't see this as the source of the problem though. There's no longer any holes to get clogged so...

Ah but the filter can still be dirty :)

My injectors had a 25 cc flow difference between lowest to highest at full pressure. I know that isn't much but after replacing the filters it was much lower, like 10 or so. Without a cleaning they may have very poor spray patterns at idle.

Yeah, I started out with that map. It has been scaled and corrected 5 ways 'till sunday since. I would be interested in viewing your map just to see how my car would react to it on a cold start. If you like you can send it to res192vu@verizon.net
Thanks
Matt

Mat, sent you the map group and the parameters, hope they help.

Kent

Ah but the filter can still be dirty :)

My injectors had a 25 cc flow difference between lowest to highest at full pressure. I know that isn't much but after replacing the filters it was much lower, like 10 or so. Without a cleaning they may have very poor spray patterns at idle.

Not a bad idea. I know that car #2 has like 52K miles or so with the original filter I believe. On car #1 one, it's not as dramatic but has a new fuel filter but still stumbles and the occasional stall.

Why would utec have a problem controlling some injectors and not others that all have the same specs other than flow rate? Have you tried swapping known good coilpacks into either one of these cars. Fatray had this problem (no high load problems) and solved it by replacing the coilpacks. This was after he removed the intake manifold multiple times to check for vaccum leaks.


Coil packs were fine when the car arrived so there wouldn't be a problem. Even with older spark plugs it ran perfectly before the modded injectors. It now has one stage cooler plugs gapped appropriately for the mods. As for UTEC having an issue with the modded stockers, other had already noted the pulse width be dramtically different from a typical injector with a cap and holes.

Not a bad idea. I know that car #2 has like 52K miles or so with the original filter I believe. On car #1 one, it's not as dramatic but has a new fuel filter but still stumbles and the occasional stall.

Not the fuel filter, the filters that are inside the injectors. 52k mlies on the stock filter is also way out of its service interval and should be replaced anyway.

Not the fuel filter, the filters that are inside the injectors. 52k mlies on the stock filter is also way out of its service interval and should be replaced anyway.


Hey man, happy New Year! Yeah, 52k is way out of service but I don't know for sure as it's not my car. I must admit, I didn't realize that there are filters inside the injectors?? Are they replaceable or just serviceable (guessing the latter)?

I think he's talking about the screen like the ones visible on the side-feeds. I'm pretty sure the top-feeds have them as well but I have never seen the top-feeds up close.

I would like to see if using a different UTEC would change anything.....or even a different management method. I've tried every d@mn thing.

When my car is warming up in the morning (or whenever), the AFRs tend to jump all over the place, above and below 14.7, until it reaches normal temps. I feel that this directly relates to the stuttering I get when accelerating. Today as my car partly warmed up, I decided to change OLF to off. A second or two later the idle leveled out and the AFRs remained constant. It idled nicely. That has to be saying something. I am going to try again tomorrow when the car is completely cold just in case it was a fluke. Hopefully it will show the same results.

if your car idled nicely with olf off, don't scale the injectors at all.

injector scaling doesn't do anything you can't do with user-programmed offsets directly in the maps.

if the fact that olf is on without scaling affects your idle, something is wrong with the utec or firmware or both.

jm2c
ken

injector scaling doesn't do anything you can't do with user-programmed offsets directly in the maps.

Yeah but the correction numbers are going to be huge. And from what I understand, to a certain extent they become less reliable when they do.

Also, when the UTEC is not OLF, doesn't it wrestle a little more with the stock ECU as opposed to totally controlling it when OLF is on?

Scaling the injectors is just like having correction numbers in the map. The more the injectors are scaled, the bigger the correction numbers, the more the maf voltage is modified.

Nothing wrestles with the stock ecu when olf is off. The ecu controls fueling. The mods you have create a situation where the ecu doesn't know what to do. Ie - it normally cycles the injectors at x duty cycle with an rpm of y and a boost of z to get h a/f ratio. With larger injectors, we make it so the ecu has to cycle the injectors much less to get the same a/f ratio. Course the ecu isn't used to cycling the injectors that slow for the amount of air it sees going into the engine, and when this happens it can't compensate correctly. If the ecu can't compensate enough for the mods, the a/f ratio goes wacky. By using injector scaling or map offsets, we trick the ecu into thinking there's less air going into the engine, so it automatically cycles the injectors less. This makes it so the ecu doesn't have to compensate as much for the changes in flow of our mods or whatever, and will hopefully be in the right range to do what it wants.

From what I've seen, another problem comes in when scaling the injectors(or removing a lot of fuel). When we remove a lot of maf voltage, the ecu thinks there's less load on the engine(from less air going in at a given rpm) and it advances the timing more then it normally would for the amount of air that's going into the engine. I really don't know what this would do to how a car runs at idle, but it would probably push it a bit closer to knocking while at part throttle. Course this is all just from what I've seen, and I'm no expert(maybe I shoulda read the title of the thread b4 I posted).

peace

whether you correct via huge numbers in the portion of the maps you can directly type into, or you correct via injector scaling, the end result is the same: the MAF voltage is offset and spoofed before it goes "into" the oem ecu. just look at the actual vs. mod maf values. with injector scaling on, even when you have a flat zero map you'll see different values in both.

when olf is turned off, then the oem ecu is totally controlling the fuel decisions, based on the maf sensor signal, which is modifiable by the utec. but injector scaling is a feature of OLF, not a requirement.

ken

Well, regardless, I turned olf off again this morning to see the verdict and it did keep idle smoother, only because it was running really rich...like low 10-something :1....once I removed a little gas so it ran around 13-14:1, it started the erratic hunting again.
I guess it's something I'm going to have to live with but I don't like it at all.

The reason that I had for the abv idea was based on the fact that I had asked a well known tuner on this message board for advice a long time ago on how to tune on 785cc injectors and he practically shot me down considering the correction factors involved....of course, he was selling reflashes so who knows.

TyranosaurusWRX - So turning off OLF didn't work much better? With the modded stockers I always see the rpms begin to return to idle and then it dumps fuel going rich. If it doesn't stall it'll go down to like 8:1 or something obnoxious like that and then hunt around for a second and the rpms will come back up. If not it'll just stall. Was yours doing that or just a poor idle. Did turning the OLF off make it not dump so much fuel when returning to idle?

So turning off OLF didn't work much better?
No, in the end it started acting the same as with OLF on....once I adjusted the afr to near normal levels. So in your case the afrs are going rich as the car returns to idle?
I guess my car is acting a little different. It actually goes lean when it returns to idle when it's cold, then hunts around back and forth until it levels out(usually after it warms up). Once it warms up the only problem I have is during "take off" or if I blip the throttle. At this point it does a little bit of a stutter and then it's fine above 2000 rpms. I noticed in my logs that the ignition timing will drop as low as 4-6 deg. Actually now that you mention it, as the tach drops down to idle, it will show real rich afrs, but not quite as severe as what you are seeing. I see about around 11-ish:1....then it will try and hunt back to 14.7 after a couple seconds.

No, in the end it started acting the same as with OLF on....once I adjusted the afr to near normal levels. So in your case the afrs are going rich as the car returns to idle?
I guess my car is acting a little different. It actually goes lean when it returns to idle when it's cold, then hunts around back and forth until it levels out(usually after it warms up). Once it warms up the only problem I have is during "take off" or if I blip the throttle. At this point it does a little bit of a stutter and then it's fine above 2000 rpms. I noticed in my logs that the ignition timing will drop as low as 4-6 deg. Actually now that you mention it, as the tach drops down to idle, it will show real rich afrs, but not quite as severe as what you are seeing. I see about around 11-ish:1....then it will try and hunt back to 14.7 after a couple seconds.


11:1 isn't bad. I could live with that scenario. Have you tried to adjust just the lower 0% timing column? As in manually set just the 250-1000 rpm 0% cells. Timing at 4-6 does sound unusually low.

That's actually a good idea. I will just have to figure out a good timing number(s) that would work for idle.

That's actually a good idea. I will just have to figure out a good timing number(s) that would work for idle.


Try bumping it to 18+ deg all the way across 0-100% columns. 250-1000 rpms cells. You'll also need to adjust the following rpm cells from 1250 up to get a smooth transition.

Example:

0% 10% 20% 30% 40% etc
250 18 18 18 18 18
500 18 18 18 18 18
750 18 18 18 18 18
1000 19 19 19 19 19
1250 20 20 20 20 20
1500 22 22 22 22 22
1750 ECU 25 25 25 25
2000 ECU 26 26 26 26
2250 ECU 26 26 26 26


Of course, you'll need to see what the ECU is doing on the timing to make a smooth transition shift in static timing in the 0% to where you've got "ECU" plugged in.

Just putting in my $0.02 just inccase it might help. I was ad this exact same problem but mine happened when I swapped out my hacked AEM intake for a friends Godspeed Blitz SUS intake w/his MAF sensor. As soon as I put it on my car ran exactly as the cars described above. I think it was the MAF sensor and not the intake but i swapped back to my stock MAF and intake and no more problem. You've tried a diff intake and all but how about a different MAF? Just a suggestion since it worked for me and I also have modded stock injectors.

That's an idea. Did your UTEC logs read MAF voltage okay? Did you look at a before and after of changing between the sensors? I had thought about this but I'm seeing the MAFv so assumed it was fine. I guess it could be "off" or something.

My UTEC logs said MAF readings were within the norm, I checked thesensor and it didn't looked damaged so I'm not really sure other than sawaping back to my old intake and MAF fixed the problem.

Hey t, I tried what you mentioned above but it seemed to just make the idle a little more erratic and the hunting a little more severe. It was worth a shot, though. I am wondering if you are onto something with the MAF sensor. My neighbor has a wrx, maybe I could talk him into swapping w/me for second.....

Hey t, I tried what you mentioned above but it seemed to just make the idle a little more erratic and the hunting a little more severe. It was worth a shot, though. I am wondering if you are onto something with the MAF sensor. My neighbor has a wrx, maybe I could talk him into swapping w/me for second.....

Yeah, I never had tried that with UTEC. On an SDS that I tuned it has a static timing advance at idle so that's what I was thinking. Let us know of any changes with your neighbors MAF (if he'll let you try it ;) )

.... (if he'll let you try it )

Yeah no doubt, may be a lot to ask. But if I find results I'll post.

fwiw, if you want to try it, at idle i see around 12-14* of timing.

Well, a buddy let me switch out my MAF sensor with his for a minute. I can't say 100% that it's definitely the problem but it's leaning that direction. When I put his sensor in my car it instantly ran real rich at idle, like 9:1, whereas with my sensor it would hunt above and below 14.7:1. And that makes sense because I have had to add so much fuel so the car wouldn't choke during a cold start.
I took some gas out of the idle column and after a bit it idled real smooth. Just out of curiosity I set the scaling to 700/420. It choked a few times around 1000 rpms but then smoothed itself out. Nothing like before when it would just lean out and die on anything under 2000 rpms. I am curious if I would have been able to reset the ECU that it would have smoothed things out a little better.
I'm still a little skeptical because of the little bit of hunting it did, but the difference in reaction between his sensor and mine was huge.

It's kind of expensive not to know for sure. Subaruparts.com has it -

22680AA310 Meter Ay Air Flow $192.29

Let us know what you do.

ok, compression is good, just replaced all 4 coilpacks: problem still there. The only other factor to eliminate is the injectors themselves, I need find a set up stock injectors.

updates?

MAF is in the mail....I hope that this is the problem.($$$) It seems very possible. I will post results.

Just a basic idea: But did you get them flow tested? If you did then scaling of 740/420 should work and if you are running rich still use the LTFT/STFT's as many have said to tune your idle.

Just a basic idea: But did you get them flow tested? If you did then scaling of 740/420 should work and if you are running rich still use the LTFT/STFT's as many have said to tune your idle.

Sometimes it helps to read more than the last 3 posts before you decide to toss advice out there. Sorry, not trying to be lame, but this advice as already been given multiple times in this thread.

tyrano - that'd be cool if that resolves it for you.

All - I'm going to fabricate another intake so that it will be more than twice as long as is currently. The MAF housing placement will stay at the end of the intake just before the filter and all tubing will remain 3.0" diameter. The only way to really do this is to run it down into the fender as a CAI would work. This is the only way to do it since this is a rotated positioned turbo and does not go under the manifold (this would be a non-issue on a MAP only system).

Todd

Oh yeah - my injectors WILL be flow tested very soon and results will be posted. I've even offered to have my customer's modded injectors (the other WRX at the beggining of this thread) flow tested for free and will post the results of his too if he wants. My thoughts are that both will test just fine and within acceptable tolorences of each other.

Oh yeah - my injectors WILL be flow tested very soon and results will be posted. I've even offered to have my customer's modded injectors (the other WRX at the beggining of this thread) flow tested for free and will post the results of his too if he wants. My thoughts are that both will test just fine and within acceptable tolorences of each other.
Did you ever get those injectors flow tested?

Did you ever get those injectors flow tested?


Yep, but with all of the other issues the injectors were the least of my worries so I never posted back. In a nut shell, they tested within 10cc's from the highest to the lowest reading ones. The test showed #1 890/#2 895, #3 895, #4 900 ml/cc. Those numbers are on the highside as the testing media is not gasoline so it has a slightly lighter weight, thus reading higher. Corrected numbers are just a hair north of 800cc's and the small difference in flow is considered to be good.

Just to be clear, the problems were various. Partly could've been from the injector flow pattern. Partly from the 3" shorty intake to rotated mount turbo (short MAF distance to inlet), and partly due to bottom-end issues.

Hope that helps! I am on the thrid engine now since I made this thread :lol:

Any updates?

I know this is old but I am curious if you ever figured out the problem.

Not sure if you are referring to me or not, but if so......I bought a new MAF which did stabilize my AFRs and helped idle a little. I found shortly thereafter that I had a cracked ringland on my#4 piston. It may have happened after the fact, but it definetly became very bad within a couple weeks. Couple the new MAF and broken piston with the fact that my valves (especially the exhaust valves) appeared to not be sealing and you have a recipe for incurablely bad idle. But yes, the old MAF was definitely part of the problem.


Any updates?

I know this is old but I am curious if you ever figured out the problem.