Guys, I had spent some time with my car earlier working on a 93 octane pump map. Let's not over analyze the log as it's not smooth but you can see what I'm talking about. This is a 3' MAF housing but like I said blow through. Turbo is a GT32 with 35R comp and as you can see keeping the boost down is a challenge as the CL Boost was at only 150.

Load Knock Mod Mod Mod
RPM MAP MAF TPS Site Count AFR Ign#1 Inj#1 Ign Fuel Boost MAF
psig V % deg duty deg % (CL) V

5020 +19.6 4.9 102 80 00 rich +26.3 63.0 +5.7 -19.5 150.00 3.4
5027 +19.8 4.9 102 80 00 rich +22.4 61.2 +6.0 -19.5 150.00 3.6
5232 +20.4 5.0 101 90 00 rich +24.9 60.1 +5.4 -20.5 150.00 3.5
5224 +20.6 4.9 102 90 00 rich +24.4 59.9 +5.2 -20.5 150.00 3.6
5341 +20.0 4.9 102 80 00 rich +24.7 62.1 +6.0 -19.5 150.00 3.5
5428 +20.6 4.8 102 80 00 rich +24.0 62.9 +6.0 -19.5 150.00 3.6
5437 +19.8 4.9 102 90 00 rich +25.1 59.8 +5.6 -20.5 150.00 3.4
5611 +19.2 4.7 102 80 00 rich +24.7 60.5 +6.8 -19.5 150.00 3.5
5807 +19.8 4.9 102 80 00 rich +31.1 61.5 +7.7 -19.5 150.00 3.6
5737 +19.8 5.0 102 90 00 rich +31.4 62.0 +7.6 -20.5 150.00 3.5

Some other issues are that this motor is kind of a franken-motor with 8.4:1 100.5mm forged pistons, all blueprinted and balanced in a STI block. Timing is super low for now until the AFR is dialed in. The heads are ported but with WRX cams so you get the idea.

Another question...anybody got an idea what's going on tiht the timing? UTEC isn't sensing knock BUT the logged timing is lower than what's in the timing map. The actual UTEC timing map never get's below 11's in that area but the UTEC log shows 6's and 7's???

wow, can I ask why your taking so much fuel away? Are your injectors scaled right? Looks like something we would have to do with mu buddies STI right now cause his fuel trims are all screwed up. Also are you supposed to go off of the MOD MAF or the reg MAF votage?

I've got the sclaed inlector size at 615 and the stock size at 420. This is requiring HUGE negative numbers to pull fuel out. IIRC, your buddies car is not blow through so this may make a big diff and also my WRX ECU sees 420 injectors when they're really 820cc's. This is a lot larger number than an STI ECU would need to compensate I think.

As far as the MAF volts, I was always under the impression that the "Mod V" is what matters as that's what the actual voltage is but I could be wrong (I hope I'm wrong or I've got problems). I'm also freaking on the timing a bit ;)

I've got the sclaed inlector size at 615 and the stock size at 420. This is requiring HUGE negative numbers to pull fuel out. IIRC, your buddies car is not blow through so this may make a big diff and also my WRX ECU sees 420 injectors when they're really 820cc's. This is a lot larger number than an STI ECU would need to compensate I think.

As far as the MAF volts, I was always under the impression that the "Mod V" is what matters as that's what the actual voltage is but I could be wrong (I hope I'm wrong or I've got problems). I'm also freaking on the timing a bit ;)

Yes, I believe the MOD MAF is what matters. In which your case your only at 3.6 volts. The MAF on the left is the stock and on the right should be the MOD MAF. So in that case you should still have 1.4 volts to go, especially since your taking soo much fuel away that should keep the MOD MAF even lower than usuall.....

peebles,

You know what I think I'm being a 'tard tonight :lol: I believe you're right on the MAF Mod v as that makes sence, I'm just not used to seeing the two so far apart.

Anybody want to address the timing issue? Like I said, the timing from the above log shows some really low timing, in fact several degrees lower than I had it in the map. If you notice the stock ECU timing, it looks to be a happy camper! What gives with this, I'm really wondering if I should start bringing the knock sensitivity down a bit. Currently, they're set -5 for all RPM thresholds as an STI UTEC has them.

peebles,

You know what I think I'm being a 'tard tonight :lol: I believe you're right on the MAF Mod v as that makes sence, I'm just not used to seeing the two so far apart.

Anybody want to address the timing issue? Like I said, the timing from the above log shows some really low timing, in fact several degrees lower than I had it in the map. If you notice the stock ECU timing, it looks to be a happy camper! What gives with this, I'm really wondering if I should start bringing the knock sensitivity down a bit. Currently, they're set -5 for all RPM thresholds as an STI UTEC has them.

Cool, Im glad I could point out that to you :lol:
Yea, about the timing I would double check your parameters and hopefully your knock sensor didnt go out for some reason....which would make sence of what is happening. Might want to pull some codes if you've got any.

Cool, Im glad I could point out that to you :lol:
Yea, about the timing I would double check your parameters and hopefully your knock sensor didnt go out for some reason....which would make sence of what is happening. Might want to pull some codes if you've got any.


Thanks man! It's a brand new sensor though. The old one (had 34k miles) reads exactly like this one does as in no change from swithching the knock sensors. This engine is noisey compared to a stock engine so I'm guessing that the stock ECU has a much higher threshold than what I've got plugged into the UTEC. As for codes, they're just runn of the mill P0301-04 misfires which are normal for UTECS.

What size MAF housing are you running? With the 2.75" TXS housing I am using we pegged the MAF out towards redline with a 35R at 19psi. It would go up and bounce around 4.7-4.9 and then when I was almost right at redline it would hit 5.0 and stay there.

Right now I am trying to find someone to make me a custom housing to use, since I am not really looking to spend $225 for a freakin Perrin BIG MAF.

-Matt

What size MAF housing are you running? With the 2.75" TXS housing I am using we pegged the MAF out towards redline with a 35R at 19psi. It would go up and bounce around 4.7-4.9 and then when I was almost right at redline it would hit 5.0 and stay there.

Right now I am trying to find someone to make me a custom housing to use, since I am not really looking to spend $225 for a freakin Perrin BIG MAF.

-Matt

Matt,

It's a custom 3" housing. If I was you, I would just get a MAF plate (Topspeed sells them as well as others) and a 3.25" pipe and have it cut and welded in place. You'll need to go back in with a rotary tool and clean up the inside of the housing though. I know mine was a bit rough on the inside originally.

I couldn't find any maps going past 6200rpms but here's one showing the progression. I think the MAF was just bouncing between 4.8-5.0 v to redline IIRC.

So should I be worried what the ECU MAF is seeing??

Todd

Load Knock Mod Mod Mod
RPM MAP MAF TPS Site Count AFR Ign#1 Inj#1 Ign Fuel Boost MAF
psig V % deg duty deg % (CL) V

5073 +18.8 5.0 102 80 00 rich +23.7 61.0 +6.0 -19.5 150.00 3.6
5257 +18.8 4.7 102 80 00 rich +25.4 62.2 +5.9 -19.5 150.00 3.5
5402 +19.2 4.9 102 80 00 rich +26.2 62.7 +5.9 -19.5 150.00 3.5
5437 +20.0 5.0 102 90 00 rich +24.7 61.0 +5.5 -20.5 150.00 3.5
5509 +20.4 4.9 102 90 00 rich +25.0 58.6 +5.9 -20.5 150.00 3.4
5574 +20.0 4.8 102 80 00 rich +24.6 63.7 +6.4 -19.5 150.00 3.5
5698 +20.2 5.0 102 80 00 rich +30.7 63.4 +7.1 -19.5 150.00 3.6
5889 +20.2 4.9 102 90 01 rich +29.3 61.7 +7.5 -20.5 150.00 3.6
5889 +19.4 4.8 102 80 00 rich +29.5 64.1 +9.6 -19.5 150.00 3.6
5931 +19.8 4.9 102 80 00 rich +29.3 63.7 +10.9 -19.5 150.00 3.5
6071 +19.2 4.8 102 80 00 rich +28.1 63.7 +11.0 -19.5 150.00 3.4
6138 +18.8 5.0 102 80 00 rich +29.1 65.1 +11.2 -19.5 150.00 3.6
5995 +16.7 4.1 1 60 00 rich +39.5 15.1 ECU. -13.4 ECU. 2.3

Yeah I would do that but I am not too fond of paying the kind of money they are asking just for the adapter. Not only that but they dont reply to the thread they posted about them in and I have PM'd them only to get no reply. But yes, its starting to look like I am going to have to make my own.

I dont see any reason to be worried, but you may want to try a bigger housing to see if it changes anything. Its very obvious that turbo your running is definitely moving quite a bit of air, especially since it is maxing out the MAF around 5000rpms!!

Once I get my UTEC in and I get it dialed in I will post my logs with both the 2.75" housing and the 3.25" housing for comparison.

-Matt

The ACTUAL MAFv is what matters. The actual sensor maxes out at approx. 5.0 volts. It doesnt matter that your utec is using a much lower value, because the sensor is still being maxed out in reality. It is a mechanical(or electrical if you prefer to think of it like that) limitation that you are hitting. What you want is a bigger housing to reduce the actual voltage that the sensor puts out.

Also, instead of running your injectors at 615/420 and pulling 20% fuel, just run them at 850/420 and pull maybe 5% fuel. Keep scaling them by increasing the 850 number up more and more until the car idles fine at 14.7 with "0" in your fuel map. If you end up hitting 1000cc and you are still too rich then you will have the pull fuel but I doubt you will see that happening.

Jeff

The ACTUAL MAFv is what matters. The actual sensor maxes out at approx. 5.0 volts. It doesnt matter that your utec is using a much lower value, because the sensor is still being maxed out in reality. It is a mechanical(or electrical if you prefer to think of it like that) limitation that you are hitting. What you want is a bigger housing to reduce the actual voltage that the sensor puts out.

Also, instead of running your injectors at 615/420 and pulling 20% fuel, just run them at 850/420 and pull maybe 5% fuel. Keep scaling them by increasing the 850 number up more and more until the car idles fine at 14.7 with "0" in your fuel map. If you end up hitting 1000cc and you are still too rich then you will have the pull fuel but I doubt you will see that happening.

Jeff


Jeff,

That's what I was thinking the whole time and then peeblesm came in and made me second guess myself :lol: It's cool though!

Well, what can I say here? Do you have direct experience with a blow through MAF and on top of that a larger housing (3")? If not, there's some things that you may not have experienced before. TXS even recommends to start out low like a 600 scaled number when running it. That was a little too much so I stuck with the 615cc number. I found my AFR bounced around like crazy when it was at 700cc even. At 650cc is where it was getting better and 615 seemed best. Steady AFR and goes quickly to stoich.

Correct me if you think I'm off base, but the way I see it the scale number doesn't mean that much as you can either pull from the map or scale it out while in OL. You still arrive at the same place. And, this is what's happening as I'm making do with the tools that I've got (UTEC but a Hydra or the likes would work better for my hardware).

As far as the MAF housing size. The way it is now in a 3" tube, I almost think that I would need a 3.5" minimum to keep the MAF voltage down. Imagine when I want to turn up the boost to say 28psi on C16 ;) That's just not going to be possible the way it is now huh!

Todd

Scaling the injectors or modifying the map will accomplish the same thing in the end, you are correct. It just is easier for some to perform the scaling to get their fuel map values as close to 0 as possible. Do you have access to your fuel trims via SSM or obd2 software?

Jeff

Do you have access to your fuel trims via SSM or obd2 software?

Jeff


Sadly, I do not! I am going on my unique ability to sense ST/LT trims and scale ;) :D Well, seriously I don't but she's steady as it's going to get right now. So I've got to be VERY close.

I just ordered a 3.5" stainless steel pipe and a few other items for my MAF housing. I will let you know how it works out.

-Matt

The ACTUAL MAFv is what matters. The actual sensor maxes out at approx. 5.0 volts. It doesnt matter that your utec is using a much lower value, because the sensor is still being maxed out in reality. It is a mechanical(or electrical if you prefer to think of it like that) limitation that you are hitting. What you want is a bigger housing to reduce the actual voltage that the sensor puts out.

Also, instead of running your injectors at 615/420 and pulling 20% fuel, just run them at 850/420 and pull maybe 5% fuel. Keep scaling them by increasing the 850 number up more and more until the car idles fine at 14.7 with "0" in your fuel map. If you end up hitting 1000cc and you are still too rich then you will have the pull fuel but I doubt you will see that happening.

Jeff

So the MAF voltage on the left of his log is really what matters and we should disregard the MOD MAF voltage on the right of his log? Also if you could take a look at my post about my buddies STI about scaling the injector and fuel trims. Thanks http://forums.nasioc.com/forums/showthread.php?t=959377

If the MAF V is pegged, so will the mod MAF. The actual MAF volts is what matters in terms of maxing out the sensor. There is no way you could get 5.0 mod MAF volts if you are removing a bunch of fuel.

I didn't feel like reading all the posts, so sorry if I try to answer something that's already been anwered. Your timing issue looks like it's probably related to temp compensation, especially since you're running a blowthrough maf.

If you wanna get the maf voltage lower, you might wanna try puting a spacer between the maf sensor and the pipe it's in. This would move the sensor closer to the side of the pipe and maybe help it read lower. I dunno how it would effect the sensors accuracy though. Ya might also wanna check to see if there's a leak after the sensor.

What kinda maf sensor do you have in there anyways? I thought wrx maf sensors only read upto 4.7(and sti ones went upto 5)? Can you just put an sti sensor in a wrx, or might that be screwin up the voltage?

peace

EDIT: You def have some other weird things going on but cosider this too:

its too hard to tell from these short logs but I think the placement of your MAF sensor is causing you problems. The MAFv shouldnt be fluctuating that bad.

To test my theory find a place where you can maintain the same load for a few seconds or more. Sometimesa hill or left foot breaking helps. use the "Fast" logging method.

If you can create a "same load" condition and the MAFv is all over the place in your logs then you are going to need to condition the air before the sensor.

check out the screen on this GM maf:
http://www.idavette.net/hib/02ls6/photos/43109b.jpg


i feel for you dude. My BTM setup didnt work.
http://njektd.com/subaru/btm/IMG_0073%20%28Small%29.JPG

There is no way you could get 5.0 mod MAF volts if you are removing a bunch of fuel.


Could you elaborate please? I don't see the correlation between removing fuel and the MAF v like you are saying.

What kinda maf sensor do you have in there anyways? I thought wrx maf sensors only read upto 4.7(and sti ones went upto 5)? Can you just put an sti sensor in a wrx, or might that be screwin up the voltage?

peace

It's a WRX sensor. I'm not sure that spacing out the sensor would be a good idea. That might create another issue or even a leak. I had actually thought about snipping the temp sensor and relocating it but I don't want to go that far yet.

EDIT: You def have some other weird things going on but cosider this too:

its too hard to tell from these short logs but I think the placement of your MAF sensor is causing you problems. The MAFv shouldnt be fluctuating that bad.



From your pic, mine is further away from the TB than yours by about 5" or so. I would take a pic of the placement on the car but I can't find my camera charger. The housing is currently held in place by 2.75" to 3" silicone connectors (it's not yet welded but I don't think it should make that much of a diff). I went into the piping and deburred and smoothed the cuts too.

The only other thing here is that I've got a crappy Greddy BOV right before the throttle body that was probably causing the fluctuations in MAF voltage. I can't seem to get it to work right and I need to find another valve. If it it's too tight it surged back pressure and if it's loose enough to vent it leaks. I've even taken out the small spring and resealed it but it's still not working well. Anyway, that's kinda off topic :)

Could you elaborate please? I don't see the correlation between removing fuel and the MAF v like you are saying.


well, say for example you're pulling 20% of your maf voltage to "remove fuel."

in order to net a mod maf of 5.0, you'd need 6.25v from the sensor.

that ain't gonna happen! ;)

todd, check your utec parameters for temperature compensation, and zero them out.

The point with the maf voltage maxin is that the mod won't be able to go up any more either since the maf can't read any higher.....

peace

todd, check your utec parameters for temperature compensation, and zero them out.


Ken,

I've got some very low temp comp set but I'll give that a try anyway. So what's the solution here? Given the MAF housing size throughing off everything, I really don't think the ECU is going to like a much higher scale number in order to have less fuel being pulled throughout the map.

Also, could you take a look at my timing thread in the UTEC forum and give me your input if you don't mind? I think you might have an insight to what's going on. I think I know but not sure (knock sensitivity maybe).

Thanks,

Todd

well, say for example you're pulling 20% of your maf voltage to "remove fuel."

in order to net a mod maf of 5.0, you'd need 6.25v from the sensor.

that ain't gonna happen! ;)

Yep! Thanks Ken.

The first MAF number is the physical reading from the MAF. I do believe 5.0v is a physical limitation of the sensor. If you max this out, you lose your ability to trim fuel accurately.

I don't see how you guys are saying MOD MAF is what cannot max out. If you max out the physical sensor, you're done, doesn't matter what your MOD MAF is. MOD MAF is always going to be far less than actual MAF using a UTEC with bigger injectors.

Okay so what does this all mean again :lol: Can we come to a conclusion on this? So does everybody agree that the sensor is maxing out? Is this regardless of what the UTEC signal states?

Also, Ken and cdvma...what's your point again about needing 6.25v from the UTEC MAF signal vs the ECU MAF signal? I think I missed the point.

In addition, I'm wondering if the fluctuations in the MAF signal was from the BOV leaking? It sits after the MAF and just before the TB.

I don't see how you guys are saying MOD MAF is what cannot max out....MOD MAF is always going to be far less than actual MAF using a UTEC with bigger injectors.

Exactly my point. If you max out the sensor and are using larger injectors, mod MAF will never hit 5.0 V. The question was what matters: mod MAF or original MAF. My explination was that its the original MAF because thats where the sensor is actually limited. Just because the mod MAF doesn't hit 5.0 it doesn't mean you have more room to grow. Ken replied by further confirming this with an example of how its impossible for mod MAF to hit 5.0 V if you are removing any fuel - the original MAF would have to be above 5.0 V which can't happen due to a physical limitation. Basically we are agreeing here.

tmarcel: your sensor is maxing out. All you have to read is the 5.0 V coming directly from the MAF sensor. Some consider 4.8 to be the effective max anyway since the curve at that point (volts vs g/s) has a high slope.

Todd

Original MAF is important, not mod MAF. So you are maxxing out the MAF sensor.

Placement of the MAF sensor in a blow through application is VERY important. If the MAF is to close to anything that causes the air to become turbulant that will completely screw the MAF readings up. AaronWRX illuded to this by asking you to create a "same load" senario by going up a hill at a steady speed/steady throttle position/steady boost pressure. Watch your MAF voltages and see if they fluctuate. If they do, you have turbulent air flow either before or after the MAF sensor.

Some of the common things that may cause turbulent air either before or after the MAF are - bends in piping within 4 inches of the MAF, piping diameter changes within 4 inches of the MAF, BOV or throttle body to close to MAF.

todd, you basically have a couple of options:

a) hammer on txs to release their speed-density software/hardware for the utec.
b) get a bigger maf sensor housing.
c) go back to draw through
d) go standalone ems

you HAVE to get that maf voltage lower.

in addition you may have to consider a reflash of the oem ecu to get the timing numbers a little more reasonable. have you been looking at the openecu project? at least buy yourself a cable!

Guys, your input is much appreciated!

Facts:

1.) it's certain that the sensor is maxxed...period!
2.) I most likely have a turbulance issue somewhere. I believe that was caused by a leaking valve (BOV) located before the TB and after the MAF. Now that I tightened the BOV I notice that the AFR goes to stoich much quicker on a basic idle so I bet that has something to do with it. I need a new valve!
3.) The placement of the MAF may not be ideal in terms of location. It's plenty far away from the TB (further than others I've seen) but is placed right after the IC piping bend from where it comes up by the battery. That's 2.75" piping to the MAF 3" back to 2.75" and then another bend before the TB.
4.) UTEC may not be the best solution for me right now :lol:

Ken,

I would love for TXS to come out with there revision for MAP based control. That would resolve not only my issues but probably 40% of the other tinkering with power mod Subaru owners. Will they ever do it? You always seem to have a better insight on this one.

Also, why would a reflash really help that much? I realize this would help out with the 0% column but what else? I think my timing numbers from the ECU are a good indicator that my UTEC knock numbers are just widely over sensitive right now.

Todd