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Old 05-09-2011, 12:48 AM   #26
Black94Snake
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I think I should replace my O2 sensor as well because its still the original and I was running a pig rich tune for a long time,
go replace them
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Old 05-09-2011, 11:43 AM   #27
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go replace them


Unplug the o2 sensor, see if that fixes it. Don't go around replacing sensors willy nilly just because they might be the cause. Jesus, the Subaru parts department must love you guys.
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Old 05-09-2011, 11:44 AM   #28
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BTW, you would have found that leak right away if you did a boost leak test...
No he wouldn't, a boost leak test would have shown absolutely nothing.
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Old 05-09-2011, 12:14 PM   #29
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Unplug the o2 sensor, see if that fixes it. Don't go around replacing sensors willy nilly just because they might be the cause. Jesus, the Subaru parts department must love you guys.
Haha agreed! When I did try unplugging th O2 sensor it didnt make much of a difference but it does seem like the readings swing quite a bit.


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No he wouldn't, a boost leak test would have shown absolutely nothing.
Good point, since the PCV valve is a one way valve only operating under vacuum. Thanks again for thinking about plugging the PCV and mentioning it
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Old 05-09-2011, 12:20 PM   #30
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Hey eggroll, btw what do you think is the best course of action for me to get my injectors and MAF dialed in? I ask because I cant go back to stock intake and injectors and Ive never found a straight answer just you are SOL. So its hard to guess what latencies are correct since my MAF scaling is all out of wack now thanks to the vacuum leak, but do you have any advice on a way to get close enough or I shouldnt worry about it and just scale them to work together?
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Old 05-09-2011, 12:36 PM   #31
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Just scale them both to work together. There are an infinite number of combinations of latency and MAF scaling that will hit your fueling target, but you'll notice that when you have the wrong latency, even with the correct final AFR (using MAF scaling to "fix" it), it will still run like crap (hesitating, afterlighting, etc).

Start with your latency close to what you think it should be, adjust your MAF to bring the AFR in line, see how it drives. Then adjust your latency by say 10% either higher or lower, adjust your MAF to bring your AFRs to target again, and see how it drives. If it's better than before, make another 10% change in the same direction, if it's worse than before then go back to your starting values and make a 10% change in the other direction. After a few iterations you'll kind of "home in" on the latency and MAF combination that drives the best, and you can start reducing your step size until you don't really notice any more improvement. It's a bit of work, but should only take a few days if you do it a couple of hours a day.
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Old 05-09-2011, 12:48 PM   #32
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Perfect, thank you so much! I definitely noticed that I have had the wrong combination for a while and it ran crappy. I will be doing exactly that and hopefully it doesnt turn out to be too frustrating and finally something go smoothly!
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Old 05-09-2011, 04:07 PM   #33
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Unplug the o2 sensor, see if that fixes it. Don't go around replacing sensors willy nilly just because they might be the cause. Jesus, the Subaru parts department must love you guys.
Because forcing the car into OL at idle is really going to help things....
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Old 05-09-2011, 04:37 PM   #34
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Because forcing the car into OL at idle is really going to help things....
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Old 05-09-2011, 04:41 PM   #35
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Because forcing the car into OL at idle is really going to help things....
If the o2 sensor is screwed up it will.

If forcing the car to open loop fixes the problem, you know the o2 sensor was sending false readings and causing the ECU to add false corrections, which means either the o2 sensor is dead or you have a pre-o2 exhaust leak. If forcing the car to open loop does not change things, you know the o2 sensor is fine, and replacing it would be a waste of money.

It's called debugging. Swapping out parts until the problem goes away should only be used as a last resort when all other methods have been exhausted. AFR problems are easy to diagnose without arbitrarily replacing anything.
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Old 05-09-2011, 05:26 PM   #36
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well, if the OP had ever replied when I asked what his AFR was at idle, we wouldnt be sitting here debating this.

Also, O2's dont always fail in a dead rich or dean lean report... As the element begins to get fouled, and resolution degrades... the reporting slows down. SO now you have a car that is potentially having large swings in AFR (causing a idle surge), because the O2's can't properly report back what the ECM needs to see.

As for forceing the car into OL at idle, it should only be done to negate large cams, poor header selection, and bad O2 placement. Making the car run in an OL table might not make his problem go away, if the targetet AFR of the OL table, is where his car is running currently. Which is another reason why I asked what his idle AFR was.

If you have the tools to diagnose the car, and someone asks what you see... do you reply "elephant"?
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Old 05-09-2011, 08:18 PM   #37
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Also, O2's dont always fail in a dead rich or dean lean report... As the element begins to get fouled, and resolution degrades... the reporting slows down. SO now you have a car that is potentially having large swings in AFR (causing a idle surge), because the O2's can't properly report back what the ECM needs to see.
I know, the bottom line is that when they fail they either don't read at all, or they read the wrong AFR. If they read the wrong AFR, the ECU adds the wrong correction to hit target, and regardless of whether the o2 is reading rich or lean, the actual AFR will be thrown off because it's based off of an incorrect measurement.

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As for forceing the car into OL at idle, it should only be done to negate large cams, poor header selection, and bad O2 placement. Making the car run in an OL table might not make his problem go away, if the targetet AFR of the OL table, is where his car is running currently. Which is another reason why I asked what his idle AFR was
What? The idle AFR target will always be 14.7, whether you're in closed loop or open loop, unless the OP changed this target in his ECU. The difference is in open loop the ECU won't make fueling corrections based on the output from the front o2. If this fixes the problem, it's pretty obvious that the corrections coming from the front o2 are wrong. I never said unplugging the o2 would fix the problem, I said that it would tell him whether or not the problem was related to the o2 sensor BEFORE he goes and dumps $150 on a new one just to find out the problem was something else. I didn't suggest it as a permanent solution, I suggested it as a debugging tool, because blindly replacing a $150 sensor (as you told him to do) when you have absolutely no reason to believe it is the problem, and can determine whether or not it is the problem in 15 minutes, is just dumb.

Unplug front o2, if the situation doesn't change or gets worse, the o2 is not the problem. If the uneasy idle and hesitation is gone, the idle smooths out, and the wideband reads the target AFR (14.7), then the o2 was the problem and he should replace it. It doesn't get much simpler than that.

You can do similar debugging by unplugging the MAF sensor. It forces the car into a rudimentary speed density calculation. If this fixes the problem, you know the problem is the MAF scaling or a leak somewhere in the intake tract or manifold. If this doesn't fix the problem, then there isn't a leak and the problem is coming from the fuel system or closed loop system (o2 sensor or exhaust leak).

Last edited by the suicidal eggroll; 05-09-2011 at 08:36 PM.
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Old 05-09-2011, 09:24 PM   #38
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I understnad what you are saying about testing the O2 and I think it is a good debugging tool as well, but not a permanent solution which I thought was apparent.

I uploaded a log of idle in post #4 if you would like to take a look at the idle AFRs. Keep in mind that I am currently changing things and retuning but yes the CL and OL idle target is 14.7.

eggroll, when doing the latencies and maf scaling, do you suggest I start out with the stock MAF scaling? And since I have a 16bit ecu im limited but I never did the hack before and I havent maxed it out since I have the bigger maf housing of the blow thru tube and I scaled down the injectors by .75 im sorry to keep laying on the questions for you but I want to learn as much as I can! so do you have suggestions about this situation how I should change things? Thanks again!
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Old 05-09-2011, 10:17 PM   #39
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No he wouldn't, a boost leak test would have shown absolutely nothing.
Really? I would think you'd here some hissing if that hose wasn't plugged up...
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Old 05-09-2011, 10:21 PM   #40
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I understnad what you are saying about testing the O2 and I think it is a good debugging tool as well, but not a permanent solution which I thought was apparent.

I uploaded a log of idle in post #4 if you would like to take a look at the idle AFRs. Keep in mind that I am currently changing things and retuning but yes the CL and OL idle target is 14.7.

eggroll, when doing the latencies and maf scaling, do you suggest I start out with the stock MAF scaling? And since I have a 16bit ecu im limited but I never did the hack before and I havent maxed it out since I have the bigger maf housing of the blow thru tube and I scaled down the injectors by .75 im sorry to keep laying on the questions for you but I want to learn as much as I can! so do you have suggestions about this situation how I should change things? Thanks again!
Start with latencies first, then move to MAF scaling...
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Old 05-09-2011, 10:27 PM   #41
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loosen the throttle cable at the throttle body. Clean the throttle body. Otherwise, everyone else's info is probably better
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Old 05-10-2011, 11:02 AM   #42
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Really? I would think you'd here some hissing if that hose wasn't plugged up...
The PCV is a 1-way valve, when the manifold is pressurized it closes. It only passes air when the manifold is in vacuum, and this air comes from the turbo inlet. This is how the system is supposed to work, so nothing is wrong with it per-se, it's just that this way of running the PCV system no longer works as expected when you move the MAF to a blow-through configuration.
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Old 05-10-2011, 11:10 AM   #43
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I understnad what you are saying about testing the O2 and I think it is a good debugging tool as well, but not a permanent solution which I thought was apparent.

I uploaded a log of idle in post #4 if you would like to take a look at the idle AFRs. Keep in mind that I am currently changing things and retuning but yes the CL and OL idle target is 14.7.

eggroll, when doing the latencies and maf scaling, do you suggest I start out with the stock MAF scaling? And since I have a 16bit ecu im limited but I never did the hack before and I havent maxed it out since I have the bigger maf housing of the blow thru tube and I scaled down the injectors by .75 im sorry to keep laying on the questions for you but I want to learn as much as I can! so do you have suggestions about this situation how I should change things? Thanks again!
Which tables did you scale down because of the MAF hack? Off the top of my head I can think of the MAF g/s, injector scalar, and all tables that depend on load (OL AFR, timing tables, etc).

What all did you change when you went to e85? You should have modified the injector scalar, and all tables that depend on IPW (ms) (tip-in, per-cyl fuel compensation (not sure about this on the 16 bit ECU), etc).

Since you have the blow through tube you shouldn't go to the stock MAF scaling. Start out with latencies that you think are close, and scale the MAF to suit. Then rinse and repeat. That is assuming all leaks are gone.
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Old 05-16-2011, 04:39 PM   #44
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So I restarted with a new map copying over some tables just because I dont know what I did in the beginning so starting over I now know what I did exactly in every table. I went through and halfed every table that used load which was quite a few.

I tried starting out with latencies using the deltas from the DW table that I have and using those deltas from stock latencies which resulted in:

6.5v / 2.24
9v / 1.732
11.5v / 1.18
14v / 0.84
16.5v / 0.532

and a scaler of 240 which is 850cc*0.96=816 for a 4% smaller scaler than the flow. then 816/2=408 for the half maf hack then 408*.7=286 for E85 but it was still running lean so I went down to 240 and it is solid at idle within +-1%.

For the MAF scaling I multiplied the whole table by 1.25 because of the 25% increase in area from the stock maf housing to the perrin blow thru tube. It seems to like that, but I dont understand why it didnt like when I divided the maf table in half for the hack, it was way too lean.

After doing this I tried doing some cruise maf scaling but I am seeing some very strange things. The timing in jumping from 4-35deg at timing and studdering and shaking the car very bad as well as spitting out very high egts because of the way retarded timing. I did experience this before I started from scratch on my map but I am thinking that it is my TPS. Look at the log and you can see that it is jumping around from 0 to 5deg and correlating with the timing jumps so I am lead to believe that the TPS is worn out and not reading correctly.

Also I was seeing similar jumps in timing at idle from 5 to 20deg when the base timing is 12 but the tps was steady at 0. What could possibly be making these things happen?
Attached Files
File Type: zip Weird Timing.zip (18.7 KB, 2 views)
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Old 05-22-2011, 05:48 PM   #45
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The PCV is a 1-way valve, when the manifold is pressurized it closes. It only passes air when the manifold is in vacuum, and this air comes from the turbo inlet. This is how the system is supposed to work, so nothing is wrong with it per-se, it's just that this way of running the PCV system no longer works as expected when you move the MAF to a blow-through configuration.
Yeah, I know that. For some reason I was thinking all plumbing was removed including the valve itself. Durrr..

Anyway, OP, did you try unplugging the 02 yet? If it runs better with it unplugged, then the 02 sensor is the issue.

I also looked at your logs and the timing is all over the place and your corrections were way high at idle. Don't really know if the TPS is causing that or not....
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Old 05-22-2011, 06:40 PM   #46
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I did try unplugging the O2 before but I just replaced it actually and it seems to be running better, not such wildly swinging AFRs but it didnt completely solve my problem. Agreed, the timing is very crazy but I do think that the TPS is to blame for that so I am trying to find my old TGV sensors to replace it but Im having trouble and dont want to buy a new one. Im thinking it should run better at cruise after that. But, what else is there for timing that would be making it spike and drop down like that? I dont understand it when the base timing at idle is stuck and 11.99 but total timing is all over the place. Can anyone shed some light into what corrections might be causing this? Thank you
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Old 05-23-2011, 11:59 AM   #47
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Im having this same exact problem. i dont know what it is either. im beginning to think its a sensor problem other than MAF and 02. TPS is a possibility and i was thinking possibly a faulty / intermittent cam sensor. you've never experienced a no start issue with it and then 20 mins later itll start right up?

not trying to jack your thread. but id like to help you out as well as have your help. More input the better.
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Old 05-23-2011, 03:09 PM   #48
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Agreed, thanks for the input. I replaced my O2 with no change and I think it is the TPS as well and I am going to replace that with hopefully good results. I checked my ground connections as well and that isnt a problem. I really want to figure this out its driving me crazy
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Old 05-24-2011, 06:31 AM   #49
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so i was able to find the problem yesterday. are you running an aftermarket fuel setup and (pump,rails,injectors)? because if you are, you may have the lines that go from the fuel pressure regulator and distribution block mixed up. i just had to switch 2 of hem around and bingo, no more problem.

make sure that the line on the nipple of the fuel regulator goes to the return side of the fuel system. lmk if u would like it drawn out for ya if it helps bro
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Old 05-24-2011, 12:48 PM   #50
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No I have the strock fuel setup and I understand how the fuel system works but thank you, lucky you figured out your problem
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