05 WRX Idle Problems from MAF or O2 sensor?

[WRX-17]

Hi guys,

I have 48k on my 05 WRX and been trying to figure out this idling issue that I have been having for a while. I have been trying to read about others issues as well but not getting anywhere. The idle seems to be constantly searching up and down staying around 1000rpm but going up to 1500 and down to 500 sometimes. My thoughts at this point are either my MAF sensor is bad or my O2 sensor is bad. I am leaning more towards the O2 sensor since I was running a pig rich tune for a long time. I am not sure but it could be related to another problem I had and still have but to a lesser degree which was bad hesitation while cruising which Im thinking could be going in and out of closed loop frequently thanks to a bad O2 sensor.

I have read about testing my O2 sensor voltages and resistance through the heater and I didn't come up with desirable numbers although I am not completely confident in. I also unplugged the MAF sensor while the car was running and not much happened, the idle raised slightly but still ran fine but when plugging it back in it almost stalled then came back to life with a lower RPM. I can attach a log of idle and one of cruising too if someone wants to take a look. Im not sure what is really going on but if anyone has some advice from me from a similar situation, advice on resting things or anything in general I would really really appreciate it!! Thank you

Applicable Mods:
Running E85
DW850
TGV deletes
Perrin Blow-Thru MAF boost tube
Ported Intake and Exhaust manifolds
Innovate LC-1

Things I've tried:
Replaced Spark Plugs: No change
Cleaned MAF: No change, unplugging MAF showed no result of being bad
Tried Friend's Good MAF: No change
Disassembled and fully cleaned IACV: No change
MAF Scaling: No change
Messed with injector latencies: No change
Replaced Front O2 Sensor: Runs better but not change
Replaced TPS: No change
Replaced ECU: No change
Checked TPS voltages and ground: Voltages in range and ground is good
Searched for Vacuum leaks post MAF: None found with carb cleaner or spraying water
Unplugged each injector to see if one didn't make a change in the idle: No result
Cleaned all connections of coil packs, TPS, IACV and MAF with electrical cleaner and applied dielectric grease to ensure good contacts: No change
Pressure tested: No change, found a crack in my blow thru tube but before the MAF
Checked for exhaust leak: None found
Checked cam gear alignment: On target, doesn't look to have skipped a tooth
Parallel Fuel Rail Mod: No change
Replace injector O-rings and grommets: No change
Replace Injectors: Put some stock injectors back in so that I am sure of the scaling and latencies in order to correctly scale the MAF, No change
Crank or Cam sensor: Ruled out crank sensor and cam sensor, no result
Rear O2 Sensor: Shouldnt affect much on my 16bit ECU but unplugging it did nothing and voltages seem fine


Next to try/other possibilities:
Fuel pump controller - doubtful
?????????

And here is a quick video to show you what the idle looks like

And here is a quick video to show you what the idle looks like

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[jaxscuby]

first clean maf

[quazimoto]

My bet would be the E85 with TGV deletes or the IAC valve. Sure post a log and a Learning View screen shot.

[WRX-17]

I should have mentioned that I have cleaned the MAF too with maf sensor cleaner and i am using a foam uni filter but it is not heavily oiled. I should also mention that I recently switched to E85 but the idle was the same or worse on 91oct so E85 didnt change anything in that regard. Here's a Learning View, Idle and Cruise log.

[NvrenuffWRX]

I noticed in his idle log that the throttle opening angle is changing and I know he is not touching the gas pedal. What could be causing this? I come from the Evo tuning world, but my throttle opening angle logs are a constant "zero" at idle. I assume WRX's have an "IACV" idle air control valve. when the IACV opens would that be reflected in the "throttle opening angle" log column by non-zero values?

Also, I noticed that his LC-1 wideband reading does not line up very well at all with the factory O2 sensors AFR reading... could be a bad factory O2 sensor. O2 sensors dont like to be run rich, which he has been for a few years.

The MAF sensor readings looked fine to me, especially since its blow through config. with an erratic idle... but i'm no expert.

Lets get some experts to chime in on this

[NvrenuffWRX]

I did some searching and your problem could be the IACV. Its worth a shot to buy a new gasket and clean the idle air control valve and see if that fixes it... cheap and simple to do.

Here is a great thread.
http://forums.nasioc.com/forums/showthread.php?t=781242

[WRX-17]

Yeah I have done that before, it wont hurt to do it again just to rule that out.

And that is one of my biggest questions as well, what is making the throttle open at idle like that? The way I have been looking at this seems like such a chicken and the egg cause and effect situation. I just cant narrow it down to what is causing the idle to raise and lower, throttle opening, timing to jump, AFRs to swing, etc.

I have done injector and MAF scaling as well and they are right on the money. At idle the corrections are less than +/- 1%

[quazimoto]

Maybe its the cruise control cable. Think there was a recall on it. Loosen it up a tad on the throttlebody.

[WRX-17]

Thank you, but I dont have the cruise control on my car so no dice

[the suicidal eggroll]

Unplug the o2 sensor and see how it behaves (having a wideband would help), that will eliminate a bad o2 as the culprit
Unplug the MAF sensor and see how it behaves, that will eliminate the MAF sensor, MAF scaling or vacuum leaks as the culprit

Could be the IACV too

[WRX-17]

Thanks for the tips eggroll, I was hoping you might be able to chime in...I have tried unplugging the MAF before like I mentioned but I took a video of what happens when I unplug it and plug it back in. It almost stalled everytime I unplugged and plugged in the MAF. Btw that whistle is just the BOV but thats way before the MAF and I have tried putting in a bigger spring and pinching the line with no change:

YouTube - 05 WRX Idle unplugging MAF

YouTube - 05 WRX Idle unplugging MAF

Unplugging the O2 sensor will just throw it into OL, right? So what will that show? I tried it and it made no noticeable change to the idle it was still searching up and down. I am going to reclean the IACV when the new gasket comes in to rule that out. Thank you!

[the suicidal eggroll]

Originally Posted by WRX-17

Unplugging the O2 sensor will just throw it into OL, right? So what will that show? I tried it and it made no noticeable change to the idle it was still searching up and down. I am going to reclean the IACV when the new gasket comes in to rule that out. Thank you!

It rules out your o2 sensor and any pre-o2 exhaust leaks. If the hunting continues when your MAF is unplugged, that also rules out your MAF sensor and any air leaks, which really only leaves your IACV.

[WRX-17]

So I cleaned the IACV and it needed it but it did not fix my idle problem. Now whats next, anyone please I could really use some help with this one!

[SVT_WRX]

Two things,

Try a different MAF
Try a different IACV

Did you do a boost leak test?

What is the position of your MAF?

Who did your injector latency? (not scaler)

Post a picture of your entire intake setup

[WRX-17]

Trying a different MAF and IACV isnt that easy as I need someone willing to help me out which I dont know of. No I havent done a boost leak test but have never had any symptoms or a leak under boost and how would that affect idle and cruise when I found no leak after the MAF. I have a Perrin blow thru boost tube and a uni filter on my rotated turbo.

I did my injector latency which im currently trying to redo in the hope that is my problem, Ive tried many different latencys that others have suggested but it hasnt helped much so Im trying to get them settled in but im having trouble

[the suicidal eggroll]

I didn't notice you were running blow through before. You did plug the line between the manifold and the PCV when you went to blow through right?

[WRX-17]

Can you be a little more specific as to what you mean?

[SVT_WRX]

Originally Posted by WRX-17

Trying a different MAF and IACV isnt that easy as I need someone willing to help me out which I dont know of. No I havent done a boost leak test but have never had any symptoms or a leak under boost and how would that affect idle and cruise when I found no leak after the MAF. I have a Perrin blow thru boost tube and a uni filter on my rotated turbo.

I did my injector latency which im currently trying to redo in the hope that is my problem, Ive tried many different latencys that others have suggested but it hasnt helped much so Im trying to get them settled in but im having trouble

What are your corrections doing at idle? Not learning, the corrections. Log them and post them up.

You didn't answer my question about the postion of the MAF or post a picture of your setup. Please Do.

If you look at your PCV valve on your intake manifold, there is a hose coming from that.

Get a boost leak test done or check for vacuum leaks with propane.

BTW, when did this start happening? It might help if you tell us when the issue began.

[SVT_WRX]

I just noticed your IAM is 8 in your learning view. You were probably knocking pretty bad at some point...

I'm thinking your issue may be mechanical...first item being the one I think it may be...

Faulty IACV
Faulty MAF
Faulty front 02 sensor
Faulty Injector

Or, you have a really bad vacuum leak somewhere. I highly recommend that you triple check for leaks using a boost leak tester...

BTW, how do you know you have had no leaks under boost?

[Black94Snake]

Idle surging like that is pretty common when tuning Fords EEC-IV (it all i have to work from... so give me a break)

Its usually from the car running too rich at idle. You say you have an LC-1... Whats your WBO2 reading at idle?

[the suicidal eggroll]

Originally Posted by WRX-17

Can you be a little more specific as to what you mean?

There's a small line that runs between the crankcase and the manifold. In a stock setup, when the manifold is in vacuum it draws air from the turbo inlet, through the heads, through the crankcase, through this line, directly into the manifold. On the stock setup this is fine because all of the air in the turbo inlet has been read by the MAF, it doesn't matter if it goes through the turbo, I/C, throttle body and into the manifold, or through the heads, crankcase, PCV, and into the manifold.

When you switch to blow through, the air in the turbo inlet has not been read by the MAF. Any air that's drawn through the heads, crankcase, and PCV into the manifold has not been read by the MAF, and will cause an inconsistent lean condition, fluctuating idle, etc. When you go to blow through you MUST block off this line between the crankcase and manifold.

http://perrinperformance.com/shared/.../pspeng410.pdf

#5 in the instructions

[WRX-17]

Yes my IAM was 8 because I reflashed it and only did some light driving so it didnt have a chance to go raise it up and no im not knocking.

I have had this problem for a long time, I tried figuring it out a long time ago and never got anywhere with it. I have been one of the first ones running this perrin blow thru and I am fairly certain that nothing was said about the pcv valve being plugged so I never did. Its apparent now that this is the source of my vacuum leak and makes sense. It is definitely idling smoother and richer because of it. My other problem is my injector latencies have been off, and messing with them has helped a lot too so I am pretty sure the root of my problems have stemmed from both of these as I even tried reverting to previous latencies and the problem was still there but to a lesser degree after plugging the pcv. I am still suspecting that the o2 sensor could be bad.

So I need to do a little more tuning figuring out the best latencies and redo my MAF scaling. Any advice on the DW850 latencies?

Thanks so much guys for thinking outside the box here for me, I cant tell you how much I appreciate it! and SVT Ill post up those things when I can thanks again

[SVT_WRX]

What are your latencies now?

When was the last time you changed your front 02? If it's been a while, it might be a good idea to replace it.

Look at your trims (corrections) while you are at idle. If they are +, you need to increase latencies. If they are -, you need to lower them. If you are pretty close to +-5 and you are still having issues, it could be that your front 02 needs to be replaced or the MAF.

Old front 02 sensors and old MAF's can wreck havoc when you are tuning. Sound's like we're getting you close to resolving your long time issue. Feels good, don't it?

BTW, you would have found that leak right away if you did a boost leak test...

[Aspenwhite25]

Shocking how no one as mentioned throttle postition sensor ,

it sends the signal to the ecu to control your iacv , if its outta wack your idle will fluctuate because its telling the ecu to do it , in your case idle fluctuates and the common fail spot for a potentiometer circuit is at the start of its travel as it moves from a thin spot to a thicker spot on the board..

on the ford EEc-Iv ecu the problem turned out to be either a ground issue or the salt and pepper shaker wire harness connectors on the main engine harness , mid year 1993 they added a 6" extension to the harness to keep the plugs from pulling apart and losing contact

[WRX-17]

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, but I would like to not spend the $150 on it if I dont need to and wanted to try to test it first. Yes it feels great to finally be getting close and have my car idle properly again!! Haha yeah you are right, I should have done the boost leak test do you have suggests of an inexpensive tester?

I was using the stock latencies for a while and they are not good for me. Ive tried DW suggested latencies but the ones that seem the best so far or at least start are 4.40/2.36/1.55/1.07/0.60