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Old 05-10-2017, 03:02 PM   #1
RedBullIndiana
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Default High, jumpy idle issue 2002 WRX. Please help.

ISSUE:
-idling in place, rpm sits just under 2k, sometimes drops but comes right back up to just under 2k.
-When I am coasting over 10 mph to a red light the rpm goes from 1k to 2k until I stop, and acts like described above.
-1st gear takeoff feels misfirey and very jerky after 5k, all other gears are fine.
-idles at -13in/Hg, and my VF39 is boosting up to 19psi.

WHAT IVE TRIED:
-boost leak test resulted in not much. Only leaking from line on top of COBB bpv when slightly over 20 psi. I couldn't get the system to maintain pressure for more than a few seconds, not sure if thats normal.

-Cleaning MAF, didnt do ****

-Seafoam, didnt do ****

-checked throttle cable and Cruise control line, seems fine

-IAVC and MAF replace last year I doubt thats the issue


Now what? any advice? I'm stumped so far. thanks
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Old 05-10-2017, 03:15 PM   #2
Samurai Jack
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Dump the COBB BPV and put in an OEM one
Check for vacuum leaks
Consider replacing coils
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Old 05-11-2017, 07:12 AM   #3
CGMTurboBoxer
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Quote:
Originally Posted by Samurai Jack View Post
Dump the COBB BPV and put in an OEM one
Check for vacuum leaks
Consider replacing coils
While the BPV likely isn't causing the issue you're describing, I still agree with this. I've also had a grounding issue, but that doesn't usually present itself as an erratic or high idle.

WHen the gas mixture changed over, I was having some strange idling issue for about a week. IT seems to have subsided since.
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Old 05-11-2017, 05:25 PM   #4
RedBullIndiana
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Isnt checking for vacuum leaks the same as checking for boost leaks? I tested to no avail. if -13 in/Hg is normal at idle then I think im good

Coils (from my experience) would seem to hesitate at hign rpms and not low, non load rpms. My car is doing the opposite.
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Old 05-12-2017, 08:53 AM   #5
svynx
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A high idle can be caused by a few things. First, disconnect the cruise control cable, or at least loosen it as far as it can go. This was my problem with a high idle. As the control box warmed up, it pulled a little on the cable, which in turn did not allow the throttle plate to close all the way. The ECU did what it could, but it wasn't enough. Another cause is unmetered air entering the system aka vacuum leak. I've also seen bad grounds cause random issues, although it's highly doubtful this would be your cause. Clean the maf again, just to be sure. Throw the stock bpv on, again, to be sure. Check your plugs for the misfire issue.
Was this tuned? Can you datalog?
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Old 05-12-2017, 09:05 AM   #6
86Dreams
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Do you have some way to log data from the car?
if you do then log AF Correction 1, AF Learning 1, AF Sensor 1 Ratio, MAF, RPM, Throttle position.
When is the last time you Cleaned your MAF? Even if you replaced it a year ago cleaning should be part of a regular maintenance routine.
When is the last time you changed your spark plugs(most likely unrelated)
Last time fuel filter was replaced?
Have you cleaned your throttle body?
Have you checked fuel pressure ?
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Old 05-12-2017, 09:43 AM   #7
RedBullIndiana
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Quote:
Originally Posted by 86Dreams View Post
Do you have some way to log data from the car?
if you do then log AF Correction 1, AF Learning 1, AF Sensor 1 Ratio, MAF, RPM, Throttle position.
When is the last time you Cleaned your MAF? Even if you replaced it a year ago cleaning should be part of a regular maintenance routine.
When is the last time you changed your spark plugs(most likely unrelated)
Last time fuel filter was replaced?
Have you cleaned your throttle body?
Have you checked fuel pressure ?
I cleaned my MAF and IACV yesterday. Been a while for fuel filter, but I dont suspect that to be the issue. Plugs are two months old. Heres pics of datalog. Pic was taken at idle. It logged about 30 seconds each with a blip of throttle.




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Old 05-12-2017, 11:40 AM   #8
86Dreams
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pics dont really cut it. a log will show these values and transitions over many different engine operating states. add in coolant temperature as well if you do log.

Fuel filter maintenance interval is about 30k miles. It will act like a vacuum leak as it ages, restricting fuel delivery.


Take a picture of Dynamic Advance Multiplier though, that wont change wiht engine state.
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Old 05-12-2017, 12:10 PM   #9
RedBullIndiana
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Quote:
Originally Posted by 86Dreams View Post
pics dont really cut it. a log will show these values and transitions over many different engine operating states. add in coolant temperature as well if you do log.

Fuel filter maintenance interval is about 30k miles. It will act like a vacuum leak as it ages, restricting fuel delivery.


Take a picture of Dynamic Advance Multiplier though, that wont change wiht engine state.
Okay ill log and upload logs later today, thanks
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Old 05-12-2017, 01:10 PM   #10
RedBullIndiana
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https://drive.google.com/file/d/0B2i...ew?usp=sharing

Hope this is sufficient. What can you see from this and how?
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Old 05-12-2017, 04:40 PM   #11
86Dreams
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Well something isnt right. Were you Idling at the Very beginning of the log? Or was the motor off?

At the very end are you coasting in gear?

Additionally DAM is 15 so the car has seen some minor knock. Out of curiosity, What tune are you running?
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Old 05-13-2017, 09:00 PM   #12
RedBullIndiana
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Quote:
Originally Posted by 86Dreams View Post
Well something isnt right. Were you Idling at the Very beginning of the log? Or was the motor off?

At the very end are you coasting in gear?

Additionally DAM is 15 so the car has seen some minor knock. Out of curiosity, What tune are you running?
At the very beginning, yes, I was idling. Also, I was coasting towards the end, with either clutch in or neutral.

I am running a protune, e85, vf39 at 335hp.
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Old 05-13-2017, 09:04 PM   #13
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Additionally, I did some heavy off roading 4 weeks ago. Lots of water and mud all over. 2 weeks ago this issue randomly started.
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Old 05-14-2017, 12:51 AM   #14
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Quote:
Originally Posted by RedBullIndiana View Post
Additionally, I did some heavy off roading 4 weeks ago. Lots of water and mud all over. 2 weeks ago this issue randomly started.
Look at the first few lines of the log. If you're idling or coaching in neutral the front o2 sensor should NOT read 22+. 22+ corresponds to zero fuel, which you would see if you were costing in gear.

Maybe you broke you're front o2 sensor? Idk. It looks like it's not reading right at idle...

Also have you checked for exhaust leaks? In theory of you had a really bad leak it could suck in air ahead of the front o2 sensor and cause a false lean reading.
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Old 05-14-2017, 11:03 AM   #15
RedBullIndiana
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Hmm that could be a possibility. Do you think a cracked up pipe could be a possibile factor? Mine is welded solid without flex pipe, maybe it cracked...need to check
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Old 05-14-2017, 07:49 PM   #16
RedBullIndiana
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So up pipe, and exhaust look perfectly fine. At idle the AFR is reading 22+ and my AEM gauge (bunged in down pipe right bedind turbo) reads tge same, so I assume o2 sensors are functioning properly.
And no CELs
Man, this is not making sense to me.
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Old 05-15-2017, 10:03 AM   #17
86Dreams
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Did you check the manifold and collectors? I would check that. if BOTH O2 sensors are reading the same condition independantly then its likely not the front O2.

Ive never had this happen to me so I am not sure what you should do. If it were me, I would remove any heat shields that may be in the front exhaust stream. I would then try soapy water on header and collectors. If this did not produce results then I would try blocking the tail pipe to see if exhaust is forced out anywhere.

If there really were 0 fueling being supplied the car would not say running.

For Reference.

Last edited by 86Dreams; 05-15-2017 at 10:29 AM.
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Old 05-15-2017, 01:49 PM   #18
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You should do a try to reset the ECU. I had a Forester which was idling too low and was dying. So it's the opposite of your problem but it might help. This the way I did it. I waited for the car to cool down all the way. Then I unplug the negative terminal then pump the brakes a couple of times. Then turn off all the electronics and I mean all of them. No radio, fans, headlights, so on, so on. Then replug the battery but don't touch anything in the car. Let it get to operating tempature and wait for the cooling fans to turn on. Then take it out for a couple of drives. I don't know if this will help you but I think it is worth a try. But my only concern with this method is I don't know if it will affect your tune in the car. So becarful if you do this. Good luck
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Old 05-15-2017, 03:34 PM   #19
RedBullIndiana
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Consulted my tuner with more datalogging and he pointed toward a vac leak in the intake manifold. So I'm going to search how I can vac test that at home, and hopefully its something minor where I don't have to take the whole thing off
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Old 05-16-2017, 12:29 PM   #20
BoxedRex
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Just in case you didn't figure it out yet. You can use carb cleaner and spray where the intake manifold gasket is. Just spray around and if there is a leak the car will change in RPMs. You can also use a water bottle with a small hole on the cap.
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