Intermittent Misfires p0301-p0304 at warm idle - Subaru WRX Forum
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#1 Old 07-19-2014, 01:50 AM
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Intermittent Misfires p0301-p0304 at warm idle

2004 Turbo WRX, axle back exhaust.

The car runs fairly well driving around. But, I keep encountering intermittent misfire CELs when idling. I am not getting any other codes. Sometimes, Iíll just get one code; other times Iíll get two to three cylinder codes.

Iíve done tons of web research and most other people have constant misfires. Again, I only get occasional misfires when the engine is warm, at idle, and in closed loop.

One of my freeze frames:
p0301
Closed Loop
Intake air temp: 123 degrees f
Air flow rate .52lb/min
Throttle position: 12%
Load value: 1.9%
Coolant Temp: 179 deg f
STFT 1.5%
LTFT: -8.6%
MAP: -15 in. HG
RPM: 710
Veh Speed: 0 mph
Ignition timing: 12.5 deg

HelpÖ.. any ideas or other links would be very, very much appreciated.

Thanks in advance
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#2 Old 07-28-2014, 12:23 AM
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Have you took a look at the plugs?

Sent from AutoGuide.com Free App

Adair
06' wrx tr
Phatbotti tuned!
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#3 Old 08-02-2014, 03:19 AM
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I will look at the plugs tomorrow morning.

I did do a ohm test on all coils and they all had very similar readings.

On numerous occasions within a month time frame, I noticed a small pool of oil at the throttle body where I cleaned it up each time without thinking. I thought it was caused by a stuck PCV. In addition, one time I was driving and the turbo started smoking. It appears it had oil on outside, but I haven't touched the turbo.

Could a bad turbo, leaking oil into the intake, cause my poor idle and misfire codes?

My throttle body looked very similar to forum post, just not as oily. But, there is a pool right in front of the throttle butterflys.

Oil around intercooler and turbo tubes
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#4 Old 08-02-2014, 03:23 AM
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What is a good way to determine if the turbo is leaking? I'm guessing seeing oil in the throttle body is enough. Right?

Does this mean a new turbo or a turbo rebuild?
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#5 Old 08-04-2014, 07:53 AM
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is your knock sensor going crazy? oil in the throttle body could be normal. turbo charged cars tend to suck some oil through through the pcv system and and oil catch can can remedy that problem. You could have cracked or seized piston rings, which can cause a misfire and excess oil in the intake as well. remove the down pipe and look at the turbine wheel and see if its oily and/or has any play to it. if not the the turbo is most likely ok and the problem is elsewhere. i just had to put 2 pistons and ring in my wrx because of a low idle misfire, and the car was picking up some bad knock so i'd check that out first
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#6 Old 08-10-2014, 09:33 AM
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Ok. I just did a compression test and all are within spec. I'm assuming a cracked piston would fail that miserably.

Good idea about checking turbo. I should have thought of that.
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#7 Old 08-10-2014, 11:11 AM
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^Not always. There are cases where people have cracked ringlands and their compression numbers come back okay. Do a leak down test as well.
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#8 Old 08-11-2014, 03:09 PM
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good compression test is a good sign, but a leak down test is needed. mine built good compression but would not hold very long
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#9 Old 08-16-2014, 01:21 AM
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Thanks for your input. My son's WRX has humbled me quite a bit.

I think it is all ironed out. Let's cross our fingers. Here's what I have done to date.

First off, all the parts you see below were replaced after failing some sort of test. I didn't want to throw parts at it in hopes it would just start working.

1. I changed a ton of vacuum hoses and clamps. They were either cracked or broke while testing or working on/testing other parts/components.
2. Changed Purge Control Valve. Sticking
3. Changed Fuel Pressure Regulator. Failed vacuum leak down test and was seeing negative LTFT at idle
4. Changed IAC; idled too low and/or too high. Looking at duty cycle and smacking it; confirmed it was sticking
5. Changed MAF since used car dealer put on a Toyota one
6. New Factory plugs; old ones had too large a gap
7. Seafoamed intake
8. Seafoamed gas additive
9. Smoke tested and propane tested intake for leaks; none found
10. Tested coils; ohm checked and used amp probe to verify spark discharge pattern
11. Compression test - physical and relative compression; within specs. Did not do leak down, probably should have.
12. Tested charging system and battery
13. Cleaned and applied dielectric on F60 connector
14 Cleaned nearly all grounds in engine bay
15. Didn't verify injector electronic discharge pattern, but instead used a stethoscope to ensure each one was working. After all of the above tests and looking at STFT and LTFT, I didn't think there were any issues with fuel delivery any longer. Mistake?

So far, the car is running pretty good and throwing no CELs (~75 miles of highway and stop and go driving); I believe it has executed all OBDII tests (will verify that tomorrow).

But, to me, it still has too low of vacuum (16 inHg) at idle. But, I can't figure out why....
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