P0012 + Dieseling + Short Terms

Problem: Car starts fine, idles fine, but when I accelerate in gear or standing still and hit 1300-1500 rpm car starts running rough, as well as engine sounds like it's dieseling on the passenger side. Also, my wideband AFR gauge goes into the 16-17's, car throws a P0012 code, and the Short Term Fuel Trims go into the .700's on the passenger side, while the drivers side says 1.002's.

Now, this doesn't start happening until the car reaches at least 150*. I did some troubleshooting without solving the problem, and went into full scale and detailed troubleshooting mode:

1. Reloaded tune - no change
2. Went back to stock tune, then reloaded tune - no change
3. Loaded my e85 tune - no change
4. Emptied all fuel out of car, and refilled with 93 octane - no change
5. Swapped drivers side (DS) phaser to passenger side (PS) - no change
6. Swapped DS VCT solenoid to (PS) - no change
7. Installed completely different phaser to passenger side - no change
8. Changed to another stock cam I've got - no change (journals looked good)
9. Moved DS injectors to PS - no change
10. Replaced spark plugs with new ones - no change
11. Moved COPs from DS to PS - no change
12. Replaced 02 sensor - no change (02 sensors at idle are changing and are within .005 or each other)
13. Replaced knock sensor - no change
14. Troubleshot wiring circuits for PS cam sensor, PS VCT solenoid, DS cam sensor, DS VCT solenoid - no faults found. All circuits have continuity and no shorts to ground or other wires in bundle.
15. Troubleshot crankshaft position sensor circuit - no faults found
16. Replaced crankshaft position sensor - no change
17. Installed completely different VCT solenoid - no change
18. Replaced complete PS head - no change
19. Changed oil pump - no change (did this one last night)
20. While changing oil pump, I also changed the tensioners and cam chains - no change.
21. Disconnected PS and DS VCT solenoids - no change
22. Disconnected PS solenoid - **change**, but not fix. Instead of going into diesel mode between 1300-1500 rpm, it moved to 2000-2300 rpm.
23. If I rev the car while dieseling and everything connected, the roughness goes away around 3200 rpm and car sounds great. Once I let off the gas and the rpms decrease to 1800-1900, the dieseling comes back.

Note: When I changed oil pump, I also pulled the pickup tube and found debris in there which looked like the slinger destroyed itself. I've got no leaks anywhere in car. Cause?

I've done everything I can think of and need some thoughts, guidance, or paths to repair. Help?

Your wideband is in the passenger side? The ecu is trying to add fuel via the stft and it still stays lean but only for a specific rpm range. Is that correct? The passenger side is the last side to get fuel. Could there be a physical blockage in the crossover or passenger side fuel rail? Maybe something that acts as a valve depending on the fuel flow? I'm also thinking a torn or malformed intake manifold gasket or leaky cmdp delete plate.

I had a problem once that ended up being a torn fuel injector oring. It would only show up at certain times due to the varying pressures in the manifold. I'm not suggesting that's your issue but it sounds like you have covered everything and it's time to start digging.

The debris in the pickup is most likely rtv. The excess squeeze out from installing the oil pan and valve covers can get cycled through the motor and end up in the pickup tube. It's happened to me anyway. The slinger is located outside of the motor so that's not it.

compression test?

RocketcarX said:

compression test?

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165 +/- 2psi on all cylinders.

BruceH said:

Your wideband is in the passenger side? The ecu is trying to add fuel via the stft and it still stays lean but only for a specific rpm range. Is that correct? The passenger side is the last side to get fuel. Could there be a physical blockage in the crossover or passenger side fuel rail? Maybe something that acts as a valve depending on the fuel flow? I'm also thinking a torn or malformed intake manifold gasket or leaky cmdp delete plate.

I had a problem once that ended up being a torn fuel injector oring. It would only show up at certain times due to the varying pressures in the manifold. I'm not suggesting that's your issue but it sounds like you have covered everything and it's time to start digging.

The debris in the pickup is most likely rtv. The excess squeeze out from installing the oil pan and valve covers can get cycled through the motor and end up in the pickup tube. It's happened to me anyway. The slinger is located outside of the motor so that's not it.

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All very good items to check and make sense and I'll do them tomorrow.

Anyone else have any ideas?

ECU issue possibly?

verified oil pressure with actual gauge?
vct locked or limited?
what valve springs? too much seat pressure with vct active will cause chain slap.
log cam position for both sides see what its doing.
zero out vct 3k and below and see what happens.

deebo05 said:

verified oil pressure with actual gauge?
vct locked or limited?
what valve springs? too much seat pressure with vct active will cause chain slap.
log cam position for both sides see what its doing.
zero out vct 3k and below and see what happens.

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oil pressure - 25psi at idle with a mechanical gauge. Besides, I replaced the pump with a completely new one from the box. At least I know it wasn't my MMR pump...

valve springs - comp cam replacements. When I installed the completely different head, I had a valve job done, springs moved from old head. Had engine builder check the spring pressure of all 12 springs, all good.

log cam position - can't. My tuner locked out all but about 12 data logging functions. a**shole tuner.

zero out VCT 3k - ??? explain

Thanks - Mike

your tuner can zero out vct in the tune under 3k to help diagnose a vct issue.
had the same thing happen to my car with 26125 comp springs. when the motor warmed up at low rpm and loading the motor the chains would slap on the passenger side first. zeroed the vct at low rpm noise stopped. I had to lock them out or change springs. It was caused by 120lb seat pressure and looser than stock bearing clearances. its just a thought to help diagnose, if your tuner is cool it wont cost anything to try.

Appreciate it brother. I'm going to try the things that BruceH mentioned on Sunday and if they don't work, I'll have my tuner lock the VCT's.

Thanks!

Do you still have cats? Not sure how the Hellion turbo kit is done.

05moneypit said:

Do you still have cats? Not sure how the Hellion turbo kit is done.

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No cats. When I ditched the Hellion Hot Side, but kept the cold side, the cats went with the change to the Zimmer Hot Side.

Update:

Replaced upper intake and TB since its attached - no change
Replaced all gaskets on both the CMDP and the intake to heads - no change
Replaced all fuel injector o-rings - no change

As always, the car exhibits none of the dieseling during startup and until it reaches about 130-150* and 1500rpm. As well as stopping the dieseling when I reach 2800 rpm.

I'm then able to rev the engine trough the entire upper tier powerband without problems.

Today, I slowly dropped the RPM and the dieseling began creeping in at 2600 rpm and continued to idle rpms. If I shut off the engine and immediately start it, idles perfectly until I tap the throttle.

Going crazy.

I saw this a day ago... 3v 5.4 truck... All tsb's had been done and redone... Cam journals were wiped out... Debris from aftermarket oil filter... I hope that isn't the problem

porkipine said:

I saw this a day ago... 3v 5.4 truck... All tsb's had been done and redone... Cam journals were wiped out... Debris from aftermarket oil filter... I hope that isn't the problem

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I'll pull the cam off and re-inspect the journals.

If there's some additional scoring, does anyone know of a fix for the head? Or a replacement is only option?

michael.konor said:

I'll pull the cam off and re-inspect the journals.

If there's some additional scoring, does anyone know of a fix for the head? Or a replacement is only option?

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You could have the caps cut and reamed like a connecting rod. It would be a good excuse to get cnc heads too.

BruceH said:

You could have the caps cut and reamed like a connecting rod. It would be a good excuse to get cnc heads too.

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Got a set for sale...??? Just in case.

michael.konor said:

Got a set for sale...??? Just in case.

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I have a set of stock heads from a 2009 GT. I just put them on my old block a few days ago.

There is a set in the classifieds for $450 plus shipping.

Can you define dieseling? I am not sure I understand what that means?

RLF9409 said:

Can you define dieseling? I am not sure I understand what that means?

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You know how when you raise the hood of a diesel engine it has that distinctive sound versus a gasoline engine? That's dieseling in a gasoline engine that's exhibiting the problems I've described.

This is unlike the "dieseling" condition in 1970-1990 cars where you turned off the key, and the car kept running.