CEL, shudders at idle

[Crumpler]

Hey Guys.
I was hoping somebody could point me in the right direction here.

Symptoms are as in the title. On start up, I get a CEL and shudder at idle. It won't die just struggles not to. If you hit the throttle it will run fine.
I pulled OBD codes PO101 and PO170.

PCV system was done (by me) three years ago. I got those same codes and CEL when system was clogged -- but never this shudder at idle.

I have a boost gauge (ipd kit) in the cabin. Typical readings were 6-8 lb boost at WOT, and 20-25 vac at idle. Now vac is all over the place because of the erratic idle.

Does this sound like PCV symptoms again or do I need to go in a different direction?

Thanks, Dave.

[hu5ker555]

Did you pull the code(s)?
Have you tried cleaning the throttle plate?

[Crumpler]

Thanks for the time Hu5ker.
I have not pulled throttle yet but it's on the list. The only thing I did was pull and replace MAF... runs stronger but still hunts at idle, no shudder or CEL now.
I have heard that ETM faults would show up as separate warning lights? Would a gunked up throttle plate do some of this?
Don't leave me yet buddy!

The codes are airflow based I think maf, etc.

[Crumpler]

Hey Gentlemen.
Still banging away on this this, help appreciated.

Codes pulled off for CEL were PO170 (maf--fuel trim), and PO101(also air flow I believe).

I had replaced PCV system essentially 18-24 months ago. At that time the lower port of the black box was 75% blocked (and I had same CEL error codes BTW). PCV replacement fixed issues at that time.

After MAF replacement, as per previous post, the car runs stronger but will still hunt at idle, with big sweeps to zero vacuum.

I started pulling things apart:

Noted oil gunk at junction of throttle pipe connection (after cooler/radiator junction) and oil junk at turbo pipe connection going into cooler/radiator -- forgive me if names are wrong here.

I see those as potential vac leaks now, but didn't have the foresight to tighten them and check performance before I kept going.

I was more concerned about PCV again, creating overpressure. My concern was that my oil pan was full of sludge at the PCV vent.
I pulled off the oil pan, and it was indeed. Seals looked fine but the PCV port was mostly occluded. Having trouble cleaning out-- any tricks? I can't see much because of the baffles.

My plan was to clean pan, replace seals. Then replace PCV system again and clean throttle at same time.
Does that sound reasonable? Am I missing anything?
I use synthetic oil, why am I seeing so much oil gunk? Bigger problem chewing through oil or normal for this engine?

Thanks ahead of time.
Dave

[vtl]

Could be that oil gunk was there all the time. Since PCV can't drain separated oil to the sump, all oil goes to intake.

What oil do you use? Switch to a higher viscosity oil like Amsoil 0w40 or Red Line 5w30 (it has high viscosity for SAE30) and change it frequently (5-7k miles).

[Crumpler]

Thanks VTL, I was using a synthetic 5w30. I will look for those choices you mentioned this time.