Running out of ideas

scojack_2001

Livin' Like A Refugee
I've been chasing a rough idle/stumbling issue for the last week... Car runs 100% perfect until it gets good and warm. Then the gremlins come out. It's loading up on fuel, bucking, surging, the whole nine yards.

Here is what I know for fact.

It's not ignition, at least if it is I haven't found it yet. I swapped out the coilpack/module with a known good unit off a 11.0 car and no change. The coilpack has a extra ground to the intake manifold.

Swapped in a MAF from the same car and still no change. More on that later.

Changed the spark plugs to fresh R43TS's gapped at .032". Fresh MSD wires and a fresh Denso oxygen sensor. The old 02 was carboned up pretty good. As were plugs 1-4, numbers 5 & 6 were a little cleaner.

Cam sensor cap is in good shape and not cracked or damaged in any way. Screw is tight and very little play. Timing chain seems tight as well.

Fuel pressure is set at 42psi line off and the TT chip is on the base settings. All the MSD50's ohm out to 12.1 to 12.4 so I don't think that is a problem.

Coolant temperature stays at a constant 170° - 175°. Nothing crazy there. Stat fully opens around 185° and it comes right back down.

Grounds on the back of the head feel intact and the bolt is tight (not that I could see a damn thing back there anyway). Negative battery cable is good and tight.

Watched the MAF counts last night on the test drive and they were all over the place. Anywhere from 255 to 5. And this IS NOT beating on the car. It didn't see more than 3000rpms last night. Just steady cruising.

The MAF counts don't make any sense to me; because the other one didn't help at all. And if I unplug it, it just runs worse anyway...

I'm almost out of ideas here guys. I'll check the PowerLogger board to see if maybe it is coming loose, but I doubt it since something like that would be almost constant.

I'm gonna try and see if a original MAF helps, and if not I guess I gotta start going into the wiring....

Could really use some help here boys! I'd appreciate it.

Scott
 

aminga

Chicks Dig the powerbulge
Original MAF or Translator?????

At constant throttle and boost (or lack thereof) are you saying the AF varies from 5 - 255
 

scojack_2001

Livin' Like A Refugee
Original MAF or Translator?????

At constant throttle and boost (or lack thereof) are you saying the AF varies from 5 - 255

Reman stock MAF. Been on the car for several years now.

And yes, just light/part throttle once warmed the MAF count is all over the map.
 

TurboBob

Resident mad scientist
Staff member
post a PL logfile.

The MAF gets its ground from one of the ground lugs on the back of the engine. Both power and ground for the MAF have factory splices in the harness. The MAF connector pins can lose tension from heat and age. The ground wires at the back of the head can corrode up inside their insulation. its worth taking them off the back of the head and moving them to the rearmost intake manifold bolt. when doing so you can yank/pull on them to make sure the wires are intact.


Since the MAF data is the glaring issue in the data, we should start there. Measure resistance from the MAF ground wire to the engine. Measure voltage with the engine running.

and try another MAF....

Bob
 

usetaboost

SAY CAR RAMROD!!
See if you have a voltage reference at the maf plug also. I wonder if a blown ecm fuse could cause this but I'm sure those have already been checked. Go through the maf circuits I'm sure you'll find the problem.
 

mikes gn

Member
i'll be watching this thread real close as that's my car to the t. except it's been 6 years ..where is the ecm fuse i never checked mine.
 

scojack_2001

Livin' Like A Refugee
Put another reman MAF it just to try it and it runs perfect! Gonna go shopping for a Translator and LT1 MAF in the morning.

Thanks for all the help guys.
 

turb

Member
Sounds like you looked at your cam sensor but didn't test it.
Easiest test there is:
Start car and then disconnect the cam sensor. Drive it and see if there's improvement. You must reconnect before starting again.
If it still runs crappy with Cam Sensor disconnected at least you'll know the problem is elsewhere.
Good luck.​
 
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