Rough idle, help

[PlaneMech]

I need some help. I cant get my 87 TR to idle. I've looked at the usual culprits and Im stumped. Car has recently installed MSD 50's. Car ran fine for several weeks after new injector and chip combo. Car has very rough idle and stumble. At idle its running rich enough to throw code 44. Can't get IAC count below 65 to 70.

Readjusted IAC, Replaced IAC.
TPS set. FP set at 42. Tried 38 to 45 lbs no difference.
Swapped MAF.
Replaced PCV valve.
Unable to locate any vacuum leaks. Tried carb cleaner and propane.
Input appreciated.

John

 

[Russ Merritt]

Compression test, coil/module, 02 sensor, plugs, wires, check the EGR valve too.

 

[GN ERGY]

I was just helping a friend of mine to get his idle set on his GN. We set it to .42 volts and when he would shut it off and start it again it would idle different. So we checked the TPS again and it was at .48 so we set it again. A couple times. His GN kept ideling rough and finally irritated him enough that he took it to a GM dealership. They replaced the TPS and found a bad connection on the ECM. You could try those 2 ideas. Clean connection to the ECM first. Then maybe swap out the TPS.

By the way I'm no X pert at this, just passing along the info I learned.

Tarey D.

 

[PlaneMech]

Thanks

I swapped coil/module assy.
Plugs are good.
Wires good.
Compression good.
I removed the EGR valve when I installed my powerplate.

Keep ideas coming in

John

P.S. anyone in DFW area got a ECM I can try, my spare died at the track late last year.

 

[Russ Merritt]

Put a vaccum guage on it, see if it's steady. Does it go good WOT? No knock?

 

[PlaneMech]

I'll put a vacuum gauge on it I was going to do that today and forgot, must have been the gas fumes.

If you play with the IAC enough you can get it to where it runs off idle ok, minimum KR. But if its a little different the car stumbles and doesn't want to accelerate with boost.

Thanks,

John

 

[Russ Merritt]

The fuel press goes up with the boost right? (regulator prob) Possible camshaft Lets not jump to conclusions though. The vaccum guage will tell.

 

[PlaneMech]

Fuel pressure is coming up ok.

Let me go throw the vacuum gauge on now.

Be right back.

John

 

[Russ Merritt]

Plugged catalytic convertor praps

 

[PlaneMech]

Ok

This thing is pulling 16lbs of vacuum at idle.
Changed O2 sensor again, and re-checked plugs. Both look good.

Need more ideas guys and gals.

Thanks,

John

 

[PlaneMech]

Oh and I'm not running a cat.

John

 

[d0n_3d]

Originally posted by PlaneMech
I need some help. I cant get my 87 TR to idle. I've looked at the usual culprits and Im stumped. Car has recently installed MSD 50's. Car ran fine for several weeks after new injector and chip combo. Car has very rough idle and stumble. At idle its running rich enough to throw code 44. Can't get IAC count below 65 to 70.

Readjusted IAC, Replaced IAC.
TPS set. FP set at 42. Tried 38 to 45 lbs no difference.
Swapped MAF.
Replaced PCV valve.
Unable to locate any vacuum leaks. Tried carb cleaner and propane.
Input appreciated.

John

guess what...do a search on this board "code 44" you will see about 5 threads that i created...i have the SAME EXACT problem as you do...have had it for a year now and still can't find the problem...my car is sensing dead lean so the ecm is commanding my 50 lb injectors to DUMP fuel at idle and cruise...BLM number is pegged at 150 and integrator is always above 128...

my car will idle for 60 seconds in closed loop...then start idling like complete crap...go into open loop and ses light comes on...code 44...i push the gas pedal and it goes back into closed loop and ses light goes away...weird ass car

i can't find any vacuum leaks...i am checking continuity on all the ecm terminals and everything is checking out ok so far...i have gone through 3 different maf sensors...3 o2 sensors (running GNX sensor now)...new delco pcv valve...replaced cracked ds header...checked for exhaust leaks, checked for vacuum leaks...i am getting 20-22 of vacuum at idle which is plenty...brand new 50 lb injectors (had this same problem with my stock injectors)...tried all kinds of chips stock and now 50's...car really and i mean REALLY smells rich...i get horrible gas mileage...i am going to try and swap ecms to see if i have a bad ecm...otherwise i was told that my intake manifold gasket could be bad and leaking internally in the intake port valleys...

i will jump for joy one day if i ever solve this problem...i have lived with it for over a year now...i sprayed carb cleaner everywhere and idle did not change...this is a very technical problem and ANYTHING could be causing it...i hate it...

 

[Russ Merritt]

Plug up the PCV right at the vaccum block, just for a minute and see if your blms come down. It happened to me too and it was the check valve I was using instead of a PCV valve. It's getting air from somewhere that the MAF isn't reading. Your sure your exhaust is sealed? Heads/headers? Your coolant temp sensor is workin right? Vaccum block is sealed?

 

[d0n_3d]

i tried just the pcv valve like stock...same thing...used just the inline check valve...same thing...used both together....same thing...used NOTHING and plugged the line up...same thing...my problem is not pcv related

 

[TurboDave]

BLM's pegged high like that are usually indicitive of a couple of problems, and it's usually one or the other.

If you're sure the chip/ECM is OK, you only have a couple of other choices, and sometimes it can be a BEAR to track them down.

1. Pre Turbo Exhaust leak.
2. Vacuum leak.

 

[d0n_3d]

Originally posted by TurboDave
BLM's pegged high like that are usually indicitive of a couple of problems, and it's usually one or the other.

If you're sure the chip/ECM is OK, you only have a couple of other choices, and sometimes it can be a BEAR to track them down.

1. Pre Turbo Exhaust leak.
2. Vacuum leak.

well i DID have a major exhaust leak before...cracked ds header...but i replaced it with a new poston's unit and was still getting the code 44!!! i thought for sure that would solve the problem...

say i had an exhaust leak...wouldn't boost be affected? because i can boost it up as high as i want instantly...i have no loss of boost or anything performancewise...i really think it's a vacuum leak SOMEWHERE...i was told to have my car "smoke" tested...never even heard of that before...i guess it can pinpoint a vacuum leak...

 

[Russ Merritt]

You use a gasket on the header?

 

[PlaneMech]

Fixed

Ok,

All seems to be working now. I kept coming back to the MAF. It passed tap test and reading at idle were on the low side but withinn parameters. Now the one on the car and my spare were doing the same thing. Installed third MAF and problem cleared up. BLM's are good and car idles now.

Thanks,

John

 

[Russ Merritt]

I am SO glad I don't have a MAF anymore!

 

[d0n_3d]

i don't use a gasket on my header, no...

as for the maf sensor...i have tried this with a stock reman unit...a new tomco unit...and now my new ls1 maf sensor...got the same thing on all 3 sensors...my problem is not maf sensor related...

i also got this code before my driver side header cracked with no gasket on it...so i dunno...i sense i have a bad intake manifold gasket...