car won't idle when warm

[buickpower]

My car starts and idles so-so, but as soon as it hits closed loop, it starts to hunt for idle, stumbles and dies. I went through with my mityvac today and checked all of the lines, which are new and there didn't seem to be any leaks. The car also seems to have a slight miss that mostly goes away as i rev it up, but once it gets warm i have to keep revving it to keep it running. The PCV valve is the correct delco part number. I was thinking maybe the maf? since it is a napa reman. unit with the stupid bottleneck design (I can't afford an oem one just yet). The car won't start or run with the maf unplugged. The ECM is one i got from a board member who tests them before selling them. Does the MAF sound like a possible culprit, or maybe ignition module? Any ideas would be greatly appreciated.

 

[TURBOTIMMER]

Unhook your egr. Mine did the same thing. Mine also had a dead spot at low rpm cruise. I unhooked my egr and it smoothed right out.

Good luck

 

[buickpower]

my egr solenoid is done away with, but the valve is still in place, although it does not have a vacuum source hooked up to it. I will make sure it is not sticking open though. Would it be best to do away with it completely? The only reason I had it in place was to possibly pass a visual, but I guess that doesn't matter really.

 

[salvageV6]

If you have a scantool check the engine temp. as displayed by the temp. sensor.

Could be a problem when hot.

 

[VernLee]

Buickpower, please post back when you find out what the problem is.

 

[buickpower]

will do, tomorrow I am going to reset the cam sensor, iac and tps to see if that helps any

when the coolant temp on the scanmaster reaches the 160-170 range is when it normally starts to hunt for idle.

I have been going through the manuals and just found that my purge solenoid is faulty, although it didnt seem to make much of a difference when running without it. I also have to get my park/neutral switch hooked up, for some reason the connector does not want to go into the receptacle on the tranny, the channels in the plug do not match up for some reason, although this was not the stock tranny, so i have to figure out how to wire that up some other way. That might help according to the manual, but i doubt it.

Compression is good on all cylinders and the plugs are all at .035, a couple of them were off by a couple thousandths. I did the propane trick and couldn't get the engine to smooth out or rev up, and my crossover leak is taken care of. One thing i did notice on the scanmaster is that the O2 sensor might be a bit lazy on the cross counts, I don't remember off the top how quickly it should cycle but it seems slow.

Sorry for the semi-random collection of thoughts, I am just thinking out loud. If you guys think of something, give me a holler. I will keep you posted Vern.

 

[buickpower]

Today I got the car idling pretty decent without stalling, it idles between 750-825 or so when warmed up. I let it run for close to 15 minutes to let the computer learn. I put a block off plate on the egr, and fixed a couple vacuum lines including the pcv hose that were questionable. I blocked off the purge canister and have it disconnected for now. It still starts to stumble on ocassion, but rarely now. My scanmaster numbers are as follows:

L8: 69-75
Int: 125-128
blm: 100
coolant temp: 170
ATS: 86....it's only 60 here but ok
tps: .5 ....I know this is about .04 too high, will adjust again
IAC: 40

my o2 sensor cross counts sort of worry me, I don't have the fast refresh version of scanmaster and they tend to stay at a given value for a while. How quickly is it supposed to cylce to 255?

So how are the numbers looking? I think the IAC is a bit high but i will be adjusting the mimimum idle air screw and resetting the tps. In fact i think the tps is high because i didn't reset it when I lowered the IAC a bit.

 

[Jerryl]

You most likely already know this, and I am in no way trying to insult your intelligence. Be sure to adjust your TPS with the engine OFF. It most likely will increase a bit at idle.

 

[TurboJim]

Originally posted by buickpower


L8: 69-75
Int: 125-128
blm: 100
coolant temp: 170
ATS: 86....it's only 60 here but ok
tps: .5 ....I know this is about .04 too high, will adjust again
IAC: 40

IAC of 40, LV8 of 70's tells me the ECM is laboring to keep it idling. Add a 100 BLM (didnt notice what injectors you had) tells me the thing is fat as heck and is loading up. What is the MAF value at idle? higher than 5 or so?

 

[TurboJim]

OK, just saw you had 37's which if memory serves me are Delphi's and I dont recall them having a "fat" idle, (been awhile since I programmed for them) so maybe you got a bad regulator or something. Have you checked for fuel in the vacuum hose on the reg?

 

[buickpower]

Jim, I've taken the vacuum line off the regulator a handful of times and haven't noticed any fuel in the line so far. The accufab is brand new but that may still be a possibility. After letting it run some more, blm's stayed at 117, and the IAC is now in the 20 range for some reason, a little better. Maf number is in the 10-15 range if i recall correctly, I will be running it more tomorrow.

Mike

 

[TurboJim]

Originally posted by buickpower
Jim, I've taken the vacuum line off the regulator a handful of times and haven't noticed any fuel in the line so far. The accufab is brand new but that may still be a possibility. After letting it run some more, blm's stayed at 117, and the IAC is now in the 20 range for some reason, a little better. Maf number is in the 10-15 range if i recall correctly, I will be running it more tomorrow.

Mike

MAF of 10 is WAY high for a 800rpm idle and will cause the car to be overfueled. If that is the actual value, you just stumbled upon the cause. Now its a matter of fixinf it.... we need to figure out WHY its reading so high

Is it a translator and maybe set wrong?

 

[buickpower]

update

I said I would keep someone posted, so that is what I am doing. The car no longer stalls. The accufab seems to be ok, I couldn't see any fuel in the line. I swapped out the O2 sensor, it was barely even moving through ANY cross counts every couple of minutes!, the new one cycles very quickly. Not sure if it is related, but since swapping the O2 sensor, the motor doesn't seem to dog when the electric fan kicks on, even though I did find out that the alternator is too small...

I also changed the old gas with some fresh 93 and regapped the plugs, and that seemed to cure the miss up. And I fabbed up a block off plate for the egr, although I doubt that was the cause of the stalling in my case. I also reset the TPS to within range, .42v.

IAC is still 40, i will turn it down to 10-20 tomorrow and reset the TPS again. LV8 is in the 50's i believe, and the maf reading is 8 g/s. 8 may be a bit high still, but it may be due to the fact that it is a cheap napa remanufactured unit.

All in all the car seems to be running rather solid right now, hopefully it stays that way, and thanks for your input everyone.