Bad idle before car warms up

[irrompible]

This problem just recently surfaced. When I start my car after it has been sitting for an hour or two my rpms will run high for maybe a minute and then they completely fall off. About 10% of the time the car will save itself. It will continue to do this until the car warms up. After it warms up the idle is great and the car runs fine.

I don't have a scan tool so I can't give you my IAC numbers, but my TPS is set at about .45 at idle and WOT being around 4.65.

Any ideas as to what I should check?

 

[are_one]

Mine does this also in the cold. I was told that it was normal, has something to do with a cold start?

 

[bishir]

If the car is dying without you hitting the gas I'd first check for some vacuum leaks and make sure your IAC settings are good. Since you don't have a scantool you'll have to set them the hard way using a digital multimeter. Your TPS sounds fine but you'll have to readjust when you mess with your IAC.

James

 

[KENNE-BILL]

Might also want to remove the IAC motor/valve and spray it clean with carb cleaner, I had this same problem on my first GN and cleaning the black soot off the IAC made everything good.

 

[irrompible]

A few move observations...

I just fixed (little over 3 months ago) a code 44 problem, turns out the vac line to the FPR had a hole in it. At that time I went ahead and replaced all the vac lines.

After I adjusted my TPS last time I went to reset the computer. After the car ran for a few minutes it threw another code 44 at me. I checked gnttype and everything they list as a possible cause has either been changed or looked at. The only thing I haven't looked into was a bad PROM being the cause. The weird thing is, it only throws the code after the ECM is reset. If I drive it around for awhile, it never gives me the CEL again.

Another thing I noticed is that the MAF on this car has no screens. I bought the car from the original owner who was an older lady, so I doubt she removed them. Am I wrong in assuming the stock MAF sensor should have 1 or 2 screens in it? I doubt this is the cause of the problem however, as the car would idle fine in the cold a month ago.

 

[NJTurbo]

These cars always have had issues on cold start-ups, the main cause from what I have found is the Prom. Get a good prom from a guy like Eric Marshall and you will be trouble free. Eric fattens them up on the bottom and this seems to have worked in both my cars.

Good Luck

 

[HellOnWheels]

Originally posted by irrompible
A few move observations...


Another thing I noticed is that the MAF on this car has no screens. I bought the car from the original owner who was an older lady, so I doubt she removed them. Am I wrong in assuming the stock MAF sensor should have 1 or 2 screens in it? I doubt this is the cause of the problem however, as the car would idle fine in the cold a month ago.

If I removed both the MAF screens on my car (87) it would "hunt" for a stable idle...constantly.

HellOnWheels

 

[bsdlinux]

Originally posted by njturbo
These cars always have had issues on cold start-ups, the main cause from what I have found is the Prom. Get a good prom from a guy like Eric Marshall and you will be trouble free. Eric fattens them up on the bottom and this seems to have worked in both my cars.

Good Luck

Eric Marshall took care of this same problem on my 009s chip.

MAF: Try to put at least one screen back. Most chips are prgrammed for 1 screen.

A V8 guy probably got a hold of the MAF thinking no screens would make it run better...LOL

 

[irrompible]

I got ahold of two screens for the MAF, here are the results. Using one screen causes my car to throw another code 44 after idling for a min or two Two screens correct this problem but the bad start-up is still there. I guess I'll have to look into getting another chip.

 

[NJTurbo]

Originally posted by irrompible
I got ahold of two screens for the MAF, here are the results. Using one screen causes my car to throw another code 44 after idling for a min or two Two screens correct this problem but the bad start-up is still there. I guess I'll have to look into getting another chip.

Eric is the man.

Make sure you give him readings and let him know what the car is doing. He will burn you what you need, providing you went over all the basics.

 

[JaBoT]

Erics chip fixed a cold start problem on my t-type i had for years (probably due to the cam) and i had tried about 5 different chips and none of them worked. My car would always hunt and then stall when cold. I put in Erics chip and it warms itself up fine no matter how cold it is outside.

 

[irrompible]

Update:

Now the car has even more problems. I'm now getting a code 44 while the car sits in gear at a red light. I had previously fixed this same problem by checking and changing the vac lines shown on this page: http://www.gnttype.org/techarea/engine/vacdiags/vac_federal.jpg

Are there anymore major vac lines I should check, and could this be an issuse with a failing fuel pump?

Thanks for any info.