This is topic Car dies on cold start in forum Tech Talk at Northern California Ford Owners  .


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Posted by Smoked50 (Member # 9592) on :
 
Everytime I start the car on a cold morning or I leave it off for a while when i turn it on it just shuts right back off, after it warms up it never shuts off, the car is a 93 coupe cammed. Any help would be appreciated thanks
 
Posted by 50DADDY (Member # 3076) on :
 
Faulty IAC maybe.
 
Posted by Smoked50 (Member # 9592) on :
 
Any idea how to test it to see if it's faulty?
 
Posted by 50DADDY (Member # 3076) on :
 
Does the idle rise on a cold start or just sit at normal rpm's and die?
 
Posted by Blind (Member # 3052) on :
 
has it been tuned? sounds like it's flooding out / too rich at cold start.
 
Posted by Smoked50 (Member # 9592) on :
 
Hasn't been tuned, It rises but not sure how high, maybe around 2k-2500 then just dies.
 
Posted by Blind (Member # 3052) on :
 
quote:
Originally posted by Smoked50:
Hasn't been tuned, It rises but not sure how high, maybe around 2k-2500 then just dies.
if the idle flys up by itself then dies it's lean, if you prime the fuel pump a few times (turn the key on/off and listed for the fuel pump to prime each time before starting) see if it still does it. Could just be a dying fuel pump that loses pressure after sitting.
 
Posted by Smoked50 (Member # 9592) on :
 
quote:
Originally posted by Blind:
quote:
Originally posted by Smoked50:
Hasn't been tuned, It rises but not sure how high, maybe around 2k-2500 then just dies.
if the idle flys up by itself then dies it's lean, if you prime the fuel pump a few times (turn the key on/off and listed for the fuel pump to prime each time before starting) see if it still does it. Could just be a dying fuel pump that loses pressure after sitting.
Yes it primes each time before starting. Would a tune fix the idle problem? or is it a faulty IAC?
 
Posted by Blind (Member # 3052) on :
 
quote:
Originally posted by Smoked50:
quote:
Originally posted by Blind:
quote:
Originally posted by Smoked50:
Hasn't been tuned, It rises but not sure how high, maybe around 2k-2500 then just dies.
if the idle flys up by itself then dies it's lean, if you prime the fuel pump a few times (turn the key on/off and listed for the fuel pump to prime each time before starting) see if it still does it. Could just be a dying fuel pump that loses pressure after sitting.
Yes it primes each time before starting. Would a tune fix the idle problem? or is it a faulty IAC?
I mean prime it several times, like 5 key on/off cycles waiting for the pump to prime each time, then start the engine.

if the IAC or fuel pump are faulty a tune wont fix it, a tune has nothing to do with fixing a mechanical problem.
 
Posted by Smoked50 (Member # 9592) on :
 
quote:
Originally posted by Blind:
quote:
Originally posted by Smoked50:
quote:
Originally posted by Blind:
quote:
Originally posted by Smoked50:
Hasn't been tuned, It rises but not sure how high, maybe around 2k-2500 then just dies.
if the idle flys up by itself then dies it's lean, if you prime the fuel pump a few times (turn the key on/off and listed for the fuel pump to prime each time before starting) see if it still does it. Could just be a dying fuel pump that loses pressure after sitting.
Yes it primes each time before starting. Would a tune fix the idle problem? or is it a faulty IAC?
I mean prime it several times, like 5 key on/off cycles waiting for the pump to prime each time, then start the engine.

if the IAC or fuel pump are faulty a tune wont fix it, a tune has nothing to do with fixing a mechanical problem.
Yeah that's what I did. Fuel pump isn't faulty. now how do I check the IAC? I know a tune won't fix a mechanical problem I was just wondering if no tune was the problem.
 
Posted by Blind (Member # 3052) on :
 
pull the IAC off and have somone turn the key to the on position..it should move consistently and about half an inch or so when the key is turned to on.
 
Posted by bentley mobs a stang (Member # 11119) on :
 
could also be the maf sensor too. if it is running a lean condition and u have a propane can, shoot some propane in the air cleaner. it will richen up the mixture and run if that is the case. try unplugging the maf sensor and see if ur problem goes away. if so you have a bad sensor.

as for testing the iac. check to see if u have idle fluctuation during steering movement, a/c is on, if its an auto put it in gear. if its bad enough it can kill the engine.

id be more inclined to say its ur maf sensor if its dying like that. the o2 sensors arent warmed up to control fuel during a cold start, so ur engine relies on the MAF, ECT, and TP sensor to control fuel during start up. and if the maf sensor has high resistence it will tell the computer that less air is going into the intake than there actually is. a vacuum leak after the maf will also give this symptom. good luck dude
 
Posted by FivePTSlow (Member # 7682) on :
 
quote:
Originally posted by Smoked50:
Everytime I start the car on a cold morning or I leave it off for a while when i turn it on it just shuts right back off, after it warms up it never shuts off, the car is a 93 coupe cammed. Any help would be appreciated thanks
Sounds like a possible vacuum leak to me
 
Posted by Bronconut (Member # 10716) on :
 
Did you ever figure out this problem?

I am have a similar issue. Just converted my 70 bronco to efi and it will die if I don't feather the throttle to keep it running at first. Once it warms up a bit its fine. Only happens on cold starts.
 
Posted by dvuspny (Member # 10949) on :
 
Look for vacuum leaks.... Including all the vacuum hoses and all vacuum caps. Under the intake and at the vacuum tree. Also vacuum test the egr. Could be an internal leak in the egr. Some cracking in the hoses and caps are not as apparent as when you roll or squeeze them in your fingers. Then you will see all the fatigue in the aged rubber components.
Dirty egr valve and iac motors are both "internal" vacuum leaks. Use new gaskets. Don't re-use the old one. Get one from parts store before hand. Not everyone carries them in stock.
 
Posted by Bronconut (Member # 10716) on :
 
So I took some advice from above and disconnected the MAF sensor upon cold start and it did not die. Reconnected after about a minute and ran fine.

So, do you think its bad or maybe just dirty? How do you clean them anyway?

Thanks
 




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