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Runs bad after cold start

Z

zipties

NAXJA Forum User
Location
So Cal
Hello,
99 Cherokee with I6 4.0 My Jeep starts up perfectly, but when cold it hesitates once I start driving, then I can hear a clunk or two coming from the drivers side of the engine bay, and then after it warms up it runs perfectly. What could this be, is there some sort of cold start sensor or valve or something, thanks everyone:us:
 
Coolant temperature sensor data is in play for cold driveability symptoms. May want to run at least a cold/hot resistance check on it and compare to the factory resistance table to see if you're in the ballpark.
 
I had the trouble warm or cold. Right after start up if I drove without letting it run for a few minutes it would hesitate and make the clunk sound in the engine bay that zipties described.
 
im having the same problem now and found this thread while searching. since yours is a 99 and a obdII, shouldnt it throw a cel if it was a O2 sensor? Mine hasnt thrown a cel yet, cleaned throttle body butterfly valve, and the iac valve. still doing the same. sorry if its a thread jack. i have a 01 with 83k miles, aw4, np231.
 
The intake air temperature sensor measure the air temperature and causes the PCM to change fuel injection amounts. Like a choke on a carburetor. Check your IAT.
 
Last edited:
Mind if I revive this one.

I have this problem now, so how do you check the IAT?
 
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