Cherokee stalls at start-up

[89cherokee]

My cherokee stalls 2-3 times after starting and then runs great. I have replaced the fuel pump, fuel filter, air fitler. The vacuum lines are clean as a whistle. I ruled out the ignition system because it runs great after warming up for about 2 minutes. Am I missing a sensor that tells the jeep at start-up that its warm? Any suggestions are appreciated. Thank you.

 

[Jeepr]

ok, I am guessing you are talking about an 89 XJ?

When you shut the key off in a RENIX-II system (like after driving a while or whatever), the ECU holds it's own power on for a little bit (about 2 seconds), during this time the ECU stores some running condition info, and sends pulses to the IAC to "OPEN" the idle passage so that there will be airflow into the intake manifold for your next attempt at starting. Without that airflow... you'll have a tough time starting and maintaining some level of initial idle... The ECU uses the B+ Latch relay in the relay cluster on the passenger's fenderwell to hold on the power after key off The B+ Latch relay is the 3rd relay in that line of relays if you count the one closest to the silver starter relay as #1 (you can swap it with #4 if your AC works to test it)

Map sensor, on the firewall. I think you can just unplug it to see if it starts and runs.

coolant sensor - below the maifolds - it's the one with the "normal" connector (that goofy-connector is on the Knock sensor)... leaving it unplugged will give you like a -40*F start-map... It's worth a try.

 

[89cherokee]

Jeepr,
Yes, its an 89 XJ. Thanks for the suggestions...next chance to try them will be Wednesday morning. I'll let you know what I found out. Thanks again.

 

[89cherokee]

Thanks Jeepr, the Map sensor seems to have done the trick. I checked the vacuum and it was fine, but the electrical connection was crudded up. I cleaned the terminals with a battery cleaner and now it works great. Thanks again for the help.