Stumble and rev at start

alexgalexg

New member
1998 XJ 4.0 206k automatic 3.5' lift

This morning i started my xj and it ran rough and then revved a few times before evening out. This whole event lasted roughly 7 seconds.

After work today it did the same thing. I highly doubt it's the iac sensor because it runs and idles great after that point.

Tune up is a year old, so is the head. Only thing wrong with it is the bearing for the mechanical fan squeals.

Just got done with a 700 mile road trip and it never gave me a problem. Any thoughts?

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alwayzAMC

New member
if it does it 1 time per start cycle i would look at the upstream O2, mine did that for quite a while, never threw a code, 1 day it threw an O2 code and would barely run constantly, not just the several second stumble every new start.
 

alexgalexg

New member
if it does it 1 time per start cycle i would look at the upstream O2, mine did that for quite a while, never threw a code, 1 day it threw an O2 code and would barely run constantly, not just the several second stumble every new start.
I need to replace that working harness because the connector broke. I have it plugged in andaccording to the obd reader it's working fine. So odd.

I did just get back from Vermont where I was in extremely high elevation and min if -8 degrees but I feel like the computer should be able to re adjust without making it run like that

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