96 XJ with Idle Hiccup

1996 XJ 148,000, brought it into Jeff Daniels and they went over the entire truck for a small fortunne, but it include a complete once over, upper and lower ball joints, new engine mounts, new front universals, reverse light sending unit, new tranny lines, rear main seal, the whole 9.

But to my utter disappointment when i got the truck back she idled with a slight putter or hiccup. I know they did a compression check and everything looked good, so I changed the fuel filter, and replaced most of the ignition system with an accel coil, plugs, wires, cap and rotor, she drives great, lots of power, but at idle there's still that little miss thats more of an annoyance if anything. I ran it with some Lucs fuel additive and that seemd to help a little so I'm still thinking fuel system...

Well that last friday when it snowed I drove up PA 476 in 4wd and by the time I made it to mid county a got a CEL and was near stalling with a nice aggressive back fire! Got it home and let it sit for a day, then drove it fine for a few more days and the check engine light went off, but we still have the putter at idle. It actually ran better when the CEL was on.

I have a flowmaster 40 on it and its gonna come off soon cause it drones like hell but do you think thats contributing to the problem along with the rusty's air tube? It almost like the timing just needs to be adjust ever so slightly.

Any ideas? I don't have the time or $$$ to bring it back to JD's :doh:

Anyone have any ideas???

A computer reset is in order if you have done mods to get the best running engine possible.

This problem started occuring after you let them work on it? Well if that's the case, bring it back!

The stock injectors have a terrible mist pattern. This causes a buildup of carbon around the intake valves and in the intake port causing the rough idle. The fuel system cleaners help quite a bit if run continuously, however there are injector upgrades that completely solve the problem.

The strategy for a symptom WITH a check engine light is always the same.

Pull the codes. Use the technology provided to you by your Jeep. Anything less is pure guesswork.

The fact that you have a symptom AND a code is not coincidental.

Post the code(s)here for comment. Your OBD system isn't perfect, but it is darn good at pointing you in the right direction; the right circuit that isn't performing to spec.

i had a hiccup at idle in mine that caused it to nearly stall regularly

problem went away after i replaced both the IAC and the TPS
never got a CEL with it tho