94 ZJ 5.2 trouble starting and choppy idle/stall til warm
12-29-2016, 04:25 PM
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Model: Cherokee
94 ZJ 5.2 trouble starting and choppy idle/stall til warm
I bought a 1994 Grand Cherokee with the 5.2 a couple weeks ago and after about 30 minutes at the guys house we were able to get it started and then it sounded like this the first 15 minutes (
) and required us to feather the throttle so it wouldn't stall until it got warm and ran perfectly fine, i was able to turn it off for 30 minutes and it started right back up until it sat over night and the problem persists. This is a project car so I'm trying to do all of the work myself and so far i have replaced the distributor cap and rotor but I'm not sure where to go from here, it takes over 30 minutes to start then makes gun shot noises loud enough for the neighbors to call the police when it backfires. Any ideas are welcome. (So far im thinking check the coil, clean injectors, and replace o2 sensor, can't get the jeep to show any codes)
12-29-2016, 05:55 PM
#2
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Welcome to the forum.
It sounds like the valves are sticking.
How does the oil look?
A compression test will show if the valves are seating properly.
My guess is part of the resolution will be to remove the heads and remove the lifters.
The lifters are probably stuck. On mine, I was able to disassemble, clean and test my lifters. About half were bad, all are good now.
My valves were lapped by me to get a decent clean seat area. A better / more expensive solution is a valve job. At that time I cleaned the valve stems of carbon, cleaned the springs, caps and keepers. I also replaced all the valve seals. All were rock hard. The replacement parts were supple.
It won't hurt to change the timing chain during the project.
The intake plenum gasket has probably failed. The TSB 09-05-00 specifies the correct way to replace / torque the parts.
Use a tap to chase all the blind manifold pan bolt holes and a tap to chase all the bolts. Verify proper threading prior to assembly by ensuring every bolt and every hole can hand tighten w/o a pan and w/o a gasket so that the pan will tighten properly.
Pick up a fresh set of manifold bolts, because the TSB 09-05-00 sequence stretches the bolts. I got my bolts from Rock Auto and the quality is great.
It sounds like the valves are sticking.
How does the oil look?
A compression test will show if the valves are seating properly.
My guess is part of the resolution will be to remove the heads and remove the lifters.
The lifters are probably stuck. On mine, I was able to disassemble, clean and test my lifters. About half were bad, all are good now.
My valves were lapped by me to get a decent clean seat area. A better / more expensive solution is a valve job. At that time I cleaned the valve stems of carbon, cleaned the springs, caps and keepers. I also replaced all the valve seals. All were rock hard. The replacement parts were supple.
It won't hurt to change the timing chain during the project.
The intake plenum gasket has probably failed. The TSB 09-05-00 specifies the correct way to replace / torque the parts.
Use a tap to chase all the blind manifold pan bolt holes and a tap to chase all the bolts. Verify proper threading prior to assembly by ensuring every bolt and every hole can hand tighten w/o a pan and w/o a gasket so that the pan will tighten properly.
Pick up a fresh set of manifold bolts, because the TSB 09-05-00 sequence stretches the bolts. I got my bolts from Rock Auto and the quality is great.
12-30-2016, 05:01 PM
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Model: Cherokee
Implement TSB 18-48-98 for the spark plug wire routing.