cptmiker

Hello All Ill try to list everything its doing
1987 Jeep XJ. 4.0
Just replaced the Intake manifold due to a broken stud on the front exhaust. Drilled and re taped ezout no go. Got everything back to gather.

Replaced leaking injectors with Bosch 0280155703 rebuild and tested before install. Replaced O-Ring on Pressure regulator.
Here are the symptoms
Low power Backfire when let off gas.
Will try to stall after about 1 to two min of running at idel.
When it stalls it does not seem to want to start for a min or two.
Fuel pressure tested and stable Prior to change and after change same when i chould keep it running.
Could this be the infamous CPS.

Just as a fyi this did this same thing before the changes. I was hoping it was just a bad manifold exhaust gasket.

Thanks
Mike.

Turbo X_J

Backfire = ignition problems.

cptmiker

Thanks Not much help but appriciate the answer.

Jooman07

Start with you ignition components. Is your dizzy cap tight and not cracked? The rotor in good shape? All wires still on the correct plugs? Correct gap on plugs? Etc...

kdot

Take off the distib, look at the terminals on the inside, make sure there are no heat sparks where it could be crossfiring.

Make sure your spark wires are routed correctly, don't want cross-firing. Check all IGN componets for wear. I had a 94 Dodge 1500 that had 3 bad terminals on the dist cap, on the underside, causing only 5/8 cylinders to fire- that truck still ran lol

cptmiker

Cap rotor plugs and wires are all new. I checked and verified Plug gap .035
All wires connected securely. I will pull the cap off and check the Distributor.

It only backfires when you let off the gas. It seems to idle smothly When you first start it. But seems to have no power when you rev it up laggin then when you release the gas it has a quiate back fire one or two of them. After a min or two it will want to shut down. I can keep it running for about three min. then it will shut down. and it does not want to start for about a min or so. just turns over. Semms like it wants to start. but will start after that rest time. I dont smell excess fuel like its running rich out the tail pipe. I will aslo be checking spark with a spark tester on each plug. I will then start testing Sensors.

Jooman07

How long have you had this Jeep? Has the timing chain been changed at all before?

cptmiker

Boy do i fell dumb I just asumed the plug wires were in the right spots per when i removed them one at a time. They were way off This is fixed now. and no more back fire and power seems to be back. But now i have anuther issue. it seem to be hunting for the idle. I am pulling the idle control motor to clean it and she if that clears up the hunting issue. I did recheck all the Vacume lines and all are connected in the correct location and none are broken the ones there were I cut the broken plastic tube and spliced in a piece of rubber Vacume tube to fix any that were Broken.

As for how long i have had this jeep about two weeks. Drove it home and it shook bad at 35mph. I figured this was the motor mounts and the fact that the plug wires were way off. I have complete the following

1. New motor mounts.
2. New intake/exaust gasket
3. Plugs
4. cap, rotor, wires.
5. New rebuilt Bosch 0280155703 injectors
6. New oring for Fule presure regulator.
7. new water pump, T-Stat. Radiator. and all water hoses.

cptmiker

OK cleaned the idle air control valve and its much better still seems to have a miss in it every 5 to 8 sec. But is running much better. I also checked to make sure the Throttle body was cleaned as well. and the butterfly was not sticking. Going to have to track do the miss that's going on about every 5 to 8 sec.