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1988 cherokee

C

Cartoad

NAXJA Forum User
Location
Kennewick,Washington
I bought an '88 cherokee, and replaced to 4.0l with a new motor(same in and out). It starts and runs but acts like it is way out of time. The timing is not manually ajustable. How do I fix this?
 
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Make sure the fuel injector wires are plugged into the right injector, check the distributor indexing if the dist has been out. Look for vacuum leaks to the MAP sensor

The list goes on
 
It's not throwing any codes. I have traced and retraced all the wires, injectors, checked the TPS, the MAP, the distributor index. The cap, rotor, wires, and plugs are all brand new and check out fine. Someone I met a week or so ago said something about having to set a "base line" timing in the ECU. If this is true, is there some software/USB cables out there I can use with my laptop to reset this "base line"?
 
Just curious, what year was the donor vehicle?
 
Ok, so you didn't mix up the flexplate/flywheel with an later model version.

Bring the engine to TDC on the compression stroke, remove dist cap and check that the rotor is in the correct position. Might be off a bit.
 
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winterbeater said:
Start checking the usual culprits. If the rotor, cap, wires and plugs are good, check the TPS with a voltmeter. No codes?
Click to expand...
winterbeater the Renix era Jeeps did not have a way to store or throw codes since they were built prior to OBD computers.
 
Test the Cam Position Sensor.
 
Ok. I'll do that. Have you ever heard of having to set a "base line" timing on one of these vehicles? The way it was explained to me was, you hook up a special diagnostic reader and reprogram the "base" timing setinngs into the ECU.
 
Cartoad said:
Ok. I'll do that. Have you ever heard of having to set a "base line" timing on one of these vehicles? The way it was explained to me was, you hook up a special diagnostic reader and reprogram the "base" timing setinngs into the ECU.
Click to expand...

Never heard of that for the RENIX. I can tell you this, my 90 will not run with the rotor dead on #1 terminal. I have to set it to the next tooth, I can't remember if that was one tooth up or one tooth down but its definitely not dead on #1. I had this battle with my 90 after dropping in my newly rebuilt original engine. Distributor timing was the whole issue.
 
I've tried moving the distributor one tooth up and then one tooth down, but it didn't help. I have also checked out the Cam Position Sensor. Everything checks out. A guy at work was saying there might be some software out there that will link the jeep to my laptop. He's done it with other vehicles, but I can't find any thing like that. Ever heard of this software? If so where can you find it?
 
Never heard of this being used. I know you can't change it, but you could use a timing light to verify that timing is now good, and see if the light stays steady as you rev it or stutters.
 
As far as I know there is no software/laptop interface for my 90.

The dealerships had a DRB II tester, but I don't know all of its functions.
 
I put the timing light on the Jeep, and at idle it was pretty good but shutters a little as I accelerate. With that being said the shutter could be from the motor stumbling all over itself, and backfiring. The thing is driving me nuts.
 
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