Renix Missfire over 2k rpm/hitting a cutoff at 2k rpm
12-03-2020, 07:26 PM
#16
CF Veteran
Thread Starter
I forgot to post the video:
I have some parts I had previously ordered coming in. today I pulled all the spark plugs, and they all looked good, and gapped correctly (.35) as far as I know that's the correct gap. I put all new wires and double checked the pattern. I also installed another new fuel filter. I have some different injectors coming, and a new ignition coil, exhaust gasket, and an ECM. If none of those fix it. I'll drag it to the desert, set it on fire and walk away.
I have some parts I had previously ordered coming in. today I pulled all the spark plugs, and they all looked good, and gapped correctly (.35) as far as I know that's the correct gap. I put all new wires and double checked the pattern. I also installed another new fuel filter. I have some different injectors coming, and a new ignition coil, exhaust gasket, and an ECM. If none of those fix it. I'll drag it to the desert, set it on fire and walk away.
12-03-2020, 07:41 PM
#17
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Ever indexed your distributor?
Tried running it with the pigtail unplugged from the distributor?
Tried running it with the pigtail unplugged from the distributor?
12-03-2020, 07:47 PM
#18
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Thread Starter
I did not index the distributor, as it ran fine before, and it is tight with no play. I just replaced the cap and rotor.
when you say pigtail, do you mean the wire from the ignition coil to distributor? what is that supposed to test for? I'm happy to do that, if I know what it is testing for?
12-03-2020, 08:03 PM
#19
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Just unplug it and see if it helps.
Sure your fuel filter isn't clogged? You can have pressure, but not enough volume of fuel.
Sure your fuel filter isn't clogged? You can have pressure, but not enough volume of fuel.
12-03-2020, 08:08 PM
#20
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Thread Starter
Which pig tail? Sorry I'm confused, if I unplug the pigtail from the distributer the engine will just die, will it not?
12-03-2020, 08:39 PM
#21
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
There's only one "pigtail" at the dizzy. Unplug it and see how it runs.
12-03-2020, 09:25 PM
#22
CF Veteran
Thread Starter
Sorry had to look at a picture of one. I'm dumb. I will try that tomorrow. without the muffler attached it's too loud to run right now.
12-04-2020, 02:02 PM
#24
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Thread Starter
Don’t know if this is helpful, but I put the old map sensor back on, runs the same.
what is the pigtail on the distributor communicating?
what is the pigtail on the distributor communicating?
12-04-2020, 04:59 PM
#25
CF Veteran
Thread Starter
Took all the injectors off, and cleaned them, I don't have a way to cycle them, but put some lucas tune up in bottle in, and let it run for a while, none of that seemed to do anything.
12-06-2020, 07:19 PM
#26
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
If the ECU doesn't see the signal, it just adapts.
12-07-2020, 06:54 PM
#27
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Thread Starter
Do you have any other suggestions? I checked my vacuum lines and found none disconnected. sprayed some carb cleaner around the intake and exhaust manifolds while it was running to see if there was a leak and didn't detect one.
12-08-2020, 02:48 AM
#28
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Year: 1988
Model: Cherokee (XJ)
Engine: 4.0
Have you done the stuff on cruiser54.com about calibrating the CPS and distributor?
It runs solid at idle, so there isn't a driver problem in the ECU for spark or injector. But it fails hard at higher rpm. To me this indicates that the ECU is making bad decisions at higher rpm relative to the mechanical reality. The big difference between these two situations is low load spark advance with RPM.
It runs solid at idle, so there isn't a driver problem in the ECU for spark or injector. But it fails hard at higher rpm. To me this indicates that the ECU is making bad decisions at higher rpm relative to the mechanical reality. The big difference between these two situations is low load spark advance with RPM.
12-08-2020, 08:33 AM
#29
CF Veteran
Thread Starter
Have you done the stuff on cruiser54.com about calibrating the CPS and distributor?
It runs solid at idle, so there isn't a driver problem in the ECU for spark or injector. But it fails hard at higher rpm. To me this indicates that the ECU is making bad decisions at higher rpm relative to the mechanical reality. The big difference between these two situations is low load spark advance with RPM.
It runs solid at idle, so there isn't a driver problem in the ECU for spark or injector. But it fails hard at higher rpm. To me this indicates that the ECU is making bad decisions at higher rpm relative to the mechanical reality. The big difference between these two situations is low load spark advance with RPM.
Yes for the CPS, but since it ran fine when I got it I didn't index the distributor. I have a new dizzy on the way, when I install it, I'll be indexing it.
