(Renix) Will the CPS die while driving...

[veedubshafer]

Give me a dope slap, too.

:twak:

 

[veedubshafer]

Ok, it wasn't the CPS LOL. No spark. Jumped the fuel pump and it shoots out of the fuel rail like crazy so the pump is good. Time to check the power in and out of the coil I guess. Have to look that up. If you have a link to that or advice speake up please. Thanks again guys.

 

[Matthew Currie]

Ok, it wasn't the CPS LOL. No spark. Jumped the fuel pump and it shoots out of the fuel rail like crazy so the pump is good. Time to check the power in and out of the coil I guess. Have to look that up. If you have a link to that or advice speake up please. Thanks again guys.

I think that on the connector to the ignition module, pin A (yellow wire) should be +12 volts from ignition switch, pin B (also yellow) should be the trigger signal from the ECU, and pin C (green) the tach signal. Diagrams I have for this are a bit fuzzy and I've been out of the Renix loop for years, but one of those should get you 12 volts +. I don't find any procedure that tells what, if any, measurable signal you should be looking for in terms of ECU input to the coil. Of course the number one suspect for no spark is still usually the crank position sensor, but a bad one doesn't usually give you an ohmmeter reading.

 

[veedubshafer]

Hmm, ok.

 

[veedubshafer]

Well, I was out testing all the wiring and such and everything was checking out fine. I saw some where on to check the grounds at the dipstick so I was moving the wiring around and didn't see anything necessarily alarming there. I plugged everything back in that i had unplugged and turned the key and it fired right up. Guess its time to sell this one!

 

[joe_peters]

Well, I was out testing all the wiring and such and everything was checking out fine. I saw some where on to check the grounds at the dipstick so I was moving the wiring around and didn't see anything necessarily alarming there. I plugged everything back in that i had unplugged and turned the key and it fired right up. Guess its time to sell this one!

Not really, just run through things again, this time cleaning all making sure they are stripped to bare metal and treating them with anti-corrosion and making them tight as possible. Those dipstick grounds are for the ECU, the ICM, the o2 sensor and more--CRITICAL.

Also, the Renix coil clips to the ICM, make sure the clips are clean and treated with dielectric grease too.

 

[veedubshafer]

Not really, just run through things again, this time cleaning all making sure they are stripped to bare metal and treating them with anti-corrosion and making them tight as possible. Those dipstick grounds are for the ECU, the ICM, the o2 sensor and more--CRITICAL.

Also, the Renix coil clips to the ICM, make sure the clips are clean and treated with dielectric grease too.

Oh ok. Its funny my other XJ ran with those wires not even bolted to the block!

 

[Matthew Currie]

I'm not sure, but I think the signals in the Renix system are weaker, or more sensitive to noise, and more susceptible to bad contacts and grounds. My old 87 was always nervy, and I found that performance and reliability improved if I just made a habit of periodically unplugging and replugging everything in sight. Later when my daughter had it, she had several bouts of problems with the bulkhead connector for the injection harness too. If yours has that (dropped in mid-88, I think), it's well worth while to take that apart, clean up the contacts, lube them and put it all back. There was also a bypass kit made for the CPS, to run it straight to the computer without using the harness at all.

Finally, in case it hasn't yet come up, make sure to check that braided ground strap between the head and the firewall. Sometimes it will look all right but actually have turned to little more than dust.

 

[veedubshafer]

Yeah, I don't have that silly firewall connector. I had an '88 parts jeep that did and I could see that thing being a problem. I am going to degrease the wiring over by the dipstick and get it lubed up and I was thinking about making a new ground strap for the back using some 8 gauge subwoofer type wire - or if I can find that cable new. Mine looks good but it may not be.

 

[cruiser54]

Another thing I did on both my Jeeps was to run a ground wire, at least a 4Ga, from the dipstick tube stud to a stud on the right side inner fender. Couldn't hurt.

 

[joe_peters]

Yeah, I don't have that silly firewall connector. I had an '88 parts jeep that did and I could see that thing being a problem. I am going to degrease the wiring over by the dipstick and get it lubed up and I was thinking about making a new ground strap for the back using some 8 gauge subwoofer type wire - or if I can find that cable new. Mine looks good but it may not be.

Pick up a 4 or 2 ga cable at any parts store if you are talking about the head to firewall ground. Braided cable straps are self-destructing crap, IMHO.

 

[veedubshafer]

Pick up a 4 or 2 ga cable at any parts store if you are talking about the head to firewall ground. Braided cable straps are self-destructing crap, IMHO.

Ok, I actually have a couple brand new battery cables I am going to make up a nice ground wire to go from the inner fender to the dipstick tube bolt or something in that order. Thanks again guys.