Pulled engine & changed all of the freeze plugs. While engine was out we replaced rear main seal, oil pan gasket & front timing chain & seal. Welded a little crack in the exhaust manifold. Replaced thermostat & a couple of heater hoses that were looking bad.
Last thing going back in was a set of Champion plugs & a new MOPAR CPM.

Still stalls when it warms up. Ignition coil checked ok but I have a thermal failure for some reason.

Last but not least ...my rear tail/brake light will NOT GO OFF. Running or not running...it's staying on......

What's up with that???

 

I had the same thing happen with my brake light a few weeks back. Either you brake light switch is sticking or going bad. I just cleaned mine up and haven't had a problem since.

 

Yeah, mine were randomly coming up about 2 weeks ago. Drained my battery once when they came on in the middle of the night in my driveway.

The brake light switch is a 10$ part and about 10 minutes to replace. That's where I would start.

 

OK........got the light situation fixed. New switch took care of it. Thanks for the replies.

Now......even after replacing the CPS.....I am still having crank no start issues after driving just a few minutes. As soon as she warms up just a little......if I turn it off and try to re-start..it's a hit & miss. Usually a miss.

If it does start it's feels like she's on 4 cylinders.

thoughts?

 

I would start by verifying that you have good fuel pressure at the fuel rail with a mechanical pressure gauge Also make sure that you have a good strong blue spark. I know when my cps went out I also had to change out my coil. Just a suggestion.

 

"I would start by verifying that you have good fuel pressure at the fuel rail with a mechanical pressure gauge Also make sure that you have a good strong blue spark. I know when my cps went out I also had to change out my coil. Just a suggestion."

Fuel pressure is good. Already checked that. We have also replaced the coil. That's why I am lost.....

 

When you did all that work, are you sure the tube to the MAP is still connected and in good shape?

 

How about good grounds at the dipstick tube stud?


Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.
　
　
If you want to upgrade your grounds and battery cables in general, contact Jon at


www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 12-04-2012

 

sounds like the pick up coil is getting bad mine done the same as yours when it was bad

 

Renix Jeeps will run without the camshaft position sensor.

 

No they won't. I have an 89 and when the cps went out, there was no running, no starting, no nothing. Which is exactly what happens with the cps goes out.

 

Let's clarify. The CPS is Crank Position Sensor. What salad is referring to on the Renix is the sync generator inside the dizzy. It's not a Cam Position sensor like 91 on. A Renix will absolutely run with it unplugged. Try it.

 

OK I got at it early today. I re-checked the "new" coil & guess what.......??? This time she's showing no good. And it's a new one. Came from O'reilly's. I'm gonna replace it with another brand.

Here's my question. Any particular brand? I have Advance Auto just down the road. I can go to Napa but it's 45 min. drive 1 way.

Also while I'm at it what is the opinion on changing out the pick-up coil underneath the dist. cap? Or just do one at a time?

I'm also taking the ground re-freshing advice & starting that as well.

No golf today.....

 

That's not a pick-up coil in the dizzy. Your Renix will run with it unplugged.....