renix MJ still randomly dies - looking for new ideas

It will go sometimes weeks or months without dying . thats what makes it hard to diagnose - I will think I fixed it, drive it for weeks or months, and then suddenly its back.

It will die, lights all stay on, if I let it sit for minute or two, then floor the gas pedal and keep cranking it will eventually start. then it might die again on the way home or maybe weeks later ... so hard to diagnose.

so many new parts - it was driving great for 100 miles and now its dying pretty frequently, again.

FML.

New parts:
mopar CPS
TPS is an older one (multiple new ones seemed to suck and not work )
ford injectors
new coil
dizzy
deleted ballast resistor
cap rotor
plugs
bosch fuel pump
FPR
ignition switch
ICM
jumped TPS ground to battery
alternator
battery
c101 delete
frequent ground refresh
new TCU
new ECU
new plug wires
cleaned NSS - (could this be out of adjustment? )
fuel pump relay
cleaned all electrical connections
cleaned MAT- looked perfect anyway
cleaned fuel pump ground
air filter
temporarily deleted EGR to help diagnose
new o2
bored TB
newer IAC
every time I've tested fuel pressure its been fine.
newer MAP - could try this again.



The only 2 things I should try last that I can think of :
New fuel filter (its fairly new but what the hell at this point )
bypass NSS or ignition switch or both and see what happens
might have a exposed wire somewhere ? I've been checking, obviously not hard enough
I could keep searching for corroded wires. I've searched and cut open the battery cables to see if there is corrosion.


Edit:
Automatic trans



__________

Manual or Auto transmission?

Did you modify the factory OEM CPS and test the cranking voltage? Was the cranking voltage at least 0.50 volts?

Have you tested the O2 sensor output itself with an analog volt meter and checked for 12-14 volts at the orange heater wire at and to the O2 sensor?

What spark plugs are you using?

I always test things like the IAT sensor and the TPS sensor right when the engine acts up, and afterwards.

Does it ever idle high or low on a regular basis or just a sudden shut down and no start?

"newer IAC" ????????????????????

Muffler bearings is missing on that list

Automatic.

Ecomike said:

Manual or Auto transmission?

Did you modify the factory OEM CPS and test the cranking voltage? Was the cranking voltage at least 0.50 volts?
I did not modify it. I had a new Standard CPS and just swapped it for Mopar. I can check cranking voltage soon

Have you tested the O2 sensor output itself with an analog volt meter and checked for 12-14 volts at the orange heater wire at and to the O2 sensor?

I need to do this I dont own a analog meter. any recommendations? I have a cheap digital that I've been using for years.

What spark plugs are you using?
you know what, I think I am running some colder plugs from last renix that ran hot, I can try to the stock hot plugs to be safe. or I might have already converted to the hot plugs. need to check.

I always test things like the IAT sensor and the TPS sensor right when the engine acts up, and afterwards.
I need to start carrying the DMM and drive it around in circles until it dies...but the problem is, it could take weeks, or it might do it right away

Does it ever idle high or low on a regular basis or just a sudden shut down and no start?
it lately has been fine. but ill take notes and start driving it around to see if I can recreate the dying and carry the DMM

"newer IAC" ????????????????????
fairly new.ive swapped a couple . this one was new as of last year sometime.

Muffler bearings is missing on that list

Click to expand...

before I sold my snap on MT2500, I was using it to check o2 voltage switching and everything else. I did not look out of whack then. I should have maybe kept that tool

What year? There is a corrosion and intermittent problem with the main wiring harness with early Renix. IIRC it was C101 above the brake booster.

old_man said:

What year? There is a corrosion and intermittent problem with the main wiring harness with early Renix. IIRC it was C101 above the brake booster.

Click to expand...

Post one says "c101 delete"

I'd bet money on the CPS then, and I don't bet or gamble, LOL.

"Did you modify the factory OEM CPS and test the cranking voltage? Was the cranking voltage at least 0.50 volts?

I did not modify it. I had a new Standard CPS and just swapped it for Mopar. I can check cranking voltage soon"

I was hard headed but Cruiser54 kept after me for months and sure enough just moving the CPS about 1/32" closer to the flex plate in my case made all the difference in the world.You just drill out the existing hole with the next larger number size drill bit and push it down towards the plate while tightening the "factory" mounting bolts.The problem had a factory TSB fix I think moving the sensor closer...but aftermarket sensors have weak magnets and a poor signal and need it even more that the OEM sensor.Lots of old threads here about it.It is an easy fix. Cranking CPS voltage must be at least .50 Volts or random dying and non starts will happen.

Ecomike said:

I'd bet money on the CPS then, and I don't bet or gamble, LOL.

"Did you modify the factory OEM CPS and test the cranking voltage? Was the cranking voltage at least 0.50 volts?

I did not modify it. I had a new Standard CPS and just swapped it for Mopar. I can check cranking voltage soon"

I was hard headed but Cruiser54 kept after me for months and sure enough just moving the CPS about 1/32" closer to the flex plate in my case made all the difference in the world.You just drill out the existing hole with the next larger number size drill bit and push it down towards the plate while tightening the "factory" mounting bolts.The problem had a factory TSB fix I think moving the sensor closer...but aftermarket sensors have weak magnets and a poor signal and need it even more that the OEM sensor.Lots of old threads here about it.It is an easy fix. Cranking CPS voltage must be at least .50 Volts or random dying and non starts will happen.

Click to expand...

I can pop it off and open up the holes thats quick and free. It never dies while cranking, usually only at slower speeds(under 30mph) around town.


yeah I deleted the c101- soldered every single connection. and opened up the harness and soldered the various ground splices.

LOL!!!!

"It never dies while cranking"

I guess they can throw a rod and die while cranking :laugh3:

Sorry I do that so much I had to have some fun with it. :cheers:

You can test the CPS cranking voltage with a DVM meter on the DC scale as I recall, before and after to see the difference and post the results

The lower the engine RPM the lower the CPS output voltage.

My 98 Euro spec diesel XJ used to randomly get an ASD signal and shut down. It typically happened only in right turns. I never actually found the root cause, but I did tons of troubleshooting to figure it out. In my searches I found the connections behind the dash tend to heat up and melt the connectors. This will allow the wires to touch in certain instances throwing the ASD signal. There is one connector in particular that is close to the steering column that has issues with this. Once the wiring cools back down the connectivity goes away and you're able to restart.

I realize you have a Renix gasoline vehicle and mine was a Euro diesel, but I found much of the wiring was very similar between the chassis's. After I hit a deer and crushed the front end I was able to buy a plug and play wire harness out of the US and it worked perfectly. Basically what I'm saying is that it's probably worth your time to poke your head under the dash and look for worn/burnt/melted connectors.

Yeah IM going to try to look for chaffed or burnt wiring. I haven't had time to get under it this week, but I plan to take a look this weekend probably.

Drilled out the cps and drove it around. Died and wont start . It will want to try to start with the tps unplugged. Probably flooded now . Also swapped the fuel filter tonight for fun.

Could a clogged cat cause this ? It doesnt rattle and runs great when it does run though. Weird .

seemed to help a bit if I unplugged the TPS. Ive tried many TPS too. and many CPS . including this one, a new Mopar.

I still say bypass the ign. switch. Even if you don't know how, you should be able to figure it out. Mine stopped dying after this.

How did you bypass it ? just ignition only? there is fuel and ignition going to it, right ? did you put it on a relay I assume?