RileyW

hi i have a 1989 jeep cherokee 4.0 (4.9 stroker)
recently i was driving it and it started jerking EXTREMELY bad and then it would die comeing to a red light i finaly got it home and it does it when idling but its random it will idle fine and normal than just die or run rough then go back to normal repeat process anyways i need help please i unplugged the MAP sensor and it shut off so someone told me its working fine then i unplugged the crank positioning sensor and it died i have no idea whats going on! and its not all the time it does the rough idle or dying it randomly does it runs fine them boom running rough or boom shuts off someone told me it might be the TPS so im going to replace that tomorrow they also said the TPS might need adjusting i need help so any help is GREATLY appriciated

RileyW

Please help!

67 GMC

There's lots of stuff on the forum for issues similar to what you're experiencing. Search out postings from Cruiser54. The has tons of diagnostic procedures to narrow down issues. Cherokees are notorious for having bad grounds. I had an intermittent problem with my '87 that was related to the ground wires attached near the dipstick stud. It would run ok, then just cut out then run fine. If I jiggled the wires, it would stop running so that narrowed it down. Do some searching first before just swapping out sensors. You don't want to waste your money.

cruiser54

Start here:

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

cruiser54

Then this:

I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else.
Revised 07/23/2012

RileyW

Thanks guys ill try this and let you know

cruiser54

We're sitting on the edge of our seats. Are you done yet?

RileyW

I started and let it run for a little while and it didn't do it this time so I checked some of the grounds sometimes my electric fans kick on and off randomly and there hooked up to the ignition so when u turn the key on they stay on but this problem with it dying on happens sometimes and when it misses its random idk what's wrong!

cruiser54

So, did you do the ground refreshing and connector refreshing?

RileyW

Took it for a drive after I replaced the tps it hasn't done it yet idk what's goin on!

cruiser54

Be happy. Do the ground refreshing and connector refreshing just cuz, okay?

The Rooster

mr Riley if it is a Renix Grounding problem... it is going to be random unpredictable... the steps that have been provided to you cut down and rule out this problem.. just because it is "fixed" today doesn't mean it will be fixed tomorrow...

RileyW

Yes I understand that that's why it freaks me out I will do all the refreshing tomorrow and let u know how it's doing thank you all for your help

cruiser54

Rooster speaks from personal experience with positive results.