GROUND GROUND GROUND!!!!

Ok so let me start by saying I have a 86 xj 2dr 2.5 4cyl. I know nobody likes a 4cyl. I've been working on getting it in tip top shape since I bought it. It was bone stock and it only cost me $600. It needed a clutch and a fuel pump. I lifted it wheels and tires ect ect. However, ever since I got it running "right" I have noticed that it has some problems. Intermittently it would run great and then it would run like crap not really anything major but just enough I knew something wasn't right. I replaced the TPS, MAP rebuilt the throttle body, new coil, plugs, wires, cap, rotor and a new exhaust. Still it had problems and occasionally it would run great (mostly after a long day of wheeling). Finally I noticed that when the windshield wipers were working good the engine was running good and vise versa. So I decided I would clean the grounds cause it's alway looked crappy very dirty and covered in oil, but I've never had a problem before on my chevy's or anything. Besides it looked like a huge PTA to get to because it grounds to the motor behind the ac compressor and the motor mount, but I cleaned it today and OMG my jeep has come back to life. I could have done this several hundred dollars ago. I've tried to make myself feel better by saying "oh I would have replaced that stuff anyway" but I know me, I wouldn't have. So I guess the moral of the story is.... Check the stupid things first. I've read post after post of people having similar issues to what I was having and never realized that ground was so important. CHECK YOUR GROUNDS!! thank you that is all.


If I wanted your opinion i would have asked for it!

It's a good point. ON the 4.0 one of the trouble spots is the cable that goes from the rear of the head to the firewall. It's a braided copper strap, and it deteriorates invisibly. The copper just turns to dust, but if it's not disturbed it looks pretty good.

Grounds are the first thing I do when I get a "new to me XJ" Find a FSM they list the grounding points and show all grounds in the wiring diagram.

Or use this:

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.
　
　
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 11-28-2011

Nice


If I wanted your opinion i would have asked for it!

Matthew Currie said:

It's a good point. ON the 4.0 one of the trouble spots is the cable that goes from the rear of the head to the firewall. It's a braided copper strap, and it deteriorates invisibly. The copper just turns to dust, but if it's not disturbed it looks pretty good.

Click to expand...

Interesting, mine was either nickel plated or stainless steel, and never corroded. I always thought it was the stock ground strap on my 87 and the 89 when I bought them used 4 and 7 years ago.