Keep in mind I just got this 88 cherokee less than a week ago.

Went to hit a mudhole in a friends pasture on the way it started to sputter like it was about to run out of gas, so I floor it just incase so I can coast it to his house. Didnt run out of gas, made a few passes in the mud hole (nothing big at all) Started sputtering again, but would seem to clear up when I would floor it. Finally it got so bad it wouldnt stay running. Then I was able to get it to start back up and feather the pedal a bit. Idles at like 300 rpms now! But cant drive it. Thought just incase it was out of gas we should pour some in , so went and got 2 gallons. Nothing changed.

Now the upper portion of the engine was not wet all all so nothing up the intake and no wet dist. (took cap off it was dry). Anyone have an idea what to look for in the morning when I go back to look at it?

 

Bump

Any ideas? 19 views and nobody?

 

It could be one or multiple of the many sensors or wires u need to check and see if u got any codes. Search " key trick " and that will tell u how to get codes off it

 

Key trick doesn't work on renix era jeeps. Gonna have to get a multimeter and check sensors, also you ought to check fuel filter and make sure its not clogged.

 

I would share the link but I'm on my phone. But you can test all the sensor on the renix. I would start with the crank positioning sensor and throttle positioning sensor. Or your fuel pressure. That's easy to check with a gauge. Most parts store rent them. Could be a clogged fuel filter. Some time and testing.




This should be it: http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

Ok thanks guys. Look forward to the renix testing proceedures. Replaced CPS a few days ago.

 

Went to look at it and it started up and drove home better than ever !!! Whatever!

So I changed the fuel filter, it was terrible full of rust. Poured a little lucas injector cleaner in the tank. Seafoam thru vac hose, changed oil and filter. Havent really got to drive it yet while I had it up on the lift I found out the drivers side hub assembly is bad so didnt want to drive it to much. Drove it around the block and seems to be ok as far as running is concerned.

@BigZXJ thanks for the link. Bookmarked it!

 

Water in the secondary ignition.


I use silicon greese on all the ends of the plug wires, plugs, dist cap towers, and around the dist cap base.

If you get water in between the plugs and wires and let it run while missfireing for a while you will get black carbon tracks that will cause more problems in the future.

 

Here's what you do when you get a "new to you" Renix era Jeep. Don't shortcut anything and this will save you countless headaches down the road. Takes less than an hour and costs $20 if yo opt to add some ground cables.

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

Since it's an 87, do this, too. very important:
Renix Jeep C101 Connector Refreshing
　
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.

Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101.
The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together.
　
　
Revised 11-29-2011

 

Cruiser54, I Have seen you post this on several threads. Great suggestion. When ever I get time I'm going to do this to my renix. Do you have any other suggestions that the engineers might have only put a half a thought into?? Seems like you know the renix and I would like know the beast.

 

Here is the outline of Renix write-ups I have done or intend to do. Note that the ones I have written have an asterisk next to them. Tell me what you want and I'll post it.

　
Revised 11-27-2011
* means instructions have been written.
　
1-Ground refreshing, adding engine bay grounds, link to Kelleys WIP*
1a-Improving the instrument panel ground*
2- Checking sensor grounds*
2a- Repairing sensor grounds*

3-C101 Connector Refreshing*
4-Connector and relay /receptacle refreshing
5-Coil/ICM contacts*

6- Snugging up intake manifold bolts
7-Throttle body and IAC cleaning
8-TPS testing and adjusting*
9-CPS testing and adjusting*
10-CPS wiring bypass
11-ECU connector refreshing
12-Distributor indexing
13-O2 sensor diagnostics
14-Setting base idle
15-Valve cover mod

 

Wow, that's alot of choices. Its hard to choose just a couple. I could PM you my email address and send me all if it would be easier. The ones I'm most interested in are 5, 10, 12, 14, and 15. I greatly appreciate the Info. For some reason the Renix fascinates me, I guess its because you can't hook a computer on it to tell you the problem. You have to figure it out. Some of the stuff I have been learning, alot of problems are just simple if you put time and effort into it.

 

Only 5 and 10 are done so far. 12,14 and 15 have yet to be written. PM me your email address or I'll post them up here for ya.