I have a 1987 Cherokee 4x4 with the straight 6. Sometimes, not all the time, It begins to run rough, with very little acceleration. I've taken it to local mechanic and he can't seem to re-enact it running rough, therefor diagnostic shows no problems. The local dealer says they can't diagnose or work on a jeep this old.

I can't seem to figure out any sort of pattern. Sometimes it happens right when it is started up, and other times it doesn't happen until it is at about 180/200 degrees. It has me baffled.

I've taken really good care of her. It was my dads when he bought it new. All things serviced when needed. Absolutely no leaks anywhere. Super clean engine. Normally runs great and quiet, until it starts running rough.

Any body else experience this and might be able to give me an idea? I would appreciate it.

 

The following tips from Cruiser will help you immensely.

https://www.cherokeeforum.com/f51/cr...x-tips-153657/

...and welcome to the forum!

 

Welcome.

Yep. Start with Tips 1 through 5.

 

Sorry it took so long to respond. With work, school and the weather it has taken me a long time to get it done.

Thanks for all the help. The link you gave, I printed and did most everything. I even did away with the C101 connector.

The vehicle no longer wants to stall and idles perfectly. Thanks!!!

But now it is the exact opposite. idles great and doesn't want to stall when I come to a stop, stays at about 700rpms. But it seems I have lost power during acceleration and seems it wants to sputter (like a muffled back fire).

My local mechanic could not diagnose it, the dealer won't touch it and Pepboys says they think it is in the ignition or some electrical problem. I'm not sure how the ignition could cause this. The dealer did install a new ignition some time back becuase it would start without a key at all, though they said they have no one that could work on the engine because of its age.

I'm going to replace the ECU ($130.00). It was pretty cruddy. I also read somewhere about by passing the ballast resistor. Any other Ideas?

 

Clogged Catalytic Converter? I have had a couple of cars that had the Cat fall apart, internally and they behaved exactly as you describe.

 

I did replace the Distributor, cap and all the fixings (wires and plugs). New injectors and replaced caps when I removed the C101 connector. Replaced the MAP, CPS, CTS, TPS, ISM and EGR too.

 

I replaced CAT and muffler last September.

 

Fuel filter?

 

I'll check it when I get it back from Pepboys today. I have replaced it the beginning of last year when I replaced fuel pump. took 3 fuel pumps before I finally got one that worked from Autozone.

 

I did check my fuel pressure before I took it to pepboys. was idling at 31psi, where it should have been. I did not check it at a high RPM though.

 

Seems like if it idles fine but has problems on accel, then it is some sort of fuel or air restriction. That's why I was thinking the Cat or filter. New Cat should be fine.

 

Test the fuel pressure at idle.
31 with the vacuum hose connected to the fuel pressure regulator: 39 with it disconnected.

Don't replace the ECU yet!!

Dirty injectors? If so, there is a really cool upgrade for under $100.

 

replacing the injectors was the very first thing when my original problem started. Wish I had read about the 703s before.

 

Which injectors did you use? New, used, or refurbished?

Did you replace the distributor?

You've performed 1 through 5? If so, what readings did you get in 5?

 

I replaced with new injectors. I think GP/Sorenson from Autozone.

I replaced distributor with new everything, including plugs and wires.

Number 5 test I had A/B reading 4.89 with B/C reading .839