Keith

Eagle, thanks for the response, I will follow your suggestions and keep my fingers crossed.

Engine was driven about a mile after it lost all the oil (hole in pan), had Mobil One oil in unit. Engine now will start and run with minor knocking, when it gets hot, oil pressure drops to zero at idle, picks back up when accelerated. Bearing problem? Or engine destroyed?

Next dumb question, does a replacement unit have to be programmed to the vehicle VIN?

Cruiser - Thank you, really appreciate the advise!

In replacing the ECU on my 89 - 4ltr - 5 speed, do the numbers off of a replacement have to match what is in the unit? If not what units will interchange?

Replaced the CPS, have also gone thru your tips, still no start. Could it be the ignition module?

Quit running and now won't start. Checked coil and there is no spark (new coil). Suggestions to follow?

Thank you, the green wire did the job. Have a Bosch FIX 7853 Remote Starter Switch.

1989 4 L. Manual 5 spd., what is the correct way to hook up a Remote Starter Switch?

Changed the O2 sensor and the MAP sensor, neither helped. Filled up today 11 mpg as compared to 17 -20 in the past.

Have had Commanche for 15 years and never changed O2 sensor, will try that. Thank you

1989 4.0 5 speed, out of the blue it has started running very rough at idle, runs great as the RPM's increase but my mileage has crashed from 18-22 Hwy to about 13 and less than that in city. Any suggestions?

Did all of the suggestions, hoses clean & OK, TB was dirty, cleaned, engine runs better still not 100% but driveable. Thanks to the responders.

1989 4.0 engine with 5 speed. Engine started stalling recently when it comes to an idle, runs fine from 1000rpm and up. In checking things I removed the rubber hose that runs from the valve cover grommet to the intake manifold and the engine runs, hook the hose back up and the engine quits. Any suggestions?

Thank you!

89 4.0 with 5 speed manual. Fuse block has a 15 amp fuse and it is marked Pass/FL, what does this fuse control? Keeps blowing but I can't find anything that doesn't work when it is blown.

Can a 231 transfer case be replaced with a 242J in an 89 4L with a five speed manual?

I had the massive leak which I surmised was the Rear Main, left a big pool every place I stopped, one nice day last fall I was changing the oil and filter and I noticed oil around the filter adapter plate where it bolts to the block. Make a long story short, replaced the three "O" rings on the oil filter adapter plate and no more leak! The oil would run down the block and then to the back of the pan and bell housing and appear just like a rear main leak. O rings were hard as a rock, easy replacement job even for a novice.

After you try the suggestions and if you still have a problem, try tightening all of the intake & exhaust manifold bolts, some are hard to get at but it cured my problem. I fought the fast idle for months and cleaned and replaced everything in sight - tightened the bolts (some were only finger tight) and my problem was solved. Have driven over a year since with no problems. Loose manifold creates vacuum leak.

Ignition lock & cyl replacement - 89 Commanche - Pictures? How to?

What you are witnessing when you open the hood and see the glow around the wires and plugs is a condition called "corona", there is an electrical field around your ignition wiring. Most people think it is voltage leaking from the plugs or wires but not so, has no negative impact on proper ignition.

I get a consistent 19-20mpg around the city (live 10 miles out so partially highway miles), freeway at 70 mph 23-25mpg. Have an 89 4 ltr with a 5 speed, clean injectors and Champion Double Platinum plugs. Short bed with almost 200,000 miles.

1989 4ltr 5speed - can the transfer case chain be replaced without removing the transfer case from the vehicle?

The E3 plug is just another gimmick, spark plugs are best defined by their heat range and electrode material. Standard Champion Copper plugs are well suited for your Jeep but the Champion Double Platinum or Irinium plugs will give you better performance and longer life, Platinum and Irinium are the best electrode materials regardless of brand, they require less voltage and wear much longer, cost is the only downside. Do some shopping on E-bay and you might find some priced way down.

I have an 89 4ltr and fought the high idle and poor start for months, read a post on here to tighten the manifold bolts for the cure and I laughed, with nothing better to do one day, I checked a couple of the easily accessible bolts and guess what, they were loose. Went thru the entire manifold from front to back and several bolts were very loose. Tightened up all bolts and my idle is down from 2000 to 600-800 and it starts and runs like new. Several of the bolts are very hard to get at but its worth the effort. The loose bolts allow vacum leaks and the resulting poor engine operation.