I own a 1987 4 cylinder jeep comanche, and after throwing a rod through and out the side of the block, I was gifted a used 4 cylinder motor out of a 97 jeep Wrangler. I did some brief research, and discovered that from 84 to 96, the inline 4 was compatible. I am discovering otherwise as my brother and I troubleshoot for hours basically everyday for the last two weeks, only to get no where... Yes it is educational, but I so want to hear my beloved jeep come to life again... I have read that if the crankshaft positioning sensor is bad, it cause the stalls and inability to idle, and I'm sure you read that considering everything you went through with your jeep. I appreciate your input immensely. I hope that it will help us in our trials. It's baffling, when you have everything connected, and there is no spark. So frustrating, when you read or are told you need a camshaft sensor, only to discover this particular year wasn't requiring one.... Or was it? I've decided that in 1987, the manufacturer of the I line 4 we're using it as a lab that for possible future modifications, and in the frenzy, forgot to make sure it was saavy for the general public. They should have had you to help them keep track of what was going on, and that should have been the manual that was contained in each one, because there is little to no specifically useful information anywhere for the 87 Comanche. It has to be the one that slipped between the cracks. In my Haines book, in the section about distributors, I think it's about 3 paragraphs long, and it tells no details of what is supposed to be included.... It probably doesn't help that the block I'm using is coming from a 97. I hope that I can get this deep to spark and I think that your information will be the most helpful so thank you, newbie

 

The flywheel or flexplate is most likely not the same between an 87 MJ and 97 TJ (on the 4.0 engines, it's definitely not). Did you swap that over? Also, unless you removed the crankshaft position sensor from the bellhousing during the swap, I would be suspicious that it got whacked and damaged. Do you have a meter or some means to check for a signal from the crank sensor or to the ignition module/coil? Is this throttle body injected? Any indication that the injector is firing?

The cam shaft sensor is needed so the engine computer can determine when #1 is on the compression stroke, but I've also heard anecdotally that the older Renix computer would make a guess if the sensor was not working and I have started mine without it plugged in before. On the later coil-rail models with shared coils, it really shouldn't be necessary since it fires on both intake and exhaust stroke but many do anyway.