93 xj no start.

Ill give you the rundown. 93 cherokee 4.0, auto tranny.
Replaced just the spark plugs. Set the gap. The jeep started up and ran good for a couple of weeks. Last night I wanted to replace cap/rotor and wires. I unscrewed the dizzy cap and pull it off. When I look down one of the thread holes for the dizzy cap crumbled. Sucks but I had a brand new dizzy. I slid it into place keeping the rotor pointed the same way as the old one. Put the old rotor on. Put the New cap with new wires on. Start up the jeep and it idles fine. When I gave it gas it stumbled big time. I put a new rotor on tried to start it. Idles fine but stumbled when I gave it some gas. Put the old rotor back on same condition. I then took the dizzy out, pulled the spark plugs out. I hooked a compression gauge up to #1 cylinder and turned the motor over by hand. Needle moved and lined up the timing mark with 0 degree. slid dizzy on and it pointed to #1 on the dizzy cap. Now it wont start. I also tried this procedure using my finger over #1 to feel the air being pushed out. Set the timing mark to 0* and repeated process. I read a service manual everything seems to match the steps perfectly. I have dead timed many motors and am stumped by this one. I have unpluged/plugged in the dizzy connection, coil connection and the cps connector. There is good fuel pressure and good spark. I also tried holding throttle open while cranking. I got it to run a couple of times but it is very rough and smokes. Which tells me the timing is off. Again I tried to dead time it. and get the same results. I tried dead timing it with the dizzy out and the dizzy in. Please help.

Seems like you are on the right track with timing it. Not too sure why its not working unless you messed something else up when the timing was a lil off. Sorry I can't be more help.

Post up here once you figure it out though I would like to know what the problem was.

I swapped in a new computer. Made no differance.

The only thing that comes to mind, and it seems trivial, but we've all done it... double check the firing order... I had an old AMC engine I was tuning up one time, and SWORE I had everything perfect, but it was giving me all kinds of BS trouble like you are tallking about, and it turns out I had the firing order all wrong even though I knew I had it right! LOL

Man I've posted this same problem numerous times, and I really feel your pain! I had done the same as you for 2 days straight and I still couldnt figure it out. If you are confident that your at true TDC (have you set it with the timing mark to 0?) and your plug wires are on the right way (not 180 the other way, or off even 1) and the Dizzy is actually sitting in the right slot all bolted down and snug, and your Cam sensor is new or at least good, and it still wont run? The last time I had this issue I found that my coil was bad, (I did the same as you and replaced the computer as well). After all that it was my coil, yeah it would fire and barely idle like the timing was bad, but the coil was shot. I tested it by (not reccomended LOL) with it out, running a ground to it and clamping it, then I ran from the battery a hot lead to the coil post, what I found was even though it showed current (blue electical arc) it was more like a lawn mower barely visible arc, and not the typical solid blue arc that would be from a good coil, (FYI if you can,dont touch either one :scared I hope this helps?

Dizzy is bolted down tight. I followed all steps in finding tdc. Rotor is pointing where it should be. Put #1 wire on then #5,3,6,2,4,. I also pulled the rocker cover off so I could make sure both springs were relaxed when turning the crank to 0* on the timing mark. I tried putting the old rotor on the new cap and also putting the old cap back on. No change. Fuel filter was changed a couple of weeks ago also.

Here is some dumb questions; is your Cam Sensor plugged in? Are your plugs wires in the right sequence? Is your coil wire plugged in? Are you getting enough spark? If your not it will run like crap, like the timing is off.. I'm just attempting to cover all of the sometimes missed bases.

It appears that your sequence is correct, but I've really messed it up by installing the plug wires in the right sequence but the wrong location on the cap, LOL apparently thats how I learn.

coil wire is on. Plugs are in right order. The plug on the dizzy is plugged in and so is the crankshaft position sensor. I dont know where the cam sensor is? The ign coil is plugged in and im getting spark at the wires.

If all is correct, then the dizzy must be off a tooth. It might be close enough timing wise to start and idle, but it appears that you're off just a little bit? I hate to say it, but you may need to pull the dizzy again, reset everything to TDC O and re-seat the dizzy. May I ask; did you scribe a mark before you yanked it the first time? Because that really would be your only indicator that the dizzy is seated properly, by re-aligning to that mark?

The cam sensor is in the dizzy, thats the plug and wire that comes out of the dizzy.

Yes it was marked. The jeep would start and idle fine. Once given some gas is fell on its face. It was getting late so I called it quits for the night. The next morning I replaced the rotor. Started it up and it idled fine. When I gave it gas it stumbled. I put it in drive and idled into the garage. After that no start at all.

I've heard of the dizzy being exactly 180* off and causing crap... that was when the guy had it marked, but said he somehow lined it back up with the mark "backwards" That's hearsay from a guy in a shop, and I don't really know how you could do that, but it's a thought. I don't think that's what you did by any means, and I'm sure you'll figure it out... Good luck

Sounds like you know what you're doing. Only one thing I could suggest (out of desperation) -- try putting the old distributor back in and rubber band or duct tape the cap on. The last time it ran good was with that old distributor????????

Tried a new ign coil just to try it. Made no differance. Also tried the old cap rotor and old dizzy. Made no change. One questin I have is...Under normal good running conditions, what part acutually will advance/retard the timing? Im used to old v8's with a mechanical advance and you have to turn the dizzy to set time.

the only thing changed id the dist. i would make sure it is indexed properly

tkiller13 said:

One questin I have is...Under normal good running conditions, what part acutually will advance/retard the timing?

Click to expand...

The computer uses CPS signal to manage the ignition timing.

I used this link http://www.angelfire.com/my/fan/dist_index.html
Everthing on mine matched.

i dont know the accuracy of that method. there is a method where you line up the rotor with the #1 tab inside the cap

After all the new parts, it must be lined up wrong. I've done that where even though the dizzy appears to be seated correctly and the tab will even line up to where I could bolt it back in, it still was incorrect. You know how you start the dizzy at almost 180 degrees at the top and then spin it into place? Try not starting that seating process in the same position, try spinning it in at different positions like 183-186 degrees or 174-180 degrees, when that damm dizzy seats correctly you'll know it, and the freakin thing will run like nothing happened, even though you're hands are busted up and your patience is gone! :thumbup: