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88 XJ Ignition issues

jsikora

NAXJA Forum User
OK guys hope you can help on this one. I recently aquired a 1988 Jeep Cherokee Chief. The guy that gave it to me told me it wouldn't start and after 175,000 miles he bought a new one. It sat for a year in his driveway. Saturday I towed it home, put a battery in it. Scraped the corrosion from inside the cap, and it started right up. It ran rough but ran. (GOOD SO FAR).

Next I went to the parts store for the usuals, Oil & Filter, Plugs, Cap, Rotor. Went back home and put all the parts on. It seemed to run better, but still scipped a bit. I degreased the motor so I could work on something i could see. The next day it wouldn't start.

So the next Friday I went and got plug wires & a fuel filter. On getting home, I attempted to start the truck, and off course. It now runs great. It gets better. We it started to run warm thne drop off, then back warm (like the thermostat was sticking) so I went back to the parts store to get a thermostat and gasket. Also in my oversellous checks of the vehicle I found a broken coil spring. Of course I ran right home and ordered a 3.5" lift kit for it (why put in stock if I need to rip it all out anyway)

So tonight I went home to put in the thermostat and spray the chassis with WD-40 (BTW Central New York really rusts stuff up). I hopped in the truck to pull it out of the garage to drain the radiator, and yup. IT WONT START. I screwed with it for 3 hours and gave up. From what I see in the book there is a coil, ignition modulale and the engine control unit. I am pretty confident it is not fuel related as I get fuel from the rail on the test port and also spraying eather in doesn't phase it.

I did pull the spark plug wire off, and don't see any spark. I also pulled the Coil wire from the distributer cap and nothing there either.

So thats where I'm at. I could really use some help guys....I told the fiancee it ran great so she let me order the lift kit....

I talked to the parts place and they told me the coil and ignition module came as one unit now, at a whopping 150.00. Is this what I should change, or is it something i'm missing.....

Why can't it be like my cj.....12 volts to the coil...wire from the distributer.....those were the days..

Jeff S.

[email protected]
 
There's a good chance that the problem is the crankshaft position sensor (CPS), which is a common failure with symptoms like yours. That's more likely than the coil. One thing you can try is unplugging and replugging the CPS connector. Sometimes that helps for a while. The CPS is mounted on driver's side, top of the bell housing, at about 1 O'clock as you look at the engine from the front. You should see its wiring harness come up from there to a flat plug. The CPS is hard to reach, and rather a pain to replace, but probably worth doing at that age anyway.
 
since you dont get a spark, it could be the CPS(crankshaft postion sensor) or its wiring harness connection. first try disconnecting the wiring harness,clean it and reconnect. the harness should be on the back drivers side of the block. the cps is located on the top side of the bell housing.
 
Thanks for the help guys. Now according to this haynes manual I have it shows the CPS on the drivers side of the transmission. Am I looking at the right thing ?

Guess what i get to do tommorrow night after work.....

JAS
 
Yes, the connection is right by the firewall

I'm guessing you don't have junk yard close?

Anyway, do you have a high speed internet connection? If so, I can email you a couple things that may help you track this down. [email protected]
 
jsikora

As a fellow owner of a 88 XJ I have lived most of the questions you will ask in the future. I have found www.rockauto.com is one of the best places to get components. They have name brands and overall have good prices. If you can hold off on the parts being shipped it can save you some money.

The problem with our XJs is the Renix ignition system - used 87-90 - has a small customer base any more. It good you want to replace those items now before they disappear.

I think I paid $180 for my ignition module + coil so you are getting a better price!
 
I had the same problem on my '89.

Separate the CPS connector and crimp the female connections a bit, spread the males a bit, slather with dielectric grease, reconnect and wrap the connection with a tie wrap to keep connectors tightly joined.

I haven't had a single problem with this in three years now.

Good luck,
Jay in MA
 
Here is a past post I have often reposted.

If on a crank but no start the unplug and replug of the cps wire harness connector gets you going you may just have a wire harness connector going bad and may not need to replace the cps sensor. Here is how to test: hook volt meter to both wires from cps sensor w. harness unplugged. Set the range on meter to less than one volt. Crank engine and if cps generates .5 to .8 or more volts it is ok and your connectors need tightening or replacing. I got my parts for a couple of $ at pepboy but advanceauto.com also has them. They were made my Dorman under the Motormite Conductite tech grad name # 85303, 85304 and 85305. There are about 5 pieces in each box. You can also get a small tool set that helps on the install number 85360. I fixed my 89 this way a couple of months ago when I got tired of unplugging and replugging the connector every few weeks. My cps was only 1 yr old so the engine side harness connector part was worn out. I replaced both the female and male side internals of the connectors and it not only starts every time but the idle was also improved. Greg

In addition your 88 has the infamous c101 bulkhead connector through which all sensors past on to the computer. It is located on bulkhead above engine on drivers side. It the connection therein get corroded and need to be cleaned and relube with dielectric greas. Also the dealer sells a special cps w. a wire harness that by passes the c101 and goes straight to the computer. Do a search on this forum under c101 and cps and you will probably come up w. that part number. Greg
 
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