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RTPG
10-09-2009, 02:20 AM
My XJ ran perfect last night. I took it to town today and while leaving the post office it coughed and sputtered. I ended up having to drive in reverse for a while, then I put it into 4WD low range and idled home. Anything more than idle caused it to almost die.

At home it would start normally and rev up fine while not in gear. I tried driving again but it would cough and sputter so I reversed back to my garage and then it started to die in gear. It would start up and run/idle until I put it into gear. As soon as I put it in gear in died.

Eventually it wouldn't start at all.

We pushed it back onto the cement in front of my garage and then I tried a bunch of stuff to get it to work.

I've replaced the CPS, tested it according to the Haynes and Chilton's manual, even bypassed the factory plug and hard wired it.

I installed a new coil as well.

I've checked all the fuseable links and fuses. All check out.

The coil does not have spark. :stars: :confused:

What controls spark?

BlueXJ
10-09-2009, 08:10 AM
ECU controls spark but it should not be a spark problem. Check the new wiring to the CPS. I bet it has a bad connection. Did you solder the wires when hard wiring it? It only carries +/- 5V so it is kinda sensitive.

Mudderoy
10-09-2009, 09:11 AM
Check your grounds around the battery and anything going to the block. If you don't see anything hanging (not connected) then run a bypass from the firewall to the block (that big strap back there) and see if that solves it.

It may be that when you put it in gear the engine torques and the ground is being lost.

Here's where I found this information... :link: (http://www.justanswer.com/questions/2c391-1988-jeep-xj-start-run)

Other than that I would check the fuel pressure, and or change the fuel filter. I don't know why it would work in reverse if it was a fuel problem though.

RTPG
10-09-2009, 04:35 PM
Check your grounds around the battery and anything going to the block. If you don't see anything hanging (not connected) then run a bypass from the firewall to the block (that big strap back there) and see if that solves it.

It may be that when you put it in gear the engine torques and the ground is being lost.

Here's where I found this information... :link: (http://www.justanswer.com/questions/2c391-1988-jeep-xj-start-run)

Other than that I would check the fuel pressure, and or change the fuel filter. I don't know why it would work in reverse if it was a fuel problem though.

You hit it dead on! It was a loose ground wire that was attached to the rear of the passenger side of the block. It was still in the big yellow connector but it would go in and out enough to cause the spark to stop.

It starts now but runs really bad. Bad hesitation and missing on at least one plug/injector.

I read somewhere that the CPS has to be aligned perfectly up against the top edge before tightening it down??? Perhaps it's off just enough to cause this runablitiy issue?

It ran really good before I did all of this so I'm guessing the hesitation and missing is related to either the new CPS, new coil or maybe another wire that came loose?

Also have a new fuel leak that wasn't there before. It's at the end of the fuel rail. :mad0090:

AND: I broke the exhaust donut when changing the CPS so now I have a major exhaust leak. :stars:

This is fun. :rotfl2:

Mudderoy
10-09-2009, 04:39 PM
You hit it dead on! It was a loose ground wire that was attached to the rear of the passenger side of the block. It was still in the big yellow connector but it would go in and out enough to cause the spark to stop.

It starts now but runs really bad. Bad hesitation and missing on at least one plug/injector.

I read somewhere that the CPS has to be aligned perfectly up against the top edge before tightening it down??? Perhaps it's off just enough to cause this runablitiy issue?

It ran really good before I did all of this so I'm guessing the hesitation and missing is related to either the new CPS, new coil or maybe another wire that came loose?

Also have a new fuel leak that wasn't there before. It's at the end of the fuel rail. :mad0090:

AND: I broke the exhaust donut when changing the CPS so now I have a major exhaust leak. :stars:

This is fun. :rotfl2:

Well I was very happy when I started reading the post, but I got progressively more and more depressed. :rotfl2:

That bad ground had to have caused the computer to be very confused. Disconnect the battery for 30 minutes to reset it.

If that reset doesn't work put the original CPS back on. The bright side is you can't break the donut again! I've never changed my CPS, but I was chatting with my mechanic while he was doing it. He just undid the two bolts, put the new one up there and bolted it down. He was looking at me talking most of the time. (he had the XJ up on the lift) I'm thinking there isn't any critical alignment required.

cheap jeep
10-09-2009, 07:35 PM
If you hook up an induction timing light(the kind you just hook around the wire) and put it on the plug wire close to the plug,it will flash on the plugs that are firing and not on the ones that aren't.

BlueXJ
10-09-2009, 10:39 PM
Could be a bad injector as well. If you have the capability to do a spray pattern test it will help pinpoint if the injectors are all equal in pattern and flow.

RTPG
10-14-2009, 02:41 AM
Could be a bad injector as well.
Ding, ding, ding! We have another XJTalk.com winner. :rotfl2:

It was a broken injector plug. Not sure how it got broken but long story short after pulling plug wires off the cap and figuring out which cylinder was dead, then testing compression (150+) and spark (shocked the beep out myself on accident) I went onto look at the injectors and upon looking closely at the plug of the dead cylinder I noticed it was sitting on the injector crooked and the metal retaining ring (actually square) wasn't all the way on. Upon taking the plug off I noticed one of the 2 wires wasn't all the way down into the plug. After pushing it all the way down so it would connect with the injector I fired the jeep up and it ran great!

The injector plug is broken but it runs good. I think it sould be OK to cut the broken one off and connect a new/not broken one?

BTW: This is 2 for 2 issues figured out by XJTalk.com members. THANKS GUYS! :thumbsup:

DETOURS
10-15-2009, 08:10 PM
You should fix your fuel leak before we read about a horrible fire!

RTPG
10-16-2009, 12:45 AM
You should fix your fuel leak before we read about a horrible fire!
No kidding!

I actually fixed it before we took it wheeling last weekend. Simple o-ring.

All is good now. :thumbsup: