My Daughter's jeep will die and then not start. The jeep is a 96 XJ Sport 4.0, aw4.

I have cleaned battery posts, replaced the coil and CPS, I have swapped relays to see if it is the ASD relay. No change there because I switched the ASD with the fuel pump relay and I can hear the fuel pump kick on. I checked fuel pressure numerous times and it will pump at 49-50 psi while running. After shutting off the engine to see how fast it drops pressure it consistently loses about 10 psi over a 20 minute period. That seems reasonable to me, but what the heck do I know! Also, the gauges work properly and codes are 12 43 and 55. The 43 is engine misfire I believe and it was misfiring while running a little, but not much, before I replaced the CPS and coil.

I plan to go back to basics and recheck grounds which I did when I was cleaning the battery cables, but plan to go over the grounds with a finer tooth comb this time.

Just wondering if anyone had any other suggestions, like maybe the pickup coil in the distributor?

Thanks in advance for any help.

 

What you really need to isolate this is the full code. It would be a PXXXX code.

What you have pulled (through the key-on, key-off technique?) is the two digit code. Not nearly as helpful as the full code, which for a 96, is available.

Get a code reader or a scan tool or go to a store like Autozone who will pull the code for free. Post it here for comment.

The full code isolates way more than the two digit. 43 is related to the ignition, (coil possibly, but you replaced the ignition coil it I know) but let's see what the full code calls out before installing any more parts. This does not sound like a fuel problem.

For grounds, you must actually FRESHEN them. Can't tell a thing by looking at them. Here is more on that....
----------------------

Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

Thanks for the replay TJwalker.

I know I did not get on the grounds so the ones you mentioned help a lot. Tomorrows task is to go through all the ground connections and anything else I can find

I am a considerable distance from any Autozone, etc. that can read the P codes for me. Would it be worth the money to get one of those inexpensive code readers from the likes of Harbor Freight or Autozone. That is about my only option given that I can get the jeep to drive a mile with out dieing out.

I have another question for you. I had the front bumper off her jeep recently and moved the small canister for the cruise control. I also had to replace some cracked/broken line going to it. Do you think that has any bearing on my problem. I just consider it coincidence and not related to my problem. The cruise control does not work and I have never bother to find out why and my daughter has never asked about it.

Again, thanks for the help.

 

Yes, an inexpensive code reader would work. But for about $15 more, you can get a decent code reader. I like the Equus brand of testing equipment. Decent quality and great price; I have had nothing but great luck with them and have set many others up with them. Check amazon, the 3020 or 3030 will set you back less than $50. I'd recommend that way before the one from Harbor.

 

Here's some things to check:
Check all sensor plug connections making sure they are not loose, and clean. apply dielectric grease to them, is that CPS plug faulty/burned?
(they get torn up sometimes)
Is the MAP sensor and its hose ok? (no leaks/disconnected)
can you repeat the problem consistently, or is it something that you can only repeat during a specific event? (ie: only when warmed up)
does it eventually start again? only to run then die ect repeatedly?
could be fuel pressure dropping from a weak pump, and you just happened to get that good reading before it dropped.
or its definitely electrical
according to this search Link code 43 misfire IMO points to a fuel system issue or interrupt/short in the ignition system.

 

Fuel pressure readings were done multiple times over the course of an afternoon. Fuel wise, I have not replaced the filter which I will do this afternoon even though it is not a very old filter.

Thanks for the areas to check.

 

Jeep details: 96 XJ w/ a 4L and aw4

I have: replaced the coil, ASD relay, and CPS. I have refreshed all the grounds that eveoryone has mentioned. I replaced the mesh ground strap off the back of the engine, It wa replaced it with a #2 gauge ground strap. I added a ground strap of #4 gauge wire from the battery to the engine by tying in into the front AC bracket mounting bolt. I added about an 8 guage wire from the bat to the radiator mounting bracket. Suffice to say I feel confident the damn thing is grounded! I can bounce around any part of the engine and body and get 000 ohm readings on my multimeter.

What I do know: I get power to the ASD relay in a variety of options. If you want I can get more specific. I do not get power to the the coil. I checked with my multimeter set on volts and at the plug going into the coil and I get nothing. ZILCH, ZERO, SQUAT!. I checked backward from the coil plug all the way to the PDC (green wire w/ orange trace). I even dismantled the PDC and check from the back side of the PDC block with my multimeter. Set on the ohms scale I get zero resistance telling me the wire is good from the PDC to the coil plug. Yet, I get zero power! I wonder where the black wire from the coil plug goes to. I cold not trace that what one out.

I did get codes of 12 43 and 55. But! Then I found the wiring harness to the upstream O2 sensor had two of he four wires shoiwing bare wire. I cut the bad sections out and soldered in 12 gauge wire to replace the bad sections. I covered them with shrink wrap, wire loom, and zipped tied them away from he exhaust manifold.

Now I only get 12 and 55.

What am I missing? Any help is greatly appreciated because I have no idea what do now.

Ladies and gents I have appreciated the help I have gotten so far and thanks for any suggestions.

 

12 and 55 are informational and not indicative of an actual issue. 12 is memory has been cleared and 55 is end of code messages. Do NOT be concerned about either of these code numbers. 43 however is "ignition control circuit" related. Keep an eye for that one to return.

So we can assume that the symptoms are still there though? Will it not even start now?? Or does it start and die? Devil is in the details.....

 

It used to start, run for awhile, and then die. It would start and idle for 20 - 30 minutes in the driveway. I would think I might have the problem fixed and take it for a test drive. Once it ran for a few blocks it would begin to cut out, and then die all together. I would then have to pull it home.

Now the jeep will crank, but not start. It does not even attempt fire. Just cranks.

I know it is getting fuel because I can smell it in the engine compartment and because of the fuel pressure checks I conducted on it earlier.

 

Those two digit codes are quite vague and in in a situation like this, aren't giving you the information you need. Did you order that code reader? A nice tool to have even when you get past this problem. You really need the full PXXXX code. By my charts, the 43 can be either a misfire or the ignition coil #1 primary circuit. (43 can actually mean 10 different things!)

*I'd pull a plug, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. This would confirm if you have NO spark or poor QUALITY spark. A pretty important data point and a simple test that I always perform with any no-start.

*Check the PCM ground wire (BLK/Tan) on the right side of the engine, clean it up and resecure it...

*I would also re-seat the connections to the computer with a small dab of dielectric grease. I suppose the problem could be the computer itself too, but if you try another one, don't buy it from the dealer, get it from a salvage yard!

*Here is a quote from a guy with a similar problem to yours: "The last thing I've tried (which an aircraft mechanic found by luck and the process of elimination) is there are two torx screws which holds the cover of the PCM on. The screws from the factory are too long, time combined with engine vibration, causes them to occasionally short out the PCM causing it to stall. The screws need to be backed out (about 1/8-1/4 of an inch) or replaced with shorter screws. I backed out the screws (located under the 3 electrical connectors connecting to the PCM, you will have to move the coolant reservoir to get to them). Since I have done this about a month ago no stalling"

*Read the below thread for further information on guys with similar issues:
http://www.jeepaholics.com/support/Topic592473.aspx

*Try a different coil wire just to be sure.

*A bad connection on the IGNITION SWITCH is another distinct possibility

*Where did you buy your crank sensor? The reason I'm asking is that there have been more than a few dead out of the box aftermarket crank sensors. Not saying this is your problem, but it is a possibility. I buy my crank sensors only from Jeep. There was a thread a while back where the poor guy had a bad crank sensor, replaced it with a new DOA one and when that didn't resolve, he replaced just about everything else on his Jeep until he bought a factory crank sensor. Again, kind of rare, but not impossible.

*I'm not sure if a cam sensor would give you a 43, but they can be tested with a manual and a meter. The cam sensor is responsible for fuel injector timing and other things. Usually a failing cam sensor would not result in no-spark, but I believe I remember a thread or two that showed when that sensor failed in a certain way, it could. Below is a link to a gent who had the same problem that you have. Unfortunately, it didn't show the root cause.

http://www.jeepz.com/forum/cherokee-...e-43-what.html

Stay on it and keep us posted!

 

First things first, TJWalker thanks for your assistance. You have been a great help.

I purchased the CPS from NAPA. I had already purchased it before I saw your posts about getting one from a dealership. I have thought about the possibility of it being a bad CPS out of the box.

Well, I have your suggestions in hand and off to the garage I go...

And yes, I have an Equus 3030 on order.

 

dkross.....we are going to get this figured out. Every once in a while, I come across a thread that hits me as one that we need to dig into. This is one of those threads! Your daughter needs her XJ!

Keep us posted!!

 

You know, and I'm just throwing this out there...

Have you cleaned the neutral safety switch?

A friend had an issue of stalling and swore that all he did was replace it to get it fixed.

I'm not an expert on this part, but for the sake of other things to try, it might be an idea.

Worst case scenario, it likely needs cleaning anyway, so it's not a waste of time or effort.

 

While neutral safety switches can often need "refurbishing", the design of them is not intertwined in any way with the circuits that provide spark.
If the engine turns over, (and his does) but has no spark, the problem is not the NSS.

 

I received my Innova 3030 OBDII reader today. Looked through the manual and then went down to the jeep to check the codes. I did it several times and got 00/00 codes. The yellow light came on and stayed on, but no codes. It cycled numerous times without change.

So as it stands right now: No codes, will crank, and won't start. I get power to and through the ASD relay, but no spark at the plug that feeds the coil. Continuity is good from the PDC to the coil's plug on the green/orange wire. no power though to the coil plug.

Would I be wrong to suspect the gray wire on the coil plug as a culprit? It seems to me if I have power through the green/orange wire to the plug then I may not have a circuit if the gray wire has a break or something?