XJ1997

Hello, I bought a 97 XJ from a guy that did a complete AX-15 conversion (from auto), Motor, trans and transfer case. Of coarse it had the P1899, P0743 and P0753 codes for the missing trans... That I can deal with...

When I got it, it was running fine and suddenly bam, P0203, Cylinder 3 injector malfunction and P0303, Cylinder 3 misfire...

The exhaust smelled very rich so I pulled out that spark plug and it was soaked in gas as the others were dry. This proceeded AFTER I replaced that injector...

So I finally took it to a shop, (never do that, hate having others work on my vehicles), The guy took four days to tell me one of the O2 sensors were cut. And he asked me if I had the PCM from the manual motor. I did have it so I replaced the O2 and disconnected the battery and put in the correct PCM. Ran fine for 10 minutes and the misfire in cylinder 3 was worse.

I love jeeps and want to keep this for a while but I am very close to junking this piece of **** very soon if I can't fix this. Don't have the time or money to leave it with a shop.... Someone help me please.....

98 JeepJeep

replace the plug in that cylinder if you havent done so yet...than replace that injector with another....

XJ1997

I replaced the injector already and tested the old one and it was fine. I'll try changing out the plug but I feel it's something between the injector pigtail and the PCM. Or the PCM itself.

mike albo

try changeing the plug wire to

XJ1997

Hey everyone, I just went out and replaced the plug and it made no difference. As far as the wires go, they are newer and show no signs of wear.

For some reason it's the cylinder 3 injector f****** up. It's gotta be beyond the simple stuff now. I've replaced all the little things...

If it is the PCM that sucks because I dont know the VIN from the donor jeep.

mike albo

just cuz the wires look good, do not mean they are,trust me on that

XJ1997

I switched cylinder three with two other wires and still the same issue. Could it be a MAP sensor? A friend of mine had a K5 and after muddin it ran like **** turned out to be the MAP sensor.

huntingman2706217

your gonna get booted off here cursin like that... this isnt pirate... i would go back and edit what you said (reason im not quoting you)... if you read the newby stuff you will find that they dont mind it but spell it all out... itll "bleep" in its place and we can all figure out what your saying from that... but says not to * any letters... just lettin ya know before they do... the hard way... lol

huntingman2706217

plug, injector, plug wire, distributor cap and points if you got one... but in this case i dont think you do... other wise itll be electrical and in that... im no help... lol

98 JeepJeep

ya your prob not getting a good spark to that cyl...just cause you swapped wires doenst mean anything....that terminal on the bottom of the dizzy cap could be corroded and not making a healthy spark...by or borrow a inline spark tester.

XJ1997

Thanks for the heads-up huntingman...

Okay here's what's new with this. I spoke to a reliable source today and they advised me of an issue that's been known to plague the 4.0's...

He told me the camshaft lobes are prone to premature wear and can throw off the timing on any said cylinder causing unburnt fuel to foul plugs and sensors leaving behind fresh gas, thus making it look like a misfire due to a bad injector or an idiotic PCM. However I'm still very skeptical about the P0203 injector malfunction code... Hmmm. And the distributor looks clean with no visible cracks or strange wear.

myredxj

Type in the search engine"heat soak". Mine had the same problem for about a year. Number three gets vapor locked. Its a really odd problem to have considering i have only seen carbed older vehicals do this.

XJ1997

That would be a probable reason except when vapor lock occurs it is very difficult to turn an engine over and that's not my problem, nor do I have any cooling issues.

That was interesting article though. Thanks.

XJ1997

Thanks everyone, the problem is solved!!!!

I spoke to a guy that works next door to my shop and he mentioned something about the wiring harness that runs behind the valve cover rubbing through the insulation and grounding the injector wire. Sure as heck I checked it and BAM problem solved!!!! Hope this helps anyone with this isolated misfire problem!

I provided a link below with image.

http://www.facebook.com/photo.php?pi...&id=1734110915

huntingman2706217

thanks for coming back and posting what was wrong... alot of people just fix it and forget us... lol