I would sing this for you arto, but I am tone deaf and cannot carry a tune.

OK, checked the plug gaps, they were all off, So AC Delco probably sucks. On the flit side I should have tested that before hand and not been such an idiot.

Once all plugs had been gapped correctly I was still misfiring on 3. We tested that with a light tester in the connector (a small light bulb was placed in the connector of the injector for cyl. 3, and did not flash, as it did in any other connector), failed, we (my mechanic really, 'we' means I was just standing there asking stupid questions) attached what I can best describe as a wide plastic clothes pin, then he inserted what looked like two needles into holes on this clothes pin, and tested for continuity, both lines tested good for power. So, we then replaced the connector on the wiring harness to the fuel injector. Reset the computer and all looked / tested good, no misfires.

On the way home, about 30m into my drive it started misfiring again, this time on cyl. 5 and 3, no longer 6 and 3. Once home I reset the computer again, and now it's back to misfiring on cyl 3.

I then went to the salvage yard to see about pulling a computer, there were none to be had of course (apparently a hot commodity), so I thought well I'll pull a wiring harness, at least that will be half the battle.....NOOOO it appears that whomever pulled all the computers was too lazy to disconnect the harnesses and instead cut all the wires, of course this was probably more than one person. I think that's just a sign of pure laziness. So please, if you pull parts from a salvage yard, try to maintain the integrity of the remaining parts you don't plan on using so the next guy can use them if needed.

I have priced out a refurbished computer on eBay, about $147. I will meet with my mechanic again to discuss, but I think this is my next item to be replaced, and or the wiring harness.
Link to refurb'd computer:

https://www.ebay.com/p/633009666?iid...SABEgI9DfD_BwE



Any advice is appreciated.

Someone asked about the fuel injectors, I place the link below. As far as whether or not they function better than what I had before, I don't know. This was my sons XJ so I don't have anything to compare it to, and right now the misfire is keeping me from having an opinion on it right now.

Link to fuel injectors:


DR

 

Will that ECU work? Its for a 4.7 V8 per the listing.

 

It would appear not, thank you.

This one?https://www.ebay.com/itm/2001-Jeep-C...AMXQobdQ8zL8DR

I'm apparently tired, and not reading these correctly, i'll catch up tomorrow.

DR

 

Contact them with your info to see.

Please e-mail us below information after purchase, thanks.

1)Vin number

2)Actual mileage

3)Part No.

**Part no. not match, don't worry, please send e-mail to us, we may have one can be match for you.

Make sure you have same part no. for your vehicle before purchasing. Please email me with any questions before bidding.

 

Yeah, I did read that. Before I order this a drop another 150 on this thing I wanted to touch base with my mechanic and get his opinion. I was supposed to go work on his network yesterday, that didn't work out, so maybe he'll call today and while I'm there Ill bring this up.

DR

 

Met with my mechanic today, he also believes that the computer has gone bad.
Ill update again once the new computer is installed.

DR

 

Installed a new computer today, the computer was removed from a work XJ.
Cyl. 3 is still misfiring.

WTF!!!

 

frustrating..here is a few things I would try

cant see that you have checked compression, leakdown, or borescope ..could be some issue such as carbon, valves, cracked piston..once compression at least is ruled out

I would be inclined to "spark test" ..its a very cheap tool, sees how far spark will jump a gap..if spark is good, I would replace or substitute No3 plug, wires, coil pack if you have coil over plug?

also run the engine at night and look for any arcing

next I would replace or substitute no3 injector

last of all, run a "piggyback" wire from injector 3 to PCM

 

Fuel Injector is bad, out of the box.
I moved the fuel injector from cyl 3 to cyl 4 and the misfire code followed, I'm now misfiring on cyl 4.
I am working on getting another fuel injector to replace what appears to be bad one, once i do and test ill update this thread again.

DR

 

not solved

this worked for about 24 hours, my wife just called to let me know the check engine light is on again. Ill post that code later.

 

I have not yet checked compression, plan to have my mech. do that soon
I have no idea what leakdown or borescope means.
This model has the ignition coil as one long bar across the top of all 6 plugs, that is new.
I can touch base with my mech. about a spark test, prob. at the same time he does a compression test.
After I swapped the 3 & 4 cyl. fuel injectors the misfire followed the injector, from 3 to 4. I have now purchased and replaced that fuel injector, as stated above that lasted about 24 to 48 hours, now the eng. light is on again. I am currently at work so I won't be able to pull that code until I get home today. I will update further at that time.

DR

 

Checked the error code: P0455, Evaporative emissions (EVAP) system-large leak detected

Assumption: this code was not previously detected due to a misfiring cylinder code taking precidence
Assumption: this code may have been the original code before I began any work on the vehicle. My son had chosen to ignore the code (even if this was not the original code I can pretty much guarantee my knucklehead son did/would have ignored it, unless it was the 'out of gas' light he would not have cared)

I am thinking either the catalytic converter and/or the exhaust system is bad. The exhaust pipes/muffler are pretty rusted, but honestly I have not done a real inspection on them. I'm in Colorado/Denver so right now is not an option with ice, snow, temp in the 20s and dropping, this will have to wait until Saturday.

Question: other than taking it to a muffler shop or a mech. is there anyway to determine if it's muffler or the cat converter?
Question: are these items easily replaced by a novice such as myself?


DR