I'm not sure if that's the culprit for sure, I didn't see the actual test on my tps so not sure exactly how their measurements were taken.

I simply believed what I was told and replaced it.

Have you also tried cleaning the electrical connectors to your fuel injectors? Try unplugging one and look at the condition of the contacts.

 

OK, I got ya.

I didn't use a analog meter, so I'm not 100% sure it was at all accurate, so I could watch for steady movement and not see nay drastic jumps.

The harness, it's been visually inspected and I'm 99.9% certain it's free from defects. It's been cleaned, brushed, plugged in, plugged out, test to ensure power, tested to ensure continuity on the injector side, followed the wire back to PCM, cleaned and brushed. Grounds refreshed...

I'm gonna have some time today, so maybe I'll try to clean the connectors on the TPS and pull it out.

thanks.
-jb

 

Well, this weekend I had the chance to replace the TPS.

Changed it out, reset ECM.

MIL went out and didn't return. Ran a few errands, drove about 10 miles, no MIL.

Went to store, jumped back in started to cruise...and BOOM MIL back on. Got home scanned codes - P0204.

Things I haven't done...

-Replace CPS.
-Swap Inj #4.
-Replace PCM.

I've checked and traced the wires from Inj #4 back to PCM. All seem well. Don't really see any visible spots where the wire could be compromised.

Any more ideas...I'm this close to letting a mechanic have at it as it's getting close to winter and I'm not dealing with this in the cold weather of NE Ohio.

thanks.
-jb

 

Did you ever get round to replacing the injector o rings? Is it a possibility to swap injector 4 with a different one in the rail to see if the problem injector moves and throws a different code?

 

Oh, no. I have yet to swap injectors.

No may be the time, seems like a somewhat daunting task. But it's time to put up I guess.

Thanks.
-jb

 

Here's a little something else, not sure if I'm on to something though...

The other night, I wanted to run to the store and the jeepster would just crank and crank and crank and never turn over. I though I could hear the fuel pump engage, so I wasn't too sure.

I didn't really do anything (that I explicitly recall) and she fired up.

Now I'm questioning the ASD relay. I know the SAME DK GRN/ORG wire runs from the ASD and is spliced to Injector #4.

I haven't checked the wiring from the bottom of the PDC coming off the ASD, but maybe I have a crimp/short in the wire somewhere in between??

Does that make sense to anyone? I'm only leaning that way considering what the function of the ASD is.

Plausible or not???

thanks.
-jb

 

If the ASD and its wiring were dicked up all the injectors would be inop; you have just one injector giving you problems.

Before swapping injectors read the resistance of the injector. Remove the connector and read from pin to pin with an Ohmeter. You should see around 12-11 Ohms at 68*F. You can have good voltage to the injector and a good ground from the PCM driver but if the coil in the injector is bad it won't work properly.

If you get around to swapping injectors take a good look at the pintle end (nozzle end) and see if it's all crappy. Look inside the inlet of the injector and see if the inlet filter is clogged.

How long have these injectors been installed BTW?

Have you ever used a good injector cleaner, like BG44K?

Edit: Disregard reading the resistance, I just re-read your original post.

 

Hi,

Ya ohms sit good with all of 'em.

I did come across this page, which seems to be very thorough..

http://www.ls2.com/boggs/dtcs/DTC%20P0204.htm

except I'm not too keen on the terminology used in some steps.

The injectors, well they are factory so 15 years. I did put some Gumout injector cleaner in before, didn't really help much.

thanks.
-jb

 

Get those injectors swapped round

If the code changes you can safely assume you have a problem injector. If the code remains the same you are most likely looking at bad wiring between injector 4 and pcm or a fault with the pcm itself. It may also be worth cleaning the ground to the pcm although that is probably a long shot.

If you have replacement o rings now is a good time. Pretty sure you'll need the fuel line disconnect tool.

ccken also pointed out bg44k. Good stuff.

 

I guess that's the plan!

I pulled a fuel rail from the JY with injectors. Cleaned and tested them all a few weeks back. Grabbed a set of o-rings from AZ [FELPRO's]. Bought a fuel line disconnect.

Only thing that concerned me was that the stock o-rings on the injectors appear to be different sizes and colors. And well, I never came to a definite answer as to if they are different o-rings on the rail side and the intake side. But the majority vote is they are the same...

https://www.cherokeeforum.com/f2/inj...stions-175362/

So, I guess will give it a try some time soon..

thanks!
-jb

 

Perfect. Best of luck!

 

Hi again,

Here's a bit of a twist...(and this has happened more than one occasion - but not the exact scenario).

Today, I jump in the jeep..fire it up. NO MIL is on. No shake no stutter, nthing - running just grrrreat!!! I'm on my way to work just crusing, no MIL.

I come to a red light, and take a right hand turn...slight stutter and BOOM MIL is ON!!! Now I haven't grabbed the code yet - will do so at lunch...

Now, this kinda happened before. I would have no MIL, and when I came to work, and slooooowed down to pull into a parking spot...MIL fires on.

Now..is there a slight chance, then when I'm turning..some wire could be rubbed and shorting?!

I haven't really looked to see where all the wires run, but I know Inj #4 runs along the fuel rail in a ganged loom, back to the fire wall, down driver side fender, under air box, to the PCM.

Strange...right?

thanks.
-jb

 

The wire bundle exiting the wire "ganged loom" takes a quick turn up to the loom that runs along the firewall. There have been multiple reports of wires in that bundle chafing on the valve cover. You might want to check wires this area closely for chafing.

I rerouted that firewall loom so it doesn't hit the valve cover anymore. I'll see if I have a pic of it.

 

Hi,

@CCKen - thanks for the tip off!! I think I found the PROBLEM!!! I triple checked (obviously not VERY WELL!!) the wire looms coming off the injectors...They ride under a plastic clip rail think and come out towards the back of engine, running down the firewall. I took your advice about chaffing on the valve cover, and was inspecting very very carefully. But nothing appeared to be rubbing against it.

Then I actually grabbed the loom...AND WHAT DO I SEE...????



THE END OF THE FUEL RAIL MELTED the loom!!! I peeled loom back..Thus melted the black tape, thus, wire insulation...and there, right there...



...an EXPOSED LIGHT BLUE (INJECTOR #4) WIRE!!!

Ok, sorry for all the CAPS..quite excited. I have to let the engine cool down a bit here, she's pretty hot before I go burning myself trying to shield the wire back up. I'm also gonna make sure no other wires are exposed.

After I'll zip tie the loom FAR AWAY from the fuel rail...

Wish me luck !!!!

thanks!
-jb

 

SUCCESS!!!!!

Thanks to all who had some pointers and direction of what to do. I missed this due to everything look A-OK when it really wasn't. Lesson learned, really, really, really, check your wiring. I didn't even bother to look on the underside of the loom...and there was my problem all along. Exposed wire was shorting on the fuel rail!!!

No more grey smoke from exhaust. No more stinky fuel smell exhaust!

Zipped tie the loom away from the fuel rail!



Fired her up, no more Check engine light!! Time to celebrate with a beer from the keg-a-rator (well what's left of it anyways)!!!



THANKS TO ALL!!!
-jb