Ok folks, I hate to keep beating a dead horse here, but I'm at my wits' end. 00' WJ 4.0 WAS throwing a P0306, so I took it to the shop, they didn't see anything wrong and reset the fuel adaptives...
It ran beautifully for exactly one week.
We took it for a 200 mile drive, mixed city and highway, with some highway cruise miles of 70 mph. CEL came back, as did the rough idle at stop signs/lights.
OK, BACK to the shop she went.
First I came here, found out to check the harness behind the head, (it's good) and the #6 injector. Told the shop that, and LO and behold, it was bad. They swapped it with the #1 injector, and the miss moved to #1.
So, they ate the labor and put an injector in.
Today, we're out running again, and I'll be DA*#ED if it didn't start doing the EXACT same thing again!
What is it with the whole one week thing?
Does anyone have any ideas? Maybe
A PCM now?
Sheesh. I swear I'm going back to carbureted, non computerized vehicles...at least I could keep them running right.
Oh, I forgot to mention, after they replaced the injector, all last week it's been a bit harder to start when dead cold. Starts right up when warm, but in the mornings and after work, I have to crank it a while to get it running.
But it always ran just fine once it was running...if that helps anything
Next cold start, before actually cranking, turn your key to the "on" position, wait 5 seconds, then turn it off. Do this twice more before cranking. When you go to crank it, see if it starts quickier.
Where is it misfiring from this time? The site of the new injector or same place as before? If it's from the new injector, then Chris is probably right and you got a lemon.
One more thing...forgive my old mind.
It just occurred to me that this problem rears its head only after fairly long (35-40 mile) high speed (65-70 mph) Highway jaunts. My weekly driving isn't like that. Short bursts on the highway only.
Could the coil rail possibly be getting hot and breaking down? It's GOT to have something to do with heat buildup, the miss, I mean. The hard start on cold start is something else entirely.
This TSB describes an issue with the fuel vaporizing in injector #3 after the vehicle has been warmed up, turned off, then restarted which results in a misfire in cylinder #3. To resolve this issue, wrap injector #3 in an insulator sleeve.
Ok, I'll read that, but mine does it while driving...don't notice anything wrong until I get off an off ramp and stop at the light or stop sign. That's when it begins.
Ok, I'll read that, but mine does it while driving...don't notice anything wrong until I get off an off ramp and stop at the light or stop sign. That's when it begins.
I have no way of checking fuel pressure, that would be a shop thing.
Same with the open or closed loop check.
I'm sure it has an EGR, it's all factory.
They checked compression the last time it was in the shop. It was 170 all the way around.
Update. Just popped into Autozone to have the code pulled. (The CEL finally came on) it's P0306 again.
Same cylinder.
New plugs, new injector in that cylinder...about the only thing left it can be is the coil rail isn't it?
It has to go to the shop for that. I don't have to tools to unlock the fuel rail.
Plus, where I live, it's a 20 mile drive just to get a code pulled. I just happen to be in a different town today, taking the wife shopping and passed an autozone. lol
See, I'm kind of in a catch 22 situation.
We're about 45 miles from home.
Agreed. Use only Champion copper or NGK Vpower copper. Also, when changing the plugs, did you make sure you got those rubber boots on the coil rail seated all the way on your spark plugs?
I put the champion coppers in.
R12ECC something something. (can't recall exactly at the moment)
Whatever it said on the underhood sticker. Gapped at .035 as per sticker.
I put the champion coppers in. R12ECC something something. (can't recall exactly at the moment) Whatever it said on the underhood sticker. Gapped at .035 as per sticker.
Do you have a EGR valve? If so remove it and cut a soda or beer can into the shape of the gasket and install it between the gasket and the valve and drive it. The aluminum can won't last forever and eventually melt. But will last long enough to tell a difference.
Ok, I just checked the receipt from the shop. When they replaced the ONE injector, they also saw fit to replace that one spark plug that was only two weeks old. Why? I have no clue.
Guess what they put in?
Bosch iridium fine wire. So, I'm off to buy ONE Champion copper plug, and a new coil rail, just so I know that's not the issue.
Wish me luck.
Ok, I just checked the receipt from the shop. When they replaced the ONE injector, they also saw fit to replace that one spark plug that was only two weeks old. Why? I have no clue. Guess what they put in? Bosch iridium fine wire. So, I'm off to buy ONE Champion copper plug, and a new coil rail, just so I know that's not the issue. Wish me luck.
Well, new plug in and new coil rail on...tiny little bit of help, but not a lot.
Maybe I need to reset the PCM?
I remember something about disconnecting the POSITIVE cable and grounding it against something else...then I read disconnect both and leave them disconnected for something like 8 hours.
I searched this and got even more confused.
I've just got them both disconnected. They're too short to reach each other, so touching them together is a no-go.
P.S. I didn't drive it, I just started it up on the car port. Should I drive it?
Oh, on the old coil rail, every single mounting post (I think that's what they're called?) was cracked from top to bottom, full length. The one between 5 and 6 had a good 1/8" gap in it.
BIG crack. Short maybe?
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Jeep Enthusiast Forums
18.5M posts
726.8K members
Since 2000
A forum community dedicated to all jeep owners and enthusiasts. Come join the discussion about performance, engine swaps, modifications, classifieds, troubleshooting, maintenance, and more!