tbburg
NAXJA Forum User
- Location
- Scottsdale AZ
Interesting experience with a coil rail. ('00, 4.0, auto)
I've had the intermittent "rough idle at hot start" problem since I've owned the jeep. Never bad enough to mess with it. On the few occasions it's lasted long enough to throw a code, it's always been "misfire, #3 cyl, intermittent". It's a known problem, usually assumed to be related to overheating of the #3 fuel injector from heat soak.
Anyway, over the last summer, the problem became more frequent. This time, multiple codes for misfires on all three front cylinders individually, and intermittent misfires on the front bank(1,2,&3) 'Didn't feel any different then before while misfiring, and the Jeep still ran the same when it wasn't in "misfire" mode.
My buddy the Dodge mechanic suggested replacing the coil rail, which I did.
I didn't have any more hot start misfire problems for the rest of the summer. Problem solved, carry on.
Now for the interesting part. I've been pretty good at recording the actual mileage I get on road trips. It's been remarkably consistent over the years, to the point I can set the cruse control at any highway speed and know what mileage I'm getting.
'Went up north to visit family for Thanksgiving. The jeep gets 1mpg better mileage then it's ever recorded - since 2003 when I bought it.
So my guess is the new rail is throwing a hotter spark then the old one was(even before it went bad). Any other theories?
I've had the intermittent "rough idle at hot start" problem since I've owned the jeep. Never bad enough to mess with it. On the few occasions it's lasted long enough to throw a code, it's always been "misfire, #3 cyl, intermittent". It's a known problem, usually assumed to be related to overheating of the #3 fuel injector from heat soak.
Anyway, over the last summer, the problem became more frequent. This time, multiple codes for misfires on all three front cylinders individually, and intermittent misfires on the front bank(1,2,&3) 'Didn't feel any different then before while misfiring, and the Jeep still ran the same when it wasn't in "misfire" mode.
My buddy the Dodge mechanic suggested replacing the coil rail, which I did.
I didn't have any more hot start misfire problems for the rest of the summer. Problem solved, carry on.
Now for the interesting part. I've been pretty good at recording the actual mileage I get on road trips. It's been remarkably consistent over the years, to the point I can set the cruse control at any highway speed and know what mileage I'm getting.
'Went up north to visit family for Thanksgiving. The jeep gets 1mpg better mileage then it's ever recorded - since 2003 when I bought it.
So my guess is the new rail is throwing a hotter spark then the old one was(even before it went bad). Any other theories?