1999 Chrysler Concorde Fuel / misfire

ONEPROUDVET

MEMBER
1999 CHRYSLER CONCORDE
6 CYL
FWD
AUTOMATIC
200,000 MILES

Ok, my car has no problem starting while cold -to- normal operating temps. But, if the car is in the range of normal temp. & Were the fan kicks on, it eithier won't start at all -or- starts very rough and I have to work the fuel pedal to keep it running. At this point I have to hold the pedal down until it evens itself out or wait till the car cools.

Now, somtimes the check engine light comes on. I've had it checked at AutoZone and they tell me that it's a missfire on 5 & 6 or 3 & 4. It seems to vary here. I have changed out the coil overs for thos cylinders with no luck.

I called the Dealer and they tell me it's the fuel pump in the tank. They tell me it sounds like a fuel pressure problem.

BUT, I would like your opinion on my situation because that's a costly repair if I can't do it myself. Note: I only use good quality gas. I use Cheveron gas with Lucus add. The spark plugs are good and the car is well maintained. But this is hard on my engine.

I need advice. Thank You!

1 Reply

ERNEST CLARK

MECHANIC
1,730 POSTS

The quality of your gas wouldn't cause this problem. If it were, you'd have problems all the time, not just when hot.

Also, don't bother with the "Lucus" additives. That's snake oil in a bottle. So long as you use good gas, and change your fuel filter when necessary, you'll never need a gas additive.

Now as for you issue, when you say you changed the "Coil overs" for those cylinders, are you saying you installed new "Coils" for those cylinders? If you've done this already, then I suggest testing both the crankshaft position sensor and the camshaft position sensor.

You'll need to be handy with a DVOM to do this. And I recommend purchasing a "Single vehicle" subscription to a data service such as AllData or Mitchell 1. This will provide you with not only the procedures but illustrations and specifications as well. And it'll come in handy on your next project.

If your CKP and CMP check out, then you could do a pressure test on your fuel system. If you are getting "Multiple misfires", and you've isolated the ignitions system as a possible cause, I'd think your's would be an electrical problem since it occurs only when hot.

So when your engine is hot and your are experiencing this problem, listen to your fuel injectors with a stethoscope to see that they're firing at this time. If they are, proceed with a pressure test, both static and operating.

Compare your readings to spec. If your static pressure is out of spec, suspect the fuel pump. If your operating pressure is out of spec, suspect your fuel filter or injectors.

Good luck.