Rick R

I have a similar problem to many I've come across in this forum with a 2002 CV with under 50,000 miles on it. Idle is fine but it bucks and acts like it's missing during light accelleration and while cruising at lower to mid-RPM's. It's not a regular miss, feels more like ignition cutting in and out momentarily and very irregular. It's never stalled or quit. Idle and heavy accelleration are smooth.
It's not throwing any codes so I'm at a loss as to where to start looking.
I just recently had my first major expense on the car when I had a dealer replace my fuel pump and filter after the original pump quit. No codes thrown for that either (which surprised me). I would have found and replaced this myself if I hadn't been stranded across metro-Detroit from my home garage. $800.00 was tough to swallow for such a simple fix.

I was very suspiscious of a fuel problem before the pump went. This problem started after $4.00/gal prices and I started hunting for cheap refills. I had 3 vehicles all start lurching like this just last fall but the '99 Taurus ended up needing new plug wires and I think I have the 4x4 pickup nailed down to an O2 sensor. All were running rough after years of reliable service so although the symptoms weren't identical I thought the similarities were more than coincidental- but no longer.

I've read where most folks have focused on plugs and coils. With mine having such low miles, being inaccessible and without any codes I hesitate to start there. I wonder if there are any PCV or air flow units that might cause this type of poor performance. Any guesses?

Bert

I'd pull all the coil packs and see if any moisture got down the holes. Sometimes the boots get a split and they arc out intermittantly. If it has a fairly steady miss on slight acceleration setting still, have someone hold a slight throttle where the miss occurs and pull one injector plug at a time to pin it down. If you find one, switch coil packs with another one and see if it follows. (It still can be a coil pack no matter the miles.)

87_Crown_Vic

have you changed the fuel filter at any point? i know when one of my cars started acting weird and bucking, people thought transmission... it turned out the car needed tune up

Rick R

Fuel filter got changed when my fuel pump was replaced by the dealer.
RTG143- Thanks for the suggestion. I'm not sure I can get the miss out of gear but I'll try that and coil pack inspections.

I was hopeful that I might have stumbled across it myself but I don't think so. I've been bothered by my charging indicator being on the low side of operating range. This last winter I replaced the battery which was the first replacement of anything besides oil and wiper blades. The battery went dead in the extreme cold which isn't too surprising for 7yrs. old. Before replacing it I measured my charge voltage after jumping the car with a battery charger. I was reading about 13.6vdc which I thought was low but OK for a mostly discharged battery. I continued the charge for another 45 minutes via battery charger after shutting the car down. Next morning it wouldn't crank so I replaced the battery.

In the months that followed as I've had this hestation or rough running and the fuel pump problem I've been watching that charge indicator and been concerned a few times when I saw it extremely low. The new battery finally went low and I pulled the alternator and had it tested- bad.

So I was hoping that maybe the rough running was due to low voltages (I'm really surprised I'm not throwing any codes during all of this). New alternator has charge indicator dead in the middle of the guage where I'd expect it. I can't quite tell if the rough running has gotten better since but it definitely hasn't gone away so I still have a problem. I've been thinking along the lines of Throttle Position Sensor or something like that. I'll see what I can dig up from RTG143's suggestions first and then maybe go there.

Long winded but I assume if I keep a running log of indications I might get enough of a history that if I can't find the problem sooner, collectively this might lead to conclusions later. Thank you both for your input.

Martel AUtos

It's most likely a boot or spark plug. I sell police Vics and we have this problem with almost all of them, so we just give them all tune ups and change the spark boots which fixes the problem. Strange that it would happen on one with only 50k though. I guess its because its an 02'