rough idle

[rogerphillips]

Hello all:
My son has a 1996 Crown Vic police car. It has been a great first car,but is now having a rough idle problem. The OBD code suggest a P0303, which is a cylinder 3 misfire.
We took it to two different mechanics, and paid a total of $250.00 in diagnostic fees. Confirmed not a bad valve. First guy said bad plugs. We changed them. Second guy said bad plug wires. Put in new plug wires, no change. We asked at a parts place. They suggested new coil packs. Changed them, still no change in the rough idle.
We are now relieved of $450.00, and still have the problem. I am thinking of a bad fuel injector on number 3 cylinder? Possible? Parts guy said injectors are a very rare problem on a Crown Vic.
It idles fine in neutral or park, but the minute you put it in drive or reverse, it rocks like a boat on the high seas.
Thanks to anyone with ideas!
Roger.

[reekor]

It sounds like a "Idle Air Control Valve" problem.

Originally Posted by rogerphillips

Hello all:
My son has a 1996 Crown Vic police car. It has been a great first car,but is now having a rough idle problem. The OBD code suggest a P0303, which is a cylinder 3 misfire.
We took it to two different mechanics, and paid a total of $250.00 in diagnostic fees. Confirmed not a bad valve. First guy said bad plugs. We changed them. Second guy said bad plug wires. Put in new plug wires, no change. We asked at a parts place. They suggested new coil packs. Changed them, still no change in the rough idle.
We are now relieved of $450.00, and still have the problem. I am thinking of a bad fuel injector on number 3 cylinder? Possible? Parts guy said injectors are a very rare problem on a Crown Vic.
It idles fine in neutral or park, but the minute you put it in drive or reverse, it rocks like a boat on the high seas.
Thanks to anyone with ideas!
Roger.

[~manuel~]

Originally Posted by rogerphillips

Hello all:
My son has a 1996 Crown Vic police car. It has been a great first car,but is now having a rough idle problem. The OBD code suggest a P0303, which is a cylinder 3 misfire.
We took it to two different mechanics, and paid a total of $250.00 in diagnostic fees. Confirmed not a bad valve. First guy said bad plugs. We changed them. Second guy said bad plug wires. Put in new plug wires, no change. We asked at a parts place. They suggested new coil packs. Changed them, still no change in the rough idle.
We are now relieved of $450.00, and still have the problem. I am thinking of a bad fuel injector on number 3 cylinder? Possible? Parts guy said injectors are a very rare problem on a Crown Vic.
It idles fine in neutral or park, but the minute you put it in drive or reverse, it rocks like a boat on the high seas.
Thanks to anyone with ideas!
Roger.

it could possibly be an injector issue.can you hear it clicking on and off?use a long screw driver and attach the end to the suspected injector and handle end to your ear with the engine running.compare it with the sound of the known good injectors.also have you checked compression at this cylinder? by the way i highly doubt its the idle air control valve as it affects air flow to all cylinders and not just #3.if anything it would cause p0300 for "random misfire"