Hey y'all, haven't been here in a while. I have another question that's probably been covered before. My friend has a 2000 3.0 coupe that runs very rough. Cylinders 1-5 are misfiring. Plugs were replaced about 6-7 months ago and still look like new. Any input is appreciated!

 

Does your engine have the coil over plug layout or a distributor? If coil over plug, I suspect one or maybe even two bad coils.

 

This doesn't really fit in the "Suspension" forum, so I'll move it to General Tech.

 

This car has traditional ignition (distributor w/ wires). Multiple misfires on this system can mean many things; spark plugs, wires, distributor cap, rotor defects or fuel delivery issues (injector, fuel pressure, fuel filter).

Suggest checking wires at night w/ engine fully warmed. Spray spark plug wires and distributor w/ a heavy soaking of water from fine mist hose or other device to soak. Crank while looking for sparks jumping from wires to ground or distributor to ground. If sparks are seen, spark plug wires, distributor cap and rotor should be replaced.

If no spark issues, then fuel delivery should be investigated by measuring fuel pressure at idle and under an rapid throttle opening. Check w/ vacuum reference line to fuel pressure regulator connected and disconnected. Pressure should be 32-40 psi w/ vacuum connected, and 41-48 psi w/ vacuum disonnected.

good luck

 

Has the EGR port on the intake manifold had the stainless tube installed on the car? Are there any other codes OR are there any other electrical issues including interior lights, etc.?

 

Oops, not sure how I managed to do that. I was really tired and out of it. Sorry. Lol

COP ignition.

The codes were P0108 (MAP sensor), P0300 (random misfire), P0302, P0303, P0304, P0305, P0306, and I believe P1399. So it's actually cylinders 2-6 and not 1-5 as previously stated.

 

Sorry for misinformation on distributor ignition. I was relying on a shop manual I have.

Having 5 COP's out or even intermittent is unlikely and suggests a fuel delivery or air/fuel control issue (intake air leak).

No other codes besides misfire?

Suggest checking Long Term Fuel Trim to see if there is any trend that migh suggest an intake air leak.

good luck

 

Seems like more than 1 person has posted about getting multiple misfire codes and it turned out to be only one or maybe 2 coils. Not all 5 that are showing codes.

 

True. Suggest swapping coils, clear codes and see if miss fire shows up with applicable codes. If the miss fire(s) change cylinders then bad coil.

 

I am one of those folks who reported one bad coil resulted in numerous misfire codes being thrown.

As has been suggested, start unplugging the coils, one by one, and then listen for the one which doesn't make the engine run even worse; that's your bad coil.