EGR Valve

[newfiejeff]

Will the EGR Valve cause a misfire and will the following cause a misfire with no code being generated.

Fuel Filter
Coil Pack
EGR Valve

I have new wires, plugs for about 4 months with no problem til about now. I have checked for vacuum leaks with no problem. THere is no problem with starting or lack of power going up hills, the gas mileage is about the same but just got a small misfire not a backfire, it doesn't matter if its cold or hot. Idling is fine except for a scattered misfire.

2002 Pontiac Montana 3.4 with about 160, 000 km.

Any ideas

Jeff

[1999montana]

Originally Posted by newfiejeff

Will the EGR Valve cause a misfire and will the following cause a misfire with no code being generated.

Fuel Filter
Coil Pack
EGR Valve

I have new wires, plugs for about 4 months with no problem til about now. I have checked for vacuum leaks with no problem. There is no problem with starting or lack of power going up hills, the gas mileage is about the same but just got a small misfire not a backfire, it doesn't matter if its cold or hot. Idling is fine except for a scattered misfire.

2002 Pontiac Montana 3.4 with about 160, 000 km.

Any ideas

Jeff

My neighbour had a 1995 Lumina van that needed to be emissions tested before the plates could be renewed.

The connection to your question(s) lies in this story.

He took it in to a friend who had all of the diagnostic gear and could do the work for very little money (my neighbour is retired).

They worked on the van for about three days, replacing worn out Ox sensor, EGR, air filter, plugs, wires and new injectors. Still had a miss and would not pass the test.

Since this vehicle doesn't offer up clues as well as the newer vehicles do through the ECM, it was a little hit a miss to say the least.

Finally, they replaced the fuel filter (turns out it hadn't been replaced since the vehicle was new!) and what a difference this made.

Ran fine, no miss and passed with flying colors.

Having said that, the fuel filter (if it hasn't been changed in 60,000 or 80,000 Kms or during the life of the van) is a candidate. If the injectors are OK, but a little dirty, two good bottles of STP injector cleaner should help with that.

If the EGR is sticking open it could effect the mixture and cause a rough idle. You could try cleaning it, but replacing it is low cost and a good maintenance GP anyway.

I've read somewhere in one of these threads that coil packs can cause this, but I would think since one coil pack services two cylinders, you should theoretically have a miss on two cylinders.