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Mis-firing on cold start


Capri22SS
01-06-2005, 07:28 PM
Just a quick question: 1999 Montana....3.4L....I have a mis-fire in the engine, just 1 cylinder but after it warms up it runs fine. I thinking it may be an intermitent coil pack. When it mis-fire's the service engine soon light is blinking, but when it clears up the engine light is on steady. If anyone can comment, please let me know.

Glen_T
01-07-2005, 05:55 AM
Can you have the code read at Autozone or a place like that? That would really help pinpoint if it is the coil pack, an injector, or something else.

The coil pack is a likely suspect, but too expensive to just swap and try it....Good luck, Glen

Capri22SS
01-07-2005, 07:48 AM
I really don't have access to an AutoZone here in the Chicago Area. Last night I did pull each spark plug wire from the coil pack and all seam to be working. I'm now suspecting an injector, spark plug or a wire. I just did the lower intake gaskets and I probebly should have changed the plugs when they were easy to get to. I'll check those first to see if I can identify which cylinder it is. Thanks for the reply.....

Glen_T
01-07-2005, 01:03 PM
I think other places will read you codes for free.

Not always wise to pull plugs while running. Best to pull the wire, start the car, check for misfire, shut it off, repeat.....some of the electronic ignitions used to warn against pulling wires while running, but it may not matter anymore.

Still could be a thermally induced coil fault....glen

Capri22SS
01-07-2005, 10:04 PM
Thats exactly what I did. I removed each wire from the coil pack with the engine not running. Then refired and was able to witness a good spark from each coil. That was the good news. Tonight I proceeded to take a chance and check continuity on the spark plug wires. Since the problem was getting significantly worse every day, my thoughts were that if there was a broken wire, the arcking in the wire may have spread wider to a point it couldn't bridge the gap. Well low and behold, wire for cylinder #6 did not have continuity when checking with an ohm meter. All the others were fine. I replaced to #6 wire from a new set and problem solved. It's now beating on a 6....WEEOO.

I'm not sure if the computer codes would have told me there was a broken wire or not. I may have pointed me to cylinder #6.

When the weather warms up, I'll change the rest of the wires.

Thanks for all the feedback guys, and if I can help out any of you, I will....

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