[cnc]

So driving the car today and started running rough....so get it home put my timing light on the ign wires got two dead cylinders...
Anyone know what these 3.8's are known to be bad for.....

[Lightfoot]

Take it to a parts store chain that does free diagnostic code reading, or borrow a friend's scanner. that should narrow it down pretty good.

Don't know if GM was still using the 2x3 coil packs in 2009 but if so, it could be one pair of coils went bad. If the two dead wires are on a single pair, I'd suspect em'. Check them with an ohmmeter and compare it to the other two pairs.

Also, closely check the cables that weren't firing for damage from mice nibbling.
Seen that on a couple cars that sit outside at my house.

[77 TRASHCAN]

Originally Posted by Lightfoot

Take it to a parts store chain that does free diagnostic code reading, or borrow a friend's scanner. that should narrow it down pretty good.

Don't know if GM was still using the 2x3 coil packs in 2009 but if so, it could be one pair of coils went bad. If the two dead wires are on a single pair, I'd suspect em'. Check them with an ohmmeter and compare it to the other two pairs.

Also, closely check the cables that weren't firing for damage from mice nibbling.
Seen that on a couple cars that sit outside at my house.

I agree. Had a 98 that had the 3-2 coils.
Chris you get your car, all painted up, yet?
I’m still going to measure that air cleaner.
Jeff

[cnc]

Ok thanks for the heads up Quick look it looked like 2 different coils but was too cold out to get a good look at the wires...
Car is in the shop for paint hope to get it back in the spring if all goes well...hahaha actually forgot about the aircleaner....

[grandam1979]

Sons Bonneville 2000 something did it also had the same coil problem.

[Peter Serio]

If it's got a 3800 series II V6 engine, a few years ago my car had that exact same problem 6 cyl car acted like it was running on 4 cylinders.

It turned out to be the ignition control module, it's located right underneath the 3 coil packs.

There is a 22 or 24 wire connector on the forward edge. Basically that module replaced a moving distributor in the modern FI cars.

It takes inputs from the ignition switch, crank sensor as well as several other sensors to decide when to fire your spark plugs.

Those do go bad from time and from heat under the hood. Beware; there are low priced knock-offs of that module!!

To get a good one you should be spending around $150- $175. They have cheap ones on-line that sell for $50 or $75 but those only last about a year,....... or less.

[Sirrotica]

A plug wire going/gone bad will route the high voltage coil through the module causing it to fail. I had that happen in one of my 3.8 Bonnevilles. If I remember correctly, I went to the wrecking yard of a friend of mine, and got a used low mile module.

When you start getting an intermittent miss don't neglect it, as it will turn into not only a set of plug wires, but also a module.

[cnc]

Well got it solved ......module was bad and made the one coil pack non functioning.....put the new module in all good....I also have a set of new wires and plugs to install they are due to be done so need to do it...thanks for the leads....appreciate it as always