: Revised Emissions Woes



BlackHatch
07-22-04, 05:56 PM
Failed again on the high HC and CO levels. I had previously changed out the plugs, fuel filter, PCV, and air filter as well. I tested the resitance on the wires and was right around the 5K/ohms per foot rule. Cadillac of course, states in the service manual to be no more than 15K ohms on any wire regardless of length.

I did and diagnostics on it and all the PCM data indicates that everything is in range. MAP sensor was functioning normally and under WOT match atmospheric pressure. Fuel trims were slightly low, I think compensating for the slightly rich condition as a result of bad wires. O2's also seemed to be functioning between the ranges provided for in the book. Anybody else got any suggestions besides wires.

I did notice that on the power balance test that when I dropped the injectors on cyclinders 7 and 8 that the idle did not change dramatically. I am guessing that these wires/coils may be shot.

What are the testing limits on the coils for Cadillac and how do you test them....standard resistance testing...?

zonie77
07-22-04, 11:54 PM
Did you check the fuel pressure regulator? How about the injectors on 7&8?

BlackHatch
07-23-04, 02:09 PM
Did you check the fuel pressure regulator? How about the injectors on 7&8?

No, I haven't checked either of those but I was just looking in that direction because I did not notice a real appreciable difference in idle quality with those injectors shut down. That indicates to me that somehow those cyclinders are not really firing at a good rate if it did not really kill the idle that much. I will check into those other items as well though.

BlackHatch
07-23-04, 05:23 PM
BTW...how do I check the coils minus replacing them in lieu of a good one...?

BlackHatch
07-25-04, 11:31 PM
bump

growe3
07-26-04, 04:45 PM
BTW...how do I check the coils minus replacing them in lieu of a good one...?

The coils are all the same. Swap two of your coils

If the problem goes with the coil, the coil is likely bad.

If the problem stays with cylinders 7 & 8 you may have bad plugs, plug wires, or injectors.

Also try misting the coil and spark plug wires (with water and a spray bottle) at night or in a dark environment; look for arcing.

-George

BlackHatch
07-27-04, 01:25 AM
The coils are all the same. Swap two of your coils

If the problem goes with the coil, the coil is likely bad.

If the problem stays with cylinders 7 & 8 you may have bad plugs, plug wires, or injectors.

Also try misting the coil and spark plug wires (with water and a spray bottle) at night or in a dark environment; look for arcing.

-George

No visible misfires. I just think the wires are worn out as are the coils. I am ordering some GM replacement from P and G and I will see about throwing a couple of new coils at it as well.

I thought there used to be a way to just test the resistance on a coil to see how good or bad it was... :hmm:

growe3
07-28-04, 01:20 PM
No visible misfires. I just think the wires are worn out as are the coils. I am ordering some GM replacement from P and G and I will see about throwing a couple of new coils at it as well.

I thought there used to be a way to just test the resistance on a coil to see how good or bad it was... :hmm:

The coils pop off very easy. Swapping a couple would be a free way to check them, instead of "throwing" parts at the problem.

If you do decide to replace them, MSD-8224 coils are a good replacement. Summit has them for abour $38 each.

-George

BlackHatch
07-28-04, 03:34 PM
The coils pop off very easy. Swapping a couple would be a free way to check them, instead of "throwing" parts at the problem.

If you do decide to replace them, MSD-8224 coils are a good replacement. Summit has them for abour $38 each.

-George

Does that 38 bucks cover just one coil or are two spark plugs run off of one coil...ie are there four coils or eight...?

growe3
07-29-04, 01:43 AM
The $38 is for one coil. You have four coils; each coil fires two spark plugs.

You are looking at about $175 ($160 + shipping & taxes) by the time you get all four coils.

That is why I would advise you to just swap a couple of coils to see if the problem follows the coil. If it does then that coil is bad.

It may also be as simple as the coil tower connections are corroded, and can be cleaned with steel wool or a wire brush to get a good connection. The towers should have nice bright metal showing to make a good connection.

Each coil is easily removable, they are held down with two 7/32" hex screws.

-George