Misfire and Catalytic Converter?

[Devast]

I recently got my 2000 ETC back from having the A/C redone (compressor and blower). When I picked the car up it was misfiring. Had run perfectly when I dropped it off. The guy who did my ac, a friend who is a Ford mechanic, said it was misfiring on #3. He checked and cleaned the plug but it immediately misfired again. His opinion is that the Cat is bad and back-pressure is causing the misfire. He suggests I get it replaced, then tune it up. (apparently they are the original plugs so with 110Kmi it needs to be done anyway)

I always figured it was misfires that caused the cat to go bad, not the other way around. What do you all think about this? Do you think a fried cat can cause this type of misfire? Should I replace the Cat, or should I do the tune up first? Obviously Im confused.

If its any help the OBD is showing current codes: P0134 P0300 P1359 B0856

Any advice is appreciated.

TQP

[Ranger]

I never heard of such a thing. This guy is an ASE certified mechanic? I would not spend money on a CAT to fix a misfire.

P1359 - Ignition Coil Group 1 Control Circuit
This sounds more like your problem. I just don't know what Group 1 Control Circuit means.

[Necrosan]

I would advise you and anyone else who knows this guy not to let him touch your/their cars.
Lots of money will be going down the drain, and no problems will be solved. (Except the old heavy wallet one)

[dkozloski]

Whenever you see the word circuit in a trouble code, immediately substitute the words wiring and connectors for circuit. Your mechanic broke or unplugged something when he was messing with the A/C. He probably knows what he did and doesn't want to accept responsibility and pay for the repair.

[submariner409]

Do a lot of homework in here and Northstar Performance and read up on how to change the plugs - use only ACDelco #41-987 Platinum. www.rockauto.com or Luke in Parts at Lindsay Cadillac over there >>>>>>>>>>> It's not the cat, and you're overdue for plugs by at least 10,000 miles.

Check the wiring connector at the ICM on each coil pack - the black area at the end of the pictured (front) coil cassette. RockAuto may have a few DELPHI coil cassettes with ICM left, but they're $185 apiece - one gray, one black.

Also check the fuel injector connector for each injector. A carefully loosened injector electrical connector is good for lots of diagnosis time........If your mechanic checked and cleaned one plug he did one hell of a lot of disassembly for nothing, because #3 is on the rear side of the engine and requires a LOT of work to get to.

[Devast]

Are the coil cassettes (black and silver) interchangable or do I need to replace the black one with a black one?

TQP

[submariner409]

I have 2 new cassettes on the shelf, one gray, one black. Except for different part numbers they are identical, as are the ICM modules in each.

Why GM made the front cam cover/cassette gray and the rear cam cover/cassette black is beyond me..............

If you want to keep the "look", stick with black. Me.......take anything the junkyard has in the same year/engine (VIN 9 or VIN Y). Yours is VIN 9 - the 8th character in the VIN.

[Devast]

OK, so as an update. I took 1/2 a day off today and replaced all the plugs and coil boots. Used the OEM replacements all of which I was able to get fairly easily. Looking at what came out of the car that job DEFINITELY needed to be done so Im happy about that. Unfortunately, it didn't fix my problem. The car is still misfiring. It is bad enough that at idle there is a rattling from underneath the car. At this point I could believe the cat is bad given that the misfire situation has been going on for a few days now. But if it is, I think that is a consequence of the problem, not its cause. Currently Im getting codes P0131 P0134 P0300 P1357 and B0856.

Unless you guys have some other suggestions, I think my next step is to replace the Coil Packet only Im not sure which one "Group 1" is. If I had to guess I would think the right (rear) one but Im not sure. Today I called about 15-20 salvage yards locally but nobody has any Eldos. I live in the Dallas/Fort Worth Metroplex... surely there is one here somewhere.

If they are interchangeable as stated above I could care less about silver or black. I just want my smooth ride back!

tqp

[submariner409]

A coil cassette from any 2000 - 2003 4.6L Northstar VIN 9 (300hp) will fit and work correctly. Seville STS, Deville DTS/Concours, ETC.

[Devast]

Ok, I found what Im looking forin a yard across town. my current question is can I safely drive my car over there without doing any significant damageto it. its about 25 miles. If I can I can do the work just down the street from the yard and make sure everything works. if its not safe to drive it then Ill have to wait until tomorrowto go get the part.

[Ranger]

Sure you can drive it. It's a misfire. Annoying, but not damaging.