Time to replace the coil packs?

[RedogOnyx]

I've been getting very small misfires for a while.

I replaced the plugs and it ran a little bit better (ACDelco Rapid fires #14), replaced the wires with the MSD set for the Grand Am 8.5 mm wires v the 8mm Accel wires that were 5 years old and I broke one pulling it off #3 and after a lot of backfiring at first it runs a lot better.

It's still missing a little bit thou. When I get on it, it misses right before the shift point / rev limiter. I did this last nite driving to work, put it up to 5800 and it missed pretty bad but it was so quick I didn't get off it before putting it to just under 6 grand and it missed again. It bucks when it misses now since putting the MSD's on, but it's only happening at very high RPM's

1 on the coil male ends shows a little bit of browning, looks like rust, 2 others are totally browned. Don't know if I want to take contact cleaner to them or just replace them all together. Personally I think I'd rather replace them. I also didn't forget about the gasket under the coil packs

Does this sound like the coils or the ign mod which I really don't wannt replace.

Orginal coils, 109,915 miles

[no_doz]

AC delco plugs? i dont know about you guys but i dont run those unless i dont have money for anything else (which is VERY rare), ive never had good luck with AC delco, which is sad considering they are one of the oldest spark plug companies out there.

but then again ford is the original automotive company, so...:P

also you could take the ign control module and have autozone, o'rielly, or advanced auto-test it.

[WrathOfSocrus]

ive never had good luck with AC delco

Oh so you haven't had any luck with most of the parts under your GM hood? I've seen Delco plugs go for 200k miles. Sure the electrodes were ugly but it was still able to spin the tires in a minivan.

Just like my '82 Buick Century said on the air cleaner, "KEEP YOUR GM VEHICLE ALL GM! USE ONLY AC DELCO REPLACEMENT PARTS!"

In my experience the coils themselves usually perform worse at lower RPMs when they are going bad but I wouldn't rule it out without testing the resistance of the coils first. I did one car and the one coil had a visible crack so I replaced it and that didn't fix the low RPM sputtering problem. When I tested for resistance one of the other packs had a resistance just 1 ohm higher than the others. Replaced that one and it was running like a champ. I would check the packs for visible damage and consistent resistance on each of the coils.

[robertisaar]

on 3100s, ACDelco is the only way to go for plugs. anything else gets devoured within 20K miles. my delcos on the other hand lasted 150K and the only reason i replaced them is because i cracked the porcelin pulling one out...

[geldartb]

ive never had good luck with AC delco.

im sorry but your either screwing something up or theres something wrong with your car.

ac delco plugs are in the engine from the minute its assembled.

its funny though your the only one on this site that will say they have problems with ac delco plugs.

[AaronGTR]

I've never had trouble with delco plugs. Of course, they aren't for performance either though so I only run them in my GP.

On topic, I also think it could be the coils and would recommend checking the resistance with a multimeter. If they appear to be fine, pull the ignition module and see if you can get that tested.

[pocket-rocket]

I normally run Rapidfires in my car, but I think I am going to switch to NGK this year. Don't get me wrong, I like my Delcos, but they are all brown at the base of them (where the metal meets the porcelain) which means they are leaking. That compression would do better being used in my engine instead of escaping. I thought maybe I got a defective set, but I tend to change my plugs as part of getting my car ready for the summer routine and it has happened on more then one set. And no, I am not running crazy retarded compression- it's stock compression atm.

[geldartb]

i had a similar problem.

it would idle and with light throttle (cruising around town) be fine but the minute you threw some heavy load on it it would miss pretty bad.

i swapped all the coil packs and the icm out with another set and it went away. im gonna heave them test later since they are the basically new set that came with my motor.

i was scanning for misfires and nothing came up. but since i swapped them out it runs awesome and pulls pretty good too.

they prob have about 8k miles on them.

[neo71665]

I have never had any problems with AC delco plugs.



Just to add Ford is not the original automotive company, Henry Ford just incorporated the assembly line process and made it work in the automotive world.

[robertisaar]

^X2, i believe Benz was the first...

[neo71665]

Kinda depends on what exactly you classify as a car, I think the stanley steamer was the first to come out with a horseless carriage but then again it was steam powered.

[robertisaar]

considering everything thats come around recently, the defintion of "car" has become VERY broad. so, i would say the first "vehicle" to move under its own power. thats a car.

[SofaKingWeToddDid]

maybe the signal is jumping from one wire to another?? how closely are they ran together? i think this can be testes with a spray bottle full of water, spray the plug wires and look for electrical jumps?? i remember my dad telling me something like this when i had an older nissan that was misfiring... it had really cheap ass old plug wires on it though... maybe one of the new ones is being pinched somewhere??

on the side note:
i use AC platinum and havent had ANY problems in 4k... lol i just put em in and took out some NGKs. they looked alright too and must have been in the motor for a decent amount of time...
ive had too many people tell me to use delco that im not gonna bother with anything else.