P0300 now.

[james1965]

well earlier I thought I might have had a trans problem with it chugging under load. I had 0 codes , nothing even in the history. yesterday however, I managed to get a p0300 and a misfire on cyl #4. So I put all new ac delco iridium plugs in it 41-101. I pulled all the coil packs off the ICM and checked the connectors for any kind of debris. made sure the blades out of the icm were clean and then I put a little dielectric grease on them. put it all back together and it cleared out the misfire right away. Or so I thought. took it out and soon as I hit 1600 rpms under a load it just sputtered, through a check engine and then it went to a blinking check engine light. when I got it back home and rescanned it, all I got was a p0300 random misfire. thought while I was in there i'd clean the MAF so I carefully removed it, it looked ok, but I lightly sprayed it with CES MAF cleaner , let it dry and then reinstalled it. took the car for another run and still the same thing. I did smell something hot under the car and figured it was the Cat Conv. so I unbolted the cat and it seems to be clear. I had a spare Cat from my other Bonneville that was scrapped so I put it on to test it out. this Cat was cleaned out, no ceramic in it.. just a empty cat. this is how I wanted to see if it was a cat issue being plugged. well it made no difference as well. Tomorrow i'm going to try some of the simple things, like check for vacuum leaks, make sure there isn't a squirrel making a home in the air box, ect... Kinda taking guesses at this point. at idle it doesn't miss a beat.

[AJT2004]

Did you also try running it with the MAF disconnected? Sometimes a faulty MAF can cause driveability issues

[96 SSEi]

you didnt mention the wires - did you check them? does your scan tool have freeze data of the code?

[james1965]

I have not fully checked the wires. I did however look for a short in them. in the dark while running it with the engine cover off, I checked for any arcing. moved wires all over, made no difference. and they were replaced 2 years ago.
on the Maf though, I have not tried it unplugged. ( makes a note to run that tomorrow )


and the scan tool I was using at the time was a actron, not near the quality of the ones i'm use to using. but to answer that, no freeze data. My Solus Pro has been broken for 2 weeks. Snap-on has it and who knows when i'll get it back from repair. he keeps saying, I need to upgrade blah blah..

[96 SSEi]

for the wires, get a spray bottle of water and spray a mist and you will see arcing if they bad

[MKMike]

for the wires, get a spray bottle of water and spray a mist and you will see arcing if they bad

x2
2 years would be a rather short time, but you never know...
a wire could have rubbed against the dipstick tube or manifold and damaged the insulation.

Without the ability to look at live data, it's surely a more difficult task.

Typically a miss under load is an ignition system breakdown.
Bad coils are not uncommon and of course the ICM might be on its way out.
I'd invest in at least 1 coil or coil and ICM from Harofreak00 (aka Andrew) or from your local junkyard.
With today's lack of QC, new isn't always better.
ACDelco will be the brand to buy if you do decide on new.

It would be wise to also check fuel pressures and, if not done in recent memory, change the fuel filter.

[james1965]

Just a update sorry it has been a while. dad passed away from cancer and so the SLE was put on hold. In any rate, yesterday I bought a ICM with new coil packs, installed them in minutes. crazy how easy they were to install. and seems to have cured all the problems. car runs fine, no missing, no bucking or anything. I don't drive it every day, but it sure makes me smile to know I can count on her again. such a beautiful car. GM shoulda killed Buick not Pontiac. Love my Bonneville. ok sorry to the Buick people..

[96 SSEi]

nice!, good you have her running as the gm engineers intended. sorry to hear of your loss: my sympathy

was the car originally your dad's? hand me down?

[MKMike]

Very sorry for your loss.

Thanks for posting back. Glad to hear the SLE is running well again.