Damage # 3

[SuperBuickGuy]

So now I'm down to one car.... my GTO. AKA my DD. With the snow, the car had a nice wash before it started, filled the tank and I parked it. Making sure to have everything disconnected from the battery (I'd had intermittent problems with the battery going dead if the car sat for more than a day)....

Saturday, the snow still wasn't gone, but I was out of other cars. So I manned the snow shovel and cleared the driveway... okay, halfassishly cleared it... first, the battery was dead - grand, whip out the charger, but I seriously didn't have time to figure out the problem. We take off in the morning, and make it a bit out of my driveay - stuck on the hill... why's that I wonder, I have a limited slip. And the dealership swore it worked fine (I went ahead and added some swearing of my own). No problem - I get the truck (it does have 2 gears - and pull the car (nice they have anchor points for shipping) up the hill. .... so two problems, manageable.

We get on the road and I'm detecting a slight miss... wtf? I get to our destination, and the miss is worse. It's a misfire from 1000 rpms to 1400 or so, when the motor is lugging. So avoid that and keep the revs up. Sat. night, I whip out the laptop, call up HPTuner software, plug it into the car and look at that.... no codes. ARGH!!!!

So I keep playing with it, first had to fight the scanner software (nope, can't have scanner and tuner connected at the same time).... then the battery goes dead. double ARRRGGHHH!!!!

charge the battery back up, put the update tunes in it.... won't start, fortunately I'd saved the original tune....

Get the car out this morning and have the laptop plugged in - recording the data. Still no code (even though I'm getting pretty good at making the thing miss). Finally, I make it miss for several seconds (until the check engine light comes on) - do I have a code? yes! I do... yay? nope - I have a "potential code, unverified" P 0300 - as we all know by now that's (say it together) a misfire.... 400 software to tell me what I already know.... awesome.

Fortunately, I was recording data and while it didn't tell me what - it did give some interesting clues.
1) the misfire occurs under load from 1000 to 2000 rpms.
2) Prior to the misfire, the Knock Retard tells the car to retard the timing (it's so you can run unleaded or super and it won't destroy the car).
3) What's interesting - in at least one occasion the timing was 6* BTDC, and the KR was telling the ignition to retard the timing another 3*....
4) oh Thank God for this - I have a 12m 12k mile bumper to bumper warranty - but I couldn't remember what the exact mileage was when I bought the car... 36797.... drum roll - I have 48227 miles on the car - IT'S COVERED!!!!! so the 3 major priced problems are on GM's dime AND I get a rental car while they fix it....

did I mention I needed to pick up a transmission? - try lifting a 700r4 into the trunk of a GTO, a can off coffee barely fits back there....

So... what are your guesses as to the real cause of the misfire?
coils?
computer?
burned valve?
Another topper story for the person who's complaining about how they broke a nail during the last storm?

[milkovich]

Could it be a fuel filter? Did it log your fuel pressure under load? Maybe a clogged injector?

[stage1scott]

When I lived in snow possible country my blazer sat from april to sept-then I worked like a dog to get it in tip top condition before snow flies again-once it was perfect again (relatively speaking-I lived in the rust belt and you could poke your hands thru the rockers) I wouldpark my other 2 or 3 good cars until spring. no matter what happened, the blazer got fixed immediately if something happened, no relying on anything else! you need to concentrat on the rescue rig completely till spring! Sorry to see the damage to the Buick and happy to hear GM is fixing the GTO on thier dime-at least you can whip up on the rental while the RR gets fixed!

[SuperBuickGuy]

Could it be a fuel filter? Did it log your fuel pressure under load? Maybe a clogged injector?

The injector cycles were consistant, it was the spark where the biggest issues seemed to be rising.... however, it could be that.... it's at the dealership now and I've got this awesome (sarcasm) Malibu to drive

I wouldn't have driven the GTO except that my truck died. I didn't notice the way the PO had run the hose, nor that the hose was pretty brittle until I was fixing it.... but I am the same, Scott, I work my tush off getting my 4x4 in top shape before the snow flies.... I may, actually, buy a second 4x4 for "just in case" (and it'd be cool to have another red and white suburban).

[dieselgeek]

Why mess with HPT if the car's stock? That might be part of the problem. Meanwhile, is the alternator charging at idle? I say that because it's possible to not have enough power to fire the coils at low RPM if there's a fault with the charging system - i have seen that a few times before.

[SuperBuickGuy]

Why HPT.... The car is currently stock, it won't be stock too much longer - so when I upgrade, I will use the HPT to make needed changes. I should put this one in bold because it's the most important - also, HPT works with the 3.6L spider motor (and can turn off VATS). And I learn by seeing - so seeing how GM tunes their cars teaches me more than surfing all the tuning forums on the internet... also the computer doesn't get mad at me for asking stupid questions...

It's not the problem because I haven't modified anything - not even the speed limiter. And I won't be modifying anything until the warranty period is over.... that'd be stupid.

It is charging fine - 13.5 volts. It may simply be corrosion (I doubt it for a variety of reasons) that is causing the starting problem; or could be a continuation of the problems from the changing of the head gaskets.... however, it's not my problem for another 500 miles as its under warranty.

However, I must not have been clear - it's missing at idle, and that miss continues as a misfire until 2000 rpm under load.... it also throws a code, and the check engine light is on. To be even more specific, it attempts to retard the timing up to 5* even if the timing is 6* BTDC. At all times of the misfire the throttle is at 43%-45%, and the retard function is active.

[dieselgeek]

Just a heads up, but GM can tell if you're reflashed the computer with HPT. Hopefully they don't go looking for it, and void your warranty (that happened to us on Spectre's 2005 GTO).

Also, GM uses very different tuning software than HPT. Either one is extremely complex!

Make sure to let us know what GM discovers about the misfire.

[Mater]

i wounder if the knock sensors are getting a fauls signal and pulling timing cuasing the cylinder to not fire

i would of unplugged them and taken it for a gental drive to see if the miss and bog stayed

[TC]

I just think you have a bad battery and that is why it keeps going bad, probably has a bad cell.......And in the low rpm's the battery just has to big of a draw on the charging system for the coils to fire properly.........

[SpiderGearsMan]

leaky imtake gaskets , clogged injector .....need misfire graphic

[BOOOGHAR]

i would say double check the output of your alternator and have your battery tested, start with the easy stuff

[SuperBuickGuy]

Round 1
Battery (6 months old) was bad - and is the 2nd battery in the 10 months I've owned the car.
Spark plug and its wire for cylinder #2 was bad

still working on the rest

[Bob Holmes]

I'm with Spidey on first take. But you'd think that it would continue the behavior at higher rpm.

But I'm troubled by the 13.5 volt charging production. I'd be looking for problems from that, also. Where are you making that measurement? At the alternator charging lug, or at the battery while the car is running? I think you're short a volt.

[Mater]

13.5 is normal with most GMs of that time. my silhouette, 01, 00, 99, and 97 GPs all only produced 13.5-13.7 volts

[SuperBuickGuy]

leaky imtake gaskets , clogged injector .....need misfire graphic

Maybe TC can instruct me on how (if it's possible) to post the recorded info from VCM Scanner