its back at the dealer...they called me and as of right now they have no idea why its doing that...thats reassuring. im kinda sick of it.

 

Mine was back at the dealer last week for misfire. Cyl #4 is misfiring like crazy now while its warming up. My dashdaq counts like 150 misfires while warming up. So the dealer at least this time was able to see the problem and record the misfiring and send it in to GM. They said I could still drive my car and they will get back to me when GM tells them what to do. I suggested they try changing spark plugs or injectors or something, but they won't. They don't want to just "throw parts at it". Well, that's fine and dandy, but this is the 4th time I've had the car in for this misfire and nothing is being done. At what point do you start throwing parts at it? I'm convinced they just don't really care and I'm getting sick of it. They always fall back on "we just have to do what GM tells us". That could be true, but I'm really SICK of hearing that!!! Should I have bought a Honda? WTF. I'm pissed.

 

150 holy ****? the most i seen was 4

 

wow thats crazy. i am getting similar treatment but i think my misfire might be different.

can someone clear somethign up for me....if you get a single misfire (within 1 ignition cycle), the car opertates normally, but flashes the SES light but once it reads that thigns are reading correctly again, it will turn th light back off. but if you get a double misfire within 1 cycle (like mine is showing) then the light comes on and that cylinder shuts down until the computer is reset?

 

Well I ran Lucas upper cylinder lube and injector cleaner through the intake manifold. Wow be prepared for a smoke show for the first mile

 

I've rad on here about the intake valves gumming up with carbon , causing problems. Something about how DI works that makes it hard for them to get lubed or something to that effect. Anyways .... which line did you use on the intake manifold?

 

They don't get dirty, they just remain dry as they don't see fuel. There may be a chance that the intake valves may get stuck open due to the car being new and very tight tolerances. Once the engine wears they will be fine as was said by "gettingausernamesucks". The line is the big one to the left (driver's side) with the pinch clamp on it and covered in the plastic loom.

 

Thats the post i was referring to. Thanks for the info

 

This is pretty much the same thing I'm seeing. Cylinder 1 misfire. I've had the car in 6 times now for it and they still can't figure out the problem. I would get the CEL once a week to the day. The 4th time they had it for 5 days with the GM engineers on the phone trying to figure the problem out. They did all sorts of things including a complete fuel system flush, and that seemed to fix it. About a month and a half later the same code came back. So 2 more times back and they've told me just to keep taking it back until GM figures it out. I still love the car though, and I'd buy it again.

 

wow. well i hope i dont end up returning it that many times. its just too much of an inconvenience for me. i still love the car too, but i hope its not with these misfires. so far so good tho, since i last picked it up.

 

Yeah, I dunno, it's been good for about 2 weeks now since they cleared it. I've been talking to a lemon law lawyer about it and he says I've got a case here. I hope you don't have the same experience either. I forgot to mention before that it always happened on a cold start, not on at night, on in the morning as soon as I started it. The dealer tried pinning it on me saying I bounced it off the rev limited, but I got that cleared up pretty quick, and they've been great ever since, I've had a rental every time it's been in. Lucky me I guess, haha.

 

Well i ran some lucas injector cleaner threw the intake and it has completely stopped falling on it's face between 2500 and 3500rpm. The way the exhaust note changed when it would hit that spot made me believe that it had to be the issue posted above . I've put 300 miles on since the cleaner and a full tank of gas and it didn't happen to me once......amazing considering it would happen often . I know it might sound crazy but my car wouldn't try and spin the tires from a 1st gear punch before ...now it starts to break em loose at 4500 everytime ...so i know it's not placebo lol. Oh i just turned 1800 miles

 

if the light just goes off from being cold . will the light ever turn off by itself if the problem goes away or do you still half to take it in to clear the code off in order to get rid of the light. cuz that would suck if it kept going on and they couldt find anything and you had to keep wasting the gas to go out andget the drive flashed.

 

The CEL will eventually turn itself off if the code isn't being thrown for a while. I don't know how long. I just clear the codes with Dashdaq. Right now mine misfires enough (just on Cyl #4) to set off the CEL almost daily.

 

Update:
The dealership now has permission from GM to start replacing parts. They told me that GM is working on releasing a recall or a TSB on this, but they don't really know what's causing the problem yet. Lol. So My car is going in tomorrow and they are going to possibly replace injectors, valve springs, and I don't know what else. And apparently they already tried running some valvoline upper cylinder lube through the intake and it didn't solve the problem.

 

gm just offered to buy my car back for the same problem...

 

I just got the misfire codes yesterday (multiple cylinder misfire, #3, #4). I was driving on the parkway in the rain, downshifted from 5th to 3th to pass someone, and the car fell flat on it face, and got the blinking CEL. It cleared up pretty quickly and the car drove normally after that. The only other problem I noticed was when I let off the gas in 5th at about 80mph, I got a lot of backfiring through the exhaust (which is stock). I have a custom tune, a K&N drop in, AEM intake tube, and about 3k miles. Any ideas what this could be?

 

Filter or MAF got wet? How's the LTFT's on your tune?

 

I was thinking the same thing about the MAF or filter getting wet. It was a torrential downpore. I'm not sure about the LTFT's; I only have a code reader, so I can't check the trims. I'm going to give Tune Time a call tomorrow to see if they have any ideas.

 

Change your plugs.

 

its your coil packs had the same problem. had all coil packs and plugs changed. it took along time but it was missing from one cycl to another at different rpm's. this was what was so hard to find. have alot of mods done to the car so this was a relief to find hope you have some luck with this.

 

Cool, thanks. Hopefully the dealer won't give me a hard time and say this was caused by the tune. Any thoughts on running one step colder plugs?

 

If the dealer finds the tune it's an easy out for them . Hopefully you have a cool service manager/ tech cause i'd say the majority would blame the tune instantly.

 

Did you ever figure out what was wrong?

 

They replaced a fuel injector on mine and it completely fixed the misfire problem. Then a few weeks later they also had to replace one of the coil packs. Cyl #3 was completely shut down.