NickD

Driving a little too aggressively I hit the rev limiter in 2nd gear at WOT. Got frustrated and slammed it in to 3rd and got back to WOT. The car took off and within a few moments I started loosing power, the engine sounded off, and CEL came. I pulled over and checked the codes, 300 - Multiple cylinder misfire, 301 - cylinder 1 misfire and 302 - cylinder 2 misfire. The engine barely idles and stalls if I give it gas so I got it towed back to me house and took this video:

Cobalt SS Awful Engine Sound - YouTube

I'm gonna go grab a beer and some dinner, go borrow a car for tomorrow and start taking a look at what it could be. It sounds like compresssed gas is being released to the atmosphere. All the piping is tight though. I am wondering if I somehow blew a sparkplug? I was wondering if anyone had any suggestions. I'll update this thread after I get a good look at things.

Bass_Waves

iTrader: (24)

Pull the plugs first lol

kdub1492

iTrader: (8)

Sounds like mine did when I blew apart a valve and shattered a plug, good luck!

Wert842

iTrader: (3)

Wow. That does sound like crapola. I really don't think its a plug though.

Sox-Fan

iTrader: (7)

sound like a subaru?

Wert842

iTrader: (3)

Almost. Lol. Definitely missing or something isn't closing properly.

kzak104

iTrader: (1)

are you tuned? are you one of those retards who sets their rev limiter to 7500-7800?

tomj77

iTrader: (2)

LOL i like this and wonder the same

Wert842

iTrader: (3)

Never actually heard of anyone revving that high.

kzak104

iTrader: (1)

i know a local

Wert842

iTrader: (3)

Mines set to 7400 but only rev to 7200 at the track but rev to 6800-7000 on the street or when doing pulls. Never went any higher though. That's pushing the limits as is though. Still on stock springs as well.

NickD

I am Trifecta tuned for 22psi with the stock rev limiter. I pulled the plugs on cylinders 1 and 2 and aside from the gap being large on one, they look fine. How would I know for certain if it's a valve? I guess I'd have to pull the valve cover off?

cranemaster

I had my car make a similar sound when some sorta cam position?/valve position?/sensor something went.

This happened at the same time my IC blew. The car was blowing all sorts of colors of smoke and eventually wouldn't even run.

The cam phaser angle screen on the rpd showed an error in the sensor...

I can dig up the warranty info... not sure if you have the same thing going on.

nota4re

Pull the other two plugs. I can virtually guarantee one of them will be visibly "telling".

kzak104

iTrader: (1)

scan for codes>pop off valve cover, look for bits laying around> compression test

colodude18

iTrader: (4)

Sub'd for future reference ;-)

lwpmoon

iTrader: (1)

I would do a compression test while you have the plugs out. It sounds like a valve isn't closing.

NickD

So I pulled the other two plugs and nothing, they look fine. On a side note I checked the gap on each plug, they are all worn badly except for one was just a bit loose at .032. I don't have time right now for the compression test so I'll tackle that tomorrow after I get back from work. If I sense something wrong, I'll pull the valve cover next.

NickD

Okay, compression tested the first cylinder and got 138lbs, went to test the second one and the engine won't turn over anymore. I'm pretty sure it's a weak battery (original battery); when I crank it, everything just flashes. The OBDII system was reporting 6.6v, I read 10.2 with a voltmeter and tossed it on charge. I'll try again tomorrow after a good charge.

CudaJoe

iTrader: (1)

get rid of that original battery. Ive been stuck many of times in a parking lot because the damn thing died in 30 mins because a stupid radar detector was plugged in. Retarded how bad the stock battery is. I got an everlast Gold, and I havent worried about my car being dead over the weekend for 2 years. Literally if I didnt start the car saturday and sunday, it wouldnt run by monday. was like that since day 1.

138 is a good number. hopefully the rest match. or.... hopefully one doesnt match so you find your problem lol.

QuickSilver_SS

What is a good compression number for an lnf with 50,000 miles on it ? Both high, low and an average ?

NickD

Before I left work this morning I pulled the battery charger off and gave it a crank, I had the gauge hooked in to cylinder #2 already so I read it real quick, 141. I'll do the other two later this evening.

As far as a replacement battery goes, I'll add that to my list, heh. I haven't had any problems until now, but it's original and 4.5 years old.

user 72239

iTrader: (4)

at my altitude of 5500+ ft, my motor was 125 across all 4 pistons. Mine had 72k miles at the time

Did a buddy of mines and his was 125 across all 4 pistons too.

574

iTrader: (5)

I don't know why it would be different from lnf to lsj but 138 is not a good number. Should be in the neighborhood of 180

NickD

FYI, I'm 230ft above sea level and have 55k miles.