Sarge91

iTrader: (10)

Ok, so to start im getting the P0300 code.. "random misfire" well that doesn't help, and then i got P1153, and after research, it seems that is when the 02 sensor "bank 2" is slow at switching from lean to rich.

Now here is the story of the problem.

I can start the car in the morning, "cold start" and it will not misfire, it will run fine. But lets say i turn it off after its warmed up and let it sit for 4 hours or less, i will crank it, and after about 20 secs it will start to misfire at ideal. I will have to rev it to about 3k for it to stop, and then i start moving, and i would say around 2300 rpm it will start back, just misfires like crazy, no power.. Once again i have to throttle it some for it to stop. Then about 1 min doing that, it will no do it again until i re crank it warm.. when it misfires, the SES light blinks for a bit, and then goes off, so it not storing any usefull codes besides the p0300.. So i have NO idea what it could be.. i checked the grounds. The o2's that are in it now are about 30k miles old. I have a 2002 Camaio SS, LT headers, Cutout, 3000 stall. There are new Spark plugs in, about 1k old. I just ordered new plug wires "needed to anyways" and i think i may have to get new o2's.. but i dont have a code saying there bad yet. I cant get a shop or a buddy to see whats going on bc its only does it when it wants, when its warm, but that only 50% of the time. So how can a slow switching o2 make it misfire under warm cranks this bad? Can anyone help? Thank you for reading my post.

chrysler kid

iTrader: (14)

what plugs and wires are you running. ngk tr5's have a maximum gap of .049 anthing more than that will cause a misfire

Sarge91

iTrader: (10)

TR6 at .030 i beleave.

LS6427

iTrader: (2)

Sarge91,

Wrong plugs...wrong gap. You need TR55 or TR5 (they are identical plugs that come with different factory gaps), your gap of .030 is terrible. You need to pull those out, put in TR55 or TR5 plugs and gap them YOURSELF to .050. No less, no more. ...NON-nitrous...

Small gaps are for nitrous and so are those TR6 plugs. Also, I think with nitrous..people are only going to .035.

Blinking SES is multiple misfires.

As far as the 02 sensors go...they don't work untill the engine is warm, I think above 122*F. Before that while its warming up, the MAF does everything. So...it could be a bad 02 sensor that acts up after the 02 sensors take over after warm up....or it could just be that REALLY small gap.

Change the plugs and gap them properly...see if it runs normally. If not, you probably have a bad 02 sensor(s).

And STOP driving it with misfires....you're gonna damage your engine.

.

Sarge91

iTrader: (10)

I run the TR6 bc of the Nitrous. They may be at .035, that or either .030. They ran fine for a month, while being sprayed. But after thinking back, im sure we gapped em at .035

Sarge91

iTrader: (10)

Yes, .035 is correct, i looked at the gapper, marks are at 35, and also i misfired this morning at work and scanned it, got p0153.. i looked somewhere, and they said it was a intake valve spring that broke.. but if i had a broke spring, would it do it all the time, and not stop when warm, like in my case?

LS6427

iTrader: (2)

Ok...then here's what you check now. Make sure that none of the spark plug wires are touching any parts of the exhaust manifold piping......bet thats it.....

They can't touch AT ALL.....

If thats not it.....might want tp pull out the spark plugs that are misfiring to check to see if they are broken/cracked.

02 sensor(s) would be the next guess. But it could be leaky fuel injector(s) too.

.

Sarge91

iTrader: (10)

Done this, still doing it, if it was a fuel problem, which i think it is, how could i tell? Since it goes away after i rev it to 3k of so about 5 times in neutral it goes away.. im stumped. Fuel filter has around 15k on it. Fuel pressure regulator bad?

LS6427

iTrader: (2)

You'll have to check the fuel pressure at the rail at idle and under throttle. Fuel injector(s) could be clogged or leaking too. Check those for leaks by taking them out and leaving them all in the rial, turn the key to the "on" position so the fuel pump primes and see if any of them leak.

.

Sarge91

iTrader: (10)

Anyways it got to a point where i couldn't stand it. Took it to a buddy, we hooked it up to a gm scanner, as usual everything seemed fine. We tested fuel pressure, it was great. Then we decided to swap the plugs once more. So put in all new plugs. It went away. It ran great for a week, then today it came back.. :unhappy:.. So im at a major lost here. Maybe something in my tune? Computer is messing up? Its just so random no one can pin point it. Ive done coil pack. Plug, plug wire. And all the other crap i said a few pages back..

Where are the grounds located at for the computer, Injectors? Maybe there loose? All ground that i can see in the engine bay are tight and clean..

Ill paypal 10 bucks who can figure it out. lol

Thanks

edward_garcia_69

iTrader: (6)

check your o2 sensor extension harness. it might have been burned on your headers. i had that happen to me. and i got the p0300 code..i hope that will help.

Sarge91

iTrader: (10)

I have, and both 02's are working great via scanner.

2002 Trans Am

Any luck?

Sarge91

iTrader: (10)

^ It was bad gas.. had water in the tank.