It may just be coincidence but every 1200 miles (I'm at just about 2400) the engine has a misfire episode. I'm going to bring it in to the dealership as soon as I can, which is Friday unfortunately. But has anybody with the SS/TC has this problem? It's the 4th cylinder again. The OnStar tech told me there is a chance it's nothing, or there's a chance there is some kind of dirt/contaminate in the fuel rail/injector.... joy. He said it would damage the catalytic converter.

 

First the car is Direct injected so no fuel rail or injectors... DI is fuel getting introduced directly into the combustion chambers. Might be your plugs or low quality fuel... You must use MUST use 91 octane or higher gasoline....

 

There are fuel rails and injectors just high pressure rails and injectors, but it is very odd that this only occurs ocasionally atleast the cylinder has been pinpointed it could be anything really.

 

You Don't have to use 91 octance, it's recommended...

 

You have to use premium...period...if you can't afford premium then you can't afford this car... putting in anything less leads to problems ($$$)

 

I do have the same condition here, It's been 2 times in one month. My GM tech told me that this engine is very sensitive to everything that could go through the intake that should not be there. He told me that my air filter was wet, due to snow getting aspoirated through the intake.

 

Cylinder number 4 probably has either a bad spark plug or a bad coilpack. Those would be the most likely problems.

 

Via GM:

Engines: Ecotec 2.0L DI Turbo VVT (LNF)
Recommended fuel: Premium recommended but not required

What does that mean if you can't afford premium then you can't afford this car...

I could understand if you bought a ferrari, but this is a 20k cobalt... I'm assuming you put 94 octane in your car because it makes it faster....

 

That should cause a MAF trouble code first. How on earth did you ingest thast much snow? The stock air box does have water drain holes in it too that is strange.

 

I had a misfire on cylinder 4 as well. It only happened once but many people have been having misfire issues as well with these cars

 

if it was a coil a code should come up for the coil and where it is so random i do not think it is the ignition system passable but more likley would be a glitch in the computer making number 4 fire wrong.

 

I got the same code after a long wet highway drive.... I checked the spark plus (and the gap) cleared the code and went about my way. I am pretty sure it was the wet weather.

 

There are fuel injectors, one per cylinder located right underneath the intake manifold. They look quite like normal injectors too. And a fuel rail does lie under there as well.

The plugs are the cause of the misfire. These plugs can be bad right out of the box sometimes and the car is sensitive to misfire due to being direct injection. A poor lplugs will show itself very easily.

Never put a gap tool in the plugs for an SS/TC it will just ruin them prematurely. Could cause that little iridium tip to fall right off then they become a piece of crap.

Actually the car is designed for 95 octane, they allow up to 8* of knock retard which GM states is perfectly acceptable. IT'S NOT acceptable. You MUST put some f*-ing 91+ in the engine.

That's retarded. They say recommended, but show me where 87 octane doesn't cause harm to the LNF.

 

What???? where do u get your info from. It's RECOMMENDED just like the poster said. Get your facts right.

My car did the same thing right after a carwash! Weird stuff as the power just down right stops????

Show me where it does?

 

Thanks for that insight Steve.

 

Car knocks 4* on 91 octane, proof enough that even 91 octane is not adequate for even the stock tune on the stock motor. Pull your head out of your ass.

 

My dumb ass dealer put 87 octane in my car. I was pissed when the sales guy said the reason was that it was ok and that the only cars they had to put premium in are the Z06 and ZR1 corvette. What idiots some peple are. 8* of KR that is insane the WOT timing on the car stock is around 9-10* with 0 KR so with 8* you would have 1-3* advance that is laughable.

 

Dealerships usually only have 87 Octane at the dealership, if they have to gas up cars like Z06 ZR-1 etc they have to drive to the gas station. And goes to show you they will put 87 even in an LS2/LS3 what morons.

 

man, i hate it when my chronic misfires.

 

Aint that the truth. Good thing it can always be started back up.

 

My car knocked 3* on 93 octane with the stock tune. It is not that GM is very agressive with the timing tables they are actaually pretty conservative it is just that the stock tune is way too lean!!!

 

Direct injection is supposed to be lean. But there is more power in fattening it up.

 

Yeah, but not as lean as they have in on the bottom 15.7:1 A/F from 3000-4000RPM that is still nuts direct injection or not. We are not naturally aspirated.

 

Yeah, you should see the faces of the dyno operators I have seen when baselining these cars all over the country. I have to convince them that its normal for the stock program. When alls said and done I try to leave them around 12.8 AFR, which is still "lean" in terms of port fuel injection, but really fat in terms of direct injection. And the car loves being in the 12.5-13.0 range especially in low rpms. Theres a lot of torque to gain from enrichment down low and cam advancement.

 

You should have seen the face on my tuner Bob when he saw the stock A/F. I had to convince him that that was normal for theses cars. He has been tuning cars for over 10 years now and mine was the first DI car he ever tuned. We set the A/F at around 12.6-12.7 it seemed to like that setting the most. Any richer it lost power any leaner and It also lost a little power.