when i go to a stop i have a problem where my car stuters a bit and goes below 1000 rpms to about 500 and it does all the time when i am stoped. and i run nothing but 93+ in my car. i have never ran below 93 oct. any answers.

i have the same problem. what car do you have? any mods? i have a 2.4L and an gm intake. the people at the dealership seem to think its my intake but i think they are all retarded.

Why are you running 93+ in a 2.2? You're wasting money and that may be the cause of your engine problems.

Put in 87 for the next few fill ups and see what happens...

i have a 2.2. i run 93 in my car becaue it is more clean and it is what i have put in every car i have ever owned. this is the only car that has done this

no mods eather

its not cleaner accually, its chemical compound just has more resistance to detonation, which you dont need

Vaccum leak, or bad (water/dirt in) fuel

i have a 2.2. i run 93 in my car becaue it is more clean and it is what i have put in every car i have ever owned. this is the only car that has done this

no mods eather

Illinformed. :lol:

u know what i ment i was not going to get tech.

I would not be surprised if filling up with the RECOMMENDED gasoline, 87, will fix your problems. If you go to the dealer, that is probably what they will tell you. Your car is BUILT to run PROPERLY on 87, not 93+.

Yeah man, go back to 87 octane.

But my question to you is have you done anything recently?

Does your RPMs jump?

Do you have a check engine light?

Murph, its not getting technical. It is what our cars are designed for. 2.2's are designed for 87, 2.4's 89 or 91, 2.0's 93. The rating has nothing to do with cleaner fuel, octane measures detonation... read this thread:

http://www.cobaltss.net/forums/showthread.php?t=64722&highlight=octane

especially the threads by D4U2S0T he thoroughly explains octane. I was running 89 for a while but it obviously didn't help.

93 is not good for your car, detonation is occurring WAAYYY too late and is robbing power.

Murph, its not getting technical. It is what our cars are designed for. 2.2's are designed for 87, 2.4's 89 or 91, 2.0's 93. The rating has nothing to do with cleaner fuel, octane measures detonation... read this thread:

http://www.cobaltss.net/forums/showthread.php?t=64722&highlight=octane

especially the threads by D4U2S0T he thoroughly explains octane. I was running 89 for a while but it obviously didn't help.

93 is not good for your car, detonation is occurring WAAYYY too late and is robbing power.

I think you're slightly mistaken

Octane alone won't retard ignition timing and detonation is not a normal (at least it shouldn't be) occurance. A detonation is a uncontrolled ignition (explosion) which can cause knocking. Him putting 93 Octane is not going to change his ignition timing nor will it cause him to detonate.

I think you're slightly mistaken

Octane alone won't retard ignition timing and detonation is not a normal (at least it shouldn't be) occurance. A detonation is a uncontrolled ignition (explosion) which can cause knocking. Him putting 93 Octane is not going to change his ignition timing nor will it cause him to detonate.oh how mine does this, but its the cams

I think you're slightly mistaken

Octane alone won't retard ignition timing and detonation is not a normal (at least it shouldn't be) occurance. A detonation is a uncontrolled ignition (explosion) which can cause knocking. Him putting 93 Octane is not going to change his ignition timing nor will it cause him to detonate.

Maybe "retard detonation" was the wrong phrase

for those that don't understand octane, let me break it down very simply. octane is ONLY a gases resistance to detonation. nothing more. how does this affect your car?

to keep it simple, in our example let's say a car is supposed to run on 89 octane. that engine is set up to burn that gas to the fullest amount possible. the optimal point of detonation is called top dead center. or, TDC for short.

when you're using 89, which the engine is designed for, the gas is exploded at just the right time so that it forces your piston down, creating power.

now, if you use octane that's LOWER than you're supposed to, your engine is igniting it too quickly, before TDC. this means that your gas is exploding while your piston is still moving up. when the gas ignites, it bounces off the upward moving piston that wasn't ready to be moved back down, and creates "knock". not good for your engine.

it's the same but the opposite (doesn't make sense, right?) for octane that's too high. it burns slightly after tdc, which again is not ideal for power.

i hope this helps a little, i tried to keep it simple.

just reiterating what I have read.

I guess there is a pretty good article on wikipedia as well.

Yeah man, go back to 87 octane.

But my question to you is have you done anything recently?

Does your RPMs jump?

Do you have a check engine light?

no i have not done anything recently to my car it is still stock. i am waiting for the waranty to go out.

yes my rpms jump

no i do not have a check engine light

you should just go to the dealer, could be somthing to do with the throttle positioning sensor

If you still have your warranty, definitely take it to your local dealership

either bad tps or iac is all screwy.

Murph, its not getting technical. It is what our cars are designed for. 2.2's are designed for 87, 2.4's 89 or 91, 2.0's 93. The rating has nothing to do with cleaner fuel, octane measures detonation... read this thread:

http://www.cobaltss.net/forums/showthread.php?t=64722&highlight=octane

especially the threads by D4U2S0T he thoroughly explains octane. I was running 89 for a while but it obviously didn't help.

93 is not good for your car, detonation is occurring WAAYYY too late and is robbing power.

Also misinformed. GM recommends AT LEAST 91 octane in the LE5 engine, same as the LSJ (although I hear you guys probably need higher), not 89 octane.

Also misinformed. GM recommends AT LEAST 91 octane in the LE5 engine, same as the LSJ (although I hear you guys probably need higher), not 89 octane.

correct me if I am wrong but does not the manual say 89 for 2.4's?

either bad tps or iac is all screwy.

Another Rhody! Where abouts in Prov are you?

correct me if I am wrong but does not the manual say 89 for 2.4's?


Correction, you are wrong:lol:
No, the manual actually says 91 or Higher Octane for the LE5 or "you might experience a loss in power and acceleration due to premature detonation." or some crap like that.

hahah ok... well i told you to correct me if i was wrong. I am wrong.

Now everyone stop wasting or trying to save money and just use the damn gas that they tell you to use... you are hurting more than helping.

hmm seems this topic took the wrong fork in the road lol


i get it too sometimes when i have my AC on but other than that the car runs fine

I'm not sure the higher octane gas is causing that much of a problem. I ran 93 octane when I got my car, for the same mistaken belief. I ran it until I broke in the engine at 500 miles, then alternated with a tank a month being 93 and the rest 87. I never had a problem with detonation, nor did I have a problem with it idling rough, and dropping down to 500rpm.

I'd run it to the dealership if it's under warranty, and beat them until they look at it.

Ok your problem is not octane, i am running 85 octane (colorado) and i have the same problem but only when the ac is on, i have a cat back and an intake.

it does not do it with the ac on. just at a reagular stop. and i will take it to the dealer ship when i get back from iraq. and no it is not because it has been sitting up eather. it is being drove every day

Check your MAF sensor, it might be either disconnected or have oil from the filter on it. Just my .02