Quick question....

[TLS_Addict]

The car sometimes gets a hesitation or a bucking under throttle, generally its under 2k RMP. However it NEVER happens when its either in neutral or the clutch is pushed in.

Here are my ideas as to what is wrong.


1. Opti-spark is bad
2. Needs plugs
3. Needs wires
4. Needs the TB cleaned

I am getting an opti-spark asap, plugs wires are coming in next week, have the wires, bought some TB cleaner. The car was sitting for a good 8 months before I got it so the injectors may be a little gummed up, not sure though. I put in some injector cleaner as well as I plan to throw a little sea foam in there to break up whatever gunk there may be.

Any other ideas or do you guys think I hit the nail on the head?

Thanks!

[JaycenK]

if it sat for 8 months it could be low octane fuel. It depends on what you put in it and when. I would dump it and refill it with 93 first and see if that fixes it. These motors run 10.25 to 1 on compression so you could be low on octane and high on hectane. The computer is going to pull all kinds of timing if this is the case and it will do that. Another could be the injectors but unlike the old problems of gum you have to worry more about the ethanol eating the injector from the inside out. Ethanol can separate in a fuel line or injector in a mater of less than an hour. In the tank it can take only a day or two. Ethanol is heavier than gasoline so it sinks to the bottom of the tank and is sucked up first by the fuel pump. Opti is a pain to get to and you are going to need to pull the water pump and the harmonic balancer. keep that in mind before starting. Opti's usually leave a tell tail trail of codes in the PCM but not always. I would start by having the PCM scanned and see if there is a bread crumb trail that can lead you in the direction of the problem. unless a problem happens for a certain amount of time the PCM isn't going to throw a CEL. if it only happens under 2k with load it may only store the code and not give a CEL because you don't spend much time under 2k with load. Opti problems usually get worse on the big end of the rpm spec not better. the more load it is under usually it fails to fire correctly. Hope you find the problem.

[TLS_Addict]

Hey guy, thanks very much.

Here is the deal. I got the car last summer/fall and put 2k miles on it. This problem only exhists once in a great while. It was a lot at first then never and then once in a great while. The check engine light never comes on but as you know that doesnt mean crap.

I always run 93 octane in my cars (LS1 GTO prior) and try to even put in fuel injector and octane boost about every 3k miles. However with the Corvette I put it in right away and it seemed to really help it but the problem persists.....very rarely I might add. Once in a while it will do it if I nail the gas below 2k rpms but not every time.

Like I said I am going to rip off the air intake system and clean the TB as well and see if that helps. Again its only under load when it has the hesitation or the stumble. When I say stumble I mean it bucks a little. I just want to get it figured out by spring because I would like to take it on about a 10 day road trip.

Where do I have it scanned? Can I use a power programmer to scan for the codes?

Thanks again my friend.

[JaycenK]

most auto parts stores can scan it for free. if you have a programer capabile of reading codes then you can do that as well. You could scan it and if that gives you nothing then do basic tune up stuff and see if that helps. Also check the intake gaskets by spraying some TB cleaner around it and make sure the intake gasket is not leaking. This was a problem on them from time to time. also there is a special cleaner used to clean the mass air flow sensor. That may be a good idea as well. I just say look at other options before taking the opti off because it is such a pain in the ass and as bad of a rep as it has, alot of the time that is not it. New front O2's as well with the tune up as long as it is not running real rich.