Ok..i bought a 91 formula firebird this summer...before i bought it, it sat for 7 years. When i went to look at it the guy hooked up the battery and it started right up. Bought it...replaced plugs, wires, cap ,rotor, coil, ignition module, alternator, thermostat, ran plenty of injector cleaner thru it, always run 91 octane, ran gas treatment thru it, changed O2 sensor, cut off cats and replaced with straight pipes....i'm sure there's stuff i'm missing here....but point is...my car STILL seems to have a miss it it somewhere!!!! Also i've checked and reset timing as well. So I was hoping to hear of more ideas on what my miss could be??? what else should I replace?? Especially since it sat so long...it runs well and is a nice car...just seems to be lacking power sometimes and still feels like there's a miss somewhere...and i'm out of ideas....and help would be appreciated. Thanks.

 

One very good way to determine condition of the innards is a leak down check. What's the mileage on the engine? Afterr sitting so long, could be something as easy as a bit of crud in an injector. IMO a leak down check is the best place to start rather then just throwing money at the car and hoping you pick the correct part. If the leak down check doesn't reveal any problems, then it would be worth it to have a reputable shop run the car on their diagnostic equipment and see what shows up there.

 

How do I go about doing a leak down check? I've thought about taking it to a shop to get tested myself...might just have to do that. The motor has 141k on it. The guy i bought it from said that he had the injectors rebuilt before i bought it. Thanks for replying.

 

A leak down checker is a two gauge system that basically put air into the cylinder, measures the air the cylinder will hold in comparison to the air going in and will show you cylinder leakdown as a percentage. A simpler (and cheaper) way to determine general engine condition is a compression check. All you have to do is remove the power lead to the coil, remove all the plugs, insert the compression gauge in each cylinder one at a time. Have someone crank the engine over and record the results. Compression from cylinder to cylinder should be even to within 5%. Most parts stores sell either system. They should come with detailed instructions and (hopefully) the counterman at the parts store should be familiar with how to do the check and what the results mean. Just do a search under "compression check" and "leak down check" on this forum or google and prepare to do some studying!!!!!