I'm looking at an '86 Trans Am as my first project car. The price is affordable, and getting it to every day driving condition won't take much. However...

The car has a V-8. I went to check it out for the first time last night. I started it up, it was rather cold outside. We had to adjust the idle because it kept stalling. We also had to manually open the air intake valve to keep the engine from cutting off because it wouldn't open by itself. Just behind that was another, larger valve that was otherwise identical. I was told that that valve was a secondary, or back up, that would open should the smaller one fail to open. Once the small one was pushed open, the engine idled perfectly. It sounded great, no knocks at all.

So then I drove it. I made it maybe a quarter of a mile, and I pressed the gas pedal to the floor and nothing happened. It was as if the car were in drive, but power idling. By this I mean that it was moving forward in idle speed. Then the engine shut off. I started it back up and pressed the pedal gently, and got the same response: the engine shut off. Once again I started it, pressed the pedal down, and it still stayed at idle, while moving forward, then all of a sudden the engine revved up and the car jerked forward and went. At the end of the street I stopped at a stop sign, turned around, pressed the gas. Again it idled for a few seconds, then finally jerked and went.

My question is this: would this be a transmission problem, or due to the valve sticking in the closed position? In my mind I can visualize the small valve sticking shut, and the bigger one opening to compensate. But If I'm wrong and this is transmission related, then the car needs way more work than I'm capable of giving it. If it's because of the valve, then I'm confident that I'll be able to fix it. I'm leaning more toward a sticky valve situation, but I want to be certain before I commit.

Thanks in advance for any advice.

William

PS

If it helps any, the engine in this car is identical to the one pictured in the Haynes manual for 1982 thru 1992 Firebirds, chapter 6, 6-1. In the photo, the air filter housing is removed and you can see both valves that I'm referring to.

I also found a picture on the internet, at http://media.photobucket.com/image/1986%20trans%20am%20engine/LEVELNIGHTCLUB/IMG_2064.jpg.
In this picture, the small valve that is open is the one that I had problems with. Just behind that you can see the larger one, in the closed position.

 

Judging from your description, your transmission is not the problem. However, something is wrong with your carb(which really isn't all that bad). You have a four barrel carburetor. The smaller valves that you were referring as sticking closed is what runs the car on a regular basis (idling, normal driving and accerating). The larger valves behind it are not back ups at all. When you stomp on the gas those barrels open up to allow more fuel into the engine and thus go faster. This would explain when you stomped on the gas and nothing happend because the carb relies on vaccumm to open the second set of barrels. With the first set closed and not providing a proper fuel/air mix the engine isn't turning over enough to provide enough vaccumm (to work property). Of course when it did have enough to open the second set of barrels your engine was then recieving fuel and air that the first set wasn't providing (and thus the sudden lurch in acceration). I'm assuming your electric choke is shot and needs replaced. If you look on the side of the carb (on the passenger side) you will notice linkage that connects ther valve you described sticking will be connected to the choke (should have a couple electrical wires connected to it.

To identify if this is the problem. Go ahead and zip tie the smaller valve open and start the car (let it warm up) and take it for a drive. If you problems you mentioned disappeared your choke is bad and is not opening up the barrels after the engine is warmed up(and starving it of air).

 

Thank you for the information. I decided to take the plunge and go ahead and get the car. This will be my first project car, and I'm looking forward to getting started on it. Here's what it looks like now:

 

Get the carb set to factory specs with everything operating properly. Ditto the ignition (timing, primarily).

It sounds like the choke isn't operating properly - start there. The air cleaner thermovac system, which operates a flap in the snorkel to bring warm air up from around the exhaust manifold, may also not be operating properly.

These carbs work great when they are adjusted as they should be and everything the factory put on is installed and working correctly. The #1 problem they have is people "fixing" them by disabling factory installed pieces.

 

Thank you for the information. This helped a lot. Now to patch a hole in the exhaust and I'll be able to drive it.