My love/hate relationship with my '86 Trans Am is slowing leaning more towards the hate side lately. It's the carb'd 305 engine, automatic.

Initially, I replaced the carb, and it ran great, even if turtle slow. I ran it again a couple of weeks ago. Still ran great, and slow. Yesterday, I got it out and it runs like a 1-legged old man. I don't know what changed. I hit the gas, it makes a roaring noise like the secondaries are opening, but I get no acceleration. None. No tranny kickdown, nothing. So, I checked my transmission cable to the carb, readjusted it for good measure, snugged up the mounting bolts for the carb, checked the tranny fluid and made sure all of the parts of the carb moved freely and were clean. All the wiring is connected. This is a 28k mile car, all original except for the carb. The original carb acted even worse.

Everything checks out. If I start out in first gear, I get the same thing. I can see the rpms jump up about 1k, but the car does not go any faster. It just sort of maintains its speed.

Anything else I should be looking for? I can't imagine what might have happened between now and a few weeks ago with it just sitting in the garage.

Thanks,
Tony

 

I'm not sure what the problem you are having based on your description. Is the engine running poorly or is the transmission not working?

 

Sounds like a plugged up catalytic converter more than anything to do with the carb or any other engine part.

 

The engine is running fine. Part throttle also works just fine. Shifts are a little hard, but it works. Full throttle does nothing but make noise! RPMs will go up, but the car maintains its current speed. It's like the engine wants to go, but the transmission is unwilling. Going uphill is a trial of patience, as I can't gain any speed. I'm going to check for vacuum leaks and report back.

Thanks.

 

It looks like the end of my TV cable is buggered up. When I tried to do an adjustment again, it just popped off. I have another one around here somewhere, I think. All my problems could be from an incorrect TV cable adjustment.

 

That didn't work. Partial throttle is ok, full throttle sucks. I give up.

I'm just going to drop a blown 383 with a TH400 in it...

 

Not a vacuum leak. There's no vacuum at full throttle; nothing there to leeeeek.

Not TV cable setting. (there IS NO "adjustment", only "setting" properly)

Sounds like a plugged up catalytic converter more than anything else.

You're likely to find also, that when a converter does what yours seems to have done, that pieces of it often get into the muffler and plug that up too.

The car will have THE SAME PROBLEM with a 383 and TH-400, as it does now. Will fix NOTHING.

 

Hi Acroyer,

It's a pretty easy thing to check, disconnect the converter from the Y pipe and take it for a ride, sure it'll be noisy but you'll know the first time ya mash the pedal whether it's clogged or not.

Might be just a wee bit easier that that whole "Throw the baby out with the bathwater" 383/TH400 "solution" you proposed

 

In park it idles fine, correct? If you push the gas pedal while in park, the engine revs up like it should? Or does it not? You need to determine if it's a engine, trans or heck even the brakes locked up in the back.

 

Everything seems to run fine in park. I will definitely do the CAT check, probably tomorrow. I was thinking with such low mileage (28,089) that the cat should be fine. But, you never know.

Thanks, guys. I'm trying to not get frustrated with this thing, but I'm old and crabby!

 

Low mileage on an old car doesn't really hold much value on anything mechanical, stuff gets old (whether from miles or time) and it fails. I agree that it sounds like it's just not breathing, hopefully that's it.

I would think that it wouldn't like to rev in park if that was the case though.

 

I would try the fuel filter also just in case. Cheap and easy and in my case problem caused by rusting tank.

 

I'll have to check the fuel lines to see if there are any other filters besides the one in the quadrajet. That one is new. I went ahead and ordered a Flowmaster cat. Even if that's not the problem, a more modern cat couldn't hurt. It's the direct bolt on, so hopefully I can get the old one off in my driveway. My neighbors, and HOA, love it when I do car repairs in the driveway! It was 75 and sunny here yesterday, and 40 and storming today.

Honestly, the cat never even crossed my mind, but when it was mentioned, it's like a bell went off in my head.

This is the 6th Firebird in my lifetime... I think I might have an addiction problem.

 

So, here's an update, finally: I got a new catalytic converter, direct bolt on, off of eBay, of all places. Black, powdery garbage that looked like old charcoal poured out of the old cat.

New cat is on, and the car runs great! I was hoping it would correct the slowness I was feeling up until now, and it did. The car is still not what I would consider fast, but at least it is much more fun to drive. I feel confident that I could take a Geo Metro light to light, now.

Now, my odometer has stopped working. Trip and regular, both. I kind of want to keep the mileage as accurate as possible, since it has a hair over 28K original. Plus, my fuel gauge doesn't work, and I was relying on the trip meter to tell me when to stop for gas!