I have a 92 camaro 305 tbi. It idles fine, runs fine. When warmed up though, putting it in reverse and sometimes rarely when in drive and stopped via brake it stalls. RPM's drop to 500 and immediately it stalls. Sometimes it tries to recover, rpms kick up to a grand or more but it drops back down to 500 and stalls. It's almost guaranteed to stall when put in to reverse from park once it's warmed up.

I put a piece of wire insulation around the screw and it kept the idle at 750 when in gear and the stalling stopped. The problem is, the insulation never wants to stay on.

I can't tune the idle throttle because gm plugged the screw, so all that's exposed is the bolt with barely any room around it. I'm going to drill out the plug this week and turn the throttle body into an adjustable one .... I suspect this will work. Any ideas from anyone?

Any ideas on what the real cause of the problem is? It idles in park fine, but when in gear even warmed up it drops too low... Could a sensor be out and the engine runs in open loop when in park but closed when in gear and thus stalls ?

My computer isn't throwing any codes. Oh, and btw, turning the fan on with my manual switch, causes the lights to dim for a bit and the engine seems to bog a bit as the fan spins up. Wonder if maybe the alternator or spark plugs aren't up to par.

 

Having the car in a state of good tune is sound practice regardless of issues. This should be rectified asap.

May be an EGR problem as you say it is only when it gets warmed up, but that is just a WAG. When was the last time it got an O2 sensor?
Yes, you can take the plug out. I usually use an 'L' pick or a drywall srew to pull them out.

 

I'm not sure exactly when the O2 sensors were replaced. But wouldn't a bad O2 sensor throw codes?

What is the car supposed to idle at in gear? Whenever I put it in park, it always idles significantly higher than when it idles in gear. How would an EGR problem cause this behavior? Could the alternator just not be providing enough charge for the rpms at idle ...since I do notice the voltage takes a momentary drop from charging to below the half way mark when i turn the electric fan on (stock). I also have no idea what the state of the spark plugs are ... Guess i'm just wondering what rpm i'm supposed to idle at when in park and when in drive but stopped and at temp. That way i know if my problem is that i'm idling too low or if it's something else not letting me idle where i'm supposed to.

 

Well, honestly, it sounds as though the car is in need of a tune up.
Until that is squared away you may be masking the problem somehow. The electrical could be a bad ground.
The O2 sensor does not always throw a code and the idle info should be on your emissions sticker under the hood. See, there may be more than one problem contributing to the symptoms you see and without being able to know the actual state of tune we have to make less educated guesses.

 

I agree with Red on this one. TBI cars get overlooked as time goes on and 15+year old plugs and wires are not that uncommon. A bad 02 does not always throw a code. Bad plug wires, cracked vacuum lines, plugged vacuum passages (underside of TBI unit) etc etc can all cause your problem. Since the car probably needs a tune up anyway, I would start there. If anything it is preventative maintenance down the road.

 

Get all new red silicone lines =D

I don't know , I have the same car and never had any issue like that and my baby has 148K strong. Hope I don't run into this before selling it off.

 

another vote for basic tune-up. Distributor Cap, Rotor, Spark Plug Wires, Spark Plugs. I bet anything that will fix it. If it DOESNT though, you can search the tech articles on how to adjust your IAC and TPS

 

I actually have the same thing going on with my 1989 tbi 305. I’ve replaced the spark plugs, spark plug wires, rotor, cap, iac valve, replaced the O2 sensor, checked the timing, replaced the battery, new alternator, checked grounds, checked all vacuum lines, no leaks in the intake, checked and replaced the injectors, rebuilt the throttle body, changed the fuel filter and Next I’m going to replace the TPS. If the TPS replacement doesn’t work then I’m most likely going to carb it out but I also want to find the problem because I do like the tbi as well.

 

Welcome Aboard!

If there is stalling during braking, check the vacuum reservoir for the brake power booster. A quick way to diagnose that is to disconnect and cap the vacuum line to the booster, but be aware that the brake system will be fully manual with no power assist,