My father and I have been restoring an 89 Camaro RS, 305 tbi (for now), and have encountered some problems. When we began the idle was fine in park and nuetral, but when shifted into gear it would stutter and die out. We replaced oxygen sensor, egr valve, plugs, thermostat, and other regular tune up stuff and it helped a lot. Now the the car will idle fine in gear until it hits operating temperature. Once at operating temperature in gear it starts to stutter and come close to dieing out, but doesn't die out, when off the accelerator.

Another problem we've been having is with the radiator fan. When we got it the other owner had it gutted out with wires had it set up to a switch under the steering wheel. We removed all those wires and re-setup the original wiring to have it come on. It didn't come on. Next we switched out the sensor and relay and still nothing. The odd thing is the fan will come on when I turn the AC on. Any suggestions would be appreciated.

 

The system has a over ride the turns on the fan to keep from overheating when ac is used, normal.

 

Thanks, but I only really included the fact that the fan turns on while the AC is on to show it is connected and can run. My main problem with that is that it isn't turning on by itself when the engine begins to overheat.

 

You need to hook a scanner to it and see what the ECM thinks the engine temp is. Your temp sensor may be bad.

 

Agreed - either the sender for the guage is reading high, the ECM sensor is reading low, the fan switch itself is buggered, or your perception of 'overheating' isnt right... GM sets the fans to come on REALLY high for some reason, high enough to make most people nervous, and it just may not be getting hot enough to switch them on. For example, my '97 Z28's fans don't come on till something like 235* or so. The 3rdgen V8 setup isn't much different. Its definitely on the high side, but still safe.

If it is one of those mechanical problems I listed, none are hard or expensive to fix.

 

Thanks man, I'll check that out tonight. Any clue why my idle is sucking in gear?

 

I'd suggest starting by checking for vacuum leaks. If its a vacuum leak, it'll probably be a small one, if it only acts up under a small load (being in gear). Check your vacuum lines for cracks, etc. Check the gasket between the intake manifold and TBI unit. Even if that gasket isn't cracked/torn, an old one can harden up and cause a small leak. Had that happen with my Qjet.

Another thing to check (if you can check this on a TBI, I don't know as I haven't done it) is to check the Idle Air Control motor (IAC motor). If it can be removed, take it out and clean it off as much as you can with some throttle body cleaner spray. Do the same with the air passage where the IAC goes. Now do the throttle bores as well with the throttle body cleaner. They don't need to be as clean as the IAC unit and passages, but they should be fairly clean.

Reading back on my old post - I don't know what I was thinking when I said it could be the ECM temp sensor causing the fan to not come on. Thats only true for dual fan setups in 4thgens AFAIK. The fan switch is the only "sensor" that could go bad and cause the fan to not come on, unless the fan fuse is blown (which is also a possibility actually).

Unplug the fan, and run jumper wires from the battery to the pins in the connector to the fan motor. If it turns on, the fan itself is probably fine. If it will not turn on automatically from engine temp, it will be either the fan switch sensor is toast, the fan fuse is blown, or a wiring issue.

(thats assuming the guage is reading correctly and it IS getting too hot. These guages read high when they fail, and the sending unit can make it either read high or low when it fails - check it with a mechanical water temp guage to verify running temp compared to the guage. Best bet is to remove the fan switch, put the mechanical guage hookup there, and then start it and run it untill its warm, and compare what the mechancal gauge reads to your factory guage. It should be fairly close. Don't run it too hot though, as your fan won't come on w/o the fan switch sensor there that you just removed unless you turn the AC on.)