i have an 89 camaro 305 tbi that is sluggish at about 1/8 - 1/4 throttle.
i will give it gas to start moving and it will spit and sputter and bog down and almost die then ill give it about 1/2 - 3/4 throttle and it will take off fine. i think it might be the idle air control sensor because my idle sometimes fluxuates upon crank ups, does the IAC control the air/fuel mixture besides at idle? i have timed the car perfect with a timing light.

things in have replaced-

-cap, rotor, button, plugs, wires, ignition module

-map sensor

-o2 sensor

-throttle position sensor

-injector O rings

- rebuild kit for the tbi

 

did u ever fix your problem ? im having this same problem and iv replaced everything i can think of.

 

Wondering the same thing. I have developed the same problem and can't seem to figure out where to go from here.

 

The IAC controls the air idle. After that the throttle plates in the throttle body unit control airflow.

 

You can try cleaning the crap out of the IAC with carb cleaner. Reinstall it and give it a try.

 

Thanks for the responses. I did put in a new temperature control switch today and that didn't help. Will try cleaning the IAC tomorrow and see what that does.

Looking at the Thermac unit. It does not work, tested it today. Vacuum is good from the throttle body. The metal hose between exhaust manifold and thermac is missing so there is no warm air getting into the thermac anyway. Not sure if this may be an issue. My manual says it will run terrible if always getting warm air but just run bad if always getting cold air. Has always been this way since I got car so do not know why it would be a problem now anyway.

Today I really paid attention to what it is doing and it idles/runs fine, purrs like a kitten, but only when just cruising normal down the road. If you try to accelerate, pass someone, go up a hill it sounds like a 4 barrel carburetor kicking in with that really low, bass, whooooooo sound. There is no acceleration/power at all. The only way I can accelerate is slowly with no more that 3k rpm.

FYI more information on new parts (last 6 months): cap, rotor, spark plugs and wires, o2 sensor, fuel injectors, fuel filter, temperature sensor, air filter, oil change, new ecm, new sensor inside towards the rear of air breather (can't remember the name of it and don't have manual with me). The only codes I am getting are for High MAT and Low MAT. I cleared the codes today so will see if they return since changing the temp sensor. About the only things I have not replaced are the knock sensor and the little vacuum valve for the thermac. Timing is dead on according to the specs for the car and injectors are working correctly. At a dead stop the engine will accelerate just fine without issue. It only acts up when under load driving down the road.

 

Wow thanks for doing all that work on my car ... What! Wait?
That is the same issue I have had fro the pas 3 months and I have followed the same path, almost to the part, I am now working with an electrician and replacing Fusible links ... sorry no luck there yet

Keep working on it there has to be an answer out there in the garage.

 

You try fuel injector cleaner? I had a similar problem and ran a heavy duty fuel system cleaner and it helped a ton. Something to consider.