Just got my 85 Iroc out of the air with fresh brakes and while on my test drive I noticed the following.

After about 4 minutes of driving when I punch the throttle to more than 25% the car boggs like crazy, almost feels like it want to die.

The car is a stock 305 with 94k and has sat the last 5 yrs before I bought it. It has a new fuel pump and I put techron in the tank at the last fillup. The SES light has not come on.. Any ideas?

Sensors, injectors????



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=Scott=
85 Iroc
96 Impala SS

 

After 4 minutes of running would imply that it bogs after warm-up. Sounds like maybe a coolant temp sensor is bad. Mine croaked after I flushed the coolant. It stayed in "choke" mode all the time. This tripped my SES because of rich exhaust, however.

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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

Could be a thrashed TPS sensor.

 

Another vote here for the TPS. But the TPS ought to cause a problem all the time, not just when the car is warmed up. The TPS is really easy to check. Use an analog volt meter, and probe the dark blue wire coming out of the TPS. The needle on the VM should go up smoothly without any jerks or gaps when you open the throttle.

 

I called a buddy of mine that is pretty knowledgeable on these cars, he suggests the o2 sensor.

Reasoning: the car runs for about 4 mins with no problem, in open loop the 02 sensor does not give any readings, when it goes to closed loop it does. The o2 sensor sends information to the computer to use in formulas for the fuel mixture. If the sensor is hosed, this could be my problem.

I am going to try this first, then look into the TPS and the logic behind it, thanks everyone for the valuable information, I will keep you posted on my results..




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=Scott=
85 Iroc
96 Impala SS

 

I replaced the 02 sensor but no such luck.
Can anyone give a good reason why it would be tps or coolant temp sensor after the car goes into closed loop? Any other idea?

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=Scott=
85 Iroc
96 Impala SS