I Recently got a 1991 firebird 5.0 tbi. after a few days of having and after cleaning a few things in the engine bay; it started accelerating on it's own.
i let it sit in drive without touching the gas; it starts speeding up. it's gotten to 30mph on it's own. it also idles funny. it rev's on it's own and it has a high idle at 1000rpm. i really dont know what to do.

im guessing it was made by toyota! sorry i have no clue. hope ya find out. ttt

Check your vacuum lines to make sure they are still connected and not leaking. If you need to spray some carb cleaner/starting fluid/brake cleaner around the lines, if the engine revs while spraying it has a leak.

1k rpm idle isn't high, mine is 900.

ill try that tomorrow morning. well when i have my foot on the break it feels like it's trying to peel out with out me steeping on the gas.

a vacuum leak will cause a rise in rpms but it all depends on the size. Fuel injected or carb car?

throttle body injection

make sure your TB is shutting all the way too.

Beat me to it god damn you!

would pay close attention to tbi mounting gasket.if memory serves me right these had a high rate of failure.also depending on how vigorously you cleaned may just need to dry out.depending on condition of harness water can cause voltages to bleed across wire at multi connectors.

I beleive you are right. i did remove the tbi but i never replaces the gasket, and i did clean it too hard (pressure washer) ...

Hello Foster382!!

Pressure washers are bad for electical componets, like the TPS!! I pressure washed a 2.8 multi port, and got some water into the TPS, made it rev like it was going racing!!

Try drying out the TPS with a hair dryer or a heat gun (on a low setting), it may solve your problem!!

TPS? thats the throttle position sensor, correct?

Si

Id check the IAC

Hello Foster382!!

Yes!! You are correct, see itsMikey's post, he confirms it too!!

Did you have any luck???

Actually yes. it is a problem with the TPS. to my findings is that it sent an error code to the ECU, BUT the check engine light never came on. So the people i bought it from have unpluged the engine light. It's a good thing i never got my inspection yet and to still be in auto Tech.

Hello Foster382!!

Now that you know it's the TPS........$25.00?????, and your good to go!!

Just speculating on the price for a new one...........bought one in 1993?, for about that$$$$!!!

Thanks Yal. It runs so much smoother now. it went from accelerating to 30 on it's own to 10mph drift.