Hey everyone,
First off, there's some great info on here. thanks for your time!

I have an 89 Fc GTU i have already put quite a bit of money into. i put a spankin new motor in and at this point it has about 13k on it.

It was originally an automatic... but i swapped that over to a GTUs 5 speed as well.
The car ran perfectly until after the 5 speed swap...
Now i have a very consistent Idle Rev, when the car is warm it bounces from about 1k to 13k.

First i checked for vacuum leaks with the Carb cleaner trick and used a whole can, got no spikes or anything.

I tried adjusting the TPS and it actually did nothing no matter what position the screw was in. From what i have gathered the TPS is **** or im just a total newb...

Any other suggestions?
Thanks for your help!

 

Did you follow the factory procedure to adjust the TPS or just start turning screws? There is a specific procedure to set the TPS properly and it must be followed.

Are you SURE you don't have any vacuum leaks? Including the nipple that would have been previously used for the slushbox?

 

Checked for the old slush box vacuum line, i'm not sure where it is. and i have not gotten rid of the nest. however, i heard at actually makes the car run more freely resulting in a small hp gain?

this wouldn't be difficult if my previous mechanic didn't blow me off, he won't even answer calls anymore.

i tried a few more adjustments on the TPS and got no changes. however, when i push up on the narrow range plunger the idle evens out until i rev it again.

Im taking the car into a renown rotary guy on saturday to check lines and any tuning issues. my previous mechanic is great with engines, but negligent at best with most other systems.

Thanks Guys!

 

Have you read the voltage of the Green/Red wire at the TPS w/key to on and the engine as warm as it should be? Should read 1 volt.

 

Took her to that rotary guy, Said the thermal wax valve is sticking. just a matter of being worn out.
a new one is about 120 bones, but you can bypass the unit as well. not sure what the repercussions would be... but messing with it a bit helped regulate the fluctuation quite a bit for the most part.
Thanks for the help guys.

 

You could try cleaning out the unit as sometimes residue builds up over time that is contained in the coolant which inhibits the item from working properly.

 

The thermowax and cold start cam have been known to stick. Cleaning out the area would be the best bet. Removing the thermowax will mess up the cold idle. Many "rotary guys" don't actually understand the systems they recommend be bypassed or removed.

 

not sure what a thermal wax valve is, can u explain further?