Need help on a 1990 ford thunderbird

hey my name is chris i told my brother to take his car to west sise tech so they can work on his car b/c i went there and they do a good job usually… it needed the brake switch that starts the car b/c you have 2 press the pedal to start the car and they supposibly changed it but they didn’t and i got the car back with it idling at 1700 RPM’s i’d like to kno what the hell they did to it if any1 has any ideas pleas tell me… thank you

Your post is pretty hazy. What brake switch to start the car are you talking about. I’m not aware of one, although if the car is a manual trans it may have a clutch safety switch.

What were the original symptoms and why did you take it there?
If the car is idling too fast this could be a binding throttle cable, vacuum leak, Idle Air Valve problem, or even bunched carpet or a floor mat pushed up too far.

oK THEY REBUILT THE CARBERATOR. THE SWITCH YOU REFER TO IS ON THE BRAKE PEDAL. FORD INSTALLED THESE TO MAKE SURE YOU HAD YOUR FOOT ON BRAKE AS THE CAR IS STARTED. SAFTEY THING. THERE IS A FEW THINGS THATWILL CAUSE THE RPMS TO RUN HIGH. THERE IS COLD IDLE SCREW.THIS ADJUST SHOULD GO AWAY AS THE ENGINE GET HOTTER IT HAS ABOUT 10 TEETH IN IT IF THEY ADJUSTED THIS TOO MUCH THE SCREW THAT REST AGAINST IT WILL NOT MOVE DOWN TO LOWER POSITION FOR LESS RPM THEN AFTER ENGINE IS HOT THE CARB IS IN COLD MODE. THERE IS ANOTHER SCREW FOR HOT IDLE IT MAYBE TOO TIGHT KEEPING THE ENGINE RUNNING TOO FAST. i .am not sure if you a medal rod or cable to operate throttle. check to see if rod is hitting something to keep from going forward all the way remove filter top and check idle if cable it could bad inside it,s cover. take both off connection and see if idle go,s down after engine is hot. timing can up the rpms to much advance. but this can cause it,s own problems in starting and running. does the engine want to keep running after you turn if off. does it sound like the battery is low on during hot starts. WST should have noticed a high idle before it left shop. another thing. If they set idle first then adjusted the air mixture second …the idle will change alot as the A?M screws are adjusted do some looking your self.

Hey, Chris, I have a '90 Tbird, too. I assume this is not the supercharged version, but the normally aspirated 3.8.

Not to offend boxwrench, but the MN-12 Tbirds ('89 - '97) all had multiport fuel injection with no hot idle or air mixture adjustment. They do have a throttle stop adjustment on the throttle body, but I would strongly, strongly advise you not to touch it. The computer expects it to be in a certain place and you can get yourself in a real hornet’s nest trying to calibrate the idle with that screw.

I think ok4450 has put you on the right path. I’d take a good long look at the throttle cable at the pedal (goes through a grommet at the top of the pedal assembly), then again where it mounts to the throttle body. There are 3 cables at the throttle body, one from the throttle pedal, one from the transmission, one from the cruise control servo. If one of them is binding, it will hold the throttle open.

Next best bet would be the IAC, they are known failure points on these motors (plus it’s 18 years old).

Don’t type like you are using an IPOD. Hrd2rd.


Also, check the simple stuff first – is all the intake plumbing (everything from the air filter housing to the throttle body) intact and correctly mounted? All the 1,000,000,000 little rubber vacuum tubes connected correctly?