street_ruler

Year: 1987
Model: Turbo II
Specifics: 5spd & 5 lug


My car has this 2k idle speed and it doesnt make any sense to me as to why. i understand that on first start it will revv up quite a bit for initial start but this is with the motor hot.

I tried to adjust the idle speed screw on the back of the fast idle valve but it really only brought the idle down like 50 rpm at max adjustment.

The other thing that comes to mind is a vacuum leak.

any other suggestions to look into?

diabolical1

iTrader: (3)

welcome to the board.

you should start checking for vacuum leaks.

this is good. more people should do this in this section when asking questions.

street_ruler

are all the vacuum lines the same inner diameter? basically im going to go to the local parts house and buy like 10 ft of hose and start replacing everything i can see.

satch

iTrader: (1)

Has it always had this high idle or did it just recently occur?

street_ruler

i bought the car 2 nights ago. but each time i test drove it, the idle was still there.

for arguments sake lets assume its been that way for a long time.

if the Fast Idle Valve, or Idle Air Control valve, i have no idea what its called on this car but they do the same damn thing...if it were malfunctioning 99% of the time you get a bouncy idle not a sustained high idle. would cleaning the FIV help here? granted it couldnt hurt.

satch

iTrader: (1)

It's possible the Fast Idle Cam is problematic. The BAC is a different item and it's the component on a turbo car that has a screw which can be turned to change the idle speed. A tight throttle cable can cause a high idle as well as an improperly set cruise control cable as well as sticky primary throttle plates as well as an AFM where the flapper door is stuck open too much in addition to a vacuum leak and improperly set timing. W/the car idling try pressing 'upwards' on the throttle linkage on the front of the throttlebody and see if this lowers the idle or not. If you suspect the Fast Idle Cam then w/the engine cold, start the car up and watch to see if the thermovalve piston extends outward some as the engine heats up. When this occurs the throttle linkage closes and thus leads to a lower idle.

street_ruler

FIC: what is this?


BAC: is this whats mounted to the right side of the intake manifold with a coolant hose going in one side of it and out the other? i messed with what i described and was only able to get about 100rpm difference in the idle by cranking down the screw. if this is like the fast idle valve on other cars, where as it heats with the water temp it opens/closes to raise or lower the idle speed i think it might be clogged. i drove the car tonight and let it idle for about 10 mins after the drive and the idle came down to 1500. I think thats if its the same functioning valve a good cleaning might help.


Throttle cable: cant be this. theres a ton of slack in the throttle cable that actually makes a bit tough to drive.

throttle cam: this is stuck behind the intercooler, but ill try it tomorrow night.

satch

iTrader: (1)

The BAC has a coolant hose running through it to prevent the solenoid from possibly freezing and no other reason. The solenoid's role is to stabilize the idle while the engine is under load and it's controlled by the ECU. It would only increase idle above the normal level if the solenoid was perhaps stuck open.

The Fast Idle Cam is responsible in helping the engine idle speed to slowly drop as the engine progressively warms up and is related to the coolant temperature. The normal idle speed on a cold engine is initially 1500 rpm or so. As the engine warms up this speed drops to 750 rpm. The service manual explains this system in detail. Also, the advanced search function found on this site will tell you everything you need to know. Any problem that can occur on your car has occured countless times over the twenty years or so of its existence and it is all documented for those willing to spend the time to read it.