With 5 speed manual transmission, when shifting gears, engine doesn't idle down, but revs high when clutch is depressed. Also seems to take a long time to idle down at red lights. Vacuum leak? How would I check?
Thanks in advance.

 

Manual trans vehicles have computer setting that holds RPMs high when speedometer is above 5MPH and clutch pedal is down, it shouldn't go up however.
Holding the RPMs between shifting lower emissions
And RPMs should hold at around 1,100 when coasting, then when speed drops under 5MPH it should drop to about 700-750RPM on a 2.5l.
An engine idling under 1,000RPMs is a big polluter, so this is also an emissions thing

To check for vacuum leak get the engine fully warmed up
Let it idle and unplug the 2 wires on the IAC(idle air control) valve, the valve will close all the way and idle should drop down to 500RPMs or engine may even stall, either is GOOD
It means no vacuum leaks

If idle stays the same then there is a leak

 

Thank you, RonD.

 

I have the same problem changed iac valve checked wires back to the computer intake gasket plugs to iac and tps changed CSS thinking of trying new computer also had engine smoked please help