Idle speed

[turbazz]

Right feel like am really getting somewhere with my car now boost leak sorted and det sensor changed.


Next job to tackle is the idle speed.


The result I was getting before sensor change( det)


Cold....1500rpm
Slightly warm ....1000rpm
Up to temperature. 1500rpm


And now


1500
1000
1250


I'm not sure if this is normal? I get the feeling the last figure should be under thousand?


So where do i start?

 

[PobodY]

It should be ~950rpm once at temperature, but it should fast idle for a minute or so before it settles-down (maybe 1250rpm).

I'll see if I can't find the official figures in the service manual.

EDIT: 850±50rpm for the SR20DET with the TPS disconnected, and 925±50 (actually +25 -75) with the TPS connected? - I can't find what the fast idle should be.

Anyway...

Diagnostic procedure 1 - High Idle After Warmup:

• Check air regulator. - Does pinching the hose cause the revs to drop?
  Try all the hoses because I found it was the dump valve leaking under vacuum at idle on mine.
• Check intake for air leaks.
• Check throttle linkage.

Diagnostic procedure 2 - Hunting:

• Check lambda sensor.
• Check injectors (they should all cause a drop in revs when you disconnect them).
• Check spark plugs.
• Check for air intake leaks.

Diagnostic procedure 3 - Unstable Idle:

• Check injectors.
• Check spark plugs.
• Check fuel pressure.
• Check lambda sensor.
• Check air intake for leaks.
• Check idle screw for clogging. - I usually just take it out and give the whole IAC valve a blast of throttle body cleaner.
• Check compression.
• Check ECU.

Is that any help to be getting on with?

 

[turbazz]

Yes i need to do diagnostic procedure one?
What about the idle screw ias?

also I was going to do my ignition timing should I resolve this problem prior to doing so

 

[turbazz]

what is the air regulator and where is the throttle linkage how should I check this