Sti Forester has fast idle issues at 2k and beyond when parked - NCT problem

F

Feakle-Forester

Sunday Drivers
The fast idle keeps surging up and down from 2,300 to 2,500, It's like there is a bad plug or idle positioner is intermittently faulty :comp26:, Who knows any other cause for this pain in the ******* :angry1:!, I have 12 Days left for retest, Extortionists !
Appreciate any positive help on this dilemma, :wall: Thanks people :subaru:
 
What do uou mean by fast idle??? is it only happening when she is after a cold start??
 
Seemingly the First Lambda sensor is the prime suspect at the moment!
Dan
 
davelegacy said:
forester sti said:
Seemingly the First Lambda sensor is the prime suspect at the moment!
Dan
Click to expand...

this would cause a bank1 sensor fault and a check engine light!
Click to expand...
dave

can you give further info? Symptoms etc
also whats the results?
Just tryin to learn a bit more
 
Fast idle test is done when the smog test is carried out by NCT tester, at 2500rpm it should stay running steady at 2500rpm for the duration of about 1 or 2 minutes,
Mine hunts from anywhere from 2000 rpm to 2800rpm and therfore makes impossible for them to do an accurate test or get a good result.
I have replaced the Pre-Cat o2 sensor with a new one ordered specially by Limerick brakes, €150.00, also replaced the Post-cat o2 sensor at the same time,
Only now it hunts like mad when driving it, until the CEL shows up and stays on and then it runs fine... No hunting AAAGGGGHHHH!!!!!! :hammerhead: :hammerhead: :hammerhead: :cuckoo: :wall: :wall: :comp26:

Totally Baffled,

Any Ideas

Mark
 
yes the hunting is still there at normal idle, but it is less evident there, shows up like the A/C kicking on. only slight difference in rpm's.
 
Code was stating there was trouble with the Precat sensor, 031 code. then I changed it out for new ones. sensors read fine till it gets to a minute of idling and then it hunts every second per second precisely, like a flasher unit oscillation. Puzzling me blind at present. Inter cooler has not been removed at all since I have had it for the past 3 years. Why?

Mark
 
A intercooler to throttle body jubliee loose or slightly off umder can and will cause running issue similer to above. Although wouldnt throw p0031 code up. Was the new sensor genuine or was it a spurius one snipped and soldered?
 
And obviously wasnt always like this if you have had 3 years. Was there anything done around same time it started happening?
 
Nothing done except serviced a few times and the timing belt 12 months ago, The Precat sensor was not genuine, it had to be snipped and soldered, might this be the reason. does it have to be genuine sensor, these things are all made by Fujitsu anyway...! Exact order from Limerick brakes was precat not postcat! Could this be a postcat sensor? :cuckoo: funny enough if this is all it is and a waste of €150.00 and hours of head wrenching torture for all concerned!!???
Also checked all the Clamps and hoses with carbcleaner spray, tightened them as well but no apparent leaks,

Opinions please?

Thanks

Mark :subaru:
 
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