Classic sti hunting when up to temp
20 January 2022, 01:34 PM
#1
Classic sti hunting when up to temp
Hi all, having a slight issue witha v5 sti classic of mine,,,, the idle is hunting between 100 and 900 ish rpm so when I’m slowing down to stop it’s almost cutting out
And then bouncing about
I’ve been told it could be the aicv which I’ve just replaced working fine but not resolved the issue…
I’ve 2 mafs here neither made any diffenvce but both were given to me so unsure on condition but when I Discon the maf with the engine running it cuts out which I belive is correct.
Lastly I was told it could be a air leak is the only viable solution to have a smoke test done….
The only other think it’s could be off the top of my head is that it’s map relatable but as far as I now the Imprezas not been mapped and is pretty much standard….
Any thoughts on what else I can do to sort it would be appreciated..
Thanks
And then bouncing about
I’ve been told it could be the aicv which I’ve just replaced working fine but not resolved the issue…
I’ve 2 mafs here neither made any diffenvce but both were given to me so unsure on condition but when I Discon the maf with the engine running it cuts out which I belive is correct.
Lastly I was told it could be a air leak is the only viable solution to have a smoke test done….
The only other think it’s could be off the top of my head is that it’s map relatable but as far as I now the Imprezas not been mapped and is pretty much standard….
Any thoughts on what else I can do to sort it would be appreciated..
Thanks
20 January 2022, 03:22 PM
#2
Could be a lot if things, smoke test will rule out the main one. Make sure both exhaust, intake and oil breather systems are tested.
Something you haven't mentioned is oxygen sensor; They can go a bit lethargic at idle which throws out the idle fuel trims. The idle can hunt as the sensor switches from rich to lean and back etc.
Think v5 is a narrowband as standard, so at idle when warm it should switch from 0.9v (rich) to 0.3v (lean) at least once per second. It it's switching slower than that the sensor maybe on its way out. Also check for exhaust leaks (like a cracked up-pipe) as that will also throw off the sensor.
BTW...if its had a bad head gasket fail, the silicates in the coolant can contaminate and kill oxygen sensors, probably not the case here but just putting that out there.
Something you haven't mentioned is oxygen sensor; They can go a bit lethargic at idle which throws out the idle fuel trims. The idle can hunt as the sensor switches from rich to lean and back etc.
Think v5 is a narrowband as standard, so at idle when warm it should switch from 0.9v (rich) to 0.3v (lean) at least once per second. It it's switching slower than that the sensor maybe on its way out. Also check for exhaust leaks (like a cracked up-pipe) as that will also throw off the sensor.
BTW...if its had a bad head gasket fail, the silicates in the coolant can contaminate and kill oxygen sensors, probably not the case here but just putting that out there.
20 January 2022, 03:24 PM
#3
I'd now be checking all vac pipes for an air leak.
My 98 forged 2.5 has just had to have the vac pipe to it's aftermarket fuel pressure gauge sender replaced as it perished.
And at the same time I'd be checking all rubber fuel pipes, as they perish too.
Mine split and dowsed a hot engine, downpipe and turbo with fuel.
Squeaky bum time😳
My 98 forged 2.5 has just had to have the vac pipe to it's aftermarket fuel pressure gauge sender replaced as it perished.
And at the same time I'd be checking all rubber fuel pipes, as they perish too.
Mine split and dowsed a hot engine, downpipe and turbo with fuel.
Squeaky bum time😳
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