Over the last couple of days my scoob has developed a problem starting up, only from cold i.e. first thing in the morning. It fires but only revs at ~500rpm and not the usual 1500rpm. I switched straight off and tried again, and it fired normally (revs up to 1500rpm, droping gradually over a few min).

The car is an Sti type RA version 2 and is otherwise driving OK, idle quality good, fuel economy good, power seems fine etc. The car is pretty much standard apart from cat back exhaust, HKS induction kit, boost controller and atmos D/V. All of which where already on the car when i got it 10 months ago.

Another thing i have noticed is that after starting from cold (normally), driving off (after idling for a min or two to warm up) and up to junctions a couple of hundred metres away, all is well. But after a mile or so the idle will drop to <600rpm. The car doesn't stall or hunt even with lights, radio, heater fans etc on. After this distance it's back to normal again.

So what do you think the problem is? and are the symptoms caused by the same culprit?

p.s. I've read the stuff about MAF sensors, but these symptoms haven't came up.

Thanks.

 

maybe the lambda is on its way out

do you have a afr guage or anything to measure it with?

 

I don't have a A/F gauge, but i do have an electrical multi meter which i can use to take a voltage reading. What reading would indicate a faulty lambda?

And would this affect the initial start up form cold?

A few minutes ago i read the fault codes from the ECU. I got 45 and then 11.
45-pressure sensor duty solenoid
11-crankshaft position sensor
The car has a boost controller, so would that cause the number 11?
And when i changed the oil, the crankshaft pos sensor was disconnected while the starter was activated. So that might explain that one, do you think?

 

yes to error code probably caused by cranking during oil change..

did you reset the ecu whilst you were at it?

probably maf (although pretty good on that age car) or Lambda as Sticky says.

 

Thanks for your replys guys.

No i didn't reset the ECU, but i will do it tomorrow and see what happens. I think i will also do the MAF test.