The engine of my very modified Sti v3 will not tick over.
It runs very well but when you take the foot off the throttle, the engine comes down the rev range like a normal engine and carries on to Zero.
Restarts perfectly, and will die immediatly if left to.

No dash light etc all seems well.

Car has Apexi with FC, and this condition arrived over night.

Have stripped and checked the Idle sensor on the manifold, checked every manifold related pipe for security, all ok.

Any ideas please?

Graham.

 

could be the maf

 

Hope not.

The MAF voltage is 1000mV at tickover; if it were faulty wouldn't the CEL be on?

Graham.

 

what you could do is disconnect the maf and if the car idles that means the maf is faulty, but if it stalls then the maf is okay.

 

IACV?

 

That's the bit I've stripped etc, but i suppose it could be knackered, but is does seem mechanically ok!
Will try the MAF test tomorrow.

Thanks for the help, appreciate the thoughts.

Graham.

 

Pull the maf connector and the engine stalls..good
Pull the idle valve connector and the revs rise when cold...good?

Now I'm stuck!

Any more ideas?

Graham

 

This is probably a very long shot but worth a check.

The girlfriends VW Polo suffered from the exact same symptons for about a year. I tried everything I could think of to resolve it, throttle pos sensor, temp sensor all the pipes etc to no avail.
Even the VW garage could not find the problem.
Then one day browsing the internet i found somebody who had had the same problem and fixed it with a toothbrush and carb cleaner.
When the butterfly in the inlet manifold is closed there is still a small gap to let in enough air so it can idle.
****e had gradually built up and completely closed this gap causing it to stall as the revs drop too low.
To look at, it appeared ok, just a little brown staining around the butterfly and surrounding body.
Took me about 5 mins to clean it up with toothbrush and carb cleaner..........
PROBLEM SOLVED

Not even sure if there is a butterfly in a subaru inlet manifold, but i would imagine there is.

Andy

 

There's a butterfly or equivalent in about 99% of cars to control the throttle, scoobs included. Only a very few cars control things differently - I think one of the new/prototype BMW (?) engines does it all by the valves. However, on most cars these days, I thought that the IACV did the job rather than relying on a "cracked open" butterfly. Normally when I've encountered this kind of problem on other cars, it's been the IACV.

Not quite sure what pulling the IACV connector leading to revs rising when cold actually means, though, I have to admit.

 

The Polo had a IACV which was working fine, but when you let go of the throtle peddle, the butterfly completely blocked all air off causing it to stall before the IACV could correct it.
Sometimes the IACV would catch it before it stalled but not very often, and the car would hunt on idle as the butterfly opened and closed.

Im probably completely wrong with this but its worth a look as it wont cost anything

Just trying to help!

Andy

 

Most excellent!
The issue arrived overnight, no gradual deterioration so the dirt in the butterfly bleed could be right!

I have one more trick to try and then will take the TMIC off (again) and clean the throttle body out.
When cold, the IVAC opens a vane valve via a magnetic actuator driven electrically.
This vane is wide open or closed and passes/bleeds air to the manifold from the inlet pipe. Pulling the connector off drops the signal to the actuator so causing a very rapid movement in the vane position. Rev change shows that the actuator is alive as if faulty there would be not vane position change.

Thanks for the input, realy helpful!

Graham.

 

If you need a IVAC to try i have a spare one or 2 lying about.

 

Thanks for the very kind offer.

I now have a tick-over.

Slackened the cable, ran the car to temperature (90 deg C) and rotated the idle valve actuator 3 degrees to catch the tickover to 880 rpm, rock steady.
Found the airbox had detached itself too so masses of air getting in on the maf side of the box.....

All seems well (today).
Will take it for a blast tomorrow and see then.

If needs be will take you up on your offer

Thanks for the help everyone.

AndyF has lead me through this lot too, top guy.

Graham.

 

Graham,

Glad it seems OK now, not the kind of thing you need after all the work you've put in.

Dave.