[Mk2] [NA] ACIS problem

[ormzy]

I'm not 100% sure if the acis system is working as I seem to lack a bit of top end power, it seems to hit a flat spot at 5k+. With the car stationary the acis actuator is being sucked and is acting on the pushrod but reving the car 5k+ the actuator doesn't move, is this normal? should the acis system work when parked? With the engine off I can freely move the pushrod to the acis so I know its not seized. I've checked the relevant vacuum pipes for splits etc and there are no fault codes. I'm no expert on the acis system but researching I understand the acis valve closes by means of the ecu cutting the vacuum. I have traced the vacuum pipe off the acis actuator to a device under the intake manifold which has an electrical connection to it. Is it a case of pulling the connector off and checking for a live feed whilst raising the revs or is there any other way of diagnosing if the acis is working?
Thanks, any help or advice appreciated.

[Kinsy]

From what I remember the ACIS system doesn't activate unless the car is indeed moving.

The cheapest and easiest fix for ACIS trouble is to replace all vac lines, which is what I did, worked a treat. If that doesn't fix it, try removing the top panel of the intake and checking to see the flaps open by pulling on the actuator arm manually. They have been known to seize over time if the engine isn't 'used'

[Kinsy]

From what I remember the ACIS system doesn't activate unless the car is indeed moving.

The cheapest and easiest fix for ACIS trouble is to replace all vac lines, which is what I did, worked a treat. If that doesn't fix it, try removing the top panel of the intake and checking to see the flaps open by pulling on the actuator arm manually. They have been known to seize over time if the engine isn't 'used'

[Chloke83]

Or i have a spare working one up for sale.

[Peter Gidden]

try removing the top panel of the intake and checking to see the flaps open by pulling on the actuator arm manually. They have been known to seize over time if the engine isn't 'used'

No need to remove top intake panel. Just try turning the lever on the N/S of the inlet manifold.

[ormzy]

All Vac lines are ok from what I can see, no signs of cracks perishing etc. The acutator and pushrod all work fine from moving them manually so I assume (unless the connecting rod operating the butterflys is broken) that the valves are moving. My main concern was that the acis wasn't moving when parked and didn't know if this was normal, so I couldn't get a proper diagnosis.
If this is normal, then I'll have to do a little more investigation. Has anyone ever heard of the acis vacuum solenoids breaking down? or problems with the system not working at all.
Thanks for the replys people.

[Peter Gidden]

If you Google the ACIS system IIRC you'll find it works on MAP and RPM. So it'll never work at idle.

[GreddyMR2]

When my ACIS didn't work, I had to change an ECU... Only that helped.
And as I remember, it also opens on the idle when you rev untill 4,5k or so. So it's not needed to run to see if it's working of not.