Aicv.. Good Or Bad.?

[terryterry147]

ok lads. been a member a while but don't get on here much...BUT ...I have a question only because I cannot seem to find / fix the problem I have..?

I believe its called the "AICV" the little sucker at the back of the intake manifold that regulates AIR on a cold start !

I have a R33 GTST (RB25DET ) I am building from scratch and up to now have been able to fix the "many" problems with a total rebuild on these things !! (and NO history ? ) to the point !

at this stage the car starts and idles sweet as a nut at about 1100 rpm WITH THE AICV DISCONNECTED.!

and DOES drop off to about 700 rpm when hot..! I have removed said part and cleaned and replaced without a win.

IF I reconnect the plug to the AICV the revs straight away jump to approx. 1700 rpm and hold there HOT or COLD..? and I mean HOT ::ie:: rad cap removed and thermostat open watching rad fluid flowing though the rad.!

is the unit shot /seized..? or am I missing something else here..? many thanks in advance for ANY help given on this, it is doing my head in..! CHEERS.

[jiffo]

Just so we're all on the same page, the 33 Rb25 has the brown plug (AAC), purple plug (aircon, etc idle bump) and the Air Regulator for fast idle during cold start. (buried under the plenum)

Which item have you been working on.

[terryterry147]

so sorry "jiffo" should have put more info IN...!

the part in question IS ::: the bigger brown plug which I believe plugs into a small motor unit::: ( this plug once connected whips the revs WAY up at any stage of engine heat..??? ) the smaller ( under this ) plug does NOTHING at all at any stage..? the air regulator I have NOT touched at this stage purely because its a "bitch" to get too..!!! hope this helps a bit , and thank you for a quick reply on this my friend...

[jiffo]

From that info your Air Reg is working properly and the fact that the AAC (when plugged in) immediately revs up the engine shows it's also working, but just getting the wrong info.

The idle is acceptable (700rpm hot) with the AAC unplugged so it doesn't look like vacuum leaks.

From basics and presuming a stock engine, is the cam timing correct and the CAS looking fairly central in its adjusting slots?

Have you checked the IGN timing with a timing light?

Have you set the TPS correctly?

That's about it for me.

[terryterry147]

many thanks "JIFFO" for your input my friend....!

DEF....no vacuum leaks here ! :: ( I screwed up when I first placed the engine in the car ( after a rebuild ) and fitted a front mount ,but was not happy with the way the piping kit had to be routed though the driver side rail "so to speak" and up over the belt cover..? so I came back behind the FMIC and followed the stock route to the intake ! )

sooooooo....after checking timing ect::: I pulled the throttle cable UP under the bonnet by hand just to get the revs up to around the 4000rpm mark (this I DO NOT recommend EVER again ) I fouled the cable and the engine revved to the LIMITER...for a few seconds !!

YES...basically stock ::: am running R34 turbo with OP6 rear/ full 3 inch exhaust / MINES ECU.

on the first "fire up" (once fitted ) the engine idled a LOT higher and have played with the TPS (after marking its position first ) the air idle "screw" in/on the side of the unit in question ect;;ect.

WILL get the girl into "Gavin woods" tuning shop when I can..! (after a new frt screen/ auto electrician to re-wire the "low beam" lights..? they don't work from the NEW switch..? but can throw power to them and they light up..?? and get the crap window tint RE-DONE so I can see out the windows..!! (lol )

BUT....there is no way I can get the IDLE down to a respectable level with all plugs fitted on the AICV..??? all the best mate Nick.