R32 Gtr Idling Problem

[seventhirteen]

Hey guys, just wondering if anyone could shed some light on an idling problem im having.

So the car in question is a 1994 R32 GTR V-SPEC II. From what I can see the car has a cat back HKS super dragger exhaust, APEXI pods, HKS EVC boost controller and turbo timer. When I got the car the AFMs were unplugged, an issue I would also would like to sort out (my guess is aftermarket ECU, but I was told it was stock when I bought it so I dont know).

So the issue is, soon after purchasing the car I straight away noticed a issue with idle first starting out as what seems to be just a slight misfire on idle ( the revs dont actually drop, the car just shakes alot but is stable around just below 1k rpm). Now when the car is like this and I turn it off and soon after turn it back on it hunts at around 500-200 rpm or just straight stalls. It usually just stalls but if I can keep it running itll soon stablize back to 1k rpm but still has the slight misfiring feel.

So I did some research and came to the conclusion that its most likely the AAC valve but I just want to confirm this before I start ripping things apart because it doesnt look like the easiest job.So any feed back would be greatly appreciated.

Thank you

[Ben C34]

Aac would normally be something to look at first, but the fact that the afms are disconnected on a stock ecu is really odd. I would be sussing that out first. How does the car drive? Also the usual plugs and coil pack clean/grease and normally clean afms/solder but on your case get them plugged in! What happens if you plug then in?

[Josh080691]

As said above.afms unplugged is sus

[seventhirteen]

Well the car drives normal with them unplugged but one of the first things I did was find the plugs and plugged them back in. Made no difference so im guessing they were unplugged because it wasnt necessary for the car to run. So im also guessing cleaning out the AFMs wont help?

How does a stock GTR run without the AFMs not plugged in? Do they even run correctly without them? Is there anyway I can find out if its got a aftermarket ECU?

Edited October 21, 2013 by seventhirteen

[Sinista32]

Passenger side kick panel. Take it off and the metal box in there is the ECU.

If you cant work out what it is take a pic and post back in this thread.

Edit: If the AFM's aren't plugged in then it is likely to be Mafless (meaning an aftermarket ECU).

Edited October 21, 2013 by Sinista32

[seventhirteen]

Passenger side kick panel. Take it off and the metal box in there is the ECU.

If you cant work out what it is take a pic and post back in this thread.

Edit: If the AFM's aren't plugged in then it is likely to be Mafless (meaning an aftermarket ECU).

Uploaded with ImageShack.us

Yeh just took a quick picture. Looks pretty stock. How can it run normally without the AFMs plugged in? How exactly do they run without them in?

Edited October 21, 2013 by seventhirteen

[Sinista32]

ok Stock

R32
RB26DETT
23710-05U62
Feb 93
Dec 94
2371M-05U62
MT

Maybe that's why it's running ruff (hunting etc..)

Go through what Superben mentioned above.

Checking further it could be a Mines re-written CPU too. Which wont change the above

Edited October 21, 2013 by Sinista32

[seventhirteen]

What are those numbers you wrote? Do those numbers indicate its a 93 model? Whats the 2371M-05U62 MT?

[Sinista32]

Type the numbers into google - there is apost on GTROC which is a UK forum.

It appears to be a stock 93 ECU for R32 GTR's. Doesn't mean your GTR isn't a 94 Model.

Just means the ECU was made between Feb 93 and Dec 94 (I think anyways, but read the thread )

EDIT: MT is Manual Transmission. 05U62 appears to be R32 GTR specific and 23710 is likely specific to ECU and date made somehow

Someone else may know as I am just ASSuming

Edited October 21, 2013 by Sinista32