The Mother Of All Unfixable Problems! (or So It Seems)

[DarkGT-R]

This problem started for me about 4-5 weeks ago after changing my R32 GTR's standard airbox filter for a BMC filter. I don't think this is causing the problem but thought I'd mention in case somebody works out what may have been accidently knocked/loosened/detached, etc...

Since then the car has begun having intermittent issues accelerating (both gentle and hard) and occasionally stalls. Stalling can occur immediately after starting or driving for a while, but it does seem to occur most when either coming off the accelerator or sitting at lights. It does it on both hot and cold days regardless of temperature.

The Car's Modifications:

Blitz ECU

Fully Rebuilt and Reconditioned Engine with Competition Rings/Bearings/Gaskets/Seals)

Machined crank and fitted crank snout

Forged Pistons

I Beam Conrods

ARP Rod Bolts

Tomei Adjustable Cam Gears

N1 Oil Pump

Modified Water Pump

Tomei Sump Baffle

Front Pipes/High Flow Cat/3.5 Inch Evolution 2 Trust Exhaust System

Hi Volume 500hp Fuel Pump with upgraded negative wiring

Boost set to 1 bar

OS Giken Twin Plate Clutch

New Battery

Steps taken so far:

Induction system smoke tested for leaks

Airflow meters cleaned

Idle Air Control Checked

New Spark Plugs

New Fuel Filter

Injectors serviced and tested

Standard Coil packs checked

Engine cover removed to confirm if overheating (no difference)

The intermittent nature of the problem is making it difficult to pinpoint and therefore difficult to resolve. The only thing confirmed severely damaged is my wallet! ()

Any and all wisdom appreciated.

Allow me to resolve this issue so that I can go on to build a finincial empire that will bring world peace and end poverty!!!

[R31Nismoid]

AFM's. Sounds like one is on its last legs

[wolverine]

^^^

x2

[Shaun O]

On a side note, is this a similar issue I sometimes have?

Boosting hard and then coming to a very fast stop with a very fast drop in RPM usually causes a stall or a drop to 0rpm and quickly puffing back up again. It idles perfectly though.

[payback21]

Check AFM cable connection too as it might have a bad connection.

[r33_racer]

+3 AFM/s

I Had the exact same issue in my road car, changed it for a new one and its perfect!

[R33NZSL33PA]

yep AFM prob

[Jmaac]

is a bmc an oiled filter?

[DarkGT-R]

is a bmc an oiled filter?

I believe it is a dry filter.

Thanks for the information so far guys. Much appreciated!

Keep 'em coming.

I'll try anything offered and the person who accurately diagnoses it gets a slab!

[R31Nismoid]

What turbos (just outta interest)

They are not listed and it makes me wonder why you would have a built motor, and stock AFM's does not really work (stock AFM generally means stock turbos)...

If it is stock turbos then i hope you realise you are playing with death by using the stockers

[Adriano]

Have you checked trouble codes? Im still betting on AFM, but the trouble code will tell you which one. you can pull the top off and resolder the afm

[DarkGT-R]

What turbos (just outta interest)

They are not listed and it makes me wonder why you would have a built motor, and stock AFM's does not really work (stock AFM generally means stock turbos)...

If it is stock turbos then i hope you realise you are playing with death by using the stockers

They are the standard turbos.

Initially, when I bought the car, I was going to do the usual thing and just modify everything EXCEPT the engine (e.g. intake/exhaust/turbos, etc...).

However, the engine disagreed, and let me know by blowing itself to kingdom come. Next thing you know I'm doing an engine rebuild, and decided to do the job properly in anticipation of future modifications. The standard turbos were checked and found to be in excellent condition, and I was told that they are safe and reliable as long as I do not exceed 1 bar of boost.

Thanks very much for your input! It is much appreciated!

[R31Nismoid]

Excellent condition or not means nothing. Simply because you cannot truly tell without pulling it apart.

They are 15-20yr old turbos in most cases.

I would be backing off to 10psi with a built motor to be honest mate. You'll have better odd's in a casino, as they are not reliable at all when getting old and running 1bar.

I'd only run 1bar on low km R34 GTR items on a built motor, and even then i wouldn't sleep easy @ night knowing the trouble just one full throttle squirt can cause.

I'm not trying to scaremonger you here either, i just hate seeing people loose big engines for silly things.

[DarkGT-R]

Excellent condition or not means nothing. Simply because you cannot truly tell without pulling it apart.

They are 15-20yr old turbos in most cases.

I would be backing off to 10psi with a built motor to be honest mate. You'll have better odd's in a casino, as they are not reliable at all when getting old and running 1bar.

I'd only run 1bar on low km R34 GTR items on a built motor, and even then i wouldn't sleep easy @ night knowing the trouble just one full throttle squirt can cause.

I'm not trying to scaremonger you here either, i just hate seeing people loose big engines for silly things.

Roger that. Will take it on board.

Anybody else have any other opinions on the acceleration/stalling issue I'm experiencing?

[R31Nismoid]

Until you swap out the AFM's with a known working set - its going to be a bit hard for any further advice from most corners as its almost pointing soley to one or both AFM's intermittently playing up.

[bigmikespec]

AFM's screwed ey...?

[Betz]

your AFM's will have dry solider for sure.

[DarkGT-R]

Thanks guys!!!

I'll check what you advised and, as mentioned previously, if it resolves the problem somebody has scored a slab!

[IM-32-FK]

its defiantly your AFM . I have the same problem in my r32 gts-t and i should be getting my z32 afm tomorrow. Hopefully it will fix the issue.

[shinaka]

Could be as simple as an electrical short in the AFM wire and plug..

Try playing with the AFM wire and plug while idling... Any consistant changes in idle or cutting off would indicate a short

Edited September 10, 2009 by shinaka