Problem Boosting On R32 Gtr

[itbmils]

Guys/Gals

I had some work done on my R32 GTR a week or so ago (air cond repaired), and since I've had the car back I've had problems holding boost and getting the car to rev past about 4500rpm (miss fire and just generally struggling to get revs up). Will not boost past .5 bar, feels like an AFM - but I know they a good.

Anyway - I think I have tracked down the problem

It looks like when they removed and refit the flexible intake pipe between the rear turbo and the AFM, that they have mangled the bottom connection. I've just removed it to discover that the bottom of the pipe has been rolled over under itself and then clamped down. This has deformed the rubber - and has been leaking once I start to build some boost (at a guess)

My question is – would a leak here be causing the problem described ?

And if so - where can I get a replacement - I recall seeing a GB for a hard pipe to replace this a while ago, but I can't seem to find that now

If anyone has one of these lying around – I'm probably interested in buying from you

I've attached a pic of the pipe that I'm talking about just to be clear

[saliya]

  itbmils said:

Guys/Gals

It looks like when they removed and refit the flexible intake pipe between the rear turbo and the AFM, that they have mangled the bottom connection. I've just removed it to discover that the bottom of the pipe has been rolled over under itself and then clamped down. This has deformed the rubber - and has been leaking once I start to build some boost (at a guess)

My question is – would a leak here be causing the problem described ?

Hey,

Don't think so - those pipes are only under atmospheric pressure (or less!) even when the car's making boost.

It's possible that the lower-pressure area at the front of the turbo inlet is 'sucking' air through a tiny gap

that may be caused by rubber deformation - meaning that your car will be running leaner than it should -

but unless your air filter's blocked or there's a rag stuffed in a pipe I doubt it'd be much (depending on the

size of the gap, of course).

You need to check _everything_ that they removed/refit - personally, if they're an OK bunch I'd be taking

it back and saying 'scuse me folks, but something seems to be wrong here, can you tell me just what

you did and maybe take a look at it'

Regards,

Saliya

[Godzilla32]

  saliya said:

Hey,

Don't think so - those pipes are only under atmospheric pressure (or less!) even when the car's making boost.

It's possible that the lower-pressure area at the front of the turbo inlet is 'sucking' air through a tiny gap

that may be caused by rubber deformation - meaning that your car will be running leaner than it should -

but unless your air filter's blocked or there's a rag stuffed in a pipe I doubt it'd be much (depending on the

size of the gap, of course).

You need to check _everything_ that they removed/refit - personally, if they're an OK bunch I'd be taking

it back and saying 'scuse me folks, but something seems to be wrong here, can you tell me just what

you did and maybe take a look at it'

Regards,

Saliya

Id be taking it back too, unless you regret having them ever touch your car in the first place. People are always trying to fix workshops mistakes...Why? If they made a mistake get them to pay for it/fix it. only seems logical.

[itbmils]

  Godzilla32 said:

Id be taking it back too, unless you regret having them ever touch your car in the first place. People are always trying to fix workshops mistakes...Why? If they made a mistake get them to pay for it/fix it. only seems logical.

sorry guys

should have said - the guys that fixed the air con are more than happy to fix what they have done. They have even offered me a loaner car for the day/days

I was just checking things over to see if it was smething obvious

to be honest - I'm not even sure that these guys even touched that pipe

[paulr33]

hey scott

i think it would, as the air would be different vs what the afm is measuring. an easy way to check would be to watch SENSOR SW CHECK and go for a fang or get a mate to drive, it would expect AFM1 to be normal and ramp up normally and AFM2 to stay pretty low cos the turbine would combo suck from the afm entry and the leaking entrance.

this would affect load axis placement as the FC does average (so does stock ecu) across both afms so you load would be all over the place, MAP TRACER viewing would prove this.

apexi have the power intake which is metal of the afm to turbo ducting but its pretty expensive, around $400 ish i think, nengun.com has it

[itbmils]

  paulr33 said:

hey scott

i think it would, as the air would be different vs what the afm is measuring. an easy way to check would be to watch SENSOR SW CHECK and go for a fang or get a mate to drive, it would expect AFM1 to be normal and ramp up normally and AFM2 to stay pretty low cos the turbine would combo suck from the afm entry and the leaking entrance.

this would affect load axis placement as the FC does average (so does stock ecu) across both afms so you load would be all over the place, MAP TRACER viewing would prove this.

apexi have the power intake which is metal of the afm to turbo ducting but its pretty expensive, around $400 ish i think, nengun.com has it

Yep - I noticed a delta between the AFM readings last night (more than 10%) - which is what made me have a look

if the Apexi power intake is $400 - I'd expect the std Nissan part to be half that anyway

[saliya]

  itbmils said:

Yep - I noticed a delta between the AFM readings last night (more than 10%) - which is what made me have a look

if the Apexi power intake is $400 - I'd expect the std Nissan part to be half that anyway

It probably won't hurt to swap them around - to make sure the discrepancy doesn't follow an AFM - mark them!

I spent 'far too long' chasing a wiring problem only to find that what I was really chasing was a 'you resoldered and replaced the wrong meter' problem

Sounds like a leak might be the cause - but would suck to spend $400 and not fix it...

Regards,

Saliya

Edited November 26, 2006 by saliya

[rb26s13]

i have that stock pipe laying around somewere if you want ill have a look pm me or msn waz(at)ipimus.com.au

[itbmils]

  paulr33 said:

hey scott

i think it would, as the air would be different vs what the afm is measuring. an easy way to check would be to watch SENSOR SW CHECK and go for a fang or get a mate to drive, it would expect AFM1 to be normal and ramp up normally and AFM2 to stay pretty low cos the turbine would combo suck from the afm entry and the leaking entrance.

this would affect load axis placement as the FC does average (so does stock ecu) across both afms so you load would be all over the place, MAP TRACER viewing would prove this.

apexi have the power intake which is metal of the afm to turbo ducting but its pretty expensive, around $400 ish i think, nengun.com has it

so - after some more checking

@ 4500rpm

AFM1 reads ~2.5 volts

AFM2 reads ~1.9 volts

I'm assuming this is BAD

Are we sure that AFM2 is the top AFM that is plumbed to the rear turbo ?

I have 2 'spare' AFMs - but I think one of those in dodgy too (arrgg)

NB I don't think the pipe is leaking any more - I may have an AFM that is FUBAR

Edited November 27, 2006 by itbmils

[saliya]

  itbmils said:

so - after some more checking

@ 4500rpm

AFM1 reads ~2.5 volts

AFM2 reads ~1.9 volts

I'm assuming this is BAD

Are we sure that AFM2 is the top AFM that is plumbed to the rear turbo ?

Hey,

I can't remember

Easy way to tell: physically disconnect an AFM, turn ign ON.

Should see 0 volts on disconnected one; 0.15-0.20 on connected one.

MARK THEM

Regards,

Saliya

[paulr33]

yeah saliya is right

unplug one and look at sensor sw check

[itbmils]

  paulr33 said:

yeah saliya is right

unplug one and look at sensor sw check

thanks guys

once I have that sorted out, and I have marked them both - my current thinking is to swap them over and check the the fault follows the AFM

is it a safe assumption that the one with the low reading is the faulty one ??

As I said - I have 2 'other' AFMs - I'll then try and rotate them in one at a time (replacing only the faulty one) and see how I go

Also - I took the car back to the auto electrician this morning - and I am disappointed to say that they have given up !!!

Their current suggestion is for me to take it to a mechanic and have a smoke test done to check for vacuum leaks etc - if it turns out to be something they have touched, they will pay for it. Otherwise I'll need to foot the bill.

I'm guessing that they will not be too interested in paying for new AFMs

Mercury have quoted $88 for a smoke test (which should only take 30mins) – so if that's all that's needed, GREAT (I bet it does not work tho)

I'm not sure if I'm happy with that - but I just want the car fixed !!!

I will post when I have a result