AFM problems - I think?

[GTS-t VSPEC]

You can't upgrade to Z32's easily, need an ECU that will cope with the different input signal, like a PowerFC.

[G0DF4Th3R]

oh really? damn i tot the SAFC 2 could handle Z32's

looks like my mechanic was wrong

[Gradenko]

caminperth, I've had this exact same thing happen to me twice in the last week, both times in really cold weather. Your first guess was right, I'm fairly sure its a voltage induced fuel cut. Its harsh too, like someone suddenly slamming the brakes for an instant.

A fuel cut defender is very risky. Because the AFM is at max voltage, the ecu really doesn't know how much load the engine is under and so can't fuel it at all well. Like flying blind. The ecu would just see flat 5V coming at it until the flow drops below 5V.

The only alternatives are lower boost on cold nights (painful for me with a bleeder), or a Z32 AFM and anything you need to get it working (ecu etc). I've heard of ppl using Z32 AFM's with blue screen SAFC's, and the SAFC II definetly supports it, but I think it'd be a cludge to get it working with our 5 dial jobbies. It could work though, the Z32 AFM's are still 0-5V, just using a different scale. The ecu can figure out closed loop for itself and the SAFC can compensate everywhere else. But it is still a huge cludge.

[GTS-t VSPEC]

Yeah, the SAFCII's do handle it, not bad for the price:D

[caminperth]

bam - you win.. good work..

Gradenko/Paul - got it spot on.. thats exactly what happens. I supose i could run lower boost when it's cold - but thats painful cause i want to go faster and take advantage of the cold weather..

hmm looks like a new ecu could be on the cards after a cooler.. i'm not interested on wasting money going down the path of dodgy fix-ups.. would like to do things properly because experience tells me it's the easiest and cheapest way..

[macka]

U can disengage fuel cut

When your SAFC is mapped on the dyno when your AFM reaches 100% your computer still pumps out pulses for injectors so the tuners just bump the AFC up or down accordingly

Its quite accurate but of course at the time u do reach 100% its time to upgrade to Z32 or MAP

[Gradenko]

I'm suprised ppl with upgraded turbos and stock afm's (aidwin?, macka?) aren't hitting the fuel cut in the this weather. We can't be flowing more air than them with our stock turbo, maybe our afm's are faulty? You two should go out "testing" tonight and get back to us.

[macka]

who said we arent gradenko

who says we dont have FCD in our machines

[Gradenko]

Are you talking about something like a turbosmart fcd? Last I knew, you had a s-afc and stock ecu. Come on, tell us the whole story.

[GTS-t VSPEC]

I think Macka has a re-chipped ECU, which will have the fuel cut removed.

[ix9]

I'm having the exact same issue with my car. So getting an SAFC-II tuned properly will eliminate this ?

I still dont know how the car senses boost ? anyone enlighten me?

Also getting an EBC in the next few weeks... I thought these negated the need for an FCD ?

[Gradenko]

Ours car's don't sense boost directly, but measure the air flow load (and density) through the afm. More boost = more air flow = higher afm voltage. So the problem we're having is, sensible boost + super dense air = max afm voltage.

[ix9]

Ahh, I see now. So the Z32 AFM with the SAFC-II would correct this situation.

Explain this to me... How can other people with the same specs not be experiencing this issue. It varies from car to car.... That pisses me off.

[Gradenko]

Z32 AFM and SAFC-II should work.. in theory. Where's steve-sst when we need him?

The difference between cars could be explained by variance in the afm's operating voltage over a (up to) 10 year period. I mean, when the car was new, they had to deal with climates that included seasonal snow, so the afm should really be able to handle cold, dense air without freaking out. That's one possible theory, but it's probably not the right one.

[caminperth]

Originally posted by Gradenko

Ours car's don't sense boost directly, but measure the air flow load (and density) through the afm. More boost = more air flow = higher afm voltage. So the problem we're having is, sensible boost + super dense air = max afm voltage.

i'm not sure if i'd call me running 0.9bar on a stock cooler "sensible" - but it's great fun..

[caminperth]

Gradenko/anyone - know a good price for either of these:

SAFC-II: ??

Z32 AFM: $320? (this sound like a good price?)

[GTS-t VSPEC]

$320 is about normal:D

[rev210]

the S-afc II does do the Z32.

Says so in the jap instructions, quite easy.

[G0DF4Th3R]

Cam - nearly got an S-AFC on ebay for 470 bucks a couple of days ago

half an hour before the thing ended it went up to 530. i set my reserve price as 500 so i lost

[macka]

I have a series 1 blue screen for sale if anyone interested

Hasnt had much bloody use

Gradenko as Paul says i had a retuned Standard computer which removed my over boost cut(air volume) and 180kmh cut but since then ive sold it and running lower boost

In fact im not running any boost i was bored on the weekend so i took the turbo off