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Removing Air Flow Cut - Rb25 R33

Finny

By Finny,
in Engines & Forced Induction

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Finny Community Regular

Finny

Posted
Posted

Hi all,

I am at the stage where I can't drive my car with out it air flow cutting. eg. AFM picks up too much air and the ECU cuts.

I have a KKR480, very high flowing 3" exhaust, FMIC, SAFCII ect.

the stock actuator is 10psi and I am hitting air flow cut at about 5500rpm even on 10psi.

I don't really have the money to go full after market management because; PowerFC $1550 + $1000 for tune. Its actually cheaper to get a Link or Microtech.

I have been looking at some remapped ECUs on ebay but I really dont trust those because you can never tell what they have exactly done to the tune, eg the car they tuned it on could be nothing like mine.

Does any one know of a cheap way to remove this bloody air flow cut.. its really anoyying the hell out of me.

Also this is a full on ECU CUT not R&R, I will make a video later to prove.

some people call it boost cut but its not techniclly a boost cut as the ECU doesn't have a pressure sensor, its triggured by the ECU picking up too much air or a spike in air flow.

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https://www.sau.com.au/forums/topic/193815-removing-air-flow-cut-rb25-r33/
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courier33 Enthusiast

courier33

Posted
Posted

I think its because you afm is at maximum voltage and cant read any more airflow, and hence cant meter fuel delivery from that point onwards. Thats why it cuts out, because from there onwards will become lean. Theres no way around it apart from bigger afm and aftermarket ecu.

Simon-S14 Grand Master

Simon-S14

Posted
Posted

the RB25 AFM is good for 240 rwkw kw... i highly doubt he's making that sort of power atm with a stock ecu.

What you'll find is that the ECu is cutting fuel. you need to either get an aftermarket ecu or get an RB20 ecu and remap that which is the cheapoer option (i have one of these)

mad082 Grand Master

mad082

Posted
Posted

yeah that is rich and retard. different people think it is different things. i had that on my r33. the cheapest option is to get a remapped ecu off ebay. if you go this way get it dyno'd straight away to check the AFR's. if they are lean then get a safc or something like that. the other option is to go a emanage ultimate. then you can remove the afm altogether if you want (with the addition of a map sensor). the emanage will be a cheaper option than a pfc and will give you about the same results if you go to a tuner that knows what they are doing (which is the same with a pfc. the quality of the tune more depends on the tuner than the ecu)

paulr33 Grand Master

paulr33

Posted
Posted

yeah 1k tune thats nuts

it would want proof every single cell was changed from the stock maps

$400 seems much more reasonalbe

and they are $1000 on ebay now a days the demand seems to have dropped off

ive seen two from memory go for around $1000 on ebay

Finny Community Regular

Finny

Posted
  • Author
Posted (edited)

No,

I have watched ebay for about the last 6 months and the cheapest one went for $1300 with out a hand controller.

The ECR33 Power FC are rare unless you want to pay $1500.

Its actually cheaper to buy a microtech and I would much prefer a microtech LTX12s over a PFC.

I live in Tasmania and don't trust any of the tuners here, I would prefer to boat my car to the mainland but year I was quoted $3000 for a Power FC installed and tuned from pritty much the only dyno tuner around here.

Its not R&R I don't care what any one says... Rich and retard is only about 4 degrease retarded and maybe between 10-11 AFRs. This compleatly cuts off.. eg no ignition what so ever... like the engine completely cuts there is no engine noise nothing. My car pings and when it pings the car R&Rs which feels like you have droped a couple of pounds of boost and thats all.

Also I already have a SAFCII and it hits 100% AFM at 5500rpm. I don't know if thats the true maximum though or just what the SAFC regards as max voltage.

Also E-Manage wont do any thing about AFM max or the cut, even with a map sensor because the E-manage translates the map sensor signal into a stock AFM signal so there for you might as well have an AFM any way because the signal can only reach so many volts.

Edited by Finny
courier33 Enthusiast

courier33

Posted
Posted

Thats why people upgrade the afm to one that reaches maximum voltage at a higher airflow than stock. If you run a map sensor on an emanage you can change the scale of the maps to avoid running out of load points.

I had the same cut thinng happen to me a couple of weeks after i purchased my r33, removed the wategate actuator pipe and forgot to re-connect it. As soon as I went flat out, I went from pinned to the seat to nearly head butting the windscreen when the turbo boost went to god knows what, and maxxed the air flow meter.

SECURITY Grand Master

SECURITY

Posted
Posted

the safc can be used to trick the ecu that the afm isnt reacing the voltage that it actually is, so it wont hit fuel cut.

the thing is, the ecu has 2 spots that ive noticed the boost cut hits. 4200 and 5500. ive maxed out both points with my turbo. what ive logged on my emanage is:

R&R starts to creep in at 3800rpm @ 3.8v. at

4200 boost cut hits at around 4.7v,

5500 it hits again at around 5v (afm maxed out as it only reaches 5.1 volts).

the emanage has a afm clamp setting, so i can tune all of these in with no worries. the safc needs to be put on a dyno with the correction values wacked in. just get it re-tuned and tell them thats whats happening.

heres a print screen of my log files:

heres where r&r starts coming in:

post-13452-1195124865_thumb.jpg

4500 fuel cut:

post-13452-1195124837_thumb.jpg

5500 fuel cut:

post-13452-1195124852_thumb.jpg

i hope it makes sence.

Finny Community Regular

Finny

Posted
  • Author
Posted

Ummm you do realize what a voltage clamp does....

I had a turbo smart fuel cut defender installed in my car when I brought it but I removed it.

This is why.

say you clamp at 4.7V so it doesn't cut

Say AFM reads 5.5V worth of air. ECU sees 4.7V.

Thats going to make it run very very lean and at those revs I wouldn't be surprised if pistons melted.

The way I know how to fix it for sure with out aftermaket ECU is this. get say 550cc injectors then run -33% fuel on your safc.

When AFM reads 5V it -33% so tells ECU 3.35V. Car doesn't run lean because injectors are bigger and there is no cut but AFM will max.

To fix AFM max run a 33% AFM bypass then you can remove the SAFC adjustments and the car will then max AFM and boost cut 33% later.

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