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When do R33s boost cut? I know it is airflow dependent not psi..

benl1981

By benl1981,
in Engines & Forced Induction

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benl1981 Grand Master

benl1981

Posted
Posted

Just want to get some feedback on the stock ECU. I am boost cutting at under 10psi....I think (not sure if boost cut or other..i.e coils)

The coils have burn marks down the side but I can see no arcing at idle or when reving the motor (I have taken the cover off the top)

Thinking now it must be boost cut.

1. What boost level do you cut out at?

My car has R34 intercooler and 3" exhaust..that's it. Tried a few different boost control methods. Both cause an engine cut. Warm or cold.

and

2. The AFM gives out a reading from 0-5 volts I believe. What voltage does the ECU determine that airflow is to high? I guess it may depend on inlet temp etc aswell?

I was boost cutting or equivalent at 3000rpm in 4th gear so it wasn't as if the inlet temp was high. Just put the foot down up a hill.. after going easy at 80km/h

paulr33 Grand Master

paulr33

Posted
Posted

hi ben,

ecr33 series 2, hits the stock boost cut around 11psi ish. feels like you hit an invisible wall (much like 180 speed cut). all the usual noises happens, boost shows 11psi on the guage and stocker gauage but you get jack all power from it. that was ecr33, pod, zorst, evc3 @ 0.80bar. then i got cooler and powerfc. afm goes from 0 to 5.10 volts. the stock ecr33 ecu doesnt know what air inlet temp is, it has no support for it. only amount of air coming in via airflow meter. do you get any popping/farting when you get this problem? the ecu dumps the timing and richens it up mega so you should get popping and farting in theory ?

benl1981 Grand Master

benl1981

Posted
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Posted

Thanks Paul!

It is like you say an invisible wall but didn't appear to pop and fart. I guess at 9.5psi I'm not far away from 11psi so maybe in fact mine is the overboost or over airflow cut.

So the AFM has to register near 5.1v to boost cut??

At the higher boost it tends to feel like it is missing sligtly as you rev it to redline (only sometimes though). Only just lately is started cutting. Running stock boost now and it is fine..although some people have had coil probs that only show up when boost increases...

paulr33 Grand Master

paulr33

Posted
Posted

what mods do you have ben? im not sure what voltage the stock ecu considers "too much" and goes into rich and retard (aka boost cut) but its probably somewhere near 4v or higher. if you run slightly lower boost do you effectively work around the problem?

Cubes Grand Master

Cubes

Posted
Posted

What you are experiencing isn't any sort of cut at all. A cut is a cut.. nothing, not an invisible wall.

You are experiencing the usual R33 ECU rich and dip safety 'feature'.

The R32 ecu on the other hand doesn't have the rich and dip safety feature. Instead it allows you to keep pushing it until BANG.. no ignition you literally loose all power, it feels like you have slammed on the brakes and the rear wheels compression lock. Its not fun and makes you seriously thing you have broke something. :D

The R32 ecu experiences this with the RB20DET at around 5500rpm @ 17psi with the stock turbo.

sr20detnz Newbie

sr20detnz

Posted
Posted

i have come across similar sort of promblem but i was running 11.9 and 11 psi boost.

At 11.9psi there was huge power dip and at 11psi it was less but it was noticeable.

When i ran my stanadard actuator at 7psi i good power curve with correct air fuel ratios.

i have dyno all the above pressures and yet havent found a suitable pressure above 7 psi.

I am trying to find out what is cause of this power dip?

Is it that the air flow meter can no read the flow of air or the ecu can not read the air flow signal given by the air flow meter?

Or it is at a specific pressure the ecu goes on to limp mode?

Are there any other factors that decide it ?

Can Safc work?

justin911 Grand Master

justin911

Posted
Posted

stock boost cut ???

ive got a r33, normal basic mods.. does that mean when it has 12psi for e.g on the boost gauge its only running at 11 ????

Im using the stock ecu with safc2, dont tell me theres some stock boost cut and i should of got the powerfc pls???

thanks :cheers:

(uve got me worried now)

Cubes Grand Master

Cubes

Posted
Posted

Do search ppls, its been covered many many times.

Its very very common for the stock r33 ecu to generate power dips through the power range. 'Generally' this occurs over 10-11psi'.

But really whats 1psi.. It could be your boost guage thats out.

paulr33 Grand Master

paulr33

Posted
Posted
Im using the stock ecu with safc2, dont tell me theres some stock boost cut and i should of got the powerfc pls???

yeah thats basically it, after a certain amount of airflow the ecu goes into protect itself mode. its not that bad, once you run around that boost level its not useful going any higher with the stock turbo as it wont make any more power.

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