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R33 Gts25t Stock Ecus

_8OO5TED_
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_8OO5TED_ Mentor

_8OO5TED_

Posted
Posted

Do the RB25 stock ecus have a disliking for boost?

I have a RB25 with full turbo back exhaust, pod and front mount and without a boost controller it makes a constant 0.8bar.

On really cold nights, it misses quite a bit under full load. I have heard the stock ECUs like to retard themselves when theres extra boost being pumped in. DUring the days it seems to run OK under full load.

Any ideas? Would a SAFC/SITC combo or PFC help this?

CHeers.

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Ezz35 Collaborator

Ezz35

Posted
Posted

well seein as i was told this just 3 days ago search!!! lol

i had the same prob, thought it was coils, but yes 33 stock ecu sucks...

had a safc2 installed and it has fixed my probs :P

pfc or safc would fix this prob i think, but theres alot more knowledgeable ppl on here that could go further in depth about it.... or a 2min search ;)

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Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

RB25 ecu's have a air flow cut not a boost cut. When you hit the cut then you will know it - the whole engine cuts out and it feels like you just slammed the brakes on.

Sounds to me by your "missing" is that the boost is putting out the spark. My advise to you would be to gap the spark plugs down to .7 or .8 and try again.

You will be suprised =)

This is a known issue with slighty modified skylines - even stock ones. Works wonders.

Do the RB25 stock ecus have a disliking for boost?

I have a RB25 with full turbo back exhaust, pod and front mount and without a boost controller it makes a constant 0.8bar.

On really cold nights, it misses quite a bit under full load. I have heard the stock ECUs like to retard themselves when theres extra boost being pumped in. DUring the days it seems to run OK under full load.

Any ideas? Would a SAFC/SITC combo or PFC help this?

CHeers.

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mad082 Grand Master

mad082

Posted
Posted

safc only gets rid of the problem if you are running lean. if you are running rich and use a safc to lean it out you may get boost cut earlier. only way to get rid of boost cut is to get a aftermarket ecu, such as pfc, or a fuel cut defender. the new fuel cut defender from turbosmart should set you back about $230, but you then need some sort of fuel computer to stop it leaning out.

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benl1981 Grand Master

benl1981

Posted
Posted

mad082 you have got it the wrong way round. SAFC only works if running rich and you are getting air flow protection.

E.g

Before SAFC:

5 volts on the AFM triggers Air flow protection and is giving 9:1 air flow ratio (rich)

After SAFC:

With the SAFC you want to lean out the fuel mixture so you intercept the AFM signal and change the 5v reading to 4.8v. This will fool the ECU that there is less load there - hence less fuel will be delivered and it may not trigger air flow protection. I.e. youmay now get 12:1 AFR and no air flow protection

Also it has to do with how quickly the rise in Air flow occurs ...e.g how quickly you go from say 3v to 5v - this may trigger Air flow protection

P.s. all values made up. But AFM reads 0-5v

0v = no air flow

5.1v = A lot of airflow (enough to make 170rwkw+)

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