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No Power, Please Help!


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ok, engine is rb25, standard except turbo back exhaust n fmic.

now engine has no top end power, made 111kw which is pathetic...

seems to pull alright until about 5,000 rpm then stuggles to rev the will pull hard from 6 to 7...

ive checked, fuel pressure, vvt, all timing marks line up, exhaust back pressure, comp tested, all 6 are 140... swapped CAS over for shits n giggles...

dont know what else to do, please help :(

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Sounds like a flat spot in the ecu! I have the same problem atm. The only way to fix it is to get a tune done with another ecu, that's if it is what i think it is.

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the stock ECU does not have flat spots on the map on purpose, or by design

the stock ecu is designed for basic engine control, reasonable power and lots of protection

it does, however, have lots of protection built in if you up the boost or make it work harder than it should

then, it resorts to simplistic and retarded mapping and fairly conservative tune settings

so by swapping ecu's youll achieve zero

the tune is hardset, it doesnt forgot or become lazy etc

id say you have a basic issue, a sensor missing or something simple

check the basics

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flat spots can exist if you are using the wrong MEC chip for your engine type

that is, if you have a RB25 and youve picked up any old R33 ECU and hope it works

i dont know why or how but it matters

i had a R33 ECU remap on my GTST and it was the wrong MEC chip and it run like ass

like absolute ASS. why i have no idea, the remapper said "WRONG MEC CHIP TYPE"

so whatever that means

so if your setup is part of an engine swap / ecu swap etc, check this

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ive been to a tuner and they said to check the timing marks which i have done... i have to which i think are unrelated, i get boost creep which the tuner has put down to the wastegate not flowing enough, as the boost starts rising it looses power... would have thought the power would rise as the boost does...

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as i said, the stock ecu has lots of protection built in

if boost is rising, something is wrong

if its a bog stock GTST with an exhaust boost should be 7psi bang on

if its spiking and going past 10psi ish then it will hit the stock ecu protection and youll loose all the power

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ive put the 25 into a r32, boost holds at 7psi, then past 5000rpm creeps to 15... ive never heard of the MEC chip?? i did buy a random rb25 ecu tho... i can run my profect b to 14psi but as it gets to 5000rpm power drops off still...

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well youve been told whats wrong, fix the boost control

its way too much for the standard ECU

it has aggressive proteciotn built in for stupidheads that try things like that

so either

turn the boost down

replace the stock ecu with a stand alone

or remap the standard ecu

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fix the exhaust

something is wrong, the std turbo should never creep like that

if the actuator is disconnected, its unlimited boost mode and the wastegate will never open

so never run with disconnected actuator

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thats the thing, i get boost creep so i cant... i get boost creep even with the actuator disconnected and the flap open...

You are getting boost creep due to poor boost control.

Nothing more, nothing less. The “tuner” claiming the wastegate ‘doesn’t flow enough’ is simply a case of he has no idea what he is talking about.

Every single other GTS-t out there doesn’t spike to 15psi – so why should yours?

I place my bets on your dump pipe. You said it was a turbo back exhaust, I bet it's a cheap/copy dump and the wastegate flap is getting stuck and only opening 50% or so, causing these issues.

The stock wastegate flows plenty - It sounds like it's being hindered.

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  • 2 weeks later...

ive tried 2 different dumps, now have a 'advance' bell mouth type on there, 2 different turbos and its still doing it. no evidence on wastegate flap on old turbo of hitting anything either...

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