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Stock Ecu And Bigger Turbo

PM-R33

By PM-R33,
in Engines & Forced Induction

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PM-R33 Grand Master

PM-R33

Posted
Posted

Hey guys,

Been having this problem for the last few months now and it's seriously giving me the shits. I'm running a stock ECU (for the time being until i get some money together for a Microtech) and a HKS GT-RS turbo (list of other mods down below). Now the problem is with boost. Boost comes on nicely up to 0.5bar at about 2500rpm or so, then it very slowly goes up to 1.0bar at 6000rpm. From 6000rpm to 7000rpm it starts skyrocketing up to about 1.5bar. Im pretty sure if i didnt have a revlimiter it would keep climbing in boost.

Now i've read hundreds of threads on boostproblems/boost creep and a lot of people have problems with this so i've tried all the logical things that it could be:

1. Actuator: It's HKS one set to its longest point which should be 14psi, however when disconnected and the flap is wired all the way open it still makes boost, at about 4000rpm it kicks is and once again nearly up to 1-1.5bar, it goes so quick i cant tell the exact boost it reaches. So it's not actuator related.

2. Dump pipe: Boost control is sometimes altered by the setup of the dump pipe, either it sucking the flap open, or keeping it shut. Now i used to have a split BOS importing dump pipe and it used to do it, now i've changed into an all in one bellmouth X-Force dump pipe and it is still doing it. So it can't be the dump.

So everything points to the standard ECU either retarding the timing that much that it is somehow affecting boost, no idea how this could work but it's the only thing i have to go on. Has any one had any experience running a bigger turbo on a stock ECU. Is the change of plenum and turbo too much for a stock ECU to handle?? I really hope the Microtech will solve it, but if it doesn't im still going to have this problem. Why won't it hold 14psi!!!! And why does it take so long for it to reach 14psi?? It's like it's doing 2 opposite things, taking ages to make boost, then suddenly making heaps of boost.

Any help or input would be great.

Thanks :wave:

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_Ryan_ Grand Master

_Ryan_

Posted
Posted

earth your standard boost solenoid, if it fixes it, then read thru Sydneykids jaycar thread, and there is a photo showing how to re-route vaccum hoses.

Warning, check with a mechanic first, this might only help if your current wastegate setup is identical to stock bar the adjustment.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Well you shouldnt be running 14psi on the stock ECU anyhow.

Why it takes so long, probably because the stock ECU is shitting itself and retarding the timing from 4000-5000rpm.

Again, this is due to you running more boost (airflow) than the stock ECU accept in its wildest dreams.

So IMO. Put the stock actuator back on till you get a ECU.

Then go looking for issues with response etc etc

In all honesty your playing with fire with that setup

PM-R33 Grand Master

PM-R33

Posted
  • Author
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use a safc as a temp messure until you can afford the full ecu

Tried that, tuner said he couldn't tune it because of the amount of the boost skyrocketing. Looks like ill just have to get the Microtech ASAP.

PM-R33 Grand Master

PM-R33

Posted
  • Author
Posted
Well you shouldnt be running 14psi on the stock ECU anyhow.

Why it takes so long, probably because the stock ECU is shitting itself and retarding the timing from 4000-5000rpm.

Again, this is due to you running more boost (airflow) than the stock ECU accept in its wildest dreams.

So IMO. Put the stock actuator back on till you get a ECU.

Then go looking for issues with response etc etc

In all honesty your playing with fire with that setup

So you agree that it's all in the ECU and that once the Microtech is in it should fix it all? This is the only thing that i can pinpoint it too. When you say im playing with fire, can it do much damage running it like that on the stock ECU? Like other than it running rich and retarding the timing, it doesn't seem to be knocking and aslong as i dont keep it above 6grand it doesnt overboost, so should it be allright for a little while longer? I'm looking at the microtech within the next month or two.

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