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The mkiv Supra Owners Club

Boost Controller - Problem Solving


mwilkinson

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I installed my Greddy Profec B Spec 2 boost controller onto Keith's (Supra-Swagger7) BPU UK Spec TT Auto on Saturday. Keith's car is BPU, uprated Whifbitz side mounted intercooler, 1st and 2nd Decat pipes etc. He also has a Blitz BOV and Defi boost and oil pressure gauges.

 

The boost controller came of my car and had been working without issue for around 2 years.

 

The install went without incident and the controller was up and running within an hour. I installed the solenoid as I had done to mine as per the following:

 

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Having installed the boost controller we went out to tune the system. Before this the car was running BOU power levels around 1.0 -1.1 bar on 2nd turbo boost. No issues at all.

 

Initially I had left the pipe from the vac pipes to the VSV connected and only caped the VSV port which runs to the actuator. Naturally the actuator port was also capped.

 

On the initial runs we saw some boost spiking, basically the boost would climb exponentially without hitting a ceiling, well I assume this as we set a limit of 1.25 bar on the Defi gauges which when breached we backed off. Although on checking peak it had gone to 1.4 bar.

 

No matter what I did to duty or gain the boost was very erratic.

 

We returned to my place and I checked all the wiring again, as many of the vac pipes as I could and also blocked off the vac pipe from the top of the engine and the other port on the VSV.

 

Another series of runs and this time no matter what we did we could not get the boost above BPU levels. 2nd turbo running 1.1 bar max. What we did find was that being an auto on kickdown the boost would not progress past 1.1 bar, but on slow acceleration to 2nd turbo the boost would build to 1.3 bar, but then drop quickly back to 1.0 - 1.1 bar.

 

Before giving up we have tried numerous runs, changing numerous settings.

 

I had also thought it might have something to do with the BOV. To rule this out I have installed my HKS SSQV 2 on Keith's car. It's working fine and having been on my car running 1.2 bar at 408 bhp I can rule this out a a cause of any issue.

 

The most logical assumption now is that the boost controller or solenoid is knackered.

 

Anyone experience this? Also, do others come to the same conclusion as me? Seeing as this is a UK spec is there something that I have missed?

 

Any help would be appreciated. It's very frustrating.

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Had pretty much the same thing, same controller!

Mine worked fine for a while and all of a sudden i got unlimited boost spikes up to 1.8bar!!

I then swapped the main unit with a friends and it worked perfect!

I have since bought a new profec B2 and only replaced the controller and all is good!

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I was hoping it wasn't going to be the boost controller itself but as you state it's the most logical thing.

 

Bummer!!

After i had done a bit of research, it seems to be a fairly common thing! There is a dude on ebay who repairs these for £75, may be worth checking out? I may get my other one done, so i have a spare!!

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No everything was working as it should, it just didnt stop boosting! No matter what setting i used, when i changed to my mates unit we used the same settings and everything worked well... And i have no issues with the new unit. I left the old solenoid in the car. So definately the control unit!

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