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The mkiv Supra Owners Club

Very odd boost patterns - BPU


mikeyb10supra

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I seem to have developed this rather odd boost pattern and its confusing the hell out of me at the moment. I am basically running with 1st cat in place and 2nd cat remove along with a very free flowing exhaust, I was convinced the other day the I had a boost leak in one of my IC couplings as when I came on boost I was convinced is sounded different to usual. I have now sorted this and im hitting 1bar again like before.

 

My problem is, sometimes when I kick down I get no second turbo and only make around 0.4bar or something and other times I will get the 2nd turbo and hit a strong 1 bar?

 

Ive read this is sometimes due to a sticky IACV actuator but im not convinced as im only hitting 0.3/0.4 bar when it happens....surely it should be 0.8 ish still??

 

Anyone got any ideas where to start :(

 

Mikey

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Did yours sound a little strange when coming on boost too?? ive been out tonight and on vaccum to pressure (0.1bar ish) it sounds like its almost hissing air which points to a boost leak? Thing that confuses me is that the FMIC silicine couplings were all checked and double checked over the weekend and still this problem persists :( and the car still pulls well to 1bar

 

Doing my head in now....might look into the VSV solution

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It didnt really make any different noises but when I put my foot down and the box dropped a gear, it should have brought tubbie 2 online but sometimes nothing, just a poor 4psi (or close to from what I remember) of boost. I found it especially annoying when overtaking on a carridge-way when you expected power there was none. I took the vsv's off one by one and ran 12v across them while blowing down one of the ports to see if they opened. The only one that didnt open was the wastegate vsv. I got one for £33 second hand, tried it to see if it opened when it arrived (which it did) fitted it and the problem has never came back :)

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