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The mkiv Supra Owners Club

My Boost Probem (video of dials) Please watch and advise!


Matt H
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Hi All,

 

Following on from my previous post:

 

http://www.mkivsupra.net/vbb/showthread.php?t=65362&highlight=high+speed+boost

 

I have taken a video (on a private road) from inside my car focusing on the dials (boost gauge and revs)

 

As you can see from the video when the boost rises to around 1.1 bar or higher its quickly gets kicked back down to about 0.9 bar then rises again to about 1.1 bar then gets kicked back down which you can tell happens when the camera jolts forward cos that’s exactly what’s happening; there is a fast and strong jolt as the car, I suppose kicks down the power.

 

I’m wondering if there is a problem with my HKS FCD but im not sure. Please watch the video (especially the experts and let me know what you think!)

 

My car is BPU with:

 

Hybrid Turbos

Dual de-cat (first decat from Chris Wilson with restrictor ring)

HKS FCD

Blitz induction kit

Blitz Nur spec r Exhaust

 

Video: http://media.putfile.com/Private-Road-Test

(I hope this works – first time I’ve uploaded a video!)

 

All advice is welcome and greatly appreciated.

 

Thanks

 

Matt

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Bit hard to tell from there because i'm on a laptop and can't hear anything :D But did you get the plugs changed? How long's the HKS FCD been in for? AFAIK these units can sometimes be a bit dodgy.

 

Had the mechanical side completely looked at by Chris Wilson, and everything is sound in that department. Its got to be elecrtical. Theres not much noise anyway, its just the drop then increase in boost and as a result rpm in such a drastic fashion thats what im trying to demostrate.

 

Think the FCD beens in for a few years but i only bought the car a couple of months back and had the problem ever since i drove it home. Thought it was gear changes at first!

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I have new Thor FCD's here, we can try one if you like, but I suspect it is NOT that.

 

What do you reckon then Chris if its not the FCD?

 

I've bought a Thor FCD today second hand (dont think its been used tho), it will be worth trying it out tho.

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looks like the FCD playing up.

 

I got a HKS one on mine too. Works fine, but u need it on the correct setting.

 

Theres a small dial. Find it near the ECU and see what you got.

 

I'll check whats on mine.

 

That would be great mate

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What do you reckon then Chris if its not the FCD?

 

I've bought a Thor FCD today second hand (dont think its been used tho), it will be worth trying it out tho.

 

For sure, I'd try the Thor FCD and see what happens, but, from the video, I suspect you may be having top speed delimiter issues, as I believe you said it only happens at the more illegal top speeds? If it was fuel cut it would happen at peak torque RPM at all road speeds in anything above 2 nd gear, at full boost. Weird one! The turbo "wastegate" being seized was not unprecidented, but I have heard of only one case of some weird top speed delimiter convertor having similar effects, although I dodn't see the car myself. A Thor top speed delimiter, correctly wired in, fixed it.

 

It's so hard to tackle these very high speed problems, from my point of view, as i jsu will not drive that fast on the public road, it's too big a risk to my licence. It would be hard to mimick it on a rolling road without temps going ballistic.

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For sure, I'd try the Thor FCD and see what happens, but, from the video, I suspect you may be having top speed delimiter issues, as I believe you said it only happens at the more illegal top speeds? If it was fuel cut it would happen at peak torque RPM at all road speeds in anything above 2 nd gear, at full boost. Weird one! The turbo "wastegate" being seized was not unprecidented, but I have heard of only one case of some weird top speed delimiter convertor having similar effects, although I dodn't see the car myself. A Thor top speed delimiter, correctly wired in, fixed it.

 

It's so hard to tackle these very high speed problems, from my point of view, as i jsu will not drive that fast on the public road, it's too big a risk to my licence. It would be hard to mimick it on a rolling road without temps going ballistic.

 

Cheers Chris, but it starts at about 90 from memory. I'll try the Thor FCD first, then if that doesnt help then well i suppose its back off to yours for a thor top speed delimiter thingy!

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Sounds a little like my problem here http://www.mkivsupra.net/vbb/showthread.php?t=72557

but after looking at the video it seems to cut boost a little quicker, but that may just be due to the speed and build up, mine seems to be down to the no 1 turbo waste gate VSV, i am in TTC but messing about with with the VSVs etc seems to cause no problems, just keep an eye out for boost going to high.

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I'm not an expert, just an enthusiast, os go easy on me if what i say makes no sense.

 

You seem to be running more than stock boost with your BPU's which is fine for the hybrids for example. Have you upgraded the fuel system at all i.e. fuel pump, fuel pressure regulator, injectors? More boost = more fuel. If your fuel system cannot meet demand then you may be experiencing fuel cut as there isn't enough fuel being supplied. Fuel pumps become inefficient with age so may need replacing or upgrading maybe?

 

I'm thinking of upgrading to hybrids myself. Would like to go single but it's a bit more pricey and insurance can be a problem. Can anyone advise on whether it's worth going hybrid with all trimmings, ie fmic, boost controller, zorst and fuel etc, or spending bit more and going single?

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