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The mkiv Supra Owners Club

Top quality calibrated Fuel Cut Defenders available now


Chris Wilson

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I have just done a new batch of these, and they tend to sell quite fast.

 

Since Greddy and TRL stopped doing their very nice and reliable fuel cut defenders I have been wondering about building a sensibly priced alternative. The great thing with the Greddy is it did not clamp the MAP sensor voltage until the pre-set threshold was reached. The HKS one was not so nice and skewed the output from the MAP sensor, thereby also skewing the fuel curve.

 

I have now tooled up to produce my own FCD that leaves the MAP sensor output *totally* unaltered until the voltage clamp threshold is reached, just like the Greddy ones did, when they were still available, but using more modern, closer tolerance components and a slight circuit improvement. It also uses the same colour wires as the Greddy, meaning the excellent on line pictorial fitting instructions at http://mkiv.com/techarticles/bcc/bcc_install/bcc.htm can be used to aid fitting, which is very easy. They come with an earth eyelet ready soldered on, meaning only three other wires to connect. Use the central stud or the main ecu to floor pan for th earth terminal, under the 10mm socket size nut.

 

They come pre set on lab standard equipment,to suit either VVTi or earlier TT models. If you have a VVTi or 1JZ-GTE let me know when ordering. I have 6 ready to ship, the last batch sold out very quickly. They can be programmed for other MAP sensor turbo engines like Mitsubishis, RX7's, Skylines, MR2 turbos, blah blah. If you can mention them on other forums where you may be a member I will be very grateful!

 

Price is £65 plus VAT with £5.80 plus VAT insured P&P to any UK

post code. That's £84.96 grand total. Please ask for a delivery

price to other places if required. Thanks.

 

 

 

 

 

- - - Updated - - -

 

I can supply wiring schematic for the VVTi if required. Just different ecu pins used, as easy to fit to a VVTi as a none VVTi engine, 4 wires to connect, one being an eyelet terminated ground wire like the none VVTi ones.

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Yes, but the Mityvac is not easy to regulate to a fine pressure level. I use an air bottle with a decent pressure regulator T'd into an accurate pressure gauge. There is quite a span on level as the sensors output voltage V pressure on their port levels seem to vary quite a bit. The 5V ECU reference source should be rock solid, so variations will be the sensor itself.

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interested, what boost pressure/voltage does the sensor clamp the reading at? the ecu is programmed to fuel cut at 1 bar isn't it?

 

I've just put my car together, factory twins vvti engine and a full 3" exhaust, I have a whifbitz restrictor ring in the exhaust so is it likely i'll need to add your fuel cut prevention sensor into the ecu loom?

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Well, the sensor doesn't do any clamping, it has enough headroom to allow the ecu map to cut fuel at about 1 Bar, it keeps reading a bit higher and runs out of range just above 1 Bar. My FCD is adjustable to clamp between 3V and 6V, and i set none VVTi ones at about 4.1V. Above that the ECU thinks the MAP sensor is going no higher and still allows fuelling. 1.2 Bar is he top limit for adequate fuelling, maybe a TAD higher... Toyota over fuelled substantially at high boost to keep the cats cool, so you have that excess to play with given a de-catted engine. Does that help?

 

With a 3 inch bore system of low back pressure you probably need a restrictor ring, depends on health of turbos and engine in general. If you don't hit fuel cut without an FCD it suggests something's wrong or tired.

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how high do they usually spike with a 3" decatted exhaust and a restrictor plate anyway?

 

I'm quite keen to get one as my car is not on the road yet but I can see the first thing to happen is fuel cut due to all the bpu stuff I've done and no restrictions in the exhaust system

 

delivery price to Aberdeen Scotland please

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Well, the sensor doesn't do any clamping, it has enough headroom to allow the ecu map to cut fuel at about 1 Bar, it keeps reading a bit higher and runs out of range just above 1 Bar. My FCD is adjustable to clamp between 3V and 6V, and i set none VVTi ones at about 4.1V. Above that the ECU thinks the MAP sensor is going no higher and still allows fuelling. 1.2 Bar is he top limit for adequate fuelling, maybe a TAD higher... Toyota over fuelled substantially at high boost to keep the cats cool, so you have that excess to play with given a de-catted engine. Does that help?

 

With a 3 inch bore system of low back pressure you probably need a restrictor ring, depends on health of turbos and engine in general. If you don't hit fuel cut without an FCD it suggests something's wrong or tired.

 

That was exact the answer i was looking for.. i dont have chris fcd but a build in fcd in my boost controllere. so needede some guidens where i should set my clamp voltage at... thanks Chris.. hope it was alright to ake inhere..

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