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The mkiv Supra Owners Club

HKS FCD STD wiring on a VVTI... Plug into MAF or MAP? Misfire and vvt malfunction


bluecoupe46

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Hi Guys,

 

I've been converting my supe to BPU (well stage 2 anyway). My car is a VVTI jspec auto.

 

Having followed the instructions as best I could (in Japanese... Useful!), I wired the FCD into the MAF.

 

Having driven the car for 10 minutes give or take and letting it warm up on idle for another 5-10 minutes it started misfiring badly :mad:

 

I would like to know whether I was right to wire the fcd into the MAF rather than the MAP (remembering the car is a VVTI)?

 

It seems strange to me, as the car was misfiring badly before I installed any bpu mods, I replaced the plugs, cleaned the plug well thoroughly, cleaned the coil packs and tightened the rocker cover bolts to spec as they were hardly even hand tight. After that the idle misfire went away, but i didn't drive it, so I don't know if the plugs fixed the original misfire...

 

If I have done the correct thing by wiring the fcd into the maf pin on the ecu instead of the map, then what could be the cause of the misfire? I did a quick code check and it came back with maf and vvt system malfunction. The car only has 75k genuine miles on the clock with regular service history and the cleanest engine oil i have ever seen, so i can't see it being a ocv filter problem. As far as I can see it would have to be an electrical problem...

 

Any ideas guys?

 

Regards,

Alex :thumbs:

 

p.s. I have tapped into the Turbo pressure sensor hose to run the boost gauge... is this also going to cause a problem? If so where's best to tap into? Being the vvti, none of the threads i have found have a diy for the vvti, they just state tap into the y splitter which I haven't got. :/

Edited by bluecoupe46 (see edit history)
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What make of FCD? The Yanks sometimes try and clamp the air flow metering signal, but I have never seen this work properly, we over here (I have no idea where "Top Secret" is, or why people are so secretive), clamp the MAP sensor signal. wiring is in this thread and elsewhere:

 

http://www.mkivsupra.net/vbb/showthread.php?273315-Fitting-FCD-into-a-VVti&highlight=fcd+fitting+vvti

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