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The mkiv Supra Owners Club

BPU Problem - Help!


Conrad

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Ok so I went BPU today with eveything but the FCD (still waiting on Thor)

 

I fitted new plugs (NGK 3330 @ 0.7mm), walbro pump, decat pipes, restrictor ring and RSR ehaust.

 

Trouble is I ws only making 0.9bar, just making 1.0bar with both tubbies online but not enough to make fuel cut kick in.

 

What have I done wrong? today was supposed to be a happy day!

 

I did however, disconnect some kind of sensor that was attached to the second cat, could this be the cause?

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the sensor on the cat i think will be the cat over temp sensor? what ristrictor ring you had put in 1bar, 1.1bar 1.2bar?

 

1.2 bar from CW, compared to the decat pipe it made the bore minimally smaller.

 

Do you think an ECU reset would work? Daft question but what's the quickest way to do it?

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pull both efi fuses, or disconnect the battery for a while.

 

that plug gap sounds a little small to me matey (doubt this would be the cause tho)

 

That gap was a lot smaller than on the plugs I took out tbh!

 

I'll do the ECU reset first thing in the morning, I've just put my best shirt on and I'm off out on the piss, cant do it now! :D :p

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Ok, just reset the ECU and took it for a spirited run. Unfortunately no difference whatsoever. The car boosts at 0.9bar every time.

 

Just to confirm I reset the ecu correctly, it's the little green 30A fuses I'm taking out? The ones that look like this:

 

http://www.thedetailzone.com/Fuses.jpg

 

I have 3 btw, not 2 as mentioned. Could the plugs be to blame for the lack of boost?

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yes those types of fuse. There are 3 green 30A fuses iirc but only two are efi (tells you on the fuse cover lid!) but pulling 3 not 2 won't do any harm!

 

oh well, it was worth a shot, maybe it is the plugs then

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By decatting a jap supe doesn't necessary force boost over 1 bar, there are quite a few jap cars (including mine) that since going BPU still don't over boost.

 

I don't even have a restictor ring and i can only hit 1.2 bar in higher gears on the coldest of days and barely 1 bar on hot days.

 

I resolved it by getting a boost controller and tweeking the settings.

 

Triy removing the restrictor ring, if that doesn't get a boost controller to up it.

 

my 2ps worth...

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I resolved it by getting a boost controller and tweeking the settings.

 

Try removing the restrictor ring, if that doesn't get a boost controller to up it.

 

my 2ps worth...

 

Steve, that's what I've been thinking mate. Already been checking controllers out on ebay.

 

I'm just a bit concerned that there's something wrong with the set-up i.e the plugs I'm using etc.

 

I'm booked in for a dyno next Sunday and wanted this all sorted before then, looks like that wont happen now.

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You would notice for sure if you had a misfire if the plugs weren't okay.

 

I would definately remove the restrictor ring like Steve said.

 

But keep an eye on the boost as you don't want it to go too high.

 

I'm not familiar with the RSR exhaust, it hasn't got a removable baffle has it?

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When I did my BPU I was getting 1.2 bar with the stock side mount intercooler which wasn't in very good condition.

 

It went down to approx 1.0 bar when I fitted my new Chris Wilson Intercooler which was obviously more efficient.

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if your in any doubt over the fuses just disconect the battery and go and have a cup of tea, why such a small gap on the plugs i dont think its your problem but at BPU i ran 1.1mm plugs and hit 1.4 bar (restictor ring quickly folowed) what are you measuring the boost with is it reliable ?

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if your in any doubt over the fuses just disconect the battery and go and have a cup of tea, why such a small gap on the plugs i dont think its your problem but at BPU i ran 1.1mm plugs and hit 1.4 bar (restictor ring quickly folowed) what are you measuring the boost with is it reliable ?

 

Blitz boost guage, I'm assuming it's reliable. The car doesn't feel a great deal faster to be fair.

 

I'm using the plugs suggested on this thread (NGK3330 @ 0.7mm)

 

http://www.mkivsupra.net/vbb/showthread.php?t=41927

 

I'm assuming they're ok too

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1st thing i'de do is take out the restrictor ring (is it a CJ) have you changed both the cats ?, if yes the car should be flying in comparison to what it was, i'de also go bigger on the spark gap as well go for the NGKs about £14 a set

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