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The mkiv Supra Owners Club

dump valve???


alan83
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Running an atmospheric BOV on a MAF equipped car is actually quite bad for your engine!

 

1, Your Mass Air Flow sensor calculates how much air is coming into the intake

 

2, Your ECU decides how much fuel to add in conjunction with the air that's coming in!

 

3, Then, you dump a load of air out the system to atmosphere without the ecu knowing (as normally this would recirculate back into the system).

 

4, your fuel mixture is now incorrect at the point of you dumping air!

 

5, if this happens at low enough revs then you can stall quite often. This generally doesn't happen with a 6speed because you dump the clutch way before the revs get too low and the ecu has time to re adjust before it stalls. But the auto doesn't work the same as its always engaged in a gear. so it sometimes just stalls the car.

 

So, you will get bad fuel mixture at gear changes or whenever you lift off and you can stall now and again until you get used to "why" the car stalls.

 

When you get used to it, you will know if its about to stall and sometimes you can be quick enough to put the car in neutral before it happens.

 

I found that my car almost always stalled if i pulled away and then braked to a stop quickly just as i pulled off.

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uk auto here running a blitz with no probs although you rarely here it dump being an auto

 

Really? I've got the SSQV on my J-spec auto and it dumps left right and centre. Slightly annoying (only had it on a week too!), but childishly amusing when it scares old ladies. Or the missus.

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