How to tune for open BOV on MAF car

Nistune topics specific to the 6802 cpu

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DanNY
 

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How to tune for open BOV on MAF car

Post by DanNY »

So the set up is Turbo -> BOV -> MAF -> throttle body
the BOV dumps to the atmosphere so under heavy load the air rushes past the MAF again and dumps out of the BOV. When that happens the car runs a little rich and back fires.

is there any way to "fix" that? Basically to lean it out on deceleration

also when i turn the A/C on the car idles very low and it stalls...what i can do to fix that

Maxima VG30ET
Manual transmission

any input or suggestions would be appreciated.
thanks!
Dan
skylinegtrhr
 

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Re: How to tune for open BOV on MAF car

Post by skylinegtrhr »

what MAF do You have?
DanNY
 

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Re: How to tune for open BOV on MAF car

Post by DanNY »

skylinegtrhr wrote:what MAF do You have?
stock maxima MAF
Matt
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Re: How to tune for open BOV on MAF car

Post by Matt »

Not really the ECU only injects based on what it sees from the MAF
DanNY
 

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Re: How to tune for open BOV on MAF car

Post by DanNY »

Matt wrote:Not really the ECU only injects based on what it sees from the MAF
good point...but should the ecu still inject when there's 0 throttle?

any thoughts on the A/C? i see the AC switch signal on nistune when i flip it on but i don't see a jump in idle so it will just stall out.
Matt
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Re: How to tune for open BOV on MAF car

Post by Matt »

AC controls the FICD (Fast Idle Control Device) solenoid which when working will increase idle RPMs by slightly increasing RPM. Some ECUs have air cond enrichment also (watch the injector time in Nistune when activating A/C)

Even on zero throttle if the MAF measures a spike on air it will tend to inject until the RPM cut limit is reached
Mike_GruiZinga
 

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Re: How to tune for open BOV on MAF car

Post by Mike_GruiZinga »

What BOV are you using, and can you adjust the spring pressure?

I use a Tial, which is fast enough to minimize this problem with the stock MAF in blow thru. I have to switched to the newer slot style maf (im using mustang HpX from vpn tuning) as these are not bidirectional mafs. They are much less sensitive to the reverse flow.

The installation was the same as a mustang cobra maf in terms of wiring, and nistune offers maf scaling for the HPX maf.
jaqattack02
 

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Re: How to tune for open BOV on MAF car

Post by jaqattack02 »

How close is the BOV to the MAF? If it's too close it may mess with the readings the MAF is getting when it opens.
Buddyworm
 

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Re: How to tune for open BOV on MAF car

Post by Buddyworm »

I've had good luck with a combination of high spring pressure and fast valve action speed when venting to atmosphere. I run the Synapse Diverter Valve with the spring at full preload in a Push configuration. The fuel mixture doesn't seem to be severely affected, I've noticed no post-shift bog and my turbo comes right back up each time i grab a gear.
enohand
 

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Re: How to tune for open BOV on MAF car

Post by enohand »

why don't you run your setup like mine?
this will prevent the ecess air from going past the maf again.

only issue is rich spot between shifts.

see the pic below

Image
88execvl
 

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Re: How to tune for open BOV on MAF car

Post by 88execvl »

with the idle problem when you switch on the AC the air feed for the FCID and AAC should come after the MAF/AFM.
Adrian
 

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Re: How to tune for open BOV on MAF car

Post by Adrian »

The solution for this BOV problem is quite simple. You have just set the max Tpulse wide between 0 and 1500 rpm as low as possible, without affecting the mixture under loud. find out the max possible pulswide to 1500rpm and set the max-tpulse slightly above. It's a 5minute job ;-)
Matt
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Re: How to tune for open BOV on MAF car

Post by Matt »

Yes that would actually work quite well, it would limit TP overshoot at the lower end RPM scale, as long as it does not limit fueling in the same area required on acceleration
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