SR20 dying after let off gas. Bad BOV location?

[diehardyouth]

Hi guys,

I bought a used blacktop SR20 from some guy and basically just dropped it in my S13 as is. It has a FMIC (I think godspeed) and a BOV mounted before the turbo. The (KA I think) MAF is mounted right after the air filter before the turbo. In summary, here is the setup:

Air filter -> MAF -> turbo -> hot (pressure) side -> FMIC -> cold side -> Throttle body

PROBLEM: When I let off the gas, especially at high RPM the car stalls. My guess is that the A/F mixture is set to one thing because of the MAF, the pressure is released and the MAF is still reporting the old value. It keeps dumping fuel, there isn't enough air and it just dies.

I'm thinking the best thing to do is to relocate the MAF somewhere near the TB on the cold side.

WHAT AM I ASKING FOR? Basically some guidance. Is this really the problem or is it something else? What is the easiest and/or best way to solve this issue? I would like to do it as cost effectively as possible. Also, would you guys recommend getting a Z32 MAF?


Thanks in advance.

[desertKAdrifter]

i had the same problem. I just messed around with the bov. i loosened the screw on it and adjusted softer , little by little until it stopped stalling. I guess it has something to do with airflow after u close the throttle, if your bov is too tight it will leave excess air and the ecu will dump fuel accordingly. the less air at closed throttle, the less fuel the ecu will dump. so yeah, just soften up the bov, it worked for me on my ka-t.

[KendallH]

BOV mounted before the turbo.

Wtf? Your BOV is mounted after the MAF before the turbo? On the intake tube? If so, its doing nothing but messing with the MAF. Your BOV has to be placed somewhere on the pressurized part of the intercooler setup (after the turbo) to bleed off pressure when the throttle body is closed. There's been speculation on hot side/cold side placement but it doesn't really matter that much on a stock SR.

The (KA I think) MAF

Get the numbers off the MAF and post them back here. If the motor is running at all it should be a SOHC KA MAF (40F00), or an SR MAF (52F00). If not, you have some kind of voodoo going on.

These are your two problems.

[ShadowMan]

Hi guys,

I'm thinking the best thing to do is to relocate the MAF somewhere near the TB on the cold side.



Someone else correct me if I'm wrong, but I'm pretty sure your MAF needs to be before your turbo so don't move that. I don't think it'll give the right readings after the turbo because the air is compressed/pressurized. And if you plan on continuing with upgrades like bigger turbo a z32 maf is a good idea. It has a bigger internal diameter so it'll definitely flow better because it's less restrictive.

[tt99ol]

You can run a blow through maf, where the maf is in the cold pipe, but you have to tune for it, your bov is causing a rich stall, also if you have a walbro with a stock fpr you get a really rich running motor especially at idle which contributes to stalling