Hey guys, Hope you can help me here. I've owned an 87 turbo II for a few years now. I've just done quite a few upgrades over the winter. Here's the problem. When I step on the gas and build boost, I get a slapping/slamming sound from the MAF. Some of the upgrades are....Greddy FMIC, rebuilt and street ported engine, HKS Sequential BOV, HKS PFC-Fcon. I am producing about 15PSI when really cranking on it. The car runs fine it just makes a slapping sound when I let off to shift. It's really anoying. I've moved the BOV from between the intake and intercooler to between the turbo and intercooler thinking that it would make a difference. No change. Please help me. I'd really be gratefull to you guys.

www.evo-imports.com go to photo gallery. Mine is the orange turbo II.
HELP ME PLEASE!!!

 

Bite the bullet and GET RID of it (and the stock ECU!!.

 

I'd really like to, but don't have the money right now. And probably won't until at least this winter. Any other ideas on what could be wrong?

 

nothings wrong, they do that. if you crank it and stand next to the afm you can hear it, open and close

 

Put the stock air filter box back on.


-Ted

 

It makes that noise because that's how an S4 AFM works. The flapper measures the amount of air going in...

 

So the slapping is never going away?? It never did it until I installed the intercooler and BOV. Why would it just start all of a sudden with those items? There must be a way to prevent it. Why would the stock intake make a difference. Either way, I have no way of putting it back on because of all the intercooler piping. Any other ideas??

 

Is there another MAF that would work in my situation that doesn't use the flapper door. Something with a hot wire setup instead that would work??

 

Yes, you can wire the MAF/AFM from a S5 TII.

 

how difficult would it be to do this. What years are the S5's?

 

The stock air-box would make the noise go away because it suppresses sounds from the intake.

 

I find it really hard to believe you can hear a little aluminium flap "slapping" around inside the AFM over the noise of the engine and exhaust. Whatever you're hearing, I'm pretty sure it's something else (probably the BOV).

Waste of time and money.

 

nope. I'm definately sure it's the maf flapper door. I stuck my finger inside the sucker the other day and cranked on the throttle. When I let off, the door smacked my finger so hard I thought it broke through the skin on the end of my finger. It hurt like hell. I think it's turbo surge???

 

could it be that your MAF sux *** it broke over winter? coudnt you try hooking up a diff. one?

 

I have a similar issue with my S5....

have issue only since greddy FMIC install on stock AFM and Stock ECU

i have mine with these variables
1. 3200rpm to 4200 rpm
2. 1psi-7psi boost
3. 30% -70& throttle

if i mush down in it @ about 3000rpm and get boost above 7psi to goes fine past 4000and all the way the redline everytime
but say i want 4 - 6psi @ 3500 rpm i get a the whole car shuddering...

almost as if the AFM is bouncing back and fourth ....

i want to mive my AFM AFTER the turbo and before the intercooler..
so the air is pushed past instead of pulled past the AFM

the pulling actio may create a negative vacumm behind the dorr causing it to flap around.

 

i got that blitz ss filter on my car. Hardly any filtering element, yet still i do not hear a slapping of the AFM. S4 TII

 

Are you rotating the AFM from stock?


-Ted

 

My problems are also very similar to yours. The problem only occured after the Greddy 2 ROW V-SPL FMIC and the HKS (actually MONZA) SSQV BOV.

 

I actually made sure that the AFM is at the same angle as it was when it was in the stock airbox.

Do you think it could be because it's a MONZA (HKS SSQV CLONE) BOV?? Maybe I need a lighter spring.
How much vacuum should it take to open the BOV with the HKS SSQV. I currently have the stock boost sensor, the HKS PFC-FCON boost sensor, the boost meter and the BOV all tapped off the save vacuum tee. Could this be the reason.

 

Anyone else have any ideas. I can't beleive that it's just something I'm gonna have to live with. I know other people with similar setup with the slapping....

 

Sounds like the boost in the intake is making it slam shut when you let off the throttle. your BOV adjusted right?

 

bad bad bad for turbo

 

I just took the adjustment screw and cranked it all the way out. It's basically just there now to plug the hole. The slapping noise has gone from slapping every time I let off, to only once and a while. I also removed the POT (I think that's what it's called) and I haven't heard it at all. The POT I'm referring to is the little thing that allows the throttle plates to close more slowly when letting off the gas quickly. I haven't actually taked it for a ride yet (bad weather), but I was able to reproduce the problem by just sitting in the garage.