So I have been having issues trying to get my car not to die coming off throttle. I am currently running a custom hand built blow through TT setup. I have designed it to be really similar to the popular kits on the market. I have narrowed my problem down to an issue between the MAF and the BOV. I have tried varying setups with my valves. I originally thought my valve was to close to the maf so i moved it into the bumper cap and still got fluctuations in the MAF voltage causing it to die.
Some forum members mentioned that even though its blow through a fully atmospheric valve just wont work with these MAF's. A few days ago I took another valve and plumbed it into my intake to recirculate it and it was better but still stalls out and is a lil herky jerky between shifts. Now I am for certain that it is a BOV issue because if i pull the vacuum line off and cap it the car runs like a champ and drives and shifts really really close to stock.

So both valves I have tried are manufactured by a close friend of mine. Machine work and quality are top notch and the valves apparently operate how they are supposed to. I used to run one on my old 90' supra and it worked great. And he runs them on his TT mustang, two 240sx's, his old SRT-4 and his boosted hardbody nissan pickup. All with no problems.

Sooo... any thoughts on this would be greatly appreciated. I am going to try an HKS ssqv we have layin around. maybe that will work. I really hope so because as it is I have to rebuild both charge pipes from my IC to throttle body to get rid of all the evidence of moving things around. If not expect to see a grip of parts for sale to help cover the cost of my LS swap lol

 

every turbo and SC kit available is a blow thru VTA design.

Are you seeing proper vacuum at idle?

 

I had to buy a stiffer spring for my tial.

 

Its kinda hard to tell. If I disconnect my valve and plug the vacuum line the idle is really smooth and the vacuum stays real steady. But with the valve connected it f's up the MAF voltage and the idle jumps around a little bit. So with the idle going up and down my vacuum tends to move around a bit.

I put a stiffer spring in the valve today and it is slightly better but still not very good and will stall from time to time. I think I may need to find a spring that will hold the valve closed at idle vacuum but will pop off with the boost pressure pressing against the valve and the increased vacuum off throttle. (im tired so I hope that came out right)