Dashpot upgrade mod. Possible?

[tekdeus]

For those that don't know, the dashpot is a simple diaphram that uses a valve to let air in quickly, but release it slowly, easing the throttle plate closed when released over a very short period of about .8 seconds.

I have a 1" GFB brand blow off valve recirculating into the accordion hose, like the stock setup, but it moves a lot of air and I still get the spikes in rich fuel and the engine stumbling/stalling effects of a BOV vented to atmosphere.

I thought that the dashpot, set higher, and releasing the throttle much more slowly, would be the ideal solution for me, and all the other people who vent their BOV's to atmophere on the stock AFM system.

What if I could find a different VTV valve from a different car with a similar system, that releases the air over 1.5 seconds? I think a 1.5 second release time would be the best solution to help burn the rich fuel spike when letting off the throttle. Any suggestions on a VTV that might do this? Maybe one from a larger truck throttle body would have more resistance? It's just a simple valve that plugs into the vac line on the diaphram, and could be installed in no time flat!

I tried 2 of the OEM VTV's in series, but it did not slow it down.

 

[tekdeus]

I found out that my dashpot VTV was faulty, so the working one I just bought should improve my problem. I decided to cut it open and have a look. There is a secondary air filter, and the check valve is near the red part of the VTV, and the the air is slowly released through a metal plug piece with a pinhole so small I could not measure it. Any idea how I could replace that part with an even smaller pinhole, like some kind of tiny fuel nozzle or something? Or use a porous material to slow the air down? That seems to be the only way to make my idea work.

 

[easternguy2005]

You might try a visit to a hobby shop.

 

[figgie]

tekdeus

the dashpot allows the metered air that is in there to be injested by the motor to cure the overly rich issue.

upgrading the dashpot will not gain anything. Venting the BOV to atmosphere is as good as removing the dashpot, which in both case will produce a rich spike when it concerns the stock TCCS.

 

[Poodles]

My BOV is vented and it stumbled for a day...hasn't missed a beat since.

Used to have it recirculated but the hose wasn't staying on...

 

[tekdeus]

My dashpot was faulty and installing the working one made a big difference! I still think my mod idea is a good one, for all those kids out there venting to atmosphere on the stock AFM.

 

[rtrdpenguin]

My atmospheric BOV never gives me any issues either, and I do happen to have a good working dashpot

 

[RazoE]

I have an atmospheric BOV, and my car stalls if I let the clutch out before I engine break to around 1500 rpms If I've just boosted, and even then it'll stumble slightly, but it wont stall...

I'll look into a faulty dashpot..

 

[gtimportfanatic]

this is why i love supras.. everyone has the same problems lol

 

[RedGT]

I found out that my dashpot VTV was faulty, so the working one I just bought should improve my problem. I decided to cut it open and have a look. There is a secondary air filter, and the check valve is near the red part of the VTV, and the the air is slowly released through a metal plug piece with a pinhole so small I could not measure it. Any idea how I could replace that part with an even smaller pinhole, like some kind of tiny fuel nozzle or something? Or use a porous material to slow the air down? That seems to be the only way to make my idea work.

I think that if you replace that disc with the oriface with a disc without any holes that you would be using the dashpot as a cusion due to the air not being able to escape. Think air shocks.

 

[tekdeus]

I think that if you replace that disc with the oriface with a disc without any holes that you would be using the dashpot as a cusion due to the air not being able to escape. Think air shocks.

True, but it wouldn't let any air out, and hold the throttle open at 2000 rpm. It needs to let air out, but at 1/2 the speed. Then venting a BOV to atmosphere wouldn't create such a massive spike in richness.

 

[cruisnhard]

just fill in one of the holes in the disc. Or you could try something like a manual boost controller type design with a spring to only allow the air you want through at certain times.