im putting together a 2.0 with stock EFI

i have heard that i dont need a decel valve, is this true?

thanks
-jim

It just adds air supposedly to keep the engine from backfiring on

de-acceleration

Mines not hooked up and it doesn't fart.

The car will run fine without the decel valve, just make sure the vacuum ports on the plenum are plugged.

It runs well without it.

I have heard that the car *might* shoot flames on extreme decelleration without it. IIRC I've seen a picture of racer chris's car when it had FI shooting flmes because of the omission.

will i be able to pass emissions with out it?

all it has to do is idle for 45 seconds

-jim

My vote is yes. I don't see why it would be a problem.

You will be fine without on all fronts.

The decel valve keeps air flowing after you snap the throttle closed. This was purely an emissions issue. You now know why auto manufacturers are all going to fly-by-wire throttle. You come off the gas quickly and the injection system is still dumping fuel. They have NO control over this.. so they close the throttle slowly controling the amount of air needed to burn all the fuel left over from you coming off throttle.

The end result is backfiring on the old school injection systems that fire in batches.



B

I don't think they test our cars decelerating. Just at a constant load and at idle.

I agree with all of the above. I just wanted to test an assumption- is it true that they got rid of the deceleration valve when they re-implemented the fuel cutoff during coast in the ECU??? Doesn't seem like you'd need it if the ECU shuts the fuel down anyway.

Jim

I thought the 2.0L D-jet had fuel cutoff on overrun.

I think I am missing the decel valve on my 2.0L. I get no back firing. But engine braking is significant with throttle off.

I can not really lift off the gas pedal and coast. My one attempt at AutoX I ran with a more experienced driver (not 914) ridding along.
They found it confusing because I could decelerate for faster corners without ever touching the brakes. I thought that was because the PO removed the decel valve.

It's just that they check the idle setting right after the constant load.

They do have fuel cutoff, but it still doesnt happen fast enough.


B

Without the decel valve, your car will be like the Energizer Bunny, it just keeps going and going.........