T/B whistle

[x-thumpr-x]

I've got a 3400 motor in a fiero, last year I put a regrind cam, ported & gasket matched the intake & exhaust. With the stock 3400 T/B I had no problems with it. I've recently put the 3.5L (65mm) DOHC T/B on the car with WOT-TECH adapter plate and it nows whistles like a banshe. Only under load and with the throttle just open enough to keep steady with traffic. It's getting really annoying having to slow down or speed up to get rid of the whistle. If I keep this up I'll learn how to play Dixie with my gas pedal.

Anyone else have this issue with these throttle bodies? It's mated to the stock 3400 intake and ported to match the T/B.

[young gun]

LX9(3500) with a 65mm in a 5th gen grand am for me and it doesn't whistle unless I'm shifting above 3.5k in which i'm on it anyways so it sounds nice if you were to ask me

[Fireball]

My 65mm setup whistles like crazy... pretty much on command

[x-thumpr-x]

I'm thining it's the IAC. The 3400 T/B has it's own port to the upper intake, where the 3500 with WOT-TECH's adapter plate goes directly in behind the T/B butterfly. I'm wondering if the IAC is closing fast enough when you put your foot on the throttle. COuld also be carbon build up in there and IAC can't close fully. Guess I'm gonna have to pull the IAC for a good cleaning and wire well the inner housing.

[ericjon262]

don't know about the whistle, but got any pics/build thread?

[robertisaar]

what kind of intake tubing are you running?

[Superdave]

I've seen that happen on an un-ported plenum when using a larger TB, once we opened it up to the adapter plate size it was fine.

[x-thumpr-x]

what kind of intake tubing are you running?

Using 3" sewer tub with a K&N filter.


Pics from all three builds are here:http://s913.photobucket.com/albums/ac339/3400Swaps/ Need to update with more fresh pics.

Version 1 & 4 are the same motor swap in two different Fieros with some upgrades done to the motor which were done to Ver 2 & 3. The pictures from Version 4 are in my old SE Fiero, the motor is now back in the GT with larger T/B and intake pipe. I dyno'd the car after doing all the work to the 3400 motor (less 65mm T/B) ran the stock fiero air intake and only got 160HP at the wheels Before all that work (completly stock) and a cold air intake (in my GT) it dyno 175HP at the wheels. Spec stage 2+ clutch is almost at the 1000km mark so think it's safe now to play with the car and try for another dyno run to see how it does this time.

I've ported the 3400 intake to match the adapter but it probably could use a little more refining. There was a bit of a lip on the bottom section after we did the final install. Other thing I could do is just go ahead and install the 3500 plenum but that needs a little work done too. Need a DIS bracket, MAP sensor & pigtail and some vacumn piping to make it work.