Dustin Butts

iTrader: (5)

Mine was doing that. I finally solved the problem by adding a carburetor throttle return spring on that little spindle thing sticking out on the throttle blade cam. I bought one of the very first FAST 90mm TB's that came out so I'm hoping it's just "new product bugs". I've been talking to FAST and trying to get another one. One of the problems I think is that the huge 90mm TB creates a heck of a vacuum near the closing point of the TB blade. The FAST TB has a very small(too weak) return spring to overcome the odd vacuum and thus the TB blade doesn't close all the way sometimes resulting in a(sporadically) raised idle. I got really tired of the weird idle crapp and having to blip the throttle all the time to drop the idle. When I added the extra return spring...voila! Idles and works perfectly now.
This kind of a "rig" should not be necessary for such a nice and expensive piece however.

I noticed on another guy's MTI 90mm TB that they use the factory(huge) return spring and cable cam. This is probably a much better design.
Anyone having issues with the MTI or TPIS 90mm TB?

SAM98WS6

Thanks a million Dustin. I will try it. Every time ive checked the hung idle though the blade was closed

Dustin Butts

iTrader: (5)

Check your air bleed hole. Did you drill a hole in the TB blade and if so how big? I had too large of a hole originally and had to braize it up and start again smaller. I was also given advice to drill the hole at the top of the TB blade just right of center(when looking into the TB opening). It supposedly helps with the "vacuum" problem. Check also that spring-loaded, allen-head, idle- air adjustment screw and make sure it isn't screwed in too far. If it's screwed in too far it will hold the TB blade too far open. Email me at pitbullZ@i-love-dogs.com for more info. I'll give you my phone nr also if you'd rather call...I'd like to get these problems worked out and work with FAST to help develop a better product and eliminate these issues.

SAM98WS6

thanks again dustin. I did not drill any hole. wasnt told to so I am going to call them and ask. I will get back to you.

Dustin Butts

iTrader: (5)

Gimme a shout on the email. I have a few more things to tell you. I learned some more things today and fixed some others..you need this info.

smokin' joe 00 ss

Which T/B do you have TPIS or FAST?

SAM98WS6

I have TPIS. Called their Tech line. Was told not to drill anything nor change the spring...it is purely a tuning issue...idle tables. I modified all of the idle tables...airflow decay etc...and none of them did anything.
Jason at Texas Speed says its a tuning issue. Thats where i bought the TB from.

This is starting to **** me off...because it went from once in a while...to all the time now...car is undriveable.

Dustin Butts

iTrader: (5)

I understand. I have the FAST 90mm TB and LSX intake. I got tired of that crapp also and began to seriously study this TB. I found a few problems.

1. The tiny bearing that is on the TB shaft on the TPS side of the TB was working it way out of it's hole. There is about a 1/4" gap between the back of the TPS and that bearing. So, basicly there is nothing to hold that bearing securely in place. When the bearing would work it's way out of it's slot it would cause "slop" in the TB shaft resulting in a slight binding or sticking open(only at idle) of the TB butterfly. Brian Tooley at TEA took a small center punch and peened the edges of the TB around the small bearing to hold it securely in place. No biggie. You can't see it because the TPS covers the bearing and all. I believe that has been my major problem all along.

2. There are two holes on the throttle cable cam for the cable to fit into. I had mine ('98) in the lower hole. But this hole on my car resulted in almost zero free play in the cable which could, theoretically ,cause the TB butterfly to not close completely. I mean it was super close to not closing all the way.
So, I put the cable in the upper hole but I had to do some slight "sizing" of the cam hole and the cylindrical cable end to get it to fit properly. Now plenty of slack, no probs.

3. The throttle cable cam is secured to the TB shaft with an allen head set screw. During one of my "high idling" episodes, I popped my hood and checked the TB and noticed the The cam was slipping slightly on the TB shaft. I imagine that this was due to the TB butterfly sticking and then the spring tugging on the cam to pull it to it's stop.
So my recommendation would be to take the allen screw out. Mark the shaft through the hole. Remove the cam. Drill a tiny indention for the allen screw to set it. And reinstall everything. Of course if nothing is binding this most likely would not be necessary.

Sam, on your TB, I guess I would recommend checking everything for binding and no slop in the TB shaft. If there is any slop fix that and insure NO binding. Then get the car idling normally at normal operating temp and check your IAC counts with a scan tool or Autotap. They should be around 40. If not try adjusting the set screw that holds the TB butterfly open till you get in that range. You must watch your TPS sensor on the scan tool also to insure you haven't moved the TB butterfly too much. The TPIS reading should show "0" at idle during this process. If the TPIS reading goes above "0" then your computer is reading "acceleration".
If your IAC counts are still way high you will have to drill a small hole in the TB blade; on the top half of the TB blade slightly to the right, nearly in line with the IAC hole in the TB, but not exactly in line with it. After you get the IAC counts where you need them then tune it through the computer.
Call Brent at TEA also. He has spent hours tuning my car to perfection. I have an 11:1 402 LS1 with 36lb SVO injectors and a 236/236 dur .580/.580 114 cam. He got the LTFT's at "0" at every point of acceleration, decceleration and cruise. This thing is an animal at WOT(505rwhp) and a baby at idle and cruise.

Good luck brother.

Damage Inc.

iTrader: (7)

This is BS, how can they let these things be released when you have to MOD them to work correctly. I'm not giving them the business if this is how they treat the modding community.

SAM98WS6

Thank you sir. I will try all of that tonight and let you know.
I does suck we have to rework these things...cutting the throttle cam off to clear the pcv hookup was a classic.

CHRISPY

Great response!!! Thanks for sharing this info!

SAM98WS6

Well I checked this TPIS TB out. There is no play in the shaft, blade looks fine too. TPIS said not to touch anything and knock down the idle tables using edit. First time throught I went 10-30%. no real difference. I went 50% last night and wala...car idles nearly perfect...its driveable again. Slight hang once in 10 miles...I think I can tune that out too. Looks like it was what TPIS said...just needed to make big changes. thanks for your help.