Mike K.

I got the dreaded high idle where you have to snap the throttle to get it to go down at times, I figured it was the bolt slipping on the throttle shaft or the TPS bearing coming out like most have said. I took off my TB and while the bolt would slip on the shaft it would not do so easily, I had to push it hard to make it go. I then checked my bearing and it was still pushed all the way in. To make sure I machined the flat spot on the shaft and now the blade will not move at all, I did not secure the bearing any more cause it was already tight in there.



I go for a drive and the same damn thing happens again, you guys have any other ideas for this? I am almost thinking that the spring is too weak or someshit cause the blade not to close all the time but who knows.

There was still some play in the blade/shaft as far as it moving back and forth in the bore but this is because the shaft slides a tad.

Any ideas on what to do next?

HOSS99

Mike,

Are you sure the problem isn't related to the tune or PCM? After I first installed my ported throtttle body for the first 100 miles or so it would idle high (1200rpm) when I first came to a stop, but then it hunt for the idle and settle at around 900.

jimmyblue

iTrader: (11)

You might loosen the blade-shaft screws and then
set them just barely-snug, and then open & let snap
shut the blade (with the stop-screw out of the way).
This will let the blade get to its favorite position in
the bore, then you can tighten the screws back up.
Of course if they've been staked or something this
is more work.

If there are signs of scrub around the seating circle
maybe you want to polish the blade edge or the bore
with some 600-grit in that particular area; no more
than necessary, probably don't need any more
bleed-by.

You might work a carpenter's pencil all around the
blade edge and the seating circle, hard graphite lube
as it were.

Mike K.

I dont think its the tune cause it only does it sometimes not all the time and if I blip the throttle it goes back down like its a TB not shutting or throttle cable stuck type of issue,

I did not notice any scuff marks but I was thinking about the lube idea myself, Ill try the loosening of the tb shaft screws as well to let it get in its fav spot but the thing is that there is play side to side that is between the throttle blade and the TB bore so wouldn't it be able to do this anyways?, its very very small amount but it is there, the throttle shaft appears to normally have some play in it?????

MeanWS6

Is this a known issue with these, I just ordered one for my 408
has it been brought to FAST's attn

jimmyblue

iTrader: (11)

Can you wind the return spring up one more
turn without it then binding when full open?

Mike K.

https://ls1tech.com/forums/generation-iii-external-engine/203226-well-made-cough-fast-90mm-throttle-bodies.html


see above thread for all previous issues, I thought I had one of these but I do not which is why im wondering whats going on with my TB .

Mike K.

I did that once already, before that it would stick open real bad. Maybe I need to do it once more? I just dont want to breakt he spring.

Mike K.

now I'm even more confused, I went out and monitored my tps voltage real closely, normally with the car off it is at .050

I turn the car on and it goes to .046, when driving and letting off the pedal I get a fluctuation from between .046 all the way to .060 it seems to be different but somewhere in this range everytime I let off the gas. when the tps voltage goes higher in this range is when I get the high idle.


I pull into my garage and the tps is at .046 i turn the car off and it goes to .050 immediatly and stays there no matter how much I blip the throttle. Now the throttle blade does move side to side a little bit so I thought it might be that.

Well with the car off I moved it side to side and the tps voltage did not change at all stuck right at .050 no matter how far left or right the blade was in the bore.

I did notice with the car off that even the slightest movement of the gas pedal will result in tps voltage increase, I mean if I barely and I mean barely just set my foot on the pedal it goes up .002 to .005 volts.

So now I am wondering,, with the car on why does the tps voltage change so much when compared to the car off? Could the tps sensor be a loose fit on the throttle shaft? Could the throttle blade actually be moving a minute amount when the car is started compared to when it is off ( this would not make sense too much though cause then I should see the tps always fluctuating even with my foot completely off the gas.)

WTF is causing the tps to change so much when the car is on but not when it is off??

Dustin Butts

iTrader: (5)

Is your throttle cable in the upper or lower hole on the throttle cable cam? If it's in the lower hole your cable probably has no slack and is catching a little sometimes. Move it to the upper hole. I had to do this. Also the upper hole has to be "wallowed" out a little bit for the cable end to fit correctly. It's a tad smaller than the lower hole.
I have also added a seperate carburetor style throttle return spring to aid in a positive closing of the TB blade.
The next time the high idle issue comes up, jump out with the engine running and check the TB throttle cable cam to see if it's stuck slightly open or whatever...
Mine works flawlessly now.

Scalpel

iTrader: (4)

Dustin, do you have pictures of how you modified yours as you described above?

Thanks man

Mike K.

If I move the connection to the upper hole won't there be too much slack? A pic of that carb spring would be perfect cause I don't know how to set one up.


Ill check the cam next time on high idle with the car running to see, Thanks for the tip.

riddler

iTrader: (4)

You could probably tighten up the throttle cable If you move it to the upper hole. I'm gonna do the spring return mod myself.

Mike K.

How do you do this spring return mod?

STREET SHARK

Mike call fast and ask for mike and tell him I sent you jerry norman, I have family members at CC I cant give out his mumber on last name! hope this helps

Mike K.

What is their main number? Do you think they will fix this for me? Or just tell me how to do the spring mod?

Mike K.

I called and talked to Hadley at fast and he thinks that I have a bad TPS sensor, hmmm, This doesn't make too much sense cause the tps comes back down to the same point everytime when the car is off but seems to rest at a different point each time I blip the throttle when the car is on.

I am more interested in trying the spring thing, Can somebody please explain how to do that mod?

Mike K.

ok here is another update, I called and talked to Jay at comp who seemed very willing to help me out His number is 810-225-2700

He said that they are now machining the flat spot on the shaft and that they would take a look at my tps sensor as well as machine the flat spot for me. Well see how it goes from here, ill post up once I know something more.

Kidsplay

Let us know how that works out for you bro.

Worm

iTrader: (2)

Hope you get it fixed man! Let us know. Man I love that sig pic