Ever have a problem with getting min air, TPS and IAC counts to line up, and still get a good WOT TPSv?.
My car was driven me nuts, being the picky chit tuner that I am.
Finally had the time and energy to play the R+R TB game.
Removed the TB, and the butterfly was 2 full turns from the closed posistion.
In the carb days we drilled bypass holes in the butterflies to resycn the opening to the transfer ports.
Soo, I started with a 1/16" hole and began drilling and R+R the TB till I got the butterfly about closed. FOR ME AND MY COMBINATION, it took 2 1/8" holes and going 1/32" at a time was a bunch of time to get it right.
I now have .42 TPSv at idle, and WOT 4.5 TPSv.
Pre drilling was .42 and 4.1...
If you were to go to far, then a little JB Weld, masking tape, and a 180dF oven would fix it.
I've done the epoxy fix for 15 years, with never a problem.
If you work on a car with a brass butterfly solder is an option.

Changed the cruise v .06
Seems to roll down faster (ie lifting off of the gas at 65 MPH)

 

Thanks for the info, THats interesting, i thought that sort of mod was only viable on carbs

How exactly does this work with the TBI? I thought it would be more beneficial to have more air passing through the edges of the throttle blades where the fuel is aimed, also, I was under the impression that your idle TPS voltage was just zeroed out on startup and everything else was read as a % it seems like the min. tps voltage would factor in no matter what if somehow throttle opening affected performance

edit...hmmm i think i know what you are getting at, you had more room under what would constitute WOT PE because you lowered the tps voltage across the board hmm

or is this GN specific?

I think i have IAC close to where it should be now (no scan tool to look at counts for now) at any rate its much improved since BobR's article showing the various tables i cut down the IAC vs map at reset table and that was mainly what did the trick for me on top of what I had allready done

[This message has been edited by Pablo (edited December 08, 2000).]

 

Depends on your situation.
On the cross fire it really like .38v at idle. No 2 ways around it. When I working on that system there were no hacs, and what I had to do was synch things by doing things like running a restrictor in the PCV, and brake vac booster.
There are many ways to do something.
Got to look at the whole system when making mods. I was relating what I had just done, and was a FWIW.
Given enough cam, you'll have to open the butterflies some for it to idle. Lack of vac, is the reason. If you run out of TPSv at WOT, then you'll have to do something.
At this stage closing the butterfly may help with the shearing action, the injectors are still gonna be spraying where they are aimed. Would be a balancing act but by going with a total of 4 small holes might be worth the effort

 

So I take it your TPS is non adjustable?
after setting the iac. Are you able to adj the tps. I usually go for a 10-20 idle iac count.
A .5x usually .58 tps close and anything over 4.6 wot
Dennis

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85 vette,383,miniram,ZF6,4.10's..best ET 11.66@1187.00 60' 1.62
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

 

Yes, it is adjustable
I much perfer a 0 or as close to that as possible IAC count. I also, limit the IAC perimaters to lessen the ecms control of engine reponse.
4.6 can get you border line in some applications for codeing with a high TPS voltage error