Anyone ever build a setup like this? It's what I'm doing right now, but information is limited on this subject, and I want to know if anyone has any tuning secretes or any tips. I already have my DTBI running, but it's not running like it should be.

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1992 RS
327, Modded TBI, Rebuilt WC T-5 5-speed, PRO 4 15" rims, Nitto's, 3.73's, SLP 1 5/8" headers, and a few other things.

 

Thier was a magazine not to long ago that had a guy do a duel TBI setup. The only thing that realy stuck to my brain was that the tq. line was flat. Instead of bilding up to the peak it shot to the peak at a low rpm then keep it till top rpm. Might not help much but might give you an Idea of whats in store.

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92 Firebird
305, Full exhaust, intake
Tbi spacer

 

tell me what you have done to setup the duAl tbi's?

what did you do harness wise, chip wise, IAC wise?

i dont know too much on this but ill share what little i do

 

Well... I'm working on it!! What kind of problems are you having?

Steve

 

My biggest problem is with the IAC valves. At first, I tried using only one, but then only the half of the engine being fed by the IAC equipped TBI was getting anything, and it wouldn't idle, just stumbled and died. So the I wired in both IAC's, it idles now, but it idles at 1000 RPMs. I can't seem to figure out how to adjust them both to slow down the idle.
As for the harness itself, I custom made it myself. I had a Turbo City one before, but it fired all the injectors at the same time, and I have mine set up to fire one at a time, mine works a whole lot better.
The chip is a custom JET chip. I'm going to start burning my own chips soon so everything will be easier to adjust.
My main problem is with those IAC's though, any tips there?
Thanks!

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1992 RS
327, Modded TBI, Rebuilt WC T-5 5-speed, PRO 4 15" rims, Nitto's, 3.73's, SLP 1 5/8" headers, and a few other things.

 

Hmmm... I don't know. When I was tossing out ideas (which is kind of like tossing my cookies) to my buddy about this setup a while back I mentioned this as a possible problem. One of the ideas we came up with was to drill a slot in the throttle blades like the carburetors do - start small, test, drill bigger, test, ad nauseum, until you've got a nice idle. If you go too big you can always J.B. Weld over it and start again with a smaller bit. I don't know - just an idea.

So, do you think it's due to both IAC's getting the same signal and both of them opening up the same amount...? You can probably ask someone with a bit more electrical knowledge (hell, maybe even the guy at your local Radio Shack) and find out what kind of doohickey (industry term) you can run inline to cut the signal in half. That way both IAC's are only opening up halfway, but the total equals what the computer needs.

Do I sound whacked or what?

Steve

 

yeah two iacs off the same signal are gonna let in double the air
youll want to cut the iac steps in the chip in every table in half i guess. I wonder if its possible to make some sort of plate to have one iac feed both intake flanges

 

Damn you guys rule! You just solved my problem. I didn't think of it until I ready your reply that these things are using the same signel, the signel is nothing more then a variable voltage! All I have to do is install resistors to cut the voltage in half! If that doesn't work, I'm goig to rplace the IAC's with manual adjustable screws and adjust it the old fastioned way; with a screwdriver.
Thanks guys!

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1992 RS
327, Modded TBI, Rebuilt WC T-5 5-speed, PRO 4 15" rims, Nitto's, 3.73's, SLP 1 5/8" headers, and a few other things.