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Question for TunedPortK5

Russell

Russell

3/4 ton status
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Hey man!

I'm busy installing a TPI setup into my 80 GMC 4x4 longbed, and I've come across a slight issue that I see you solved already. How did you manage to hook up the throttle cable from the stock TPI car? With the one I have, the end that goes into the firewall is at an angle, and is way too big for the stock hole...

Thanks for any info you can offer!

Russ

PS -- Sorry for posting the question here, my paypal payment for full membership hasn't gone through yet, so I cannot send private messages yet...
 
Don't worry about the angle on the engine bay side of the cable.

If your cable is anything like the Camaro one I'm using, it's WAY longer than it needs to be, and will end up with a graceful bend in it that won't bind. IIRC, you just have to make sure the end inside the cab points towards the pedal.

I HAD to bend the throttle cable attachment point on the gas pedal though, it was getting nowhere near full throttle travel with the pedal attachment point in the right spot for a carbed application.

I didn't heat the attachment point up to bend it, but it felt to me like it was fairly close to breaking, bending it cold, as I was.

I had to cut my firewall up a bit too, and didn't do a real good job getting it just the right size. I think only one of the clips works, but in the driving I've done, it isn't an issue. It's in there, just not as secure as GM liked.
 
I used a Lokar TPI throttle cable. It is cut to fit and worked pretty good. I don't get WOT but that is ok, I don't need it.

Harley
 
If I'm not mistaken, if you don't hit a certain value with the TPS, you don't hit power enrichment. (pump shot)

I could be wrong on this, I haven't studied it much, but I know a certain TPS value is important to PE.

I'm sure theres a bunch over on thirdgen or in the factory service manual. I need to study up on it, I only get a bit over 4 volts at WOT, which IS WOT.
 
Yeah, thats why I want to be able to get WOT out of my throttle body, that and to spank a ricer or two if needed be ;)
 
I definitly get to power enrichment phase. I don't get WTO but I do get to PE for sure. I found that out when I was running a hard grade. I was in 3rd gear doing 65 an it was cruising fine with a little more throttle input up the hill. For ****s and grins I opened the throttle up more and it responded quite well and was ready to start accelerating hard on a 6-7* grade.

I probably only get 2/3 total throttle movement out of my cable but it is plenty for PE and daily driving work. I can get alot closer to WOT if I move my pedal linkage to my other throttle body bracket but I loose low speed control of the truck because the throttle opens so quickly. I can't rockcrawl with it like that.

The second I open the throttle with the pedal a little bit the throttle blades open alot and I go from idle to 1500 RPM in a split second which is VERY bad for crawling and DDing. It is great for quick power and throttle response but I don't need those things.
Harley
 
My TPI engine came from an '87 Corvette and the throttle cable from that application wouldn't work in my '75 K5. I wandered through a junkyard looking under hoods until I found a cable that would work. That was a lot of years ago, but I seem to recall that it came from a late 80's Grand Am or other similar sized GM car. :)
 
Last edited:
dyeager535 said:
If I'm not mistaken, if you don't hit a certain value with the TPS, you don't hit power enrichment. (pump shot)

I could be wrong on this, I haven't studied it much, but I know a certain TPS value is important to PE.

I'm sure theres a bunch over on thirdgen or in the factory service manual. I need to study up on it, I only get a bit over 4 volts at WOT, which IS WOT.
Click to expand...

power enrichment is usually based on the rate-of-change of the TPS and the rate-of-change of the MAP or MAF, not the absolute values. The faster the TPS changes, the more enrichment. Same goes for change in engine load (MAP or MAF).
 
If you use a cable out of a 89 or that body style with tuned port and trim your cable hole a little you'll be set, and with WOT.
 
Yeah, found that too...in the MAF stuff, it's a percentage based on throttle opening, and pretty small, in the 20% range.

Only issue with the TPI throttle cable is that GM changed the way they hook to the throttle body in about '90 or so.

Sounds like you've got the cable out of the same vehicle, so you'll be set there though.
 
BTW, on that donor FWD car, did the cable mate up to the stock truck firewall cutout, or did you have to cut?

Probably a direct fit I'm guessing, since I already bought and installed the cable that requires cutting the firewall. :)
 
I don't recall having to do any mods to make the cable work but then again that was around 1989. :confused:
 
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