Throttle body

[clayhilldave]

I have an '89 Ranger 2.9 and would like a larger throttle body. My brother has a wrecked '86 Bronco II with a 2.9. I thought the '86 had the larger TB but just by eyeballing it, they look the same. What year 2.9s had the larger TB's?

 

[chrwilkins30]

86 & 87.

I just pick one up at the junkyard a few days ago.

 

[Big Jim M]

Why??? All you can possibly do with a larger TB is to make it run WORSE! Unless you are going completely THOUGH the engine with mechanical modifications you will be making a mistake!
Big JIm

 

[clayhilldave]

Throttle Body

Ok..Thanks Big Jim...I'm NOT a mechanic...I thought it would run better...more air...Thanks for the advice...I appreciate it... Dave

 

[chrwilkins30]

why would it make it run worse. If a 2.9 came with one how would it hurt to put on one that came with a smaller one? why would they put a bigger one on 86&87 if it hurt performance?

 

[AllanD]

Actually there is a point to the larger TB on 2.9 engines that are run oin '88-92 engine management, but... (and this is a medium sized "but")

The larger TB doesn't do what you think it does....

What it does do is lets a full throttle ammount of air into the engine while you
DO NOT put the pedal against the firewall/floorboard seam

The effect of this is with the throttle NOT 100% the engine management stays in "closed loop" and therefore doesn't go to the 100% throttle default of "CPFR"

CPFR = Completely Pig Fooking Rich

If you are expecting a performance boost from the bigger TB... prepare for disappointment, what the bigger TB does it does at 3/4-7/8" pedal

When I was running a 2.9 I actually added a stop to the throttle to prevent it from ever giving the WOT signal from the TP sensor to the computer.

You could push as hard as you wanted to on the pedal, but the throttle
linkage STOPPED at 7/8.

Frankly this is more of a "mileage mod" than a "performance mod"

Unless you understand exactly how things work, and that is to say how they REALLY work, not just how you happen to "think" they work, you shouldn't be modifying things...

there are reasons I managed to squeek 26mpg out of a 2.9 engine in a Ranger supercab
with 4.10 gears

AD

 

[Zachalanche]

I have the larger TB on my 89 and as expexcted it takes less pedal to make the engine go. And the power doesn't feel like it drops off as fast on the top end 4700+ RPM. However, this hasn't been proven on a dyno or by any other measurable means. Gas mileage is the same. I suspect port matching my intake may allow the larger TB to be more effective, but on a stock 2.8 the smaller TB is appropriatly sized for the amount of air the engine can suck in and provides more precise throtle control. If you aquire the larger TB for very cheap or free, it won't hurt anything to try it, but I wouldn't go out of my way for this mod.