first off, a big thank you goes to BABOLT for helping me out with this.. even though it wasn't one of his throttle bodys, he told me what i needed to do.

tools needed:
8mm socket & ratchet (to adjust idle set screw)
phillips screw driver (to loosen TPS screws)
multimeter (to measure TPS voltage)
pins (to stick thru the insulation on the wires to the TPS) - optional

how to check your TPS voltage:

turn key on, but dont crank engine
put positive lead of multimeter on grey w/ white stripe wire (middle wire)
put negative lead of multimeter on grey w/ red stripe (bottom wire)
i used straight pins to poke thru the insulation.


you should get under .99 volts.. anything over, and you'll need to adjust it.

make sure you have your idle set where you want it by moving this set screw:

tighten- increase idle
loosen- decrease idle

loosen the TPS screws slightly:


turn the TPS clockwise to raise the voltage.
turn the TPS counter clockwise to lower the voltage.

move the TPS slightly, and check with the multimeter.. when you get it to where you want it, tighten it back down.

 

my voltage was 1.01 before, and .983 after.

 

Brooks

Thats a Great little tech article.

Thanks

Don

 

Great post.

 

Does that always need to be checked or only if you have a problem?

 

Sorry to ask but what does this accomplish?

 

it should be checked if you have installed a single bore throttle body just as the topic suggests...

i was having some "surging" problems, and this seems to have cured it.

 

TPS stands for Thottle Position Sensor. It is basically what tells the computer at what postion the throttle is located. If it is set wrong you will have idle/drivability problems. If it to high the EEC thinks you are at part throttle when you are not. It can close the IAC (idle air control- it thinks it's NOT at idle now) and add fuel basically bogging/surging the engine. If it is set to low, at WOT the computer thinks you are at say 7/8 throttle. Think about the fuel maps (a/f ratios) and it will make perfect sense why it needs to be set correctly. BTW, some TPS's are not very adjustable due to the way they are made. They don't have grooves that the screw is in therfore you have VERY little wiggle room.

Haven't really found out the specifics for the L's, but I know on the turbo Fords (SVO's, T-bird's, XR4Ti's, etc. ) it can really be a pain. As much as a .05 volt difference can cause the engine to idle roughly or cause weird throttle response.

 

Thanks guys. I know what a TPS is, but I didn't know that improper voltage settings can cause idle/drivability problems.

 

One more thing, is if you change the idle set screw position, then you should check the TPS setting, since moving the screw will change the closed setting.

 

Mine was .925 now it is .995 and it idles and sounds much better. Thanks

 

cool man.. glad it helped you out..

 

Just a couple questions...

Would it be "ideal" to get this voltage setting to the same level as it was before switching single bore throttle body? (assuming that your truck was running well with the stock throttle body)

What does Ford call out as the spec voltage for this adjustment? is it a voltage range or is just anything below 1.00 volt ok (seems like a pretty loose tolerance)??

Btw... Clonetek how well do you like the single bore? Any real noticeable throttle response?

 

Nice job on the How-To clonetek. Should be sticky'd.

-Mike

 

So you set your engine idle with the set screw on the throttlebody? I thought the IAC controlled curb idle. To set curb idle don't you unplug the IAC and set the idle at say 500 rpms in park with that idle set screw and then replug the IAC. This way the idle control valve has some range of motion to attain the correct idle.