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View Full Version : 300x TPS Bracket Fab Up To Eliminate Linkage Bind-DIY



Liberator*21
08-07-2012, 12:21 PM
This will apply to "SOME", not all 300x motors. Some, don't know why, have a problem with linkage bind because of the direct linkage rod angle from the throttle cam to the TPS ball socket. This can be seen at the TPS when applying throttle, the entire TPS wants to move until enough pressure is applied to slighty change the angle of the linkage. If left as is will cost you a TPS sooner or later, I speak from very recent experience. I bought a new TPS and after mounting it and checking the TPS voltage I noticed the binding just by moving the throttle arm by hand (cable disconnected). This is how I fixed the problem. Please note that an OEM TPS ROD will now be to short, an adjustable rod must be made up to make up for the increase in distance due to the TPS rotation.

Hers an older pic of the adjustable rod I made;

http://i177.photobucket.com/albums/w201/90profx/TPS%20Link%20Rod/TPSROD010.jpg


Made a new TPS bracket out of 1/8", 6061-T6 aluminum plate using the OEM bracket as a pattern. Two things were modified from the OEM bracket, the 4 TPS threaded holes were rotated 5 degrees "CW" as was the center clearence pocket. This opening is for the expoy bead on the back of the TPS sealing the rear cover to the body, as it won't sit flush on a flat surface due to the epoxy bead. So here it is is photos:


Here you see the stock bracket and the one I fab'd up;
http://i177.photobucket.com/albums/w201/90profx/TPS%20Mounting%20Plate/Bracket1.jpg

This pic shown the 5 degree threaded hole rotation "CW" from the stock position marked "X";
http://i177.photobucket.com/albums/w201/90profx/TPS%20Mounting%20Plate/TPSPlate003.jpg

This pic is with the hole tapped and the clearence hole in the center for the epoxy bead on the back of the TPS;
http://i177.photobucket.com/albums/w201/90profx/TPS%20Mounting%20Plate/TPSPlate005.jpg

TPS mounted to the new bracket, it's now obvious to see the TPS plug is now angled upwards from where it's normally center between the 2 forward mounting screws;
http://i177.photobucket.com/albums/w201/90profx/TPS%20Mounting%20Plate/TPSPlate006.jpg

My DDT showing that after 10 throttle advances from idle to WOT, the TPS voltage always falls back within spec. +/- .008;
http://i177.photobucket.com/albums/w201/90profx/TPS%20Mounting%20Plate/TPSPlate007.jpg

frontline
08-08-2012, 08:17 PM
Sweet- I have noticed what your talking about - where and what did do to make that turn buckle on rod - and what did you use for the throttle roller ?

frontline
08-08-2012, 08:18 PM
Also have you experimented with different tps voltage settings?

Liberator*21
08-09-2012, 06:50 AM
Sweet- I have noticed what your talking about - where and what did do to make that turn buckle on rod - and what did you use for the throttle roller ?


Also have you experimented with different tps voltage settings?

I have a machine shop at the house, used a mill and lathe, but it can be made with simple hand tools too, just take your time. Throttle roller was made out of Delrin, a much harder plastic than OEM.

Yes, I have played with the TPS voltages at idle and my set up like to stay under .500 or it loads up on long idle zones. Fuel pressure runs at 40 psi.