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Erratic TPS readings

1K views 14 replies 4 participants last post by  theknurl 
#1 ·
Tried to measure the TPS while cleaning air filter. Only to find that i cant get a stable reading out of it, jumps all over the place.

TPS dead?
 
#2 ·
Are you having rideability issues?
 
#5 ·
Use an ohmeter...preferably an old analog type. Measure the resistance as you slowly open and close the throttle. Readings should smoothly change from low to high (or vice versa depending).

Twitchy needle on the analog or jumpy numbers on the digital tell you the potentiometer contacts are worn or dirty..... TPS is faulty.
 
#7 ·
Your engine is a B4 right? Year? Please put that info in your signature line.....
 
#8 · (Edited)
?

ViggenF4;
You don't use an Ohm meter to set TPS.......I know that would be the logical way>:)
You need to lie to the ECU and tell it that's it's at 2.3° with a VDST from Techno Research

Ed;
The TPS on MVs is a dual slope.......I know, that doesn't make any sense either
The TPS is available at any Harley Davidson dealer for $39.......MV doesn't sell them

Ask any BMW mechanic what to set the TPS on an R1150......381 Ohms.......NOT 300-400 like the book says:wink2:
 
#9 ·
@theknurl @ViggenF4: this bike is a hybrid. It is an F4 frame...of indeterminate year. It has a B4 910 engine....again of indeterminate year.

Things like this make me crazy as the manuals do not directly apply and diagnosing and issue can be problematic as you can't tell if the bike should use VDST, MSDT, a voltmeter...or what.

ViggenF4...please, so we can help you, put that data in your signature line. The year is very important.

Of course, if you have used other Throttle Bodies, this gets more complicated.......
 
#10 ·
Noel.....regardless of the actual signal usage and method of "setting"....the TPS is a 3 wire potentiometer and the test process I use applies. Erratic (not smooth) changes in resistance while going from fully closed (idle) to fully open (WFO) indicate worn or dirty internal connections and a failed (failing) part.
 
#11 ·
Dirty rheostats (TPS) can be "wiped" several times to restore functionality....if not severely pitted or worn internally.

"Wiped" means to move the rheostat several time through its entire range.

Sometimes the erratic reading is caused by a light corrosion layer.
 
#13 ·
It really makes a difference when it comes to the electrical systems.
 
#14 ·
Have set the TPS to 150mV when butterflies gently pressed shut.

Idle screw is set so that its 400mV ish at idle, thats what the bikeboy.org suggests is good. And it runs in the region of 1400rpm idle on clocks, and it was 1300 in real life.

Has worked so far, now just out of curiosity checked it again while doing the air cleaner service.
 
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