No signal at TPS


Go Kart Newbie
What’s happening:
When the car is rolling in neutral and I push the clutch in and then release and then rev, the TPS signal is low nearly 0 and the engine speed does not increase much. But when I roll in neutral and don’t push the clutch in+out and then rev, the TPS signal is high around 50 and the engine speed increases as expected (you get a rev).

I cannot explain this any simpler. Here is a log (attached) while rolling, where pink is TPS and white is accelerator pedal position and gray is engine speed

-first two revs are without first pushing the clutch in and out and pressing the accelerator pedal (notice high TPS signal and engine speed response
-final three revs are with pushing the clutch in and out first, and then pushing the accelerator pedal (notice very low TPS signal and much lower engine speed response)

If you take this one step further, every time an up shift happens, you have to push the clutch in and then let out and then add gas, and obviously the car would be rolling. This is the exact scenario that I explained above that’s giving low TPS signal, which means every up shift is messed up….everytime I let go of clutch on the up shift and add gaas there’s a clunk as the flywheel grabs the clutch disc. And it didn’t used to be like this.

This doesn’t happen at a stop by the way, only happens when the car is rolling. And downshift rev matches are fine because the clutch is fully in when I’m setting the revs, clutch in is fine. It’s only when clutch out happens that TPS is messed up…

So why would clutch position and rolling be requirements to observe this problem. It’s very specifically happening when those two conditions are met that I get low TPS. And then the low engine speed is straightforward to me from there, that’s dictated by TPS. The car didnt used to do this. I used to think this was happening randomly, but I finally figured out when it happens and when it doesn’t but don’t know why



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