Don't expect too much from a Variohm. A new resistive TPS gave me stable readings and fine throttle control at low power, the same as the Variohm. The only problem was the resistive TPS eventually became erratic. The charts attached show the TPS signal before and after I replaced the TPS on a TreK1130, with only 10,000km on the display.
On the upper chart, the jagged green line is the signal from the original TPS. On the lower chart, the smooth green line is the signal from a new resistive Delphi TPS I fitted. That was only $75 delivered via eBay. Interestingly, the original TPS gave a smooth output in a static roll-on test, it only went that bit wobbly with the engine running. Engine vibration is likely to be a factor in the poor contact between the sliding contacts in the original TPS, while running. (The O2 feedback in the lower chart shows it is too rich, so I adjusted that later to reduce fuel consumption and avoid ECU adaption causing erratic behaviour.)
If you have problems with low-speed behaviour, the TPS signal is the first thing to check. It that is OK the problem might be the fuel map. If you have an O2 sensor fitted, the O2V signal will tell you if your fuelling is the problem.
When I bought my TreK it was very fussy at low revs and had very poor low speed torque. The intake and exhaust butterflies had been disabled, but it still had the stock fuel map. The O2V signal showed 1.15 at low speed, indicating a very lean condition. I adjusted the map to achieve feedback consistently between 0.95 and 1.00. That transformed the bike, making it purr like a kitten, with strong torque from idle. More recently, both my TNT899 and TNT1130 ran roughly at low speed. I did the same thing. I adjusted the maps to eliminate lean low speed running. Both now have civilised behaviour, with progressive throttle response. I also increased the fuel on deceleration to stop backfiring and give a smooth transition from deceleration to acceleration.
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