Any problems with not using the TPS?

7 replies to this topic
  • Paewraul

Posted July 31, 2006 - 07:25 AM


My 426 is set up as a SM, so I have alot of road and constant throttle riding. Without the TPS plugged in, this thing runs great! NO Surging anymore! Any danger in not using the TPS?

  • Thumper_Bloke

Posted July 31, 2006 - 07:59 AM


I have alot of experience with ignition advance on 4-stroke engines. The TPS, when disconnected, sets the CDI to the wide-open-throttle map (or curve). Before the TPS was ever used on engines, we had one advance curve. So, most engines can run with a single advance curve.

The only thing to watch for is this: if the advance isnt high enough, you will get excessive heat into the header (and exhaust valves). But if its not glowing cherry red while you cruise down the street, you should be ok.

I disconnect mine for the street, and reconnect it for the trails. However, on the trails it pops and makes silly noises. I dont like the stock CDI mapping.

  • Chas_M

Posted July 31, 2006 - 08:00 AM


No, there is no danger of disconnecting the TPS. Your gas mileage might suffer a little bit. The TPS functions primarily to advance timing during part throttle operation.

  • creeky

Posted July 31, 2006 - 09:03 AM


When I installed the Edelbrock on my '00 WR400 last year, of course I could not use the TPS. The bike runs terrific, fuel mileage is better than with the stock carb.

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  • 06WR450FSM

Posted July 31, 2006 - 10:56 AM


I run 90% of the time on street & highway in supermoto setup and experimented with disconnecting the TPS and blocking the Air Cut Valve (ACV) open. I found that just blocking the ACV nearly eliminated the surging and I prefer the throttle response of having the TPS hooked up. I leave it as-is when using the dirt wheels on the trails - primarily tight, winding, rolling woods riding.

I'd like to know how effective a Powernow is at eliminating the surging and generally rough power delivery under 5000 rpm in 5th gear on the highway.

  • Paewraul

Posted July 31, 2006 - 11:51 AM


I think I plugged the ACV, but I'm pretty sure it was to keep it closed, not open. Maybe I'm mistaken. I had to do it to have a chance at figuring out the jetting, and I get some good pops during decel. Thinkin about opening it back up now that the jetting is squared away.

Not sure I noticed a big difference, other than the surging with the TPS unplugged.

  • 06WR450FSM

Posted July 31, 2006 - 01:38 PM


ACV blocked open or closed - hmmm - its been a few months... Its whichever way doesn't require rejetting.

But here's a big deal: when I installed the vapor computer with water temp gauge, I found out the water temp on the highway is only 60 to 65F warmer than ambient!

My water temp was only 140 to 145F when it was 80F. That's probably bad for lubrication since the oil will be thick while you are running at relatively high rpms combined with real operating loads.

I blocked off about 60% of both radiators and now am getting 90 to 100F above ambient, which is where it should be. Sitting at a stop light for 5 minutes isn't so good, but wasn't good before either.

  • toyota_mdt_tech

Posted July 31, 2006 - 04:22 PM


No danger at all. Its used only for ignition advance. Yours will end up in a fixed mode or default.


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