10' Dragon 800 WOT not actually WOT

[Dzlsmok]

I have a 10' Dragon 800 155" and I noticed an odd issue when riding the trail back to my truck last weekend. At Wide open throttle (flappy paddle pinned to the bars) it would max out around 7700-7800 RPM. If I let off the throttle ever so slightly it would pull fairly hard to 8150-8200 RPM. I couldn't tell you what it does in the powder as it was discovered on my way back after riding all day. There are no other issues to speak of, the sled runs great with exception to this odd problem. The issue is not intermittent and it is 100% repeatable.

• TPS set as per the FSM using one of the 9v plug in harness.
• Idle is 1650 RPM.
• Voltage regulator is of the latest design.
• PCV 5 TPS set as per the dynojet instructions from SLP.
• 150 ish Miles on top end. Indy dan monoblock and MTNTK durability kit.
• PAR 13.6:1 head.
• Reeds had no sign of issues when top end completed.

The throttle cable free play is the only unconfirmed thing I can think of.
Any ideas would be greatly appreciated!
Thank you

 

[retiredpop]

What are your plugs like when you operate at WOT? Sounds like you may be a bit lean. When you back off there isn't as much air flow through the throttle bodies and with the same amount of fuel from the injectors you get a better mixture so more power.

 

[volcano buster]

Fuel filter condition?

 

[Dzlsmok]

• Plugs were new when top end was done.
• Fuel filter was done at the same time as top end.
• Sled had a total of 934mi at the time of doing the top end. (Pulled it apart to inspect, because its a dragon, and found both skirts of the monoblock cracked on the intake side. I did not have any other reason to tear in to it but I am glad I did.)

I think that if it were that lean I would experience detonation/check engine light. The plugs have always had a medium shade of brown to them and do not seem to indicate any lean conditions.
It seems more like a setting/electronic issue rather than a mechanical issue. I hope to get time tonight to check/adjust throttle cable freeplay.

 

[retiredpop]

It's doubtful but I suppose it is possible that the TPS has a fault at the very top end of it's range. You could check that out easy enough with an ohm meter.

 

[Dzlsmok]

• Throttle free-play was within the .010-.030" specification.

TPS testing as follows:

• Powered up with a 12v supply and looking at it on my laptop through the power commander 5 software: 0.903 VDC
• So I spooned in to the back of the ECM connector for the TPS return with my Fluke multi meter: 0.92 VDC
• TPS shows smooth actuation from 00-100% throttle both on the Fluke and on the PC5 software. (I do not have an analog voltmeter)
• FSM shows spec for TPS at idle to be 0.93-0.95 VDC.
• With my Fluke spooned in to the back of the ECM (At the TPS return signal) and the 12v supply REMOVED, I started the sled. With the engine running the TPS is showing 0.83 VDC on the Fluke.

Is there a specification for WOT TPS reading? I forgot to write down what was measured last night when messing with it.
I know that it states NOT to set the TPS using the PC 5 software, but I have read a few posts where people have successfully utilized the PC 5 reading to set 100's of sleds. My initial check/set during top end was done using a 9v TPS plug in harness with a new battery and a power supply of 0.499 VDC measured at the TPS. And all that I set with the little harness did not change.

 

[retiredpop]

There is no spec for WOT reading that I have seen. I know the old carbureted ones were 4.0 volts and I would expect the CFI to be about the same. Maybe a dealer could give you an idea what they see on their software if they even look at that reading.
I have only used the 9V TPS plug in tester to set the TPS. As far as I know the plug in tester mimics the 5 VDC that the electrical system should generate when running. Have you measured the 5V lead on the TPS by bridging onto it when it is running to see if it is actually 5V?

 

[Dzlsmok]

I need to verify the 5 VDC supply to the TPS. I will also do it running vs 12V supply.

 

[Dzlsmok]

I completely reset the TPS, starting at baseline, using the Power commander software and it runs better. I also reset the power commander TPS range. It still had the top end fueling issue. I started to play with the fueling tables in the power commander and the top end was actually too rich. I started to pull small amounts of fuel out of the 7000-8200 RPM range from 80% and up throttle position. It runs much better and has gained roughly 200-250 RPM on the top end and no longer has the dead spot at WOT.

Is there any place that has multiple maps for the PC5? I am just interested in seeing what other people have done with theirs. I started with SLP's map.