Throttle Position Sensor (TPS) Calibration

RotorWrench

Well travelled
Location
USA
Spotted the unicorn rider! Although I wonder if your altitude has anything to do with it. I'm under 100ft altitude, and my Himmie was always grumpy on cold start before Booster Plug. You're over 5K ft, right?
I don't know about nmroadrunner but that's close to my elevation and mine improved with leaning. But to really throw in a wrench, a co-worker put a Booster Plug on his '22 and his is now better. He's about a 1000' lower than me but still pretty high.
 
I don't know about nmroadrunner but that's close to my elevation and mine improved with leaning. But to really throw in a wrench, a co-worker put a Booster Plug on his '22 and his is now better. He's about a 1000' lower than me but still pretty high.
This intrigues me. Trying to put this in context for myself to better understand how this ECM and EFI works....how is that a Booster Plug, which is fundamentally an IAT trick or "conditioning" of the signal to the ecu, can make these bikes run better when the ability to adjust the TPS to our unique environ via .xxx vdc does not? Granted one is IAT, other is TPS. Not at all the same though both techniques are conditioning a signal.
I have some experience building/installing MegaSquirt ecu's into race cars and the datalogging and tuning was absolutely fascinating. I can say with certainty that tuning for max hp/max dyno#/best ET was relatively easy. Street manors and drivability were WAY more challenging. This includes cold starts. Granted, individual throttle bodies, huge cams, etc were a tough game for genteel mannerisms.....tho it gave me a great deal of respect for the engineering that went into most of the road going vehicles we use everyday. This REH cold start issue falls into this category.

Ok rambling. And not wanting to steer this thread "off topic" in any way. My attempts at .55 and .53 have yielded no improvement. As Tom D recommended, next stop is .68. Results later this evening.
 

RotorWrench

Well travelled
Location
USA
This intrigues me. Trying to put this in context for myself to better understand how this ECM and EFI works....how is that a Booster Plug, which is fundamentally an IAT trick or "conditioning" of the signal to the ecu, can make these bikes run better when the ability to adjust the TPS to our unique environ via .xxx vdc does not? Granted one is IAT, other is TPS. Not at all the same though both techniques are conditioning a signal.
I have some experience building/installing MegaSquirt ecu's into race cars and the datalogging and tuning was absolutely fascinating. I can say with certainty that tuning for max hp/max dyno#/best ET was relatively easy. Street manors and drivability were WAY more challenging. This includes cold starts. Granted, individual throttle bodies, huge cams, etc were a tough game for genteel mannerisms.....tho it gave me a great deal of respect for the engineering that went into most of the road going vehicles we use everyday. This REH cold start issue falls into this category.

Ok rambling. And not wanting to steer this thread "off topic" in any way. My attempts at .55 and .53 have yielded no improvement. As Tom D recommended, next stop is .68. Results later this evening.

Yes, true, a perplexing issue. Based on my experience with other bikes, not the Himalayan, the hacks required to improve operation indicate to me a map issue. It seems like the current map doesn't have sufficient set perimeters to employ based on available sensor inputs.

Since you have tried a lower value (leaner) TPS setting then indeed a higher (richer) value may work for you, or it may not respond at all.

The ECU uses the aggregate of all sensors to determine a setting, so I'm really not sure if changing one sensor value is always a good thing. I've found out that sometimes misadusting one sensor can cause performance issues because the ECU may now be getting some conflicting signals, if other sensor values aren't adjusted to match.

I really don't know the true total effect it has. Either way, good luck.
 
Yes, true, a perplexing issue. Based on my experience with other bikes, not the Himalayan, the hacks required to improve operation indicate to me a map issue. It seems like the current map doesn't have sufficient set perimeters to employ based on available sensor inputs
I share your thinking re: MAP issue. A single long stroke cylinder is a less than ideal environment to get a clean steady MAP value for the ecu to use. It can be averaged tho Im willing to bet our EFI is not especially up to this task. Im guessing its pretty basic like the rest of the bike.. Just conjecture at this point.
I am not able to get to the garage this evening unfortunately. More .vdc content to stay on topic as I get some.
I dont belive I mentioned it previously…..elevation is ~1300’, recent ambient cold start temps 58-74deg F.
 

RotorWrench

Well travelled
Location
USA
I share your thinking re: MAP issue. A single long stroke cylinder is a less than ideal environment to get a clean steady MAP value for the ecu to use. It can be averaged tho Im willing to bet our EFI is not especially up to this task. Im guessing its pretty basic like the rest of the bike.. Just conjecture at this point.
I am not able to get to the garage this evening unfortunately. More .vdc content to stay on topic as I get some.
I dont belive I mentioned it previously…..elevation is ~1300’, recent ambient cold start temps 58-74deg F.
Ok, thanks for the environmental conditions. I'm curious as to what your TPS value ends up being for a better start and idle situation.

With mine at .57-.58 my elevation at home is a little more than 4500'. Morning cold starts averaging the past week 34-42deg F. Afternoon cold starts 75-82deg F.
 

MikeM

Well travelled
Location
So Cal USA
I share your thinking re: MAP issue. A single long stroke cylinder is a less than ideal environment to get a clean steady MAP value for the ecu to use. It can be averaged tho Im willing to bet our EFI is not especially up to this task. Im guessing its pretty basic like the rest of the bike.. Just conjecture at this point.
I am not able to get to the garage this evening unfortunately. More .vdc content to stay on topic as I get some.
I dont belive I mentioned it previously…..elevation is ~1300’, recent ambient cold start temps 58-74deg F.
Did you ever find a setting that work? Mine needed .70 at sea level. Idle RPM was 1250. It started and idled better (never stalled) but still felt lean all over the power band.
 
Mike,
No joy. Somewhat surprising to me but .55v got it to stay running on the first try for about 2 weeks.......I would not call it a "night and day difference". She still struggled a bit immediately after firing up but would *mostly* not stall. And lately it has relapsed into needing 2-3x to keep it running upon first cold start of the day. I will try the .68-.70v as suggested more for my own curiosity but ultimately I concluded that fiddling with TPS values is akin to splitting hairs.....perhaps somewhat effective but not a great nor consistent solution.

Once I realized I was experiencing a lean surge under various light load conditions I realized this bike seems just..... too lean. IMHO. I ordered a booster plug as conditioning the IAT temp seems a more reliable, consistent route to better fueling. 6% more fuel during open loop for an otherwise stock Himmie seemed a great idea to me.
 

tom_d

Well travelled
Location
US
Set it to .70 and she fired up and stayed running at 42 deg F this am. Good sign. I finally got tired of messing with a pin into the TPS connecto and probes on my multimeter and bought the KTM 6 pin to OBD2 adapter so I can use my OBD2 dongle and hopefully see the TPS value on my phone screen.
I think it will give you throttle percentage, but I am curious about that value with your new settings. :) Hope it stays solid for you.
 

MikeM

Well travelled
Location
So Cal USA
Set it to .70 and she fired up and stayed running at 42 deg F this am. Good sign. I finally got tired of messing with a pin into the TPS connecto and probes on my multimeter and bought the KTM 6 pin to OBD2 adapter so I can use my OBD2 dongle and hopefully see the TPS value on my phone screen.
Good news, now get it good and hot and adjust the idle speed. It might rise on you now with your TPS at .70ish.
 

Flicka

Well travelled
Location
Italy
Set it to .70 and she fired up and stayed running at 42 deg F this am. Good sign. I finally got tired of messing with a pin into the TPS connecto and probes on my multimeter and bought the KTM 6 pin to OBD2 adapter so I can use my OBD2 dongle and hopefully see the TPS value on my phone screen.
Now that you have the OBD2 it would be interesting to see the throttle percentage with tps 0.70 V, also I ask you to report the temperature reading in the intake when you have mounted the boosterplug, thanks in advance
 
I think it will give you throttle percentage, but I am curious about that value with your new settings. :) Hope it stays solid for you.
Yes this occurred to me as I thought about it. I'm going to see % vs .vdc. Not sure what I'm going to do about it. The % is just a calculation based upon .vdc so it shouldn't be too hard to learn which % corresponds to .55, .62, .70 but it forces me back to fussing with the pin/connector. Which is what I'm trying to get around.

It'll provide the other infos as requested however. Onward......
 
Okay, the KTM 6 pin to OBD2 adapter arrived. I connected it to the harness under the seat, connected my VeePeak OBD2 dongle to it and turned on the bike key. Fired up the app on my phone and it all connected as intended. I supposed I'm a skeptic when it comes to ebay and Amazon technology managed by myself but it worked well, as intended. The app I"m using is Car Scanner and while I need to better learn how to use the tool, I was able to see IAT, ign timing, rpms and TPS % to name but a few.

I wanted to corelate the .vdc to the TPS % I was seeing on the app/phone. I inserted the pin and could get no readings on the multimeter. Tried and retried. I'm not making contact at the connector with the pin I assume. I was concerned I might have damaged the harness/connector with repeated pin insertions..... I tend to always assume the worst. No CEL however and the app showed expected value and changes with the throttle application.

So no corelation was established. The interesting thing I noted in real time as you can graph/datalog.....at idle, the tps % jumps a bit. It is not absolutely consistent. There is noise. Set to 5.88 %, it bounced between there an 6.33%. Not even half a percent yet not a clean signal. I wondered if some cable shielding would resolve that...or if it's even worth resolving.

I rode it at 3.x% TPS, 5.88% TPS and found hiccups in both...mostly low speed throttle "tip in" stumble or surges. Set the idle TPS% to 9 and she seems pretty happy with idle and throttle response but I don't have any ride time to say if she's happy or not.

Edit to say that at 9% she is buttery smooth with no surges or hiccups. Idle is indeed a bit high when she's good and warm....1500rpm ish.....so I'll dial that back modestly but overall....winner.
 
Last edited:

MikeM

Well travelled
Location
So Cal USA
Since my throttle body is sitting in a box I grabbed it to check the base setting of the idle screw. This is just in case someone gets carried away playing with TPS and the Idle speed and finds their bike running poorly. My bike was running really good in regards to cold start and idle. Very consistent and never stalled.

My idle screw was set half a turn out from all the way closed (turn clockwise until it stops then back it out half a turn) and my TPS voltage was .69 to .71. Anyway that should give you a starting point on a 2022 US model if you get lost.
 
Top Bottom