3 gallons or less in your tank!!

[justinator]

its showing right on the money at full pull is 100% from TPS, havebt looked at reading at idle for tps %, but ill tell you we are all on same page here because when sled is cooler than say 140 deg , the throttle responce is snappier than when im at 174 normal operating temp, i think i need the target afr in the tune stepped up a bit to richen it up at idle and low throttle positions. i think i have the tuning capability with my flasher..... i know they said i can adjust timing and boost..... I WONT THOU but i wonder if AFR is adjustable?

The closed loop does nothing and is inactive below 5000 rpm on TD tunes is what I was told. Viewing my logs this information seems accurate. I know if I partially plug my exhaust at idle it gets pig rich and doesnt change so the closed loop isnt doing anything to correct idle. Try simply bumping up your fuel pressure some more, this will richen the idle and low speed and once closed loop is active it will take care of keeping you at target afr. If this works and takes care of your problem you can talk to Ben and see if he will give you a revised tune or advise you to just keep running with increased fuel pressure.

 

[KnappAttack]

The closed loop does nothing and is inactive below 5000 rpm on TD tunes is what I was told. Viewing my logs this information seems accurate. I know if I partially plug my exhaust at idle it gets pig rich and doesnt change so the closed loop isnt doing anything to correct idle. Try simply bumping up your fuel pressure some more, this will richen the idle and low speed and once closed loop is active it will take care of keeping you at target afr. If this works and takes care of your problem you can talk to Ben and see if he will give you a revised tune or advise you to just keep running with increased fuel pressure.

I noticed however if upping the fuel pressure that it does nothing to help the lean idle, which seems so crazy. I can turn it to 60 even 70 lbs and it doesn't go rich at idle. Now I can lower the pressure below stock 43 key on and it does go lean.

Upping the pressure helps though as you start getting into the throttle more, but going way up in pressure for idle, nothing... Scratch my head on that.

 

[justinator]

Interesting for sure, I never tried it but assumed it would work. I wonder if the injector pulse at idle is so narrow that the increased psi makes minimal difference vs times when pulse width is longer??

 

[max rolph]

I noticed however if upping the fuel pressure that it does nothing to help the lean idle, which seems so crazy. I can turn it to 60 even 70 lbs and it doesn't go rich at idle. Now I can lower the pressure below stock 43 key on and it does go lean.

Upping the pressure helps though as you start getting into the throttle more, but going way up in pressure for idle, nothing... Scratch my head on that.

it might max out the spray pattern at the pulse width ecu is dictating at idle, what is the tune calling for for afr at idle??? lowering the afr will tell the ecu to hold injector open longer to reach target.

 

[KnappAttack]

it might max out the spray pattern at the pulse width ecu is dictating at idle, what is the tune calling for for afr at idle??? lowering the afr will tell the ecu to hold injector open longer to reach target.

I have multiple other sleds setup identically with the exact same hardware and they are are all at 11.9-12.0 when they idle & have a nice smooth idle. Its almost like mine has a vacuum leak, which would also be a boost leak one would think, or a bad TPS or TPS setting, and it sounds like yours is acting the same. I was able to up the fuel pressure 4 lbs and help the stumble down low, but as I look at it now I may be making up for a bad TPS possibly. I first though I had a idle air control valve goin bad until I noticed the A/F values at idle. I don't think its severe yet but its an annoyance to me that's not perfect.

I just haven't had time to work on mine to verify and correct it, as I have other customers sleds to get done first. I have a wife goin for surgery next week and will need to take care of her when she's done too. So my time is going to be limited to get this figured out yet this season. I may not get it figured out this season even, but I'm sure it has to be fairly simple like the TPS.

 

[sideshowBob]

I have a wife goin for surgery next week and will need to take care of her when she's done too.

Things that really matter in life...hope all goes well.

 

[max rolph]

we will work on figuring out together.. you keep me posted and ill do the same

 

[KnappAttack]

we will work on figuring out together.. you keep me posted and ill do the same

I fired up another sled identical to mine today and noticed it too has a hunting idle along with a leaner A/F mixture when warm. Its also idling at high 13's. Its a 20 Thundercat that doesn't even have a couple hundred miles on it. So, I'm questioning on wether its a bad TPS. I just know it acts the identical way that mine does. I'm beginning to think that some engines just idle richer or leaner than others, maybe the TPS setting is just a little bit off one way or the other perhaps.

I have to think that just turning the TPS a bit should richen or lean out the A/F at idle. I know they tune dirt bikes richer using the TPS, but what effect would this have on the timing curve or the top end A/F I wonder...

Anyone know how to check the TPS setting or parameters on the 998? I checked the service manual and found nothing for the settings or testing. It referred to using the settings and instructions provided with the Yamaha diagnostic testing tool, so pretty much worthless for information regarding the TPS settings or testing.

 

[Fords4life]

Knapp, could it be diffrent fuel blends?? This season diffrent times i get the same thing, hunting or surging idle, but my afrs vary from say 11.7 to 12.8, depending on where i got fuel, i only use 2 places, and only notice this problem from my local small town station, what do you think??

 

[KnappAttack]

Knapp, could it be diffrent fuel blends?? This season diffrent times i get the same thing, hunting or surging idle, but my afrs vary from say 11.7 to 12.8, depending on where i got fuel, i only use 2 places, and only notice this problem from my local small town station, what do you think??

While fuels could certainly change due to specific gravity a slight bit. We shouldn't see one sled at 11.8 and the next one at 13.8.

The sled I fired up today is also running Torco race fuel as he's a lake racer.

I have to wonder what a slight change to the TPS would do. I don't think idling at high 13's is an issue at all, but the surging idle is kinda weird and would lead one to think idle air control valve issues.

I'd like to see max get his stumble resolved, but I really believe a 4 pound increase in fuel pressure may do it for him.

 

[Fords4life]

While fuels could certainly change due to specific gravity a slight bit. We shouldn't see one sled at 11.8 and the next one at 13.8.

The sled I fired up today is also running Torco race fuel as he's a lake racer.

I have to wonder what a slight change to the TPS would do. I don't think idling at high 13's is an issue at all, but the surging idle is kinda weird and would lead one to think idle air control valve issues.

I'd like to see max get his stumble resolved, but I really believe a 4 pound increase in fuel pressure may do it for him.

Would be nice to know what the ohm specs are for setting tps, good luck with this, i know you will keep us posted.

 

[0degC]

The closed loop does nothing and is inactive below 5000 rpm on TD tunes is what I was told. Viewing my logs this information seems accurate. I know if I partially plug my exhaust at idle it gets pig rich and doesnt change so the closed loop isnt doing anything to correct idle. Try simply bumping up your fuel pressure some more, this will richen the idle and low speed and once closed loop is active it will take care of keeping you at target afr. If this works and takes care of your problem you can talk to Ben and see if he will give you a revised tune or advise you to just keep running with increased fuel pressure.

The closed loop is speed activated.

 

[max rolph]

in my case im really not getting and idle surge as much as a stumble when quickly applying throttle... but only when at operating temps where my idle afr is 13.8-14.0, when its only warming up and is around 100 deg the AFR is low 12's and the throttle is crisp and no stumble, no where else is there a stumble in the whole TPS movement,,,, and because it doesnt stumbel when in low 12's leads me to conclude it needs more fuel while idleing and since soo many members here say theres is at 11.8-12.1 ish basically answers our question.... now we just have to find solution. Im hoping there is a way to increase fuel pulse at idle, The flasher only allows low speed cruise, medium cruise and WOT, mine is set at 13.7 low, 13.5 med and 11.9 wot. there is no setting for idle and apparently its stated that the flasher for auto tune is only after 5000 rpm or a certain MPH. Mine is a 2020 thundercat and im wondering if when the Cams were put in that it changes the idle parameters and does Ben or Dave change factory idle settings. if it is TPS as Knapp suggests, is there a way/reading what they do at factory when locked in place.???

 

[max rolph]

Soo Knapp, i upped my fuel pressure to 52lbs and richened up my low cruise on flasher from 13.7 to 13.5, ( dont know what rpm thats for) went and tested, my idle is at 13.7 and with full tank of 100 octane and ran some high speed summer road runs,,, seemed way better on the lower end on off throttle now hitting 9100 on short pulls in -20'c did not get low enough in tank tpo see if sudden stops or abrupt cornering will effect it or not..... will prob have to wait till weekend to test in northern quebec.

PS. on anaother note.... i just changed my centre shock from that factory chinese look alike to the 24 clicker FOX shock from a 2016 zr6000 XC, and added the HyGEAR TWISTED dual springs to it and also to the front iQS shocks, originally the factory had 3" sag on front from factory and on high speed trails with big whoops would bottom easy even setting shocks on firm, it would be to stiff and jarring, i just installed the HYGEAR twisted set and set to 2" sagg and the middle shock at .250" pre load afer install. OMG what a diff, yes the sled sits a little higher in front but now i have all on soft setting and sled just soaks up the studders and whoops. i just gave HYGEAR my 220LB weight and the sled and they sent a matched set up.... so far soo good

 

[KnappAttack]

Soo Knapp, i upped my fuel pressure to 52lbs and richened up my low cruise on flasher from 13.7 to 13.5, ( dont know what rpm thats for) went and tested, my idle is at 13.7 and with full tank of 100 octane and ran some high speed summer road runs,,, seemed way better on the lower end on off throttle now hitting 9100 on short pulls in -20'c did not get low enough in tank tpo see if sudden stops or abrupt cornering will effect it or not..... will prob have to wait till weekend to test in northern quebec.

PS. on anaother note.... i just changed my centre shock from that factory chinese look alike to the 24 clicker FOX shock from a 2016 zr6000 XC, and added the HyGEAR TWISTED dual springs to it and also to the front iQS shocks, originally the factory had 3" sag on front from factory and on high speed trails with big whoops would bottom easy even setting shocks on firm, it would be to stiff and jarring, i just installed the HYGEAR twisted set and set to 2" sagg and the middle shock at .250" pre load afer install. OMG what a diff, yes the sled sits a little higher in front but now i have all on soft setting and sled just soaks up the studders and whoops. i just gave HYGEAR my 220LB weight and the sled and they sent a matched set up.... so far soo good

That is good to hear. I know upping the pressure helped mine the same way, I did not however richen the low speed cruise.