Primary TPS Adjustment Voltage Values

[tdragger]

The bike has been running somewhat funky here lately and I had a brief "high idle" issue last weekend.

Thinking that the primary TPS may be failing, I hooked up TuneECU and performed the "Adjust ISCV" function on the Testing page.

When the function starts, the first thing it asks you to do is set the TPS to read 0.60 volts. Mine was sitting on 0.62 so I made the adjustment back to 0.60.

The next step after some whizzing and clicking, the test asks to adjust the TPS to 0.72 volts. Mine was reading 0.77 which is too far out of range.

My question is, if I make the second adjustment back to 0.72, isn't that going to throw the first setting (0.60) out of adjustment?

Or is making the adjustments setting the range and that the computer will make the appropriate adjustments to make the range 0.60 to 0.72?

 

[DEcosse]

No, the two are not interactive
The first sets the closed position and the second by how much it opens.

Neither adjustment was really necessary in your case
Spec for TPS 'zero is 0.6 +/- 0.02 i.e. 0.58 to 0.62
Spec for opening is closed position voltage + 0.12 (+/-0.05)
i.e. starting voltage + 0.07 to 0.17
0.77 is 0.6-0 + 0.17 so is within spec also.
Yes, on the 'edge' but I personally would not mess with that.

I used to interview young graduates for engineering positions in my company
My favourite 'trick' question was "would you consider yourself to be a perfectionist?"
Of course almost universally (eager to impress) they would profess that they were!
My next question was "Do you know what a specification is?"
For most the penny dropped - no negative points for those recognizing at that stage, only for those who continued in their insistence.
I actually had one senior engineer who insisted on dialing things in to the nth degree for absolute 'precision' - I had to remind him that every minute he spent screwing with something that was already in spec on that multi-million dollar piece of equipment was costing the customer a lot of money in lost production time.

Of course its not parallel with personal stuff, where your time & desire for perfection is of your choice - but the point is specifications are there for an acceptable limit of operation, even right at the very extreme of them!
At the end of the day, if you have an unlimited budget of time & money, you can strive for perfection (and there's nothing wrong with that!) - but being anywhere within the limits of specification is perfectly acceptable.

In this actual case how critical do they have to be?
The 'closed' position is set electronically anyway so having it 'perfect' is moot - i.e. the ECU recognizes the 'offset' and applies it to the measured voltage.
For the +0.12 (+/- 0.05) that is just setting the 'fast idle position - that has a pretty huge range (relatively) already anyway and is not of real significance to running condition

p.s. Idle speed is a function of how much air it gets - not fuel.
So most likely cause of high idle is too much air - a leak.

 

[Mark Dunn]

Hi tdragger,

Did you follow the instructions in the manual and move the stepper motor's actuating arm back to provide a gap between itself and the little roller cam on which it bears? If not, the bike will likely run but it won't feel right because there will now be an offset voltage added. DAMHIK.

Regards,
Mark Dunn

 

[tdragger]

I appreciate the replies.

About a month ago I adjusted the speedo correction factor and reloaded the tune. (full process was download the tune, adjust the value, and upload back to the bike)

Ever since this it seems that the bike is idling on 2 cylinders and will occasionally die when rolling up to a stop.

The "high idle" issue that I referred to is the classic throttle stick when the TPS is going bad. I was cruising at about 50 mph and rolled the throttle off but the revs stayed at about 2200. Classic TPS symptom and I know it well as I'm on my 3rd TPS already. Maybe at 72k miles I should go ahead and replace it anyway.

I did notice a few nights ago that I must have inadvertently turned the O2 sensor back on last month. I disabled it and reloaded the tune but it doesn't seem to have made a difference. The bike has been running great this year (for a few years in fact) so a bit perplexed at what may be the problem.

Going to ride it down to Maggie Valley this weekend and maybe one of the folks attending will be able to guide me in the right direction.

 

[warp9.9]

I appreciate the replies.

About a month ago I adjusted the speedo correction factor and reloaded the tune. (full process was download the tune, adjust the value, and upload back to the bike)

Ever since this it seems that the bike is idling on 2 cylinders and will occasionally die when rolling up to a stop.

The "high idle" issue that I referred to is the classic throttle stick when the TPS is going bad. I was cruising at about 50 mph and rolled the throttle off but the revs stayed at about 2200. Classic TPS symptom and I know it well as I'm on my 3rd TPS already. Maybe at 72k miles I should go ahead and replace it anyway.

I did notice a few nights ago that I must have inadvertently turned the O2 sensor back on last month. I disabled it and reloaded the tune but it doesn't seem to have made a difference. The bike has been running great this year (for a few years in fact) so a bit perplexed at what may be the problem.

Going to ride it down to Maggie Valley this weekend and maybe one of the folks attending will be able to guide me in the right direction.

I will be there and might be able to assist you. Plus I know there will be others with valuable knowledge that will help.

 

[DEcosse]

... The "high idle" issue that I referred to is the classic throttle stick when the TPS is going bad. I was cruising at about 50 mph and rolled the throttle off but the revs stayed at about 2200. Classic TPS symptom and I know it well as I'm on my 3rd TPS already....

Do you mean that the throttles stick open because the TPS is not physically allowing it to close?
An erroneous TPS reading by itself (i.e. throttle actually closed but reporting a higher voltage) would not cause it to rev high - that can only add gas; it needs air to actually increase the speed.
I guess I'm surprised that the TPS could 'stick' with enough force to physically overcome that of the throttle return springs.
But I surely would not argue against it!

 

[tdragger]

The early model TPS would develop a flat spot on the rheostat (for lack of a better term) inside the head of the unit, particularly around the setting for cruising speed. You close the throttle on an off ramp and the bike would keep on going. Literally you had to hit the kill switch before it would let go. Upon restart it would be fine until it "stuck" again.

Very common issue with early model Rockets. Lots of info on this board about it.

The newer model TPS has a blue rheostat inside the head (old was black) and it supposed to resolve the issue. It doesn't totally resolve it but the TPS seems to last longer.

 

[warp9.9]

Also for those who have a Professional Triumph Technician install a new style TPS it still can fail to operated correctly.
Below is a shot of the one they did on Big Al's bike.

Obviously they were worried about it vibrating off so the used a little more torque then needed (look at the screw head)
Go Triumph but learn to work on it yourself

 

[Mark Dunn]

Do you mean that the throttles stick open because the TPS is not physically allowing it to close?
An erroneous TPS reading by itself (i.e. throttle actually closed but reporting a higher voltage) would not cause it to rev high - that can only add gas; it needs air to actually increase the speed.
I guess I'm surprised that the TPS could 'stick' with enough force to physically overcome that of the throttle return springs.
But I surely would not argue against it!

Hi DEcosse,

My 09 standard (which apparently should have had the newer TPS) had the old one with black innards and suffered the high idle problem. When I took it off to see if anything obvious was wrong I found that it was 'lubricated' by what I can only describe as semi-trailer axle grease. The grease had hardened and was sometimes preventing the rheostat from returning to the home position. I cleaned it out with alcohol and relubed with Mobil synthetic grease. That fixed it for quite some time until I presume it developed a flat spot. Then problem returned and I replaced it with the new type. No problems since (touch wood).

Regards,
Mark Dunn

 

[DEcosse]

Thanks for detailed explanation
When I say I'm shocked I don't mean in a way to cast any doubt, just that it's quite amazing when you consider whatever force is being applied at such a small radius can be greater than the springs! But clearly 'stuck' is not really quantifiable - it's absolute!
Actually when I cast mind back to the very first generation Triumph EFI systems - the 97 Speed Triple & Daytona T595 - those had a sticking issue too, with a shaft o-ring at the TPS that would swell and 'clamp' it. But it didn't even need the seal so the simple fix was just to remove it!