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TPS Fault on Stelvio NTX (2012)

AlanNZ

AlanNZ

Cruisin' Guzzisti
GT Contributor
Joined
Sep 20, 2013
Messages
227
Location
Auckland
Do TPS go bad? My Stelvio has developed a ramdon, intermittent hesitation at mid-range which is not repeatable i.e. at certain revs. This disappears if I tweak the throttle (change throttle position up or down). The bike does not miss - so does not feel like an ignition problem. I have reset the TPS recently. The only work I have done recently is replacing the exhaust Y joint seals (I have re-torqued the header and exhaust clamps 2-3 times). I soaked the oxygen sensors in petrol overnight to clean them (2 stroke petrol as it turned out). Could this be related? No fault codes have shown up. I haven't replaced the fuel filter in the while - and thought it could be a fuel problem; however, if I acceleate hard when the fault occurs, the bike acceleates well - which would indicate that it is not a fuel blockage.
I found a thread on TPS replacement - however this did not state why it was being replaced.
Any suggestions gratefully received,
Regards
Alan NZ
 
The correct way to clean the lambda sensors is with a torch. The small ones you can pick up at a hardware store is sufficient. The oil from the 2 stroke fuel may have harmed the sensors. Yes a TPS can go bad. It is just a variable resistor.
 
john zibell said:
The correct way to clean the lambda sensors is with a torch. The small ones you can pick up at a hardware store is sufficient. The oil from the 2 stroke fuel may have harmed the sensors. Yes a TPS can go bad. It is just a variable resistor.
Click to expand...
Thanks John. I will pull the lambda sensors out and clean with heat. Would damaged lambda senor(s) cause the throttle hesitation I described?
Regards
Alan NZ
 
Last edited:
V700Steve said:
Sounds like a flaky sensor. You should be able to see it if you put a meter on it. Small graduations will jump all over.
Click to expand...
Thanks Steve. The diagnostic tool I used showed a smooth TPS graph through the throttle range. I could not see any jumps/dips in the curve. However, the fault is ramdom (not consistenty repeatable) so may not show problems when the bike is cold in the workshop.
Alan NZ
 
AlanNZ said:
Thanks Steve. The diagnostic tool I used showed a smooth TPS graph through the throttle range. I could not see any jumps/dips in the curve. However, the fault is random (not consistently repeatable) so may not show problems when the bike is cold in the workshop.
Alan NZ
Click to expand...
Since it is a variable resistor, it may not show any issues until it warms up.
 
Individual descriptions of the problem being experienced can differ from person to person, so this is another possibility.

If the ignition wires are original and if they were ever pulled up during removal, instead of lifted frim the lower access hole, you could have a fine crack in the wire and intermittently the spark can ground to the cylinder. This missfire/ hesitation occurs very randomly as you describe.
 
scottmastrocinque said:
Individual descriptions of the problem being experienced can differ from person to person, so this is another possibility.

If the ignition wires are original and if they were ever pulled up during removal, instead of lifted frim the lower access hole, you could have a fine crack in the wire and intermittently the spark can ground to the cylinder. This missfire/ hesitation occurs very randomly as you describe.
Click to expand...
Thanks Scott. I was aware of the plug cap issues and replaced these with the NGK caps early on. I also put cable ties around the cap body, with a vertical tail, so I was pulling on the cap when removing (as well as levering from the access hole). The hesitation does not appear to be a misfire - hence my TPS suspician. As you will know, the throttle on the Stelvio is quite sensitive. When this issue occurs, it's like the throttle is in a flat spot and I need to twist the throttle a reasonable amount before the engine responds.
Alan NZ
 
Understandable.

My Stelvio in stock configuration did the same thing. I utilized GTM’s fueling solution to fix that forever.

I can highly recommend GTM’s full fueling setup with the Power Commander and Autotune 300 for flawless fuel control. I’ve had it 10 years now and it has been phenomenal on my 2012 Stelvio NTX.
 
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Had one with worn out shaft bushing on the TB on the TPS side would cause all sorts of little stumbles and hiccups.
 
gringo said:
Had one with worn out shaft bushing on the TB on the TPS side would cause all sorts of little stumbles and hiccups.
Click to expand...
This is surfacing more and more, and they are NLA as new and big $ if so. Real bummer. I’m a lucky one with my personal bike, but I’ve had numerous ones in my shop and one currently (and several who doubted my diagnosis and contacted others here to question me on it, implying I didn’t know what I was talking about).
 
GTM® said:
…but I’ve had numerous ones in my shop and one currently (and several who doubted my diagnosis and contacted others here to question me on it, implying I didn’t know what I was talking about).
Click to expand...

😤 😩 😖

God can I relate…

“Help me. Help me. Please…Help me. Oh, I don’t believe it is that.”

🙄 😵‍💫 🤯

Bye Bye Felicia!
 
Worn shafts on fuel injected BMWs occurs also. However, on those we can put bushings into the throttle bodies to take care of the wear. Haven't tried that on a Guzzi TB yet. The factory angle set may make it more difficult.
 
AlanNZ said:
Do TPS go bad? My Stelvio has developed a ramdon, intermittent hesitation at mid-range which is not repeatable i.e. at certain revs. This disappears if I tweak the throttle (change throttle position up or down). The bike does not miss - so does not feel like an ignition problem. I have reset the TPS recently. The only work I have done recently is replacing the exhaust Y joint seals (I have re-torqued the header and exhaust clamps 2-3 times). I soaked the oxygen sensors in petrol overnight to clean them (2 stroke petrol as it turned out). Could this be related? No fault codes have shown up. I haven't replaced the fuel filter in the while - and thought it could be a fuel problem; however, if I acceleate hard when the fault occurs, the bike acceleates well - which would indicate that it is not a fuel blockage.
I found a thread on TPS replacement - however this did not state why it was being replaced.
Any suggestions gratefully received,
Regards
Alan NZ
Click to expand...
A development: After convincing myself the problem is a TPS issues, because I thought the bike was not missing, I have just found two new stored codes on the Stelvio. P0136 Lambda sensor (right): invalid signal; and P0351 Coil left: to low. The coil fault would suggest I am getting a miss (is that correct?).
I have reset the faults and will take the bike for another ride to see if they reappear.
If they do, what's my next move?
Any suggestions greatfully received.
Regards
Alan NZ
 
I offered you the very well known wire shorting issue and you promptly shot me down.

The problem is thoroughly documented in the forums.

SEARCH is your best friend now Alan.
 
scottmastrocinque said:
I offered you the very well known wire shorting issue and you promptly shot me down.

The problem is thoroughly documented in the forums.

SEARCH is your best friend now Alan.
Click to expand...
Ha ha - so you did Scott - and I made the fatal mistake of eliminating that issue because I did the spark plug cap change when Stelvio was relatively new. Back to basics. One quesiton - will a bad coil and bad HT lead throw up the same fault code?
Regards
Alan NZ
 
It is a very real possibility. Yes.

As I tried to tell you before, this issue I was describing, has nothing to do with the cap itself but rather very fine cracks in the wire sheath material. 50,000 volts seeks the path of least resistance.

It becomes very pronounced when wet.

I have seen and replied to dozens of high tension wires randomly grounding out on the cylinder head.

I have never myself, nor read about or seen somebody replace a coil on a Stelvio NTX ever.

Good luck.
 
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