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Offline bixxer bob

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TPS, TBs and, just to make it interesting, Air Pressure Sensor
« on: October 19, 2019, 11:04:39 PM »
I've been chasing problems on my Gen 1 2013 Tex for over a year now.  No dealer help because I've never had any fault codes to go on until recently.  An unrelated side issue was it running rich but I fixed that and wrote it up here:,18597.10.html

The problem started with it dropping the throttle.  I'd see an overtake opportunity, drop from 6th to 4th, open the throttle and go.  During the overtake I'd ease the throttle, pull the clutch slightly and hook 5th at which point it would drop to tickover.  Closing the throttle fully and opening it again would pick it back up, but it was a tense moment.  It started to do this fairly regularly and unpredictably.  Which wasn't helpful.  Despite checking several times there were no codes to go on.

The next development was erratic behaviour on cold start up.  Normally it would rev to around 2000rpm, sort itself out, then slowly decrease the revs as the temp rose.  Totally as expected iaw the mapping.  Then at a cold start it would rev to 2000, dropping to 1000, back to 2000, drop to 1500, drop to 1000 or variations on that pattern.  At about the same time it started to run erratically at low revs in traffic and was down on power, about 100bhp instead of 135.

I investigated everything I could think of but increasingly suspected the TPS, especially as I knew about the early ones failing, however, mine was out of warranty so I was in denial as it were.  Then things came to a head, sort of.  It failed to start and I had a code for the first time.  I can't remember the number but it was throttle motor stuck open.  I also noticed a buzzing noise that I'd heard before but had assumed to be the fuel pump.  On investigating, I found that, on a closed throttle, the butterflies were vibrating which immediately pointed to either the motor or the TPS.  I cleaned the TBs butterflies and pivots and the problem went away and it rode normally for about three weeks but then the rough running, throttle dropping and buzzing returned. 

At this point I was ready to change the TPS but at around 100 quid I still wasn't convinced and - if my old 955i was anything to go by - it would need setting up properly afterwards.  Then I found a complete TB assembly on Ebay complete with fuel rail, injectors and TPS. Best of all it had come off a known running bike and I could see from the photos all the yellow paint seals were intact.  100 quid lighter (as opposed to 1600 quid for just the TBs from Triumph) I was all set and did the swap.  The result was both good and bad.

The buzzing stopped - good news ! But a new fault developed.  On blipping the throttle while cold the revs would drop below tickover and recover to around 1200 rpm - the target figure, but as it warmed up properly blipping would cause it to drop to 500 rpm then stall. Bu***r.

I started checking everything over and found as I disconnected the pipe from the TBs to the air pressure sensor the revs increased slightly which I put down to air bleeding into the TBs but when I disconnected the loom from the air sensor, still with the pipe open, it ran normally.  I then checked : Air sensor disconnected, pipe disconnected - runs fine, cover end of pipe, revs drop, reconnect pipe, revs drop, disconnect pipe reconnect loom revs drop.   The only configuration where it would run normally was with both the pipe and the loom disconnected.  At this point I contacted the TB seller and bought am air pressure sensor off the same bike.  Ten quid as opposed to 80-odd. 

On fitting it, hurrah! Everything running normally.  I did the 12 minute tune then took it out for a test ride;  at first it wasn't quite it's old self, but by the time I'd put 50 miles on it, it had trimmed itself out and was back to normal. 

I'm hoping I haven't tempted fate by typing this up  but, fingers crossed, I seem to finally have my old bike back.

The TBs came of a 2014 bike and, interestingly, although the same to look at, the TPS has a different part number on it so I'm hoping it's the updated type.

I hope this is of some use to some other sufferer down the line  :002:

Next project is to research how the TBs work, what I need to test them and, hopefully, work out a fix because as these bikes get older, dealers lose interest and parts dry up it might be we'll need to know.



Online XCaTel

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Re: TPS, TBs and, just to make it interesting, Air Pressure Sensor
« Reply #1 on: October 20, 2019, 06:59:15 PM »
Great write up bixxer bob - someday somewhere that valuable info will save someone's bacon.  :047:

Offline pcarnut

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Re: TPS, TBs and, just to make it interesting, Air Pressure Sensor
« Reply #2 on: November 05, 2019, 03:51:07 PM »
Great info, and good job tracking things down, thanks for posting this!
2018 T12, 2014 TEx, 2011 1050

Offline Icy

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Re: TPS, TBs and, just to make it interesting, Air Pressure Sensor
« Reply #3 on: November 05, 2019, 04:09:42 PM »
 :460: I'm always amazed at you folks who know their engines and can maneuver in and out of this thing with this proficiency. Thank you for posting this here too  :821: :821: :821:
"It's easy to learn how to speak, it takes a lot more to learn how to actually say something." ~Icy

Offline NiK

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Re: TPS, TBs and, just to make it interesting, Air Pressure Sensor
« Reply #4 on: November 06, 2019, 11:03:22 AM »
Great report Bob!
I think your bet on the TPS part number is correct. My ex (early) '14 had it replaced and I seem to remember the dealer told me the number was indeed different. Never had any unexpected stalling ever since.
Anyway, good job mate!


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