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2003 Triumph Sprint RS 955i
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Discussion Starter · #1 ·
I’m new to motorcycles and have just purchased a 2003 Sprint RS 955i. Still working on my tests. The previous owner told me that the bike had an issue with low tick over and that he fitted a diode between the ECU. But now the engine management light stays on all of the time. Does anybody have any ideas what the original problem would have been and how to fix it?
 

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2000 Triumph Tiger 885i 2000 Triumph Sprint ST 955i
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Do you have an Android device? Are you at all mechanically or electronically adept? If the answer to both questions is 'yes', then go to the Google Play store and download and install "TuneECU" and buy yourself a Lonelec USB cable and an OBD2 adapter that is on the approved by TuneECU list, to connect to that Sprint of yours.

First step once you've done the above, is to find out what code(s) are stored. I'd be willing to wager it's a TPS out of range problem. A diode is a 'one way' electrical valve, I'd suspect what was actually fitted was a resistor to increase the apparent resistance reading of the TPS to lower the idle close to stock.

Don't be surprised if there are several codes stored. The trick is to clear ALL of the codes, and then go for a test-ride to see which ones come back. Those are the real codes and should each be addressed in order. Fix a fault, clear all, ride, fix a fault, ride, repeat.

So, do us all a big favor and be sure to update this post with whatever you did to resolve the problem. If you try something and it didn't work - post that here too.

Good luck!
 

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And when you have done that

Check plugs and HT leads

Check air filter is clean and sitting in its box ok, and gasket is ok

Check throttle body intake manifold gasket

Check fuel tank hoses, especially the breather pipe

The original problem could have been any of the above. It depends how well the previous owner looked after the bike.:unsure:
 

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he fitted a diode between the ECU.
A diode?! Between the ECU and what? That's weird. Can you ask more to the previous owner?

As other said you ought to read the fault code by any mean, the more obvious being TuneECU.

Either the windows version (not maintained any more but still work perfectly for your bike year) which requires a cable or the android version that requires a bluetooth adapter (simplest solution) or a cable adapter (require an OTG compatible android device).
 

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First step once you've done the above, is to find out what code(s) are stored. I'd be willing to wager it's a TPS out of range problem. A diode is a 'one way' electrical valve, I'd suspect what was actually fitted was a resistor to increase the apparent resistance reading of the TPS to lower the idle close to stock.
Are you referring to P0123? The cause can only be the TPS ground disconnected to me.

I can't see any reason to fit a diode on the TPS other than not knowing about TPS reset (using TuneECU). Resetting the TPS (while throttle released) aims at getting the relative throttle position to 0 (as you probably know already). BTW we don't know yet where is this diode fitted.

Another reason might be that bypass throttle balancing screws are to mush screwed in then letting too few air going in at idle, rendering the ECU unable to restore the correct idle rpm (1200) using the IACV. A malfunctioning IACV could be the cause as well.

So first thing first: Diag w/ TuneECU.
 

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Aaand - while you have the tank off, check the three IACV vinyl hoses. The rubber ends on them tends to dry rot and crack or even shatter.

You can either spend stupid money on OEM replacements, or buy some 1/4" (6 or 7MM) vacuum hose and replace them.

Check the 'signal' hose to the ECM as well - it's the same type hose.

Oh, and be very careful what you set the tank on when it's off the bike - it is easy to damage the fuel level sender wires.
 

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2003 Triumph Sprint RS 955i
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Discussion Starter · #7 ·
Do you have an Android device? Are you at all mechanically or electronically adept? If the answer to both questions is 'yes', then go to the Google Play store and download and install "TuneECU" and buy yourself a Lonelec USB cable and an OBD2 adapter that is on the approved by TuneECU list, to connect to that Sprint of yours.

First step once you've done the above, is to find out what code(s) are stored. I'd be willing to wager it's a TPS out of range problem. A diode is a 'one way' electrical valve, I'd suspect what was actually fitted was a resistor to increase the apparent resistance reading of the TPS to lower the idle close to stock.

Don't be surprised if there are several codes stored. The trick is to clear ALL of the codes, and then go for a test-ride to see which ones come back. Those are the real codes and should each be addressed in order. Fix a fault, clear all, ride, fix a fault, ride, repeat.

So, do us all a big favor and be sure to update this post with whatever you did to resolve the problem. If you try something and it didn't work - post that here too.

Good luck!
Thanks, you have given me plenary of things to look at. I will let you know the outcome.
 

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2003 Triumph Sprint RS 955i
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Discussion Starter · #8 ·
Are you referring to P0123? The cause can only be the TPS ground disconnected to me.

I can't see any reason to fit a diode on the TPS other than not knowing about TPS reset (using TuneECU). Resetting the TPS (while throttle released) aims at getting the relative throttle position to 0 (as you probably know already). BTW we don't know yet where is this diode fitted.

Another reason might be that bypass throttle balancing screws are to mush screwed in then letting too few air going in at idle, rendering the ECU unable to restore the correct idle rpm (1200) using the IACV. A malfunctioning IACV could be the cause as well.

So first thing first: Diag w/ TuneECU.
Something else to check, thank you.
 

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Something else to check, thank you.
No, I would:
1-ask the po where the diode is fitted and why,
2-get TuneECU and get it to connect to the bike,
3-chech the TPS relative and absolute values. Check especially that the relative TPS is at 0 when the throttle fully released. Please not that the relative TPS value can't be negative.
4-do a throttle body synch if possible (vacuum gauge needed for you model), starting w/ a base setting of 1 1/2 turn from fully screwed in for the 3 TPS bypass sceews, and from that point adjusting only cyl 2 and 3. If you still get a low idle, then try 1 3/4 turn on all 3 cyl and then adjust 2 and 3. Cyl 1 is the lft most while sitting on the bike.
 

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Discussion Starter · #10 ·
Something else to check, thank you.
So, I found the diode. The lamba sensor had been disconnected and a diode fitted (lamba sensor elimination kit) to the ECU side of it leaving the lamba sensor cable floating around.
I connected the lamba sensor back together and did started the engine AND LEFT ON TICK OVER ONLY, I did this 3 times, and Hey Presto the light is out.
I don't have my license as yet so unable to take it for a test ride.
 

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OK great. Go figure why the guy did that.
As a last work you may want to double check whether the O2 sensor voltage is swinging between 0 and 0.9V.
To achieve that you have to get TuneECU installed either on a PC a an android device and get an adapter.

Anyway sooner or later you'll have to get TuneECU. So rather don't wait for real trouble.
 

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Discussion Starter · #12 ·
OK great. Go figure why the guy did that.
As a last work you may want to double check whether the O2 sensor voltage is swinging between 0 and 0.9V.
To achieve that you have to get TuneECU installed either on a PC a an android device and get an adapter.

Anyway sooner or later you'll have to get TuneECU. So rather don't wait for real trouble.

Thanks, I have the Lonelec and TuneECU and plan to test it later today. I tried it with a phone yesterday but it didn’t show the power on light and wouldn’t work. I will test it with a laptop later.
Thanks for your help and advice.
 

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I always used the windows version.

However I use a bluetooth adapter w/ torque lite on my android phone for basic stuff on cars and bike.

Showing the O2 voltage is a basic stuff BTW. Torque lite will show a graphical view which is more convenient for the O2 sensor voltage. Very easy to use.
 

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You look a bit young to have such a great bike straight after your test. And you seem to have got a parking ticket on your own driveway. What's the world coming to?
 

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Now that you mention it Sam says he doesn't have his license yet.
The history of this forum shows that owning a sprint as a first bike tells the bike won't last long. I'd put a big shim on the throttle blocking it for more than half the full open T.

Down here on the other side of the channel young drivers aren't authorized to start w/ a more than 54HP bike. Seems wise to me.
 

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I think it's 47bhp here, or a restricted bike that had no more than double that originally. That applies if you take your test under the age of 24 as far as I know. There should be similar for cars.
 

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I was joking based on Sam's profile picture obviously (I hope) - but a genuine thought about the wisdom of having an RS as a first bike did go through my mind too!
 
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