that old surging problem

[NZDeano]

Hey, I know this is old stuff for most but please bear with me. After having a stock Triumph Race Can and it's appropriate tune installed by a Triumph dealer last riding season at 10,000km service my surging problem all but dissapeared.
Just been on first good ride of this season, but when ever going through a town (50km an hr) it was so hard to hold steady rev's. Didn't matter what gear or rev's it was doing. Weather was hot, fan coming on at lights etc. Bike is 03 with only 16,000km on it. Intending to put plenty more on it this year but not a happy camper about surging!
1. Why doe's this model do this so badly? Is it because of poorly designed mapping and early injection system?
2. What could have changed between May (bike parked up) and now?
3. What's the fix?

[iansoady]

You will get several (conflicting) answers but mine follow:

1. Why doe's this model do this so badly? Is it because of poorly designed mapping and early injection system?

I believe it's because the map tries to achieve a stoichometric mixture at certain points - effectively when the A/F target is 14.5. It does this by monitoring the O2 sensor.

It therefore hunts up & down, overshooting each time hence the effect of surging (like opening & closing the throttle).

2. What could have changed between May (bike parked up) and now?

O2 sensor gone bad?

3. What's the fix?

Remapping so that the A/F is never at 14.5. At least that's what fixed mine. You're welcome to a copy of my map (Tuneboy format) if you want it.

[Bixxer Bob]

Just one additional point, after changing any 14.5 values to less than 14.5 (13.5 will do nicely) do a 12 minute tune to reset the trims or else you won't feel any immediate effect.

If you fancy doing a bit of development for the benefit of all on here though, before you do any of that (I assume you are running a standard off road tune) do you have the kit needed to balance your throttle bodies?  I've never had the chance up till now to see how much balancing the TBs without doing anything else affects surging.  It would be interesting to find out.  I'm not saying that's what it is but TBs can go out of sync very quickly and it would be nice to eliminate it.  Balancing the TBs accurately is the single most simple and effective job you can do for your Girly.

[Bixxer Bob]

. You're welcome to a copy of my map (Tuneboy format) if you want it.

Ian, I use Tuneboy too as you know, but if I'm passing out maps to TuneECU users, I use Tuneboy to upload the relevant map to my bike then useTuneECU to download it and then email it.

[NZDeano]

Hey Bixxer & Ian,
thankyou both for your replies. my sincere apology for late response - been away. Have just completed a decent ride and surging problem is still there although not getting any worse.
Bixxer - I am keen to try the throttle balancing to see if this makes any difference before trying other solutions.
Ian - I would be keen to try a re-map and appreciate the offer of a download from you.
I am going to PM you both to discuss further.
Cheers