So this is just a thought, but this winter I replaced my original throttle body gasket on my 1999 ST. After 16 years the thing literally crumbled to dust in some spots. Some parts just get past their "expiration date" like this and rubber bits exposed to gasoline, I suppose. It was a fairly easy job once the tank was off. I haven't gotten the bike back out yet post gasket replacement, but it seems to be a good bet that there could have been air leaks there previously.

I figure a sufficiently bad air leak on one cylinder could make the bike pretty jumpy at low throttle (like mine was). You can test this by spray starter fluid at the gasket while the bike is running.

Also, you would be surprised how much he correct chain tension can tone down jumpiness. I noticed a richer map helped mine, as well. It's really nothing to be nervous about.

 

I would say the TPS may be shot. The starting point of the potentiometer race may be worn out.

You may rotate the TPS (two screws) in such a way this part of the race is no more used and then reset again the throttle body.

You may see the problem w/ tuneECU looking at the throttle indication (engine off) while rotating the throttle very slowly.

Fred

 

Thanks for your reply, I tried adjusting the TPS, but when the two torx screws were loosened I had very little adjustment, and couldn't get the reading less than 0.67 on Tuneecu

 

Just curious what constitutes light throttle. On my 99, the sweet spot is almost right at 3k RPMs, anything over and it pulls like a race horse, below that, more like a mule.

 

Yeah, about the same, I've had 3 Triumphs previously, a 750 trident, 900 Tiger & 1200 Daytona, sone none with the fuel injection 955 engine, is this just how they are?
I fitted a smaller front sprocket (17 teeth) yesterday which has helped quite a lot, as it's has increased the revs for any given speed.
I can certainly live with it as it is, but I was just curious as to whether a map upgrade would help.

 

I put a smaller (17 teeth) front sprocket on yesterday which has helped quite a lot. However the rear concentric hub had seized in the swing arm & the whole thing needed stripping down.
It transpired it was the caliper carrier that was seized to the hub, preventing it from turning, anyway, it helped me notice a number of chipped teeth on the rear sprocket, so that was replaced too , luckily the chain was good.
As I mentioned above, the judder is not horrendous, just a niggle really, & if it's just a characteristic of the bike I can stop looking to put it right.

 

My Gen 2 (w/18T front) will pull from a little under 2k, maybe 1700-1800. My Gen 1 wants 3k or more. I think this is a problem that needs fixing on my Gen 1 and not a characteristic of the model, but I could be wrong. I haven't done anything with the TPS yet, but I did replace all the IACV hoses.

Cheers,
-Kit

 

Cheers mate, that's what I'm thinking, but I don't know if the 10003 map on my bike is out of date or not?
I'm considering taking it to the local dealer, but if I'm going to be forking out cash & not gaining anything????

 

Looking at the TuneECU map list, I suspect that that map is well out of date if you have an MC1000 ECU. My 2000 has an MC1000, but earlier ones had the MC2000 ECU. VIN 089737 and all subsequent 955s got the MC1000. Here are the maps listed on TuneECU's site:

Sprint ST/RS (up to VIN 089736) / Sagem ECU MC2000
9888 OEM Sprint ST/RS (up to 2000 model year) with standard exhaust (no catalyst)
9889 OEM Sprint ST/RS (up to 2000 model year) with standard exhaust (with catalyst)
9890 OEM Sprint ST/RS (up to 2000 model year) with standard exhaust and with aftermarket exhaust (TORS)

Sprint ST/RS From VIN 089737 to 139276 / Sagem ECU MC1000
10077 OEM Sprint ST/RS standard exhaust (with closed loop catalyst)
10078 OEM Sprint ST/RS aftermarket exhaust (TORS)
10150 OEM Sprint ST/RS standard exhaust

Cheers,
-Kit

 

Thanks for that Kit, looks like mine is well out of date, I might have to take it to the dealers for an upgrade, I don't trust myself to do it with Tuneecu, the dealers will charge me appros £65, so it's worth it if it makes the bike run better, & now I know it has an out of date map.....

 

Wow. Our dealers here will do it for half that and I would still feel like I was being robbed.

Cheers,
-Kit

 

It's lean - that model series all are - that is exactly why it is juddering.
Your best bet honestly is to load one of the custom tunes from the TuneECU library
A new OEM map will likely make no difference

I've plugged her into Tuneecu & tried re-setting the TPS, the voltage shows 0.67 at tick over, both before & after the reset.

I'm not sure if you already realize this, but zeroing the TPS will not create any change to the actual voltage - only aligns it within the map.

One more thing you can do is to try raising the CO (idle Fuel Trim) which will make it richer at idle and a bit off-idle. That should really be adjusted while connected to a CO instrument but you can try 'feel' and just increase it a bit.

 

It's lean - that model series all are - that is exactly why it is juddering.
Your best bet honestly is to load one of the custom tunes from the TuneECU library
A new OEM map will likely make no difference


I'm not sure if you already realize this, but zeroing the TPS will not create any change to the actual voltage - only aligns it within the map.

One more thing you can do is to try raising the CO (idle Fuel Trim) which will make it richer at idle and a bit off-idle. That should really be adjusted while connected to a CO instrument but you can try 'feel' and just increase it a bit.

You were right again DEcosse, the updated map 10150 made the judder even worse. I tried a modified map designed to be used with an after market exhaust (mines standard), & it improved the judder significantly. Only downside is that it seems to bog down a bit when you wack the throttle open from about 4k revs, it's like a bit of a flat spot, but not worth bothering about.
Now I know what I'm doing with the Tuneecu, I will keep trying different maps until I find the best one for my bike.

 

Is there anyone near Otley, North/West Yorkshire boarder who could help me with Tunneecu?

 

According to AA route maps I'm 83 miles away from you, in Cumbria if that's any good (it is MC1000 ECU, is it?). My 2001 RS is just the same despite replacing throttle body gasket, balancing TBs, setting CO (correct setting makes it worse), new fuel and air filters, downloading custom map, etc, etc.

 

Thanks for that Howard, but I've taken the plunge & just uploaded the 10150 map that Kit mentioned. It's just going through the 12 minute reset & then it's out for a test. I'll let you know how it goes, but I appreciate your kind offer.

 

Oh, yes I've replaced the iacv hoses as well!

 

So what do the number & colours mean on the maps, I assume the higher the number, the richer the mixture (more fuel)?

 

Use the stock map and add say 5% (for start) using the trim table (rather than changing directly in the primary F table) in the region where you are having problem (bottom left quadrant of the table i.e. low rpm, low throttle opening);
test run and see how it goes; amend accordingly to increase further as required.
You generally can't get into trouble adding fuel.
Note that you must make the changes, save it (ideally with new name), then download it to affect change.

 

Thanks again DEcosse, I'll try that later this week, back to work in the morning :brick

 

Is this a good place to mention the FPR Mod?

 

Yes, of course it is.........what is it :dunno

 

Having used the bike today for my commute, the judder/hesitation was massively improved when gently riding at 30-40 mph, I'm not sure if the bogging down I reported yesterday was a figment of my imagination, but I didnt notice it today.
I have had a little tinker with a couple of maps & saved them, I might try them when my rest days come around again, but if there is no noticeable improvement, I'm happy with the 10078 map I'm using at the moment.

 

I'm glad you asked that, as I've also been wondering if a TPS reset has to be done every time?
EDIT: comparing the 10078 and 10150 maps, I thought the 10078 map looked leaner in places (this confused me). But I was looking at the F map only, not taking into account the A/F ratio.

D'Ecosse gives a good explanation in this thread:
http://www.triumphrat.net/ecm-and-fi-tuning-help-tips-and-tricks/370793-tuneecu-af-tables.html

And many thanks to D'Ecosse for the info so far. I'm learning from this (and other) thread(s).

 

Have a look at this post also - explains the relationship between the F table value and the A/F value - and how it is possible to have a higher mass of fuel delivered with a lower 'F' cell value - http://www.triumphrat.net/ecm-and-f...elp-tips-and-tricks/539938-o2-sensors-wideband-and-narrow-band.html#post6028618

Don't get me started on how I feel about the FPR mod .......................
But justinm410 highlighted part of the problem (how calibrated is that hammer anyway?) - the other being that whatever you do affects the fuel delivery across the entire spectrum rather than selectively where it needs it. OK - I guess you did get me started!

 

There appears to be a bit of an issue regarding the FPR mod, so let's all just calm down, and pretend I never asked what it was....ok?

If I understand you correctly DEcosse, modifying the map isn't just a case of increasing or decresing the values at any given point, so I think I'll play it safe & just stick with the 10078 map I'm using now. The bike is running the best it has since I've had it, & I don't want to cause any damage to the motor.

 

You are correct, but that is why there is an injector flow setting. It will adjust the flow across the entire range. The bike will be unridable long before the point at which you'd be causing damage. I, personally, would encourage you to play with the injector flow setting. 5% or so adjustments at a time and record the results. It really does make huge improvements.

 

Fair point well made, I will have a fiddle with the settings, it appears the 10150 map is better at higher revs, whilst the 10078 is better at lower revs, so I can see a bit of a hybrid of the two coming along.

 

Because you only feel like you know where it is. There's no definitive way to say that it's lean at a particular cell or group of cells in the table without the shotgun method, just from riding it. Now if you had a flat spot right at 3k, for example, I completely agree. I figured we were talking about a generally over lean low end.

 

I figured we were talking about a generally over lean low end.

If so, why would you adjust injector flow settings that will have an effect across the entire rpm and tp range?

 

Because then your alternative would be shotgun adjusting the bottom, say, 1/3rd of cells in the map in a helter shelter manner. I feel like that will result in more undesirable areas of fueling than simply adding a bit more fuel to the top end as well as the bottom end. Especially for someone with no experience editing a map, I think this would be safer.

We're not talking shooting flames out of the pipe, here, just 5%.

 

Because then your alternative would be shotgun adjusting the bottom, say, 1/3rd of cells in the map in a helter shelter manner.

That is not exactly a good analogy since your method is the shotgun one, just blasting everything, as opposed to where it matters.

What is 'helter skelter' about targeting the specific area where the OP reported the issue?

 

For my '06 Sprint that global approach would have been a disaster. After fitting a TOR exhaust and loading the appropriate tune my Sprint gained an irritating flat spot around 3500 rpm and turned into a gas-guzzler. To see any improvement by a seat-of-the-pants method I would need to focus on specific areas, add or subtract fuel and see if the problems got better or worse.

I chose a far better method - expertise and a dyno. The dyno work on my Sprint added more fuel to the mid-range while some was taken out at the top end across various rpm and throttle settings. The result was only a modest gain in power, but the way it delivers is just so smooth and sweet. Worth every penny.

 

I'm going to add my two cents about your bike and tune. I just checked and I am running the same 10078 tune and mine fuels perfectly although I am likely further above sea level than you. Maybe there is something else going on if it still stumbles?

 

Found a shop nearby that will do an RPM to A/F graph on the dyno for $50. I'm going to do that. Way cheaper than a full tune and I can quit the guess work.

 

Found a shop nearby that will do an RPM to A/F graph on the dyno for $50. ....

Check what you're getting for $50
Note that you will need a graph for each throttle increment.
What you are probably getting for $50 will only be a full-throttle pull.

 

So, I've loaded a map onto the bike that I've modified from the original 10150 to run richer at lower revs & smaller throttle openings, & the bike is the best it's ever been. She no longer judders on a very light throttle at 30-40 mph, doesn't sound as agricultural below 3000rpm, and pulls like a train through the gears.
I'm pretty sure it's as good as I'm going to get it, & I'm delighted with the results.
Thanks to everyone on here for your help, especially DEcosse, I owe you several cold ones when you visit Yorkshire.:notworthy:notworthy