115 replies to this topic

[Studley Ramrod]

Ok, I've got your email addy so I'll hide yours in yer post.

 

Manuals emailed.

[Oldgit59]

Ok, I've got your email addy so I'll hide yours in yer post.
 
Manuals emailed.

Thanks a lot, I received your email and the manuals. Great help, much appreciated. Happy new year.

[Studley Ramrod]

 Happy new year to you too.

[Northantstdm900rider]

Hi, 

 

Sorry to go back to the CO2 settings which has been very well covered on the site, but I thought I would let you know that after purchasing a 900 in October 23 with 13500 miles and living with the rubbish snatchy throttle, I finally got round to checking the bikes CO2 settings. Ive done the airbox mod, ie disconnecting the wire from the ecu and thought it was about time that the settings were checked. To my surprise C1 was on 28 and C2 was on 10. Ive reset them to C1 15 and C2 on 20 as a start and will check to see if the bike feels any better, when the rain stops! 

 

Im sure there must be many TDM owners who live with this issue, but my 2003 appears to be well out of spec and I believe checking the CO2 readings should be something all owners should check, just for piece of mind

[Nog]

Im sure there must be many TDM owners who live with this issue, but my 2003 appears to be well out of spec and I believe checking the CO2 readings should be something all owners should check, just for piece of mind

 

What do you mean "well out of spec" - these are set up at the factory, so I doubt they are out of spec at all as they are set for your specific engine.

 

If you read through the posts (it's a big one  ), around 2016 Fixitsan mentions that the CO (not CO2) levels are really just like the idle jets on a carbed bike, nothing more, as above around 3k rpm the CO values are ignored as the O2 sensor is used and then simply the ECUs fuel maps.

 

There's a lot of misunderstanding with these settings - the bike has no way of measuring the CO level, that's why it's a factory setup value (from my understanding). You will not cure the snatchy throttle with this as that on/off jerk is caused by the fuel injectors shutting off when the throttle is closed.  All FI engines do this, but some do it better than others, but being a fairly big twin, when the injectors kick back in on a little throttle you feel a jerk as the sudden torque kicks in.

 

The CO can certainly help with the low rpm range smoothness but I think a lot of people 'feel' something that's not there after playing with them.  Have a play and see what you think, but to really improve the bike it needs a reflash to turn off the injector shut off, or as I've found, something like a power commander or EJK box added.

[fixitsan]

Hi, 

 

Sorry to go back to the CO2 settings which has been very well covered on the site, but I thought I would let you know that after purchasing a 900 in October 23 with 13500 miles and living with the rubbish snatchy throttle, I finally got round to checking the bikes CO2 settings. Ive done the airbox mod, ie disconnecting the wire from the ecu and thought it was about time that the settings were checked. To my surprise C1 was on 28 and C2 was on 10. Ive reset them to C1 15 and C2 on 20 as a start and will check to see if the bike feels any better, when the rain stops! 

 

Im sure there must be many TDM owners who live with this issue, but my 2003 appears to be well out of spec and I believe checking the CO2 readings should be something all owners should check, just for piece of mind

 

 

As mentioned by Nog, the CO settings seem to only be idle jet equivalents, which are only relevant in low load and low speed situations.

There needs to be some correction allowance made for fuel injectors, because they all deliver slightly different volumes of fuel. This is a very common situation in cars, when you replace an injector they need to be 'programmed' with a number corresponding to a value written on the side of the new injector. This usually is a correction value corresponding to a flow rate for the injector, depending how far from the ideal flow rate it is, under test conditions

 

The ECU uses this value to open and close the injector for longer or shorter, depending on it's flow rate

 

In the airbox, underneath the air filter, there are two snorkels connecting from the airbox to the throttle bodies. These 2 snorkels have different lengths. In tuning, a longer snorkel gives more low torque, and a shorter snorkel gives less torque but more power. This might mean there is some tuning effect in play on the TDM too (although there is the possibility that the asymmetry of the design maybe helps with noise instead. Not sure)

 

The different snorkels have different flow rates, and again, this affects how much fuel should be injected.

 

Having played around with the CO on my bike quite a bit, I came to realise that, in a case like yours, where there was a difference value of 18 points, when you come to increase the value of one cylinder you should change the value of the other cylinder by the same amount, importantly retaining the difference between the two original CO values.

 

In your case, C1 was 28, C2 was 10'. I believe it's safe to increase these values, but always keep a difference of 18, as that is what the factory chose, presumably while the engine was on a test rig, or because those were the batch correction values of those particular injectors.

 

As you've reset them to 15 and 20, you've made the difference between them 5, in the opposite direction. As an experiment, using your C2 value of 20 as your desired C2 value, try setting C1 at 38, thereby restoring the difference of 18, and see if it makes much difference.

 

Note that a lot of this is conjecture, as there is no information available from Yamaha about the real meaning of this setting.

Diesel fuel injector coding is almost required when replacing a diesel injector (they refer to the correction value sometimes as 'trim codes' , but if you don't do it the vehicle will still run, just not as sweetly.

 

For petrol vehicle's, modern ECU's learn each injector's parameters by sampling the exhaust gas.

 

I think new injectors are probably 99% close, and the trim/correction value gets the injector operation to be 100% accurate

 

I don't think the ECU in the 900 is sophisticated enough to be self adjusting injectors.

 

Another way the injector flow can be calculated (and then compensating for it) , is by monitoring the common rail fuel pressure during the firing of an injector. Perhaps this method works best for diesels, which run with enormous fuel pressure. But, the TDM900 doesn't have a fuel rail pressure sensor, it uses a more primitive pressure relief valve to control fuel pressure instead

 

Interestingly, the Yamaha R6, a four cylinder bike, only has two CO settings too, C1 and C2, and not C1, C2,C3,C4 as you would expect.

It uses C1 to control the injection for outside cylinders, and C2 for the inside two cylinders. So that throws a spanner in everything !

(Inner cylinders run hotter)

They suggest only increasing values by a maximum of 7 for the R6, but that could just be hearsay/guesswork.

 

So, there's nothing absolutely conclusive here, But I assume each injector has a slightly different flow rate, which is critically important to get right, at low load/low speed running, and we know there are two different throat lengths of snorkels, so it would be unusual for both settings to be identical, so to my mind, if the CO value is a correction parameter, the most important thing is to keep the initial difference between the two values the same, whichever way you tune them, higher or lower

[dablik]

My head hurts Chris, makes sense what you say, i think ! and it's quite informative, thank you 

[fixitsan]

My head hurts Chris, makes sense what you say, i think ! and it's quite informative, thank you 

   Unless we get someone from Yamaha to say exactly what CO is for, Carbon Monoxide, or 'COrrection', we can't be sure either way, but I prefer to keep any difference between the two settings the same, so if i increase C1 by 10 I increase C2 by ten also.

[trevini]

I think (believe) its for CO adjustment as the workshop manual suggests making adjustments with a co probe in the exhaust.

In theory at least, if you set the right cylinder with the probe in the same side exhaust and repeat the process for the left, the difference between the two should be the same throughout any further adjustments if you keep the difference the same.

Edited by trevini, 07 June 2024 - 10:35 am.

[fixitsan]

I think (believe) its for CO adjustment as the workshop manual suggests making adjustments with a co probe in the exhaust.

 

 

Well yeah, then it makes sense it's for carbon monoxide
 

[Studley Ramrod]

Soooo, how about balancing the throttle bodies ?  Surely should have some effect on low rpm if they're not balanced ?

[fixitsan]

Soooo, how about balancing the throttle bodies ?  Surely should have some effect on low rpm if they're not balanced ?

That's probably another way the system could get it wrong, because the TPS only monitors one of the valves, the other is offset against that

[trevini]

I spent some time very carefully balancing the throttle bodies on mine (using the screw that must not be touched according to the manual) quite early on in ownership. I closed the air bleeds completely and set the balance at 3k rpm by using the cable adjuster to "set" the throttle to hold the revs. Mine wasn't far out, but possibly enough to make a difference. I kept a check on the TPS (via the dash) throughout the procedure and it never altered, so just adjusted the balance between the throttle bodies and didn't affect the TPS reading. Once back on idle, I checked the balance and fine tuned a little with the air bleed screws. Virtually no adjustment was needed on those. Mine runs very smoothly and has never suffered from the lean surge at about 2800rpm like some have reported. 

 

The above procedure is pretty much what Moto Guzzi specify to balance the TBs on my V11with a couple of exceptions for setting the TPS which is set mechanically by voltage reading on the MG.

Edited by trevini, 12 June 2024 - 01:16 pm.

[Studley Ramrod]

Good to know Trev. I'm sure Mr Henty has balsanced the tb's too. Gimme carbs any day 😁

[ABurtchaell]

After reading various articles on changing the CO settings to smooth out the fueling on my TDM 900 I made some adjustments (Co1 Cyl is now set to 23 and the Co2 cyl is set to 31). This has improved the low speed fueling (eg: going round roundabouts and hairpin bends) a lot, so thanks for all the info.

 

One thing I do want to ask though is that all the artilcles I have read always seem to have different vales for each cylinder, can anyone explain why they are not set them same for each cylinfer?

 

Thanks for any info.

[leehenty]

If you look in air box the intake stacks are different lengths
So the air flow is different. C2 always serms to be set higher than C1