Rough transition from off to on throttle

[SinNH]

Well I've 0=0ed and synced my TB's three times since last spring trying to get out the choppy transition from no throttle to a bit of throttle,if I really,really feather the throttle it's ok but with normal usage it's rough. The bike runs great,pretty smooth idle,and very little surging,starts fine.

The lowest setting of my TPS is .007 volts,tightened it and adjusted L TB to .370,synced cables with carb stix ,and adjusted the BBS to same vacuum with idle at about 1150. BBS out about 1/2 turn.TB's stay within about 4-5mm of merc vacumm from idle to 5000.

All orings new ,no intake leaks,so I guess the only way to really fine tune it is with a fuel controller.

 

Any other suggestions ?

 

I'll probably buy a Techlusion and keep my Cat active.

 

Thanks

Steve

[russell_bynum]

First...0=0 should be a one-time procedure for the most part. Unless you have to replace the TPS or otherwise muck with the TPS/left throttle stop screw, you should not ever have to do it again.

 

On to your problem...I spent most of a weekend playing with my R1100RT to see what I could do about that very problem. It's been a while, so hopefully if I remember any of this wrong, someone will point that out.

 

The motronic considers "idle" to be any TPS voltage below .400 volts. So...if you've done the 0=0 so that the TPS is at .370 and your bike is sitting there idling, the Motronic sees .370v from the TPS. as you start opening the throttle, the throttle butterflies start to open and let more air in. But, the TPS is still below .400 so the motronic says "still at idle...don't change anything." As you continue opening the throttle and the butterflies continue to open, you will eventually hit .400v on the TPS. When you go above that, the Motronic suddenly wakes up and says "ok, let's boggie".

 

Someone with more brains than me can explain the "why", but the abrupt off/on transition happens because the butterflies are opening before the motronic recognizes that you're no longer at idle.

 

The solution is to get the idle voltage on your TPS as close to .400 as you can. Keep in mind, of course, that it'll fluctuate a bit due to slop in the TPS itself, so you don't want to shoot for .399. You'll have to play it by ear and see what works for you.

 

Also...of course, you can't just dial up the TPS to a higher voltage using the idle stop screw since that'll result in an idle that's too high. You have to start the 0=0 over from scratch, but set the TPS "0" (you stated that this was .007 on your bike) to something a little higher. Complete the 0=0 and see where things are. If you end up with the idle speed too high, go back to the beginning of the 0=0 and bump the TPS "0" up a bit higher.

 

This is a tedious process since it will often require you to do several 0=0's before you get it where you want it. Don't rush this and don't cut corners.

 

 

The result, on my bikes anyway, was a very noticeable smoothing of the off/on throttle transition.

[SinNH]

First...0=0 should be a one-time procedure for the most part. Unless you have to replace the TPS or otherwise muck with the TPS/left throttle stop screw, you should not ever have to do it again.

 

On to your problem...I spent most of a weekend playing with my R1100RT to see what I could do about that very problem. It's been a while, so hopefully if I remember any of this wrong, someone will point that out.

 

The motronic considers "idle" to be any TPS voltage below .400 volts. So...if you've done the 0=0 so that the TPS is at .370 and your bike is sitting there idling, the Motronic sees .370v from the TPS. as you start opening the throttle, the throttle butterflies start to open and let more air in. But, the TPS is still below .400 so the motronic says "still at idle...don't change anything." As you continue opening the throttle and the butterflies continue to open, you will eventually hit .400v on the TPS. When you go above that, the Motronic suddenly wakes up and says "ok, let's boggie".

 

Someone with more brains than me can explain the "why", but the abrupt off/on transition happens because the butterflies are opening before the motronic recognizes that you're no longer at idle.

 

The solution is to get the idle voltage on your TPS as close to .400 as you can. Keep in mind, of course, that it'll fluctuate a bit due to slop in the TPS itself, so you don't want to shoot for .399. You'll have to play it by ear and see what works for you.

 

Also...of course, you can't just dial up the TPS to a higher voltage using the idle stop screw since that'll result in an idle that's too high. You have to start the 0=0 over from scratch, but set the TPS "0" (you stated that this was .007 on your bike) to something a little higher. Complete the 0=0 and see where things are. If you end up with the idle speed too high, go back to the beginning of the 0=0 and bump the TPS "0" up a bit higher.

 

This is a tedious process since it will often require you to do several 0=0's before you get it where you want it. Don't rush this and don't cut corners.

 

 

The result, on my bikes anyway, was a very noticeable smoothing of the off/on throttle transition.

Russell,

I agree. I don't redo the 0=0 all the time,just the balancing.

What you say makes sense,but I was just following ,I think, the information that Rob Lentinni ( sp?) put out years back and saying getting the TPS as close to .370 is the sweet spot.

Too bad I just put all the body parts back on, I'd give .4 a shot

Next bored day I'll set up with .4 v and see what happens.

Thanks,good explanation.

Steve

[T__]

Steve, it’s difficult to believe a couple of hundredths of TPS voltage would cause your problem.. I have seen lots of OEM TPS settings on the 1100/1150 be in the .365-.375V area with perfectly clean throttle response.. If you monitor that TPS voltage you will find you are well above .400 volts with about any movement of the throttle so unless you only move the throttle one thousandth of a degree you should be well above .400 volts at any throttle movement.. You might try a quick test by raising the idle RPM about 50-100 RPM’s using the choke (actually fast idle) lever as that will force higher TPS voltage at idle.. There is also the fact that your problem doesn’t appear at light throttle openings,, small throttle opening would keep the TPS voltage lower for longer,, a quick opening would get you quickly out of the pre .400v range.. Did you do your TPS setting with a good (known accurate) high impedance voltmeter so your meter didn’t add load to the TPS output?

 

Difficult to tell what you have there without actually having hands on & doing some testing but it seems more like fuel or spark mapping related as most if not all quick throttle-up is handled by fixed spark & fuel mapping.. It’s possible (but somewhat unlikely) that your O2 sensor is acting weird & playing games with the fuel or spark cell learn so the mapping is skewed at quick throttle movement.. I guess a quick test would be to run with the O2 disconnected to see if that changes the throttle response..

 

Maybe check the base ign timing to be sure that is correct (might not be the entire problem but can make a difference)

 

Back to the fuel mapping—if you have low fuel pressure (weak pump output or low pump voltage) it can bring on an enleanment at throttle up off idle,, same with low injector voltage (same pulse width at lower voltage equals less fuel flow)..

 

Maybe use an analog (needle type) voltmeter & track your TPS voltage as you quickly advance the throttle,, if your TPS has a worn spot or other reason it doesn’t track smoothly at or just off idle it can easily cause that off idle hesitation (it is usually just as bad at light opening as fast opening but still worth looking at)..

 

You also need a lot of spark to light off the lean mixture at quick throttle opening low RPM’s so even a plug wire with high resistance or malfunctioning spark plug could be adding to your off idle problems (check plug wires for being fully seated in coil & not arcing to the R/H TBI cam or engine block.. Have you tried new spark plugs?

 

On a problem like you have about all you can do is work your way through all the systems & verify all is working correctly & everything is within specifications..

 

Do you still have the stock CCP in place? If so try removing that (as a test) as some of those 2.2 systems ran pretty bad with the stock CCP in place.. If it gets better without the CCP in place that might help you in the direction you need to take to solve your problem..

 

 

Twisty

 

[russell_bynum]

Twisty,

I would have never believed it myself given how a very small throttle movement results in a pretty big change in TPS voltage. But, I do know that I tried this on my RT and Lisa's RS with the same result. I guess it's possible that this is just my "butt dyno" speaking, bu I don't think so.

[russell_bynum]

First...0=0 should be a one-time procedure for the most part. Unless you have to replace the TPS or otherwise muck with the TPS/left throttle stop screw, you should not ever have to do it again.

 

On to your problem...I spent most of a weekend playing with my R1100RT to see what I could do about that very problem. It's been a while, so hopefully if I remember any of this wrong, someone will point that out.

 

The motronic considers "idle" to be any TPS voltage below .400 volts. So...if you've done the 0=0 so that the TPS is at .370 and your bike is sitting there idling, the Motronic sees .370v from the TPS. as you start opening the throttle, the throttle butterflies start to open and let more air in. But, the TPS is still below .400 so the motronic says "still at idle...don't change anything." As you continue opening the throttle and the butterflies continue to open, you will eventually hit .400v on the TPS. When you go above that, the Motronic suddenly wakes up and says "ok, let's boggie".

 

Someone with more brains than me can explain the "why", but the abrupt off/on transition happens because the butterflies are opening before the motronic recognizes that you're no longer at idle.

 

The solution is to get the idle voltage on your TPS as close to .400 as you can. Keep in mind, of course, that it'll fluctuate a bit due to slop in the TPS itself, so you don't want to shoot for .399. You'll have to play it by ear and see what works for you.

 

Also...of course, you can't just dial up the TPS to a higher voltage using the idle stop screw since that'll result in an idle that's too high. You have to start the 0=0 over from scratch, but set the TPS "0" (you stated that this was .007 on your bike) to something a little higher. Complete the 0=0 and see where things are. If you end up with the idle speed too high, go back to the beginning of the 0=0 and bump the TPS "0" up a bit higher.

 

This is a tedious process since it will often require you to do several 0=0's before you get it where you want it. Don't rush this and don't cut corners.

 

 

The result, on my bikes anyway, was a very noticeable smoothing of the off/on throttle transition.

Russell,

I agree. I don't redo the 0=0 all the time,just the balancing.

What you say makes sense,but I was just following ,I think, the information that Rob Lentinni ( sp?) put out years back and saying getting the TPS as close to .370 is the sweet spot.

Too bad I just put all the body parts back on, I'd give .4 a shot

Next bored day I'll set up with .4 v and see what happens.

Thanks,good explanation.

Steve

 

Don't go for .4..that's too high and there's too much of a chance that fluctuations in the TPS due to slop in the sensor itself will push it over .4. You're trying to get closer to .4, but you don't want to actually get to .4. If you're and .370 right now, maybe try .380 or .385.

[Jim Moore]

Maybe try something simpler to start with. I like to take all the slack out of my throttle cables. It eliminates the area where I am off idle with the throttle, but not getting power yet.

[SinNH]

Steve, it’s difficult to believe a couple of hundredths of TPS voltage would cause your problem.. I have seen lots of OEM TPS settings on the 1100/1150 be in the .365-.375V area with perfectly clean throttle response.. If you monitor that TPS voltage you will find you are well above .400 volts with about any movement of the throttle so unless you only move the throttle one thousandth of a degree you should be well above .400 volts at any throttle movement.. You might try a quick test by raising the idle RPM about 50-100 RPM’s using the choke (actually fast idle) lever as that will force higher TPS voltage at idle.. There is also the fact that your problem doesn’t appear at light throttle openings,, small throttle opening would keep the TPS voltage lower for longer,, a quick opening would get you quickly out of the pre .400v range.. Did you do your TPS setting with a good (known accurate) high impedance voltmeter so your meter didn’t add load to the TPS output?

 

Difficult to tell what you have there without actually having hands on & doing some testing but it seems more like fuel or spark mapping related as most if not all quick throttle-up is handled by fixed spark & fuel mapping.. It’s possible (but somewhat unlikely) that your O2 sensor is acting weird & playing games with the fuel or spark cell learn so the mapping is skewed at quick throttle movement.. I guess a quick test would be to run with the O2 disconnected to see if that changes the throttle response..

 

Maybe check the base ign timing to be sure that is correct (might not be the entire problem but can make a difference)

 

Back to the fuel mapping—if you have low fuel pressure (weak pump output or low pump voltage) it can bring on an enleanment at throttle up off idle,, same with low injector voltage (same pulse width at lower voltage equals less fuel flow)..

 

Maybe use an analog (needle type) voltmeter & track your TPS voltage as you quickly advance the throttle,, if your TPS has a worn spot or other reason it doesn’t track smoothly at or just off idle it can easily cause that off idle hesitation (it is usually just as bad at light opening as fast opening but still worth looking at)..

 

You also need a lot of spark to light off the lean mixture at quick throttle opening low RPM’s so even a plug wire with high resistance or malfunctioning spark plug could be adding to your off idle problems (check plug wires for being fully seated in coil & not arcing to the R/H TBI cam or engine block.. Have you tried new spark plugs?

 

On a problem like you have about all you can do is work your way through all the systems & verify all is working correctly & everything is within specifications..

 

Do you still have the stock CCP in place? If so try removing that (as a test) as some of those 2.2 systems ran pretty bad with the stock CCP in place.. If it gets better without the CCP in place that might help you in the direction you need to take to solve your problem..

 

 

Twisty

 

Thanks Twisty, I'll try to answer in correct order,

I used a Fluke 73 to set the TPS and Greenlee analog to check the ramp of the TPS.

Actually the problem is the worst at light throttle openings.

Ok will check the change with the O2 sensor disconnected,have not done that before.

Timing is spot on.

Fuel pump well maybe,it runs great a WOT.

Plug wires are/should be ok, I had to replace one last summer,($110!), plugs are brand new,Bosch single electrode.

Stock CCP,last summer I tried all the jumper configurations and thought stock was best for me,but you know I never tried it without any jumper,I'll give that a shot too.

Bike is totally stock.

 

Thanks,

Steve

 

[SinNH]

First...0=0 should be a one-time procedure for the most part. Unless you have to replace the TPS or otherwise muck with the TPS/left throttle stop screw, you should not ever have to do it again.

 

On to your problem...I spent most of a weekend playing with my R1100RT to see what I could do about that very problem. It's been a while, so hopefully if I remember any of this wrong, someone will point that out.

 

The motronic considers "idle" to be any TPS voltage below .400 volts. So...if you've done the 0=0 so that the TPS is at .370 and your bike is sitting there idling, the Motronic sees .370v from the TPS. as you start opening the throttle, the throttle butterflies start to open and let more air in. But, the TPS is still below .400 so the motronic says "still at idle...don't change anything." As you continue opening the throttle and the butterflies continue to open, you will eventually hit .400v on the TPS. When you go above that, the Motronic suddenly wakes up and says "ok, let's boggie".

 

Someone with more brains than me can explain the "why", but the abrupt off/on transition happens because the butterflies are opening before the motronic recognizes that you're no longer at idle.

 

The solution is to get the idle voltage on your TPS as close to .400 as you can. Keep in mind, of course, that it'll fluctuate a bit due to slop in the TPS itself, so you don't want to shoot for .399. You'll have to play it by ear and see what works for you.

 

Also...of course, you can't just dial up the TPS to a higher voltage using the idle stop screw since that'll result in an idle that's too high. You have to start the 0=0 over from scratch, but set the TPS "0" (you stated that this was .007 on your bike) to something a little higher. Complete the 0=0 and see where things are. If you end up with the idle speed too high, go back to the beginning of the 0=0 and bump the TPS "0" up a bit higher.

 

This is a tedious process since it will often require you to do several 0=0's before you get it where you want it. Don't rush this and don't cut corners.

 

 

The result, on my bikes anyway, was a very noticeable smoothing of the off/on throttle transition.

Russell,

I agree. I don't redo the 0=0 all the time,just the balancing.

What you say makes sense,but I was just following ,I think, the information that Rob Lentinni ( sp?) put out years back and saying getting the TPS as close to .370 is the sweet spot.

Too bad I just put all the body parts back on, I'd give .4 a shot

Next bored day I'll set up with .4 v and see what happens.

Thanks,good explanation.

Steve

 

Don't go for .4..that's too high and there's too much of a chance that fluctuations in the TPS due to slop in the sensor itself will push it over .4. You're trying to get closer to .4, but you don't want to actually get to .4. If you're and .370 right now, maybe try .380 or .385.

 

Ok thanks Russell,I'll go for .385,my TPS did vary maybe .008 plus and minus when snapping the throttle a few times with the VOM connected.

Thanks,

Steve

[SinNH]

Maybe try something simpler to start with. I like to take all the slack out of my throttle cables. It eliminates the area where I am off idle with the throttle, but not getting power yet.

Thanks for the input Jim,the slack is less than one mm or so, It is a good point so many guys overlook,I ride other guys bikes with throttle cable slack and/or cable drag and I wonder how the heck they can put up with it.

R.Lentinni recommended 1mm ,I like to have less,anal about smooth throttle feel,clutch feel,etc

 

thanks,

Steve