150mV TPS re-hash

[Wayne Orwig]

Just as I thought there's about 300 mV between each row
The ECU starts registering at 156 mV but why that value, why not zero or 50mV, because if you used zero the pot would be touching the end stop at the same time as the throttle plate touched, which one is holding it?
Using a value above zero ensures that it never touches
Given this information when the bike is set up for idle around 500 mV it never gets to use the values in the bottom row.

The fuel map has 16 steps. Why waste steps below idle where it generally will never go. Those steps are better served providing fueling detail near and above idle.

[Meinolf]

Hi,

I believe 1.5M is also 3.6 or 525mV +/- 25mV.

forget about the 525mV. The actual TPS opening at idle is what is is at the desired idle speed, there is no reason why it must be a specific value. The program code of the 15M/RC doesn't require or dictate it.

Bypass screws, idle ignition values, fuel values at idle and CO trim, amongst others, influence the AFR and thereby idle speed. Just think of the power the engine creates with a given AFR. With a fuel mixture of λ 0.86 you get the highest power. With a mixture above or below that value the power is less.

So the TPS setting is set to whatever is needed.

Cheers
Meinolf

[scra99tch]

The CalVin 15M does use 3.6 degrees (unlike the older P8, which was 2.1 degrees, or about 384mv).

A full blown setup would be, air screws 1/2 turn, unhook left T/ linkage. back out left idle stop. set TPS=150mv. Turn in idle stop for 540mv (you should now be at a physical 3.6 degrees plate opening for good idle). Reconnect linkage. Balance idle with idle stops. Tweak TPS=540mv if needed. Balance high speed w/ screw on linkage.
That was the setup instructions Guzzi provided years back. They did NOT want you to tweak the air screws for idle balance. But you can and I sometimes do. I believe their thinking is that if you open the air screws too much, you may close the butterflies too much to make up for it.

If I get in a machine that is running OK. I do NOT do the 150mv part. Waste of time IMHO since you already have close to the proper amount of air going in so the throttle plate is close to the required 3.6 degrees already. Why screw it up. (you don't see people on a Norge/Breva/Griso/etc backing off the idle screw. In fact it is forbidden.) I usually just set air screws to 1/2 turn. Then idle speed/balance with idle screws. Then 540mv TPS tweak. Then fast speed balance on the linkage. And go ride.

With plate screws I take it? not TPS screws.

[Meinolf]

Hi,

The fuel map has 16 steps. Why waste steps below idle where it generally will never go. Those steps are better served providing fueling detail near and above idle.

having a TPS breakpoint slightly below or exactly at the TPS setting used at idle significantly eases finding the proper fuel value required for a desired λ. The program code calculates injection time based on rpm and TPS (and many other factors) and interpolates if either is in an in-between state. The interpolation works better if it is between two breakpoints.

Cheers
Meinolf

[Wayne Orwig]

With plate screws I take it? not TPS screws.

No, the TPS. That would be to tweak it so it is 3.6 degrees (540mv) at a good idle. If you don't the idle mixture and spark advance may be off near idle.

[bmc5733946]

If I get in a machine that is running OK. I do NOT do the 150mv part.  I usually just set air screws to 1/2 turn. Then idle speed/balance with idle screws. Then 540mv TPS tweak. Then fast speed balance on the linkage. And go ride.

This is what I was alluding to earlier, if it runs and idles this is what I do.

Brian

[Wayne Orwig]

If I get in a machine that is running OK. I do NOT do the 150mv part.  I usually just set air screws to 1/2 turn. Then idle speed/balance with idle screws. Then 540mv TPS tweak. Then fast speed balance on the linkage. And go ride.

This is what I was alluding to earlier, if it runs and idles this is what I do.

 :1:

Why fix it if it isn't broken.

[rodekyll]

Meinoff --  Good information!  Keep it coming.  I'm learning a lot!   

[scra99tch]

Not sure if you've experienced this but the TPS could only show .176V on guzzi diag before it went full 4.999V.  As in I could only twist the TPS before it went to fully closed and shot up to 4.999V. Using a screw driver I could turn the TPS and get the full range with out any spikes or unexplained voltages. 

[Wayne Orwig]

Not sure if you've experienced this but the TPS could only show .176V on guzzi diag before it went full 4.999V.  As in I could only twist the TPS before it went to fully closed and shot up to 4.999V. Using a screw driver I could turn the TPS and get the full range with out any spikes or unexplained voltages.

That is not real measured voltage, correct?
I believe you are just referring to software voltage. Once the voltage gets so low, I believe it runs off of the 'end' of the software tables and jumps around like that. In real life the TPS voltage never normally goes that low, so ne reason to make tables for it down there.

If you are seeing to jump like that on a real voltmeter, there is a problem.

[scra99tch]

would guzzi diag and a voltmeter be that far off?  I'll check with voltmeter but can't be certain I am at the correct MV with guzzi diag.

[Wayne Orwig]

would guzzi diag and a voltmeter be that far off?  I'll check with voltmeter but can't be certain I am at the correct MV with guzzi diag.

The ECU can not translate the voltage when it get close to 150mv. So software can not be used near 150mv. I think this was covered in the Guzzidiag thread if you want to search it.

[Tom H]

would guzzi diag and a voltmeter be that far off?  I'll check with voltmeter but can't be certain I am at the correct MV with guzzi diag.

Yes, it can be off.

I had it beat into my head to use a digital volt meter AT the TPS wires to get the CORRECT reading. GD won't read the voltage correctly as it relies on the ECU.

Why this is, I don't understand? But when people who understand this stuff say do it this way, you do it!!!

Hope this helps,
Tom

[scra99tch]

I'll turn the screw out again and recheck,  I did check it at the .549mV and it read .545mV on meter.

[Chuck in Indiana]

Yes, it can be off.

I had it beat into my head to use a digital volt meter AT the TPS wires to get the CORRECT reading. GD won't read the voltage correctly as it relies on the ECU.

Why this is, I don't understand? But when people who understand this stuff say do it this way, you do it!!!

Hope this helps,
Tom

Paul explained it in the Original thread. Below idle voltage, the computer doesn't output enough information to set the tps with GD. You'll get zero mv or around 200 mv IIRC when moving the tps. There just aren't enough steps available to properly set it.

[scra99tch]

Sounds good and last but not least do you guys tend to put a little pressure or rely on a snap of the butterfly to do your baseline 150mV measure.  If I gently seat it I get 220mv if I twist with a little force I get 153mV.

I looked inside for carbon build up and did not notice any just a little oil residue.  But it does stick.

Thanks again.

[Kiwi_Roy]

Sounds good and last but not least do you guys tend to put a little pressure or rely on a snap of the butterfly to do your baseline 150mV measure.  If I gently seat it I get 220mv if I twist with a little force I get 153mV.

I looked inside for carbon build up and did not notice any just a little oil residue.  But it does stick.

Thanks again.

I found that as well, you never get the exact mV twice that's why I use a slip of paper between the idle screw and the throttle arm, run it in until the paper is just gripped then a tad more for luck.
I don't know anything about the linkage on your bike but I do this for a VII Sport and EV.

I did some experimenting with a wide band fuel mixture meter and found you can move the mV up and down about 50 mV without noticing a difference in the mixture.