2001 California Stone TPS adjustment

[Gwilliam]

Hi all,
I am once again looking for some advice from those with more experience than me!
I have a 2001 California Stone to which I have installed a K&N air filter into the housing with no lid. The exhaust has had the centre silencer replaced with an H pipe and Lanfranconi Competizioni mufflers have been fitted in place of the originals. A Power Commander has been used to modify the fuelling to keep the mixture correct for the extra volume of air flowing through the engine.
Once all of these components had been installed I was very happy with the noticeable increase in mid range performance of the bike for several years.

Things started to deteriorate a couple of years ago with rough running in traffic which got progressively worse causing lots of popping and banging at low speeds and light throttle openings.
To cut a long story short, after a lot of mis-diagnosis on my part Vagrant suggested a defective Throttle Position Sensor. Whilst I couldn't understand how this could only affect one cylinder, his previous experience caused me to change the item.
I set this up using a digital voltmeter to the recommended 150mv closed throttle and adjusted the idle screws to a value of approx 530mv and balanced the throttle bodies with carb sticks. The air bypass screws are both one turn open.
My problem is that despite still using the same Power Commander map the bike gives every indication of running lean. It intermittently spits back through the inlet at low engine speeds and pops through the exhaust on deceleration. The plugs are also a very pale colour rather than a chocolate brown.
Having checked and replaced various components to exclude the possibility of air leaks etc I am left wondering if I should try changing the base setting of the new TPS? I have heard of people using this as a method of enriching the mixture throughout the rev range. When searching old posts somebody had used this method on a pair of similarly equipped Jackals where one was running rich and the other lean. They were able to get both running well although the TPS settings were either side of the standard 150mv.
Unfortunately I don't have access to Guzzidiag so my options are limited but as the problems seem to have appeared since changing the TPS I am hoping that adjusting that may resolve them..
I would be grateful for any input or ideas.

[fotoguzzi]

Myself, I would relocate the power commander to the trash can and learn how to use Guzzidiag. Why don’t you have access? You do have a computer right?

Isn’t it rather loud with no air box cover? I’m pretty sure you gain more noise than performance with the cover missing.

[Guzzidad]

   Are you sure you set the TPS with closed throttle? You disconnected the linkage between the throttle bodies and backed off the idle screws? And you cleaned the throttle bodies so the butterfly could fully close? My notes say the TPS should read 384mv at idle. After balancing the throttle bodies at 4,000 rpm's you then balance them again at idle using the air bypass screws. They probably won't be set exactly the same. That should get rid of most of the intake and exhaust popping.

[John Croucher]

The TPS primary function is ignition timing.

[Gwilliam]

Myself, I would relocate the power commander to the trash can and learn how to use Guzzidiag. Why don’t you have access? You do have a computer right?

Isn’t it rather loud with no air box cover? I’m pretty sure you gain more noise than performance with the cover missing.

The Power Commander with the appropriate map to suit the intake and exhaust modifications worked very well for 10+ years until the TPS problems arose. It provided a fully reversible setup that I could remove to put the bike back to standard if required.
I'm guessing that even if I had Guzzidiag I would still need a source of fuelling maps to provide something appropriate to the existing modifications which I would then have to upload to the ECU to replace the standard map.
The K&N high flow air filter and removal of the air filter lid and snorkels do have a measurable effect on the dyno and if noise was a concern I would never have installed the H pipe and Lanfranconi Competizioni mufflers!

As I said it all worked well for many years until the TPS failed so I still feel that I haven't got it back to the setting that it had originally.
I intend to unplug the Power Commander today and take the bike for a ride to see if there is any difference in case the Power Commander has failed. If that proves to be the case then maybe if will be time to investigate Guzzidiag.

[Gwilliam]

   Are you sure you set the TPS with closed throttle? You disconnected the linkage between the throttle bodies and backed off the idle screws? And you cleaned the throttle bodies so the butterfly could fully close? My notes say the TPS should read 384mv at idle. After balancing the throttle bodies at 4,000 rpm's you then balance them again at idle using the air bypass screws. They probably won't be set exactly the same. That should get rid of most of the intake and exhaust popping.

Thanks for your thoughts.
Yes, I am sure about the setup procedure although my sources state 150mv for initial setting and 520mv for the idle screws. I balance the throttle bodies at various engine speeds using the linkage adjuster and set the idle speed using the air bypass screws.

[Gwilliam]

The TPS primary function is ignition timing.

I thought it set a base line for the ECU's map of both the fuel and ignition timing.

[Vagrant]

I run 540mv on my 2001. The 374 is for a 1998 EV. Make sure the bike is off, not running and the throttle and fast idle lever are both closed. The air screws should have been closed for set up and only one opened slightly for the final idle.  JMHO, but I don't worry about the 150 once it was done correctly once. If the 3000-4000 RPM is right and the idle is right you are fine. Spray some carb cleaner around the rubber intake to heads boots. You sound like an air leak. FWIW, my 01 needs to be +30 trim s/u worth Guzzi dia.

[Gwilliam]

I run 540mv on my 2001. The 374 is for a 1998 EV. Make sure the bike is off, not running and the throttle and fast idle lever are both closed. The air screws should have been closed for set up and only one opened slightly for the final idle.  JMHO, but I don't worry about the 150 once it was done correctly once. If the 3000-4000 RPM is right and the idle is right you are fine. Spray some carb cleaner around the rubber intake to heads boots. You sound like an air leak. FWIW, my 01 needs to be +30 trim s/u worth Guzzi dia.

Good to hear from you again Vagrant.
You have told me about using 540mv as an idle setting and mine is just over 530mv. I set it as you say with engine off and balanced the throttle bodies with the linkage at 3000 - 4000rpm using carb sticks. I had both bypass screws open 1/4 turn but have now opened them both a full turn to obtain the correct idle speed.
I am sure that you are correct about the air leak which I believe is where the L/H throttle spindle passes through the throttle body. This unfortunately may have some effect on the TPS as well as it does not necessarily return to the same point every time. I would love to rebush and reseal the throttle body and spindle if only for peace of mind but parts are not readily available.
As I have a bigger airflow through the engine than standard I do need some method of inceasing the fuel supply to match. I tried removing the Power Commander today to establish whether it was doing anything. The bike was so lean without it that it was pretty much unrideable. I therefore richened up the fuel map at low engine speeds and small throttle openings to compensate for the suspected air leak. This has helped a lot and I will play with the values to fine tune it until I can sort the throttle bodies one way or another.
I have spent a lot of time and effort looking for any other air leaks, replacing manifold rubbers etc. It is only at high manifold vacuum when the throttles are almost closed that it is most noticable. The small air leak is sufficient to cause a problem under those conditions but at larger throttle openings when a far greater volume of air is passing through, the extra leak is proportionally insignificant.

Thanks again for your input ,- I still owe you one for your original TPS diagnosis!

[Vagrant]

I might be making this up as the memory isn't what it used to be, But, I think someone here or on another Guzzi site did put bushings in the throttle bodies. This was a common problem with the 2 stroke concrete cut off saws. The concrete dust ate the throttle shafts up. New carb was usually the solution.
Try a search here or maybe somebody else will pipe up who remembers it.

[Gwilliam]

I might be making this up as the memory isn't what it used to be, But, I think someone here or on another Guzzi site did put bushings in the throttle bodies. This was a common problem with the 2 stroke concrete cut off saws. The concrete dust ate the throttle shafts up. New carb was usually the solution.
Try a search here or maybe somebody else will pipe up who remembers it.

There's nothing wrong with your memory.
I too read about it on one of the forums and took notes of what part numbers and specifications of components that were listed. Unfortunately it wasn't a straight forward process to obtain the parts involved and it all got put on the back burner for a while.

I have also received a very interesting message informing me that there is a recognised fault on the 15M ECUs which allows the idle trim setting to switch to full lean for no reason. This could certainly cause the symptoms that I have been experiencing and so I will have to find a way to get Guzzidiag up and running to check its current setting.

[Gwilliam]

I might be making this up as the memory isn't what it used to be, But, I think someone here or on another Guzzi site did put bushings in the throttle bodies. This was a common problem with the 2 stroke concrete cut off saws. The concrete dust ate the throttle shafts up. New carb was usually the solution.
Try a search here or maybe somebody else will pipe up who remembers it.

Hi Vagrant,
I too remember reading the post on rebushing throttle bodies and after a little searching I found it:
https://www.v11lemans.com/forums/index.php?/topic/22077-throttle-body-rebuild/#comment-253999