Seem to me I recall reading somewhere the WOT voltage can be adjusted at the ECM.
I recently dumped my FIM chip for one from FBF

Just did a sync and it runs much better now with the Staintunes and the FBF.
I still have issues at anything above 3/4 throttle
TPS is working fine but I am reading 4.67 volts at WOT
I get a better response when I avoid WOT and crank it up as the RPM goes up


Question is for those of you been down this road before, and if memory serves
the minimum WOT voltage needs to be 4.8volts to 5 volts for the ECM to add the proper amount of fuel

I'm thinkin my injectors may need a good clean but just wanted to see what others have run into along this line

The Staintunes sound much like the Rennsports but louder and without the rasp of the Rennsports, makes me wish I'd grabbed those Bubs recently...you need earplugs for anything over a two hour ride]
but they do sound sweet

some time ago I was given a pdf file containing the procedure to set the Marelli P7 & P8 for the 851 & 916, here is a "copy&paste", pleas bare in mind i have never tried, however it could be a good base to start with


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P7 or P8 ECUs (851/888/916SP)
On these ECUs there is an external screw adjuster located next to the 35 pin harness connector. This is usually under a grey plastic cap which can be removed for access. The screw adjuster has a range of four turns, or plus/minus two turns. The default position is in the middle of the range. When you screw the adjuster clockwise the mixture is richened. The adjuster has no end stop, so if you over-adjust the screw the trimmer just rolls over at the maximum or minimum setting, without damaging the trimmer. Each time the trimmer rolls over a tiny click is just audible.
So to set the default position, all you need to do is turn the screw clockwise five times, and listen for the tiny click when the trimmer rolls over. Note the position of the screwdriver blade, and then turn counterclockwise for two turns. The trimmer is now in the default position.
Since the trimmer is simply a potentiometer which puts out a signal from 0 to 5 volts, you can also set your default position using a voltmeter placed on the centre terminal of the trim pot, inside the ECU. You should set the default position to 2.5 volts.
How do I set the trimmer correctly?
Firstly let's look at the factors involved in the mixture system:
The fuel entering the engine is controlled by the injectors, principally by how long they are open for each engine cycle. Typically at idle they are open from about 1mS to about 2mS. The CO trimmer affects this duration as shown in the table above. This change is the same for both cylinders, and cannot affect the CO cylinder balance.
The computer measures the butterfly position using the Throttle Position Sensor (TPS). This sensor is precisely aligned on the butterfly shaft and afftects not only fuel delivery but ignition advance as well. Many owners are tempted to move this sensor on the shaft, as you can get more fuel delivery from the ECU in this way. But there are several goods reasons not to do this:
• The Weber TPS sensors are NOT LINEAR. If you change the position from the factory setting, not only do you change the fuel delivery but you change the ignition advance. This means that the bike will have too much advance at partial throttle, leading to detonation (pinging) problems which were not there before.
• The factory used a specific setting for it's mapping, and we use the same setting for our mapping. So if you want to achieve optimum results with our chips, then you should set the TPS to the factory settings. Then your engine will operate as close as possible to the engine we used for testing.
The air entering the engine is controlled by two things, the throttle butterfly and the air-bleed channel. These two factors are inter-dependant, ie you can get the same amount of air with a shut throttle and open airbleed as with an open throttle and shut air-bleed. The difference is that the ECU does not know how the air-bleeds are set, whereas it does know the throttle position. So you can change the air entering the engine either by opening the throttles (which the ECU knows about and makes an
adjustment for) or by opening the airbleed. The salient point here is that the butterfly and the airbleed are designed for two different functions.
The butterflies are designed to deliver the same amount of air to each cylinder under load conditions. This is achieved by synchronising the butterflies using a vacuum guage or 2-channel CO meter.
Because the butterflies are not perfect, the airflow will vary between the two, especially at low throttle settings. It is impossible to maintain exact synchronisation through the throttle range, so the butterflies are synched where they are most critical, ie in the range one-third to one-half throttle. This can be easily achieved on a brake dyno.
The designed purpose of the air-bleeds is to achieve cylinder balance at low, or idle, throttle settings, where the butterflies are effectively closed on the stop screw. The bleeds are adjusted to give either matching vacuum or CO for both cylinders.
Clearly the idle can be set in a number of ways, since the mixture and balance are interdependant, along with the butterfly synchronisation.
So unless you are familiar with idle setting then we suggest you leave this to a dealer with the right equipment. To properly set the CO you need a CO meter !! If you don't have one it is very hard to pin down the relationship between the CO trim, the air bleeds, and the butterfly position.

[second part]

So to re-iterate the variables:
• Throttle Position Sensor adjustment.
• Butterfly synchronisation.
• CO Trimmer setting.
• Air Bleeds.
We use the following sequence to correctly align all parts of the induction system. This sequence is essentially the same as the factory recommended sequence:
• Set the Throttle Position Sensor on the throttle shaft. To correctly do this you must:
o Completely back off the idle stop screws on both throttle bodies.
o Use the Mathesis tester or a Digital MilliVoltMeter to read the throttle sensor voltage. To do this you should tap the butterfly with your finger to ensure that the butterfly is completely closed against the body. Then you turn on the ignition and measure the voltage on the throttle sensor:
P7 or P8 ECU: Pins 11 and 17.
1.6M ECU: Pins 16 and 30.
1.5M ECU: Pins 22 and 11.
o If the sensor does not read 150mV Plus or Minus 2mV then you need to adjust it:
-Slacken the lock screws on the throttle sensor using a screwdriver or 7mm socket.
-Carefully move the sensor whilst reading the voltage.
-Retighten the lock screws a little at a time, each time reading the voltage and adjusting the sensor.
-Note that you should probaly overshoot the reading by about 5mV on slack screws, because when you tighten them the reading will change by about 5mV.
- Repeat until perfect. This takes a lot of practice.

o The factory manuals specify +/- 5mV but we feel that this is not accurate enough. many owners will attest to the difference in performance when the sensor is set perfectly.

o Re-set the throttle stop screw (or screws) so that the engine idles at around 1200 rpm. This is not a final setting for the stop screws, merely a step in the procedure. Typically this will produce a voltage of around 300mV on the TPS. This value is completely arbitrary and is not important. Many people misunderstand the factory manual in this regard and will try resetting the TPS until they get 1200 rpm idle and exactly 300mV on the sensor. THIS IS WRONG !!!. The actual voltage on the sensor at idle is irrelevant to correct sensor positioning on the throttle shaft. Trust Me !!
• Synchronise the Butterflies:
o Close the airbleed screws completely by adjusting CLOCKWISE. If you don't do this then the throttle vacuum will still reflect any air passing through the bleed channels and the butterflies will not be perfectly synched.

o Attach vacuum guages to the manifold port on each cylinder and run the engine.

o Adjust the throttle butterfly link shaft until vacuum is identical.

o Rev the engine and confirm that vacuum tracks on both cylinders throughout the throttle and RPM range.

o Re-adjust the link shaft until satisfactory results are obtained.

o Do Not adjust the throttle link shaft after this point.!!

• Set the IDLE Balance by adjusting the airbleed screws counterclockwise and confirming that the vacuum is identical for both cylinders at idle. You can rev the engine and observe vacuum tracking through the rev range, and then observe idle vacuum restabilising. NOTE Since the airbleeds are designed to iron out any irregularities in the throttle's function, by their nature there is no default setting, unlike the idle screws on a carburettor. If anything the default setting is fully closed. Airbleeds can also be balanced using a 2 channel CO meter. In this case, just adjust the bleeds until both cylinders have the same CO.
• Adjust the IDLE Mixture. Finally you get to set the CO Trimmer ! This will affect both cylinders by the same amount, so you need to set the airbleeds first. A typical CO figure for idle is 4% to 6%, but automotive regulations usually specify a CO of under 1% to meet emmissions standards. A V-twin will idle very poorly if the CO is set below 1%, so if you are really bothered try a setting of about 3%. Note that you may need to finesse the airbleeds at this stage.
• Adjust the IDLE RPM. Set the idle rpm at the manufacturer's figure (usually 1100 - 1200 rpm) by adjusting the throttle butterfly stop screw (or screws). We recommend 1200 rpm for Ducatis and Guzzis, possibly 1500 rpm for Ducati 996SPS models.
• Finally, note that the last three steps are usually repeated until an acceptable balance of Idle Balance, Idle Mixture, and Idle RPM are obtained. This is normal. Do Not adjust the throttle synchronisation link shaft once it is set in the early stages. If you do this now, you will need to go through the entire sequence again.
So hopefully you will have an engine which now idles, accelerates, and delivers full power faultlessly. Again, if you are not confident about all of these steps, then we suggest you use a dealer who has the skills and equipment. It is not worth adjusting the CO trimmer unless the entire sequence is followed without skipping any steps.
===========

Thanks Angelix
I have that doc

The pot I am referring to is inside the ecm and is not the CO adjustment.
I don't think the CO trimmer is capable of changing the range of the voltage supplied to the system only modifying the voltage provided.
So if you have 150mv at closed throttle and 4.67 at WOT the CO trimmer can only shift the voltage within that range in combination with your throttle sycn and air bleeds to bring(hopefully) your CO within range
So if the ECM only sees 4.67 volts the injectors will not increase the pulse width enough to provide the fuel required for WOT operation

Hey Gert

What kind of air box are you running? You are the MyECU if I remember ?

On my 907 the PO opened it up. I'm thinkin this may be at the root of my issue.

With the airbox open the baro sensor is not going to see the same level or pressure as with the stock airbox which is going to change the fuel mapping regardless of whose chip you install.
G sent me a file in Italian on the P7 from a Guzzi I think
Just ran it through a translator and it states the nominal TPS range for these systems with the Nonlinear TPS should be 4.5 to 4.8 volts

So 4.67 is in the normal range

It also gives me all the sensor ranges

So I think I will tape the airbox up
Clean the injectors
Adjust the airbleeds a little and work on the CO

Interesting outcome Angelix

My air box has the top cut out with K&N and the Staintunes

I do know my airbleeds are open a bit too much as the idle is about 2k when fully warmed up so I'm a little on the lean side

Will take care of that in the next few days after I get the sprag done.

Can't get it started at all cold and barely when warm so the cover has to come off tomorrow

I am at present testing w a WM P8.


There must be a recommended setup for the FbF chip you bought, Higgy.
What does FbF recommend f the specific chip you bought, do they have multiple versions?

if possible you need to find out what the ecu is reading at wot. but i'm not sure what available software will talk to a p7 - not all do. the p7 was replaced by the faster, more capable p8 because that's progress.

4.67 sounds a bit low to me, i'd expect at least 4.8. i haven't got software here that runs the old dos mapping program, but the top line on the map is generally 79 ish degrees throttle, and the line below that is low 60. so it may not matter anyway.

looks like 4.67 is the minimum wot range

Been awhile but I finally got back to the 907 tps issue, turns out the nut at the end of the vertical throttle body was hanging on the molded coolant hose keeping the throttle plate open about 5 degrees every time I hit the throttle. The flat of the nut just happened to line up against the hose edge perfectly. My big dumb fingers would be just enough extra force to push it off the flat and close the throttle to set the initial sync and tps. Then I would start it up and goose the throttle to keep it running and back against the flat holding the throttle open just enough to muck up the rest of the process. Quick wire tie of the hose and no more issues.

907 now purrs again