MV TPS set-up for WCT (World Class Tuning) chip installation

As with every aspect of performance, there is a mountain of lore and misconception to be scaled before you can get on with the stuff that actually does something positive.

One is the issue of TPS set-up;

There will, usually, be someone who tells how he turned the TPS until the bike ran perfectly.

Setting the TPS voltage too high tells the ECU that the throttle is open more than it actually is. Since the map usually supplies more fuel with greater throttle position, this can richen the idle and the rest of the low throttle drivability.

If that's the extent of ones capability to adjust fuel injection, you should probably leave your fuel injected bike alone.

I'll get to 'why the set-up procedure is important' in the next subject.

Another is air-by-pass screw adjustment;

It is common for people to think that the idle air bypass screw setting is a specification. It's not, it's an adjustment for the idle speed or, in the case of the MV, to synch #1 throttle blade with #2 and #3 with #4.

Chips and Maps

The assumption that a chip or a Dynojet map will solve all your problems is optimistic at best.

The vulnerability lies in several areas.

First, is fuel pressure; stock fuel pressure regulators have a fairly wide variation, Harley-Davidson specs from 3.75 Bar to 4.25 Bar as the fuel pressure. That represents a plus and minus variation of 3.3%. Fuel pressure variations have the same percentage effect at the WOT and the idle ends of the map.

Second, is engine performance variation; this is probably less for liquid cooled engines than for Harleys, but there is the potential for at least a couple percent plus and minus. Most of that effect is at the top end of the map, however, idle can be effected.

Third, is TPS set-up; (I told you I'd get to it!) if you are going to use an existing map, you have to have some common starting point. TPS adjustment is that. This will have the greatest effect at the lower (idle) corner of the map, which will have a large influence on the next variable.

Fourth, is idle mixture adjustment; this compensates for small variations in an engines air requirements at idle. It compensates for air by-pass differences from one example to another. Idle mixture adjustment changes the voltage of the entire map by the same amount, this means it has a larger influence at idle and a small influence at WOT, the same as TPS adjustment.

Fifth (through infinity), is any change in cam timing, exhaust configuration, port casting, variation; Fortunately, there is a limit to the aftermarket equipment available for the MV f4.

Trying to chase any four variables will make it nearly impossible to solve your problems without completely re-mapping every point!

Therefore, because I can create an entire map, I don't need to worry about these variables, but you do! Because I do try to do a standard set-up, there is a chance that, if you do the same set-up, the chip I made for one bike might work for yours.

I developed the chip for Michael Shea's '99 F4. I didn't do the complete FI set-up procedure (shame on me) because the information wasn't available. I had to use the Ultimap diagnostic software to determine if the TPS was set anywhere 'in the ballpark'. It was set at something like 1.6 degrees, which turns out to be just right.

The size of the throttle blade and the displacement of the cylinder means that it should need a low setting like that to supply the correct amount of air for idle. A larger cylinder displacement would require a little more throttle angle at idle.

I called Todd Fischer,  who works for the local MV dealer, to ask about the set-up specs for an MV. He couldn't find any information on the subject and didn't get much help from the distributor, so I asked Brad Black, of Moto One.

A reminder

Just in case I forgot why I have my particular opinion on the subject of TPS set-up, Mark Turczyn is trying to get his 984 engine to work better.

I built the engine 5 or 6 years ago for John Hoppers. Mark bought it from John, and has since had Bruce Meyers rebuild it. Mark has known since he pought the engine that the TPS set-up is way off, and has lived with it. He did try to do a proper set-up (at my encouragement, I think) but it doesn't even start when he adjusts it correctly.

Since I did the work as a sponsorship (along with some parts) I didn't take the time to do 'the set-up'. As I stated earlier, since I have the software I don't need to do the set-up. The bike ran great with the map I created.

Now that the engine has changed, even if in small increments, it needs to have the map changed and Mark doesn't have a good starting point.

Now I wish I had done it right the first time.

This is one of the many reasons I say; 'I'm an idiot!'

About MV TPS set-up, from Brad Black

Here it is, in total, right from the E-mail

just the same as any 1.6/1.5m bike really.  just a bit more fiddly.  so, at risk of telling you how to suck eggs (and a good way to get out of cutting pastry circles for mini quiches - it's my mum's 60th on friday, altho i've done the white chocolate mango mousse for tomorrow - and away from mink deville) here goes:
undo the throttle cable bracket at the tb so the cables are totally slack.
the idle stop screw you get to from the front, so you need the airbox off for this.  wind it out a ways (like my american?) so the throttles are fully shut.
wind the balance screw so the lh pair open a little more - ccw i think.  this just lets the rh pair close fully.
set the tps to 150mv with the throttle blades shut.  we use the mathesis for this, so i have no idea which wires do what.  same as ss/m at the tps.  16/30 at the ecu?
wind the throttle stop screw back in to give 295 - 300mv, which is the idle setting.  the spec is 1.5 to 1.7 degrees if they have a mathesis handy.
balance the throttle left/right pairs (with all airbleeds full in) using vacuum from cylinders 2 and 3.  getting someone to hold the tank up with it all plugged in and running is the easiest way to do this.  you can get to the balance screw quite easily from behind.
set the balance and speed at idle with the air bleeds.  the spec is 1100 rpm and 4 -5% co with the thermo fans on.  the "thermo fans on" bit is important.  i tend to idle them a little on the high side, and at the rich end.  stops them stalling on overrun/clutch in.  altho too rich and they run funny.  and backfire.  man does that make the (expletives deleted.) (Editor)
something we got told is that you need to be very careful with oiling air filters.  clean them and just spray over lightly with filter oil.  too much oil really effects low speed running i'm told.  i think because the numbers are so small at idle that the trimmer acts very quickly, so the variation from lean to rich is quite quick, exaggerating the low speed wackiness.
that's all i can think of, as i would do it.  no tricks.

Brad sent a further explanation of how he zeroes the TPS. It follows.

when you look at the throttle bodies from behind, there are the two screws between the left and right throttle pairs.  the screw on the left is the balance screw for the pairs, the screw on the right is the idle stop screw.  this isn't the screw i back off when doing the tps setting tho.  i don't touch this one.
the screw i wind out to close the throttle plates is the one at the front of the throttle bodies, which the idle stop screw visible from behind rests on.  the screw at the front is "sealed" with yellow paint, so i just dig all that out and wind it out.  think it's a 2.5mm hex piece.  the reason for using this front screw is that the idle stop screw at the rear usually doesn't wind out far enough to let the throttle plates close fully.


The only thing I have to add, is that I added a couple degrees of ignition timing at idle to this chip, because they are pretty unstable at idle with the typical timing. With this change, the engine will idle reliably with a leaner idle fuel setting than the 4-5% Brad has found with the stock maps.

To Continue

For best results, you aren't even close to done.

Once the TPS is set, the bike should be put on the dyno and have the fuel pressure adjusted for best power. That would be around 13.5:1 with a Dynojet A/F ratio meter (it is really an oxygen sensor, so the A/F ratio is roughly implied rather than directly indicated.)

After that is done, as the idle A/F ratio has moved with the pressure change, re-adjust to 14:1 on a Dynojet, or 2.5% CO if you have a 1, 2, or 5 gas analyzer.

Finally, the chip is FIM compatible, with an Ultimap (formerly FIM) Hand Held Terminal or the new Ultimap software, it allows adjustments in 7 zones. However, you will not be able to add any fuel from 11,000 RPM up because the injectors are at 100% duty cycle from 11,000.