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Discussion Starter · #1 ·
I just received my new Zero Gravity "tall" touring shield today. Just had a chance to install it, and it seems to make some difference in wind deflection from the stock model. I also just installed a FIM 161 chip that also arrived today. I don't have slip ons yet (still looking for a let of carbon fiber) but the chip by itself seems to be a big improvement (maybe a little rich but not awful). Flipping the throttle in first nows makes the front end a lot lighter feeling on the pavement compared to the stock chip. It also seems to pull better midrange on. I can't wait to try it with slip ons and a K & N filter. Hope to get out over the weekend for a solid ride. Peabs
 

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I'm assuming you have a ST2 based on the FIM 161 chip??? I believe the 161 is solely for the ST2. Anyway, if everything is dialed in correctly you are going to notice a wonderful difference in your bike. I put the FIM 161 chip in my ST2 and personally site it as the one best modification I did! My local Duc dealer says that the FIM chip is "adjustable" where as other chips are not which is why you pay so much more for it...mine cost $180.00 vs the DP or FBF chips at considerably less $$$ . Enjoy!
 

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Discussion Starter · #3 ·
Hi Blue ST2, Sorry, I forgot to mention that the bike is an ST2. The FIM 161 I picked up on Ebay, new in the package for $128. From what I had read, it was the chip I wanted to try. So far with a 10 minute ride, I am pleased. Hopefully my grin will only get wider. Thanks
 

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Peabs:

The 161 will get rid off the flat spot around the 4000-5000 RPM.

You should note when you replace the chip you should also dial-in the fuel trim. It is an electrical pot next to the chip. The best way to do that is to connect the bike to a CO meter and measure the CO content of your exhaust. There is a better than 50% chance that your bike is running WAY richer than before which will also affect your fuel mileage.

BTW, the trim-pot does not have a mechanical stop so adjust it gently. If you go hard on the adjusting screw you can break it. The total range is about 270 degrees. CW will lean the mixture and CCW will richen the mixture. If you decide to try it, use a plastic tip screw driver and ground yourself so that you do not accidentally cause a static arc.

-Fariborz
 

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st2lemans said:
Never had one. Maybe US bikes have different chips than European bikes?

Tom
Don't know about that either, but my ST2 had a bad "spot" at 3800 RPM that felt like the ignition was breaking up or fuel delivery wasn't right causing some roughness or mild sputtering. It used to pop and fart out the airbox...more so when riding two up (under load). I had it brought to the dealer three times to trim the mixture which helped but didn't completely cure the lack of response I was feeling. I dropped the FIM 161 chip in and the engine smoooooothed right out with not flat spots, breakup, or popping noises...much better responsiveness and throttle feel.
 

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BlueST2 said:
my ST2 had a bad "spot" at 3800 RPM that felt like the ignition was breaking up or fuel delivery wasn't right causing some roughness or mild sputtering.
The 161 reduces that, but doesn't eliminate it 100%. On the FIM website, they even state that that cannot be 100% eliminated, as it is a computer design problem and not a mapping problem.

FIM FAQ said:
8 - My Guzzi/Ducati has a misfire at 3400 rpm on steady throttle - why?

Firstly, some background on the Weber 1.6M ECU as used on 1100 Sport and 916 Biposto.

The controller is the Motorola 68HC11, a chip developed ten years ago for injection applications. Delco ECUs also use this chip. Although it's only 8 bit it has 16 bit math, and is found in many other applications as well as injection.

The timing is derived from one sensor at cam speed. On Ducatis this is the cam drive jackshaft, on Guzzis it's in the cam drive in the timing chest. The sensor collects 48 pulses plus 2 gaps (known as missing tooth triggering) totalling 50 intervals, for a resolution of 14.4 degrees crankshaft per pulse. The ECU derives both engine speed and phase from this sensor. By phase I mean the point in the firing cycle of each cylinder.

Previous Ducati and Guzzi models used a processor which took 2 triggers, one directly from the crank at 90 degree intervals, and one phase trigger which took one pulse from the cam drive, ie once per two revs, to identify engine phase.

Herein lies the first, and most common, problem with all of the late model bikes. The ignition timing is derived from a half-speed sensor, which is prone to mechanical backlash... this means that under certain engine conditions, the gear which triggers the sensor is wobbling slightly between drive and trail on it's driving gear. In other words, the advance is calculated from an interval which can vary depending on mechanical slop in the cam drive.

Two factors affect this. First, the period immediately before the relevant ignition point is used to calculate the degrees of advance as a fraction of the overall period of 14.4 degrees. So variance on the interval produces variance on the fraction. Secondly the computer also calculates RPM from the same interval. The ECU has a sophisticated acceleration / deceleration algorithm which anticipates what is happening next, based on the history of recent pulse intervals. If the pulse intervals are getting shorter, the ECU assumes acceleration and modifies the ignition timing to accomodate a predicted shorter interval in the next pulse. If the pulse intervals are lengthening then the ECU assumes deceleration, and also trims the advance.

Now, if the interval is changing from shorter to longer, PULSE BY PULSE, the ECU is buggered because it cannot tell if the engine is in acceleration or deceleration. So we have a misfire situation. This is precisely the kind of operation you mention where your engine stumbles on cruise at 3400 or 3800 rpm. As you said, the engine pulls fine on drive, but if the engine is slopping around on constant throttle, the ECU can have difficulty working it all out, and you get a stumble. In my opinion this stumble is a "wild card" ignition pulse, maybe 10 or more degrees out, as the ECU tries to figure out an engine mode. You would also observe that it only has one bad ignition pulse usually, which often completely stops the engine. We have been observing this phenomenon since 1995 when the 1.6 was introduced on Ducati 748SP models.

The funny thing is, the rpm point at which this happens is different from Guzzi to Ducati, even from 1100 Sport to Daytona RS. But there's the rub, because each engine has different bore/stroke, different resonances, and each individual engine is microscopically different to the last. That's why some bikes seem to runs flawlessly, and others of the same type stall at every traffic light.

Further, the previous ECU did not exhibit this fault to any great degree. Remember that this ECU used an RPM (and ignition) trigger which was on the crankshaft, with no possible backlash. The only time this fault shows on the older ECU is when the main bearings are failing, and the crankshaft is wobbling on the bearings. This also produces a sequence of short and long pulse, which confused the ECU in a similar fashion. This I have seen dozens of times, with disbelieving customers who refused to listen to me when I said their misfire was caused by failing main bearings! It proved true in almost every case. (or crankcase, because a broken crankcase does the same thing by allowing the crankshaft to wobble in the cases).

The solution.. there is no solution yet. Again I am treated with disbelief when I suggest that to get rid of a misfire you split your 916 engine and re-shim the jack-shaft end float, and check the play on the jackshaft bearings. "But it's the computer" they cry.

A final comment on this misfire problem. Both Ducati and Guzzi produced a model which switched from the P8 ECU to the 1.6M ECU in mid-production. The 1994 916 Strada (solo seat) used a P8 ECU, and the Biposto (95 - now) uses a 1.6M. The engine spec did not change at all when they swapped to the new ECU, but suddenly the bikes had a misfire. Some people even traded their Stradas on a Biposto, only to find they had exactly the same power, but with an added misfire. The same applies to the Guzzi Daytona Racing (P8, C cams) and the Daytona RS (1.6M, C Cams).

We are still trying to find a fix for this in software, but I confess I don't think it is really possible. The main reason it is more prevalent on Guzzis is simply the variance in manufacture compared to Ducati.

Tom
 

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st2lemans said:
The 161 reduces that, but doesn't eliminate it 100%. On the FIM website, they even state that that cannot be 100% eliminated, as it is a computer design problem and not a mapping problem.
Tom
Wow, that was educational. That exactly how my bike felt when I bought it...stumbling at steady throttle at 3800 RPM. Thanks...now I know I wasn't crazy each of the times I brought my ST back to the dealer and said "it feels as though the ignition is breaking up, misfiring or something". They said...NO, the ignition and timing are fine it must be a fuel adjustment or mapping problem.

All I can say is that when the FIM 161 chip along with a set of DP pipes were added to my ST2, the feel of the bike was like night and day! Yes the pipes added a nice new sound and perhaps a bit more power but the feel at the throttle was very noticeable with a much more responsive engine and smoother acceleration which was why I sited the FIM chip as the one best thing I did to my bike. I love the way my bike runs now and feel it should have been in this kind of running order from the factory.
 
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