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Discussion Starter #1
My F4 is quite sluggish below 6000rpm, above that its fine but idles and starts ok.

I'm in the process of getting the injectors sent away and serviced, that may be the problem, maybe not, but after issues ive had with perished fuel tank hoses there is probably crap in them.

Anyway, the confusing thing, while I was stripping the bike down to take out the injectors, I noticed the #3+#4 injector feed wires which are marked 3 + 4 were the wrong way around, so I switched the leads onto the correct injector, fired the bike up and took it out the road for a test run.

Now the bike started up and idled fine, but to the best of my knowledge its running the same, below 6000rpm the same and above the same.

My limited knowledge is telling me that switching the leads should make a difference to the running of the bike as the injector would be squirting in fuel at the wrong time???

:confused::confused::confused:
 

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I am not completely sure, my knowledge is most about the Brutale. Does your bike have a 16M ecu? Anyway i think 2001 F4 does not have sequential injection and it does have batch fire injection so it squirts 1+4 and 2+3 at the same time (not timed in relation to the combustion cycle, it is crank angle timed i think). So if the connectors were marked correctly you set them back to as intended. If they were marked incorrectly you set them as unintended. If they are wired as unintended fuel atomisation might be slightly different than cyl 1+2. And the 2 cylinder might run slightly richer or slightly leaner. I have no idea of how much richer or leaner. You could double check by lifting the tank and take airbox off, start the motor and see if 1+4 and 2+3 squirt at the same moment. You could also multimeter the injector connector and ecu connector pins to see if 1+4 lead to the same ecu pin and 2+3 lead to the same ecu pin.
 

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I have pretty much the same bike (2000 model). I'd say mine is pretty much the same. From 5k to redline it pulls like a frieght train. Below that it's vastly different. What's especially noticable is the hole at 4k.

I think you're on to something by cleaning the injectors. My bike sat for the past 4 years and had 3,900 miles when I bought it...over an almost 20 years span! The more i ride it, the better it gets on the bottom end...but it's still not linear. That 5k-6k blast of power feels like an 80's turbo car the way it hits.

Once your injectors have been cleaned, please let me know your experiences?
 

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That 4K dip and the lack of linear power below 5K is ECU tuning. Done at the factory for emissions. There are many discussions about it within the forum.
 

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Discussion Starter #6
Thanks for replys, I had to leave home for a rushed job, I'll post up more findings when I get back in the next couple of days
 

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If you search all post using ECU Tuning, you will get 35 pages of results.
Thanks for taking the time to look up the threads (they are usefull to me) for me but i was not referring to ecu tuning in general but more specific to where the "4K dip and the lack of linear power below 5K" is discussed. Do you know where that is covered?
 

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In any thread talking about ECU tuning generally.

Teh ECU tuning in the Northeast thread covered it, but here is the original map and the tuned map for my 312R...you can see the dip and the low response below 5K.

312R Dyno Run (initial).jpg

312R afterBIG.jpg
 

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There is still a dip in the tuned map?

Was timing not addressed during the tune, or is it something that timing cannot resolve?
 

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That's as good as it gets. Timing was adjusted. The small opening settings are difficult at best.

Those that have ridden my 312R do not notice the dip or lack of power at low RPM....it is smooth as can be.
 

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?

AFR 15.5 @ 6,000 RPM.....
No wonder it's got a hole in the power band>:)
 

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Discussion Starter #15
I am not completely sure, my knowledge is most about the Brutale. Does your bike have a 16M ecu? Anyway i think 2001 F4 does not have sequential injection and it does have batch fire injection so it squirts 1+4 and 2+3 at the same time (not timed in relation to the combustion cycle, it is crank angle timed i think). So if the connectors were marked correctly you set them back to as intended. If they were marked incorrectly you set them as unintended. If they are wired as unintended fuel atomisation might be slightly different than cyl 1+2. And the 2 cylinder might run slightly richer or slightly leaner. I have no idea of how much richer or leaner. You could double check by lifting the tank and take airbox off, start the motor and see if 1+4 and 2+3 squirt at the same moment. You could also multimeter the injector connector and ecu connector pins to see if 1+4 lead to the same ecu pin and 2+3 lead to the same ecu pin.

Pic of my ecu and it looks like 16m.

Took off the air box and started up the bike but there's no way you can see the injectors working as the butterfly flaps are covering the inlets, I will leave the leads with the correct numbers corresponding to the cylinders.

Sent away my injectors today, not sure when I will get them back, but I will report any findings.

Kev.
 

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Did you try to adjust the idle CO from the trim pot?

Have you checked the CO values?

I highly doubt there is anything wrong in the injectors. Its all in the tuning, stock form its just awful!!!
 

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Did you try to adjust the idle CO from the trim pot?

Have you checked the CO values?

I highly doubt there is anything wrong in the injectors. Its all in the tuning, stock form its just awful!!!
I have to admit that I was shocked to learn / realize such a coveted bike had such terrible mapping; although, it not having dual injectors or a catalytic converter meant some trickery to pass emissions, I'm sure!
 

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Discussion Starter #19
Did you try to adjust the idle CO from the trim pot?

Have you checked the CO values?

I highly doubt there is anything wrong in the injectors. Its all in the tuning, stock form its just awful!!!
Once I get the injectors back from being cleaned/serviced and it is not running any better I will give this a try.

My main reason for getting this done is what happened because of perished internal fuel tank hoses.

https://www.mvagusta.net/forum/20-m...ls/239225-f4-750-fuel-pump-dead-injector.html

Kev
 

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Took off the air box and started up the bike but there's no way you can see the injectors working as the butterfly flaps are covering the inlets, I will leave the leads with the correct numbers corresponding to the cylinders.
I am sorry for putting you in the wrong direction, i did that one time to check if all injectors were squirting (wide open throttle) but indeed you won't be able to see if the injection timing matches.
I do think you should verify if the injectors are wired correctly. You can pull all injector connectors (number them with tape) off, pull the ecu connector off (ECU pin 5 and 22 are the injectors pins, see manual). Get a multimeter set it to resistance (Ohm) or the buzzer function if it has it. Cyl 1+4 should be connected to pin 22. Cyl 2+3 should be connected to pin 5. And offcourse injector cyl 1 should be connected to cyl 4 and 2 to 3. (This is all based on the Brutale manual but it should be the same for an F4 with this ECU.)
 
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