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Discussion Starter #1
Finally this summer I've spent the necessary time to try various combinations of tuning to try and solve the stalling problem that has plagued my 2006 910s for the last 3 years (since it was new). My bike would stall when pulling in the clutch coasting to a stop in hot weather, or when just idling at a stop light (again in hot weather). On a 90 degree day, the bike would stall 3-4 times per minute when riding in stop & go traffic. I had learned to never let go of the throttle and basically keep the throttle cracked at all times.

I had synced TBs, adjusted the TPS according to the FAQ, replaced plugs, replaced SPU, tried different gas, etc., etc. I'd done it all and nothing really fixed it. This year I started making bizarre and drastic changes to the tuning to see what made it worse. Through a bunch of trial & error adjustments, I gradually figured out that the richer I made the bike at idle the worse it got. But with the ECU trim screw fully leaned, and the air screws fully leaned, and my power commander fully leaned at idle, etc., etc., it still was stalling.

So for kicks and giggles, I decided to "lean out" the mixture at idle by purposely misadjusting the TPS sensor. Now according to the FAQ on setting the TPS, the "correct" setting is 150mV with the TBs fully closed an slightly jammed. The FAQ also says that most Brutale's come from the factory at around 90mV when closed, and so you usually have to increase it to 150mV. (For the record, mine was always at 150mV).

So I figured I'd set my TPS to be 50mV with the TBs closed, thinking that mis-adjustment would cause the ECU think that the TBs are more closed than they really are, which would make the ECU call for less fuel, and therefore make things even leaner especially at small throttle openings. Poof! Bike has been running almost perfect for over a week now. I say "almost" because every once in a great while it still hiccups, but it has never stalled since.

So against all recommendations, the correct setting for my TPS is roughly 50mV with the TBs closed and jammed. All the other Brutales on the planet apparently like it set to 150mV. Go figure...
 

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Weird thing. But good for you to have it solved. Maybe someone else with the same problem can try it out too.
 

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Well....I gather it doesn't stall anymore.!
 

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Discussion Starter #7 (Edited)
how does it run with the TPS so off from the recommended?
it runs eff'n perfect! i may even try 25mV on the TPS to see if i can get the last bit of hiccuping to go away, but i'm hesitant to touch it since it's never run this good before. Keep in mind the TPS setting has the biggest affect at the smallest throttle openings, and has progressively less impact as you open the throttle more and more. IOW, say my TPS is off by 0.5 degrees-- well, 0.5 degrees is a big difference in air flow when the TB is almost shut, but 0.5 degrees is only a small difference in airflow when the TB is significantly open.

the "hiccup" i refer to is when the mixture ignites back through the intake valves and up into the throttle bodies, causing the intake to lose vacuum and the engine would skip for a rev. the hiccuping is also the cause of the stalling (when you got a really bad hiccup or two hiccups in a row it would stall)
 

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it runs eff'n perfect! i may even try 25mV on the TPS to see if i can get the last bit of hiccuping to go away, but i'm hesitant to touch it since it's never run this good before. Keep in mind the TPS setting has the biggest affect at the smallest throttle openings, and has progressively less impact as you open the throttle more and more. IOW, say my TPS is off by 0.5 degrees-- well, 0.5 degrees is a big difference in air flow when the TB is almost shut, but 0.5 degrees is only a small difference in airflow when the TB is significantly open.

the "hiccup" i refer to is when the mixture ignites back through the intake valves and up into the throttle bodies, causing the intake to lose vacuum and the engine would skip for a rev. the hiccuping is also the cause of the stalling (when you got a really bad hiccup or two hiccups in a row it would stall)
Sounds like you're compensating for a bad injector design (bad at idle fuel flow rates). Glad to hear you came-up with something that works though; good on ya! A stalling bike is an unsafe machine.
 

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Thanks for the info, I might try that the next time I everything apart. Here's a thought, if most bikes come a 90mV maybe it's the correct setting versus 150mV which everyone believes it is.
 

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I have the same problem intermittently with mine as well. I was at Fast By Ferracci telling the service manager about it when Eraldo Ferracci himself walked up and suggested that the engine was not running lean enough. Maybe I should take it over and let him adjust it "properly".
 

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Discussion Starter #12
i wish i had an exhaust gas analyzer that could give me AFR readings with an O2 sensor. then i would have some idea of where the engine is running at different RPMs and throttle positions. but they're several hundred $$$ for a good one.
 

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Call them, don't order online. their amazon price is 259 and they will equal it over the phone.
 

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Hummm Toyota is recalling cars for engine stalling. Seems MV should be doing the same.......
Mine suffers from this same thing. It's almost as if someone is just reaching over and hitting the kill switch. :wtf:
 

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Discussion Starter #18
ok i bought this A/F meter-- nice little unit and seems to work well. and the verdict is... drum roll.... when idling, my bike is running *super* lean with an A/F ratio of about 25:1. as soon as you go off idle and make the RPM "jump" to 2200, the mixture immediately goes to 13:1. recall there is no throttle position that gives you an RPM between 1300 and 2200, instead it just jumps from idle to 2200. well, there is no A/F ratio between 25:1 and 13:1, it jumps to 13:1 in perfect unison with the jump to 2200 RPM.

this is both strange and expected. i've purposely leaned out my idle mixture because the leaner it is, the less it stalls. so the fact that A/F is super lean 25:1 at idle isn't that surprising. what's strange is that the bike stalls frequently if the mixture is any richer than 25:1 at idle. even at 25:1 i still get a very rare hiccup at idle (which is the precursor to stalling) where the mixture ignites back up through the intake manifold.

what do you think? got any ideas on what's going on here?
 

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Ok sorry I know I am 3 years later than the last reply...

First of all, sorry for my bad English

I've been reading this thread with an open mouth. This is exactly the same problem i've got with my 2004 Brutale 750. It has riden 17500 km
I've been doing all the maintenance myself with the free Marelli 16M software from Adam Colley. See his thread about this.
- I connected my laptop to the MV and adjusted the TPS at 1.7 degrees.
- I adjusted the CO% with my trimmer in the 16M ECU to 4.0%. Manual says it has to be between 3.0 and 4.0%. At stock it was full lean!!! What the hell...
- with Adam's software I am able to modify, tune myself the mapping from my bike. This is only for the fuel mapping but not for the timing advance. Tickover was slightly low at about 1050 rpm so Adam has changed it to 1150 rpm.
- I balanced the throttle bodies with my Carbtune. They are all about 1 1/4 to 2 turns out (to the left from fulle close).

Just made a nice ride. Stalled only once at pulling the clutch when approaching the stopping lights. mmmm Ok it was only once in 200kms but still I dont want to have this happen, its scary.
The other annoying thing I cant get rid of is the hiccup or stuttering.
This is exactly how "ridesideways" describes it:
"i still get a very rare hiccup at idle (which is the precursor to stalling) where the mixture ignites back up through the intake manifold"

I again connected my Carbtune to the MV to see if the air bleeds were off or different from each other since my last adjustments. They were still ok but.... when the hiccup occured when turning around at idle I could see that the Carbtune vacuum went back to 0 at cylinder 4 while the other 3 cylinders were holding the vacuum at the same position. This occured a couple of times in the 15 minutes I was watching it.

I think this can be 2 things therefore it is only a hiccup on cylinder 4:
1) its time to get my valves checked. I dont really think this is the issue because as I read the forum it seems nearly everyone has this issue. I dont think everybody has a wrong valve!!
2) maybe the fuel injector is giving a bad spray and has to be cleaned or put a new one in

Another thing to know is that 2 years ago I put in a new SPU unit. The old one was defect/broken. I put a new latest version inside that works fine.
 

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ok ,understand what you are doing,now 150mv or 200mv or 90 mv or whatever you set it at is up to you,when using vdsts software and you then reset the tps it will always show 2.3 degrees every single time.what i am trying to say is close the throttle bodys fully shut manually, hook up your vdsts software hit tps reset and it will show 2.3 degrees or whatever your bike is maybe 1.9 degrees.now just wind in the idle screws and watch the degrees rise I set mine at 4.6 degrees,when done reset the tps again with the software and it will show 2.3 degrees.so what you can do is set the throttle bodys at any opening ,i am experimenting from 2.3 to 2.6 degrees to see the effects on the bike.

in other words the software fools the ecu ,regardless of what position the throttle bodys are set at. give it a go guys,but you have to do this manaully using the idle screws.2 of them .

cheers eddy
 
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