F4 Running poorly at low RPMs - MVAgusta.net
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post #1 of 71 (permalink) Old 05-29-2019, 11:30 AM Thread Starter
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F4 Running poorly at low RPMs

Hey guys, Derrick here. I typically don't post but, rather spend my time lurking and gathering info. Anyway I come to you guys with a problem that I haven't been able to figure out thus far. I have a 2012 F4 RR Corsacorta that's running like shit below 4500 rpms. The only engine mods at the moment are exhaust flapper valve disconnected and Bodis slip-on. Below 4500 rpms it backfires pops and sputters and idles really low. Feels like its misfiring or running on less than 4 cylinders lol. Above 4500 it feels like the shower injectors kick in or something and the bike rips. I did some research on this forum and found a few really old posts that i'm not convinced relate to my F4. To date I've ruled out the ECU, bad fuel, fuel pump, fuel filter, fuel lines and the fuel injectors and fuel rail as well. I'm fortunate enough to have a second working track F4. So I swapped these working items to my street F4 and it ran just as poorly. Last night I pulled the plugs and inspected them and all look normal. Meaning, they don't look wet or fouled. Regardless I'm going to replace them with fresh plugs this evening. However, if it runs the same that would only leave coils and or the TPS correct? Any ideas would be greatly appreciated. Thx guys!

Last edited by ESBKLife; 05-29-2019 at 11:33 AM.
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post #2 of 71 (permalink) Old 05-29-2019, 11:54 AM
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I'd be looking for vacuum leaks. Did you swap ECUs also?

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post #3 of 71 (permalink) Old 05-29-2019, 12:04 PM Thread Starter
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yes I did. I swapped in two actually. I have a OEM MV "Race" ECU on stand by as well as the ecu from my track F4. Both had the same results.
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post #4 of 71 (permalink) Old 05-29-2019, 12:07 PM Thread Starter
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BTW, I'm following this thread as well but my problem isn't with a 312 or just at idle. https://www.mvagusta.net/forum/20-ma...ough-idle.html So not sure it relates

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post #5 of 71 (permalink) Old 05-29-2019, 12:30 PM
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Since the problem exists outside of the ECU, then you have to check downstream things.

It is Fuel, Vacuum or Spark.

How did you eliminate the fuel system?

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post #6 of 71 (permalink) Old 05-29-2019, 12:39 PM Thread Starter
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Originally Posted by silentservice703 View Post
Since the problem exists outside of the ECU, then you have to check downstream things.

It is Fuel, Vacuum or Spark.

How did you eliminate the fuel system?
I swapped the entire tank from my F4 track bike. it has fresh fuel just added this past weekend. I also swapped the entire fuel rail with injectors.

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post #7 of 71 (permalink) Old 05-29-2019, 12:43 PM
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Alrighty then! It is either spark or vacuum....you said spark plugs look good and not fouled, so I would be looking for vacuum leaks.

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post #8 of 71 (permalink) Old 05-29-2019, 12:54 PM Thread Starter
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Alrighty then! It is either spark or vacuum....you said spark plugs look good and not fouled, so I would be looking for vacuum leaks.
Now that I that you mentioned vacuum and I think about it a bit. The bike does lope at bit at idle which makes perfect sense for a vacuum leak. Thank you sir! I'll start checking the vacuum lines when I get home tonight.

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post #9 of 71 (permalink) Old 05-29-2019, 01:42 PM
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What was the last thing you did with this bike immediately prior to it starting to run poorly at low rpm?

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'07 Ducati Monster S4Rs, '07 Ducati Monster 695
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post #10 of 71 (permalink) Old 05-29-2019, 03:25 PM Thread Starter
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What was the last thing you did with this bike immediately prior to it starting to run poorly at low rpm?
That's a very good question. This bike has a history and not all of it good. But the short version is, it was being painted. The slightly longer version is, the last time the bike ran properly or ran at all was approx 8 months ago. Since then it's been with my painter. Don't get me started on why he had the bike that long, as that's another topic of conversation However, my feeling is that, in the time he had the bike, the vacuum line(s) developed a leak or cracked or who knows while sitting, or that happened during reassembly? So the bike hasn't run in nearly 8 months until recently. So I've gone through the bike (for a second time) and did all the things you should be before firing up a bike that's been sitting for a long time. Anyway, it started fine but as I mentioned before, runs like crap at low rpms.

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