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post #1 of 18 Old 03-14-19, 23:41 Thread Starter
MadMel
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MAP Problem

Hey everyone.

I haven't participated in the forum in a couple of years, but I'm still racing the 2011 675R and still loving the bike. Hi again to everyone who's still around.

I crashed at my last race meet, and since putting humpty dumpty back together again I've had a new issue with the bike. It runs fine throughout the rev range, except between about 2000 and 2500 RPM. In that range it stutters and stumbles, and will stall if I'm not careful to rev it out and slip the clutch.

It felt like a fueling issue, so I cleaned and re-oiled the MWR air filter, dropped new spark plugs in, cleaned the fuel filter and swished out the tank, and used fuel from a different petrol station. The problem still persisted after that, so I installed TuneECU on my phone (my laptop with TuneECU is long gone), did some poking around.

What I found was that the Manifold Absolute Pressure for all 3 cylinders drops to zero in the problematic rev range. Here's some TuneECU screen captures:
So I swapped the MAP sensor with the barometric pressure sensor (they're the same unit), and the same problem persisted, so I don't think it's the MAP sensor itself. All the hoses seem to be connected well.

Has anyone seen this before and solved it, or have any ideas where to look next?

Cheers,
Mel
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post #2 of 18 Old 03-15-19, 01:42
MacBandit
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Is it always an exact rpm or just in a general range? If it's a range then it could be vibration shaking a bad connection or broken wire.
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post #3 of 18 Old 03-15-19, 04:13 Thread Starter
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Hi MacB.

It seems very consistent, right around 2200 the individual MAP pressures start flicking on and off, not all at the same time. Add a hair more throttle and they all go to zero and stay there until you move out of the problem range.

When I just started the bike it took a lot of turning over before it fired. Which I have experienced before... CPS. Could a soon-to-crap-out CPS cause the MAP issue?
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post #4 of 18 Old 03-15-19, 15:06
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Quote:
Originally Posted by MadMel View Post
Hi MacB.

It seems very consistent, right around 2200 the individual MAP pressures start flicking on and off, not all at the same time. Add a hair more throttle and they all go to zero and stay there until you move out of the problem range.

When I just started the bike it took a lot of turning over before it fired. Which I have experienced before... CPS. Could a soon-to-crap-out CPS cause the MAP issue?
My cps just went on my 2012 motor, I thought it was fuel system at first, I had just refueled, until I figured out it wasn't sparking. No Spark no map pressure? It was intermittent at first then stayed broken. It never threw a code but it did fail the ohm test.

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post #5 of 18 Old 03-15-19, 19:48 Thread Starter
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Quote:
Originally Posted by t_bare View Post
Quote:
Originally Posted by MadMel View Post
Hi MacB.

It seems very consistent, right around 2200 the individual MAP pressures start flicking on and off, not all at the same time. Add a hair more throttle and they all go to zero and stay there until you move out of the problem range.

When I just started the bike it took a lot of turning over before it fired. Which I have experienced before... CPS. Could a soon-to-crap-out CPS cause the MAP issue?
My cps just went on my 2012 motor, I thought it was fuel system at first, I had just refueled, until I figured out it wasn't sparking. No Spark no map pressure? It was intermittent at first then stayed broken. It never threw a code but it did fail the ohm test.

t_bare
Thanks for your thoughts. I just checked the CPS impedance, it's 224 ohms. Not sure how far off 200 is normal for these. But I've read on here about a CPS being toast even though the impedance was ok, so it might be worth swapping it out anyway.

Forget to mention in the OP that no fault codes are showing up.
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post #6 of 18 Old 03-15-19, 19:49
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MAP is a function of the piston drawing a vacuum into the cylinder, and has nothing to do with the positive pressure going out the exhaust pipe.


Perhaps try measuring the 5v reference voltage vs sensor ground at the sensor, and see if the voltage changes vs rpm.

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post #7 of 18 Old 03-15-19, 20:19 Thread Starter
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Quote:
Originally Posted by DonTZ125 View Post
MAP is a function of the piston drawing a vacuum into the cylinder, and has nothing to do with the positive pressure going out the exhaust pipe.
??? What are you responding to?
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post #8 of 18 Old 03-15-19, 20:37
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Sorry - t_bare made the comment, "No Spark no map pressure?" to which I make my response. Sorry for the confusion ...

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Shift Sensors - Quick Shift Controllers
North American Distributor for Shifting ContRoll
=> Bolt-on / Plug-in QS kits for Triumph 675/765
=> Bolt-on / Plug-in Reverse (GP) Shift kit for Triumph 675/765
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post #9 of 18 Old 03-16-19, 00:43
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I was going to mention CPS as well when I posted yesterday but I didnít because I figured you might see some weirdness with the RPM reading in TuneECU at the same RPM if the CPS is failing. I still think you might have a power supply issue. That could be anywhere though.
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post #10 of 18 Old 03-16-19, 04:33 Thread Starter
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Thanks for the replies. I'm out of town for a few days, but will pull some wrenches next week.
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