M900ie coughing through intake

[sdl2112]

Hi all,

I have a 2002 M900ie, had it since new.  I recently took it in for maintenance at the dealer including a Rexxer remap to help low/mid RPM response.  I have Arrow slip-ons.

The issue I'm having now is coughing through the intake at light load between 2k-4k RPM.  It is becoming very annoying to the point I don't want to ride.  It wasn't doing this before the remap.  After the remap I noticed the problem, took it back, they retuned and said there was a small leak between the head and intake manifold…but same results.  They went back to the stock tune and said it did the same thing. They say the vertical cylinder is out putting high hydrocarbons levels.  I'm pretty confident in the mechanics but they are at somewhat of a loss on what the issue is. They suggested it may be the valve seats or guides.

Anyone have similar issues?  Any suggestion on what it might be?  Thanks in advance.

-Scott

[Speeddog]

What was included in the "maintenance at the dealer"?

Did it do that before you took it in?

It ran OK with the Arrows before you took it in?

[brad black]

while i have no explanation for it, it seems to me that the rexxer 2002 m900ie map is leaner than the std.  8% ish maybe  from memory.  there's no offsetting factor that i know of.

[sdl2112]

What was included in the "maintenance at the dealer"?

Did it do that before you took it in?

It ran OK with the Arrows before you took it in?

Thanks for your reply.

The other maintenance included valve service, cam belts, fork rebuild, new tires,  the tune also included a K&N filter, previously a std paper filter.

It wasn't doing that before but it was running rough in the low RPMs I think typical for our bikes.  This is what I had hoped the Rexxer tune would help.

I had the Arrows on essentially since new and we always had a hard time with the tune...it was running just OK...Just to note that with the Rexxer tune it does run better except for the very annoying times it coughs.

[sdl2112]

while i have no explanation for it, it seems to me that the rexxer 2002 m900ie map is leaner than the std.  8% ish maybe  from memory.  there's no offsetting factor that i know of.

First thanks for the reply Brad...I think I read every article pertaining to my bike on your website...very informative.  I think it helped renew my interest in my bike 

This is the only Duc I have owned so I'm a little unsure what to expect.  Hope you can help answer.  First should this cough problem be fixable?  I sure hope so.  Could it have something to do with the heads?...The mechanics offered to inspect (remove) the vertical head for 2hrs labor...does the high hydrocarbon levels tell anything.  I could probably talk with them for more details.

I've tried placing the old paper filter, removing the std airbox cover with little to no effect.  I marked the before and after retune air bypass screws, then proceeded to adjust then from all the way closed to way past the tune location...hard to tell a difference.  It also seems the coughing is worse when the engine is at temperature 200-230F.

Any suggestions welcome

[Howie]

It could be a head problem, but extremely unlikely and removal to determine that is not needed.  A cylinder leakage test, valve clearance check and checking valve guide wear with the head on would do.  Lean misfire would cause the high HCs, as well as popping in the intake.  Air bleed adjustment will do nothing for mixture at 2-4K rpm. 

Fix?  Assuming Brad Black is correct about the Rexxer map (very safe assumption) your cure would be a better reprogram or dump the Rexxer, go back to stock, and go the piggy back route or going back to a closed air box.  On your vintage Monster, exhaust after the crossover makes little difference in tuning.

[koko64]

Interesting.

My brother used a modification specific FBF map on his PCIII for a 900ie Hi comp, open A/B, pipes. Even with open A/B, the FBF map reduced fuel down at low rpm (it added fuel later in the rpm range) and cleared up some lumpy/rough running there. The map was very close, so he was lucky.

The bike always was pretty rich with the stock ECU at low rpm and idle, even after a thorough tune. I'm guessing Rexxer must have tried to address this but cut back a little too much. I would give the ECU back to them for another (gratis) reflash.

[jduke]

Download GuzziDiag, order the cables and hook it up and read your trim setting. On my 01 M900Sie I could increase the CO with the software. My reading was 15, I increased it, test rode it, increased setting, etc. until bike ran strong. I think my final setting was 40.

[brad black]

2002 is 5.9m ecu, they ran much worse with pipes and std ecu than the 00 - 01.  i've never seen any other reflash map than the rexxer, except for the one i have developed.

the idle trimmer on the 5xm ecu is 3.6 times stronger than the 1.5m, so +40 is a lot on a 5xm.  +40 to me on a 02 is something wrong.

afaict the rexxer map is leaner.  dunno why.

check for voltage drop at the horizontal coil.  i had one that was inconsistantly up to 2v below battery.  actually had a few issues with m400ie in the same way.

you need to go through everything and make sure the tune basics are right (fuel filter, tps setup, etc), then look for an something wrong.  the one i did with the voltage drop is much better with battery voltage relayed to the coils (and a new voltage reg and reg - battery wiring) than it was previously, but it's better again with my map.

high hc is usually way too rich (co can be misleading if very rich) or bad valve sealing.  give it a leak down.  or wind the air bleeds out while measuring and see if it cleans up.

[sdl2112]

Thanks again for the replies...

Here's what I have found so far.

I checked input coil voltage with an o-scope.  With a 13.6V battery voltage I saw 12V peak pulses to each coil.  They both looked identical.

Preparing for a compression and leak down test I removed the spark plugs and noticed the vertical plug took no torque to remove.  It felt like it was hand tightened with a socket maybe.  The crush washer wasn't crushed.  The front horizontal took a little torque to remove but the crush washer was maybe half.  I know plugs require little torque but this was not correct.  I torqued properly but the problem still exists.  Hard to tell if its any better.  It's been cooler here lately so engine temp is not as high so it's hard to tell if/when things are better.

I performed a compression test at ~135F oil temp.  Throttle wide open Vert cylinder = 120psi, Horiz cylinder = 125psi.  I added about a teaspoon of oil (read somewhere you could tell if leak is rings or not)  to each cyl and it went up ~2psi each.

I performed the leak down test with 50psi at the same oil temp.  I tried 100psi but the Horiz cylinder always turned the crank.  I saw the same results at 50 vs 100psi on the Vert cylinder so I think the results are ok.  Anyway the Horiz cylinder measured 7%, the Vert cylinder 8%.  I have a borescope and both intake valve look nearly pristine...the Vert a little more discoloring than the Horiz.

Btw the bike has 16k miles...never abused.

[brad black]

a leakdown test tells you what is happening in the engine, but you'll need to run it and get rid of the oil you put in it to get a clear answer.  the crank only turns if it's not at tdc.  the slot on the flywheel should be pretty accurate.

check the voltage at the coil +ve with a multimeter, it's just a 12v supply.  if battery voltage is 13.6 and you've only got 12v at the coils that's a 1.6v drop.

[sdl2112]

I tried many times at TDC lining up the mark and visually looking at the piston.  Tried nudging a little here and there.  Anyway I got the same result on the other cylinder at 50 or 100psi so I think it's close.  Part of what i was looking for was how much difference there was between cylinders. 

Btw, my test description was out of order...I did the leak down test prior to the compression test so there was not any added oil to the cylinder.

I checked the voltage at the coils with a multimeter as you suggested.  This time I ran it at about 2k rpm where the regulation voltage leveled off at 14.58V (is this a little high?).  Both coil inputs measured 13.23V, a difference of 1.35V.

[ducpainter]

The 14.58 volts is a little high by Duc standards. Does it go over that as the revs go higher? If so you may have a regulator issue.

I think Brad's point is you seem to have a large voltage drop to the coils, which while may not be the root of your problem, is not right.

[Howie]

14.58 is high, how accurate is the meter you are using?  Maybe I am not understanding something, but the voltage going to the coil is voltage amplified by the module when the engine is running, no?  Is the oscilloscope an automotive type?  If so, you can measure available voltage to the plugs by pulling the connector away from the spark plug and watching the voltage increase.  Do not increase the gap enough to cause misfire, since you can damage the expen$ive ignition module.  You should get over 18K volts.

[sdl2112]

The 14.58 volts is a little high by Duc standards. Does it go over that as the revs go higher? If so you may have a regulator issue.

I think Brad's point is you seem to have a large voltage drop to the coils, which while may not be the root of your problem, is not right.

The 14.58 is pretty much the max...revving doesn't go higher.

I agree with the voltage drop.  I think it may just be the design.  It looks like both injectors, both coils and the fuel pump are on the same circuit.  I can't see how it's actually wired...star point or some daisy chain but the wire looks no bigger than 22awg....  I work as a power electronics engineer for my day job so I'm very familiar with voltage drops...I just hope they considered that in the design or there could be bad connections somewhere.

btw howie...I'm curious how do you check for valve guide wear with the heads on?