Monster S4R idle issues when fans come on. Please Help!!!

[eburns996]

Hey everyone, fairly new to the ducati world but not as new when it comes to working on my own machines. I am having an interesting issue with my 06 s4r. Seems to be every time the fans come on(225 degrees F) my idle gets all choppy and the bike doesnt want to run until like 4k rpm. As soon as the bike cools down the issue goes away. Also will have some throttle surge if this happens more then once. Does anyone have any insight? My dad has an 06 s2r so i swapped rectifiers with him to see if that would solve the problem and it did not. Any insight would be appreciated. 

[Speeddog]

Hmmm.. that's a new one.

[S21FOLGORE]

How "new" is the S4R to you?
How long have you been riding that thing?

The first thing you should do (if you haven't done already), is to check the coolant level.
(Also, do you know who did the last coolant change?
Because the coolant filling method described in (genuine) Ducati's service manual is WRONG.
If you follow the manual, you'd end up not having enough coolant in your system, which will cause problem.)

(I wrote about it years ago.

http://www.ducatimonsterforum.org/index.php?topic=56984.0

Yes, the thread is ruined by photobucket. I think I really should fix this thread (I mean this coolant change thread in tutorial section).

Anyhow, ... start from there.

[Speeddog]

Does the idle get choppy *exactly* when the fans come on?

[eburns996]

Hey, thanks for the response. Ive had the bike since April. Put around 2-3k miles on it and then tore it down for a valve job. So i was last to change coolant and its full. I dont know the filling method you are referring to, but to my knowledge you fill the rad and bleed all the air out right? Yes, idle get choppy right when fans come on and is pretty much fine when they are off. This is why I first checked the rectifier.

[Speeddog]

Hey, thanks for the response. Ive had the bike since April. Put around 2-3k miles on it and then tore it down for a valve job. So i was last to change coolant and its full. I dont know the filling method you are referring to, but to my knowledge you fill the rad and bleed all the air out right? Yes, idle get choppy right when fans come on and is pretty much fine when they are off. This is why I first checked the rectifier.

Sounds like when the fans come on it's pulling the voltage down on the ECU or fuel pump or coils or injectors.

Best to examine the wiring diagram and see which parts it might be effected.

[RB]

Sounds like when the fans come on it's pulling the voltage down on the ECU or fuel pump or coils or injectors.

Best to examine the wiring diagram and see which parts it might be effected.

Thanks for the responses folks, my son and I have been scratching our heads over this for a few months now. we did notice a burned connector on the rectifier connector.
Anyone know if the LT Snyder book explains the Stator test? I'm at work and the manual is home.
Also,
are there any workhshop manula links for the 06 S4R? I have the s2R, but I haven't been able to find the S4r.

Thanks
RB


Storing this quote and link for reference
http://www.ducatimonsterforum.org/index.php?topic=68426.0

snip...
.Disconnect the connector from the stator to the regulator.  Run the engine at a speed of 2K RPM.  With an AC voltmeter measure across all three wires, two at a time.  If you read 28-33 volts all is good.  While you are there check the condition of that connector.  If bad, replace with one of better quality or eliminate.  You must also replace any burnt wire.  If good, clean and pack with dielectric grease.  Often that connector is the cause of your problem and a contributor, if not spotted, to component failure.  Reassemble and retest.  You want to see 13.5 - 14.5 volts at 3K RPM. 

[ducpainter]

It's available from duc.nu for short money as a pdf download... http://duc.nu/?model=monster ...scroll down.

[RB]

^^^

thanks!!

[Speeddog]

Check AC votage across all 3 possible pairings of the yellow stator wires.

At idle should be 16-ish VAC, and get over 50 by 5k rpm or so.
It can get up to 100VAC, just so you're aware.

[Speeddog]

Oh, this too:

http://bradthebikeboy.blogspot.com/2012/11/charging-system-diagnosis-procedure.html

[RB]

Thank speeddog he measured voltage across the stator and it looked good so he cut the bad connector out and crimped it for now. Bikes runs slightly better. We will check the link out you posted thanks
RB

[Howie]

Sounds like you are in the right direction.  You might still have voltage drop in the charging circuit.  This includes simple things like dirty battery cables or poor ground.  Load test the battery as well.  The fans are a rather large draw.  Check voltage at the ignition coils when the fans come on as well.

[booger]

In stock condition, these bikes need electrical remediation pretty badly. I had weird problems too, like the bike shutting off at random, all cluster lights lit up. I knew what it was, no troubleshooting needed. Just replaced the rectifier with a MOSFET unit. They all do the same thing. You will continue to have issues with the stock item I'm afraid, because it's universally accepted that they are garbage.

I also installed a Motolectric starter circuit wiring kit and a Shorai lithium. These are solid upgrades, no filler. I like to be able to depend on whatever I'm riding to not break down, also to not catch fire or whatever. But maybe that's just me.

[Stuka Pilot]

I would isolate each fan one at a time to see whether the fan itself is drawing too much current, then work through the system via elimination.