Can a bad battery cause the bike to throw codes and run rough?

[briandk]

Bike: 2013 forty eight with Khrome Werks tapered 3" and Arlen Ness Big Sucker, FP3.

On the last ride it started running rough. Idle and higher revs seem OK, but when accelerating from a stop and cruising at steady speeds it feels like it cuts out for a half second or so once in a while. After I got home I read out the codes and got a P0374 (Crank Position Sensor)

Lately it also started complaining about the sidestand when trying to start it in neutral on the jiffy stand which I read can be a sign of a bad battery.
Measuring the resting battery voltage the next day I got 12.3v which is very low, so I have a new battery on the way.

Does this sound like symptoms of a bad battery or is there more going on, like a bad CPS?

[Toejam503]

Checking the "Grounds" is a no-brainer. The worst culprit is the ground peg/terminal on the engine case.

[IXL2Relax]

When you're having issues with the electrical system, use this Sportsterpedia section about
checking the battery cables, voltages and grounds - DO THIS AS MAINTENACE, TOO:
http://sportsterpedia.com/doku.php/t...place_to_start

Be sure to do the 4 voltage tests and report the results.

Here's the SP section on the CKP Sensor:
http://sportsterpedia.com/doku.php/t...shaft_position

It certainly can cause issues.


IXL _______ >>>> My Motorcycle Chronicles Are Here <<<<
For Sportster Tech Info:
Ride On The Sportsterpedia - A Toll-Free XLForum Information Highway!

[Tomcatt]

Originally Posted by briandk

Measuring the resting battery voltage the next day I got 12.3v which is very low, so I have a new battery on the way.

Does this sound like symptoms of a bad battery...

Yes. Put in a good battery first. See how it runs and go from there. Modern electronics don't work well with low system voltages.

[sportsterdoc]

A. if battery voltage was measured directly at the battery and if the battery was recently on a charger and/or ridden some distance with normal charging voltage, then it may be a battery issue. Battery age?

B. If battery voltage was measured through battery cables, then check both ends of both cables.

C. Considering age of bike, especially if ridden or parked in rain, remove ground stud on top of trans, clean external and internal threads, reinstall with conductive (copper-based) anti-seize. This should be routine maintenance.

http://xlforum.net/forums/showthread...1784651&page=3

[sportsterdoc]

Issues with this thread were due to corrosion of the internal transmission threads for ground stud

http://xlforum.net/forums/showthread...ighlight=plane

[Andy56]

Corrosion forms where oxygen can get in. It would suggest that at some point that stud came loose for the time it takes.

When you read through the documentation from the likes of Molex the one reason that crimps work is because all the air is squeezed out so corrosion cannot form.

The 2008 and 2017 I have here have been perfect because the studs have never been disturbed.

[kitabel]

Corrosion forms where oxygen can get in

How does air get into a steel bolt in an aluminum casting thread?

[Andy56]

Read the post #6. The stud was rusty so didn't make a proper connection.

If the stud is not done up properly then it won't be gas tight. If it came loose at some point it then goes rusty. The owner does the screw up without taking out and cleaning it and you get a high resistance joint.

[briandk]

I swapped the battery and the CPS, but was still having issues. In the end most of the rough running seems to have been from an exhaust leak where the headers connect to the slipons. I still feel something that feels like a little bit of a lean surge when cruising at speed, but it's much much better. I still get a CPS code P0374 occasionally though.