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[jchamb]

I recently bought a 2003 Screaming Eagle Road King, the bike has the SE 103 motor, Vance & Hines Oval slip-ons and a SE air filter.  Bike had 18,000 miles when I got it, and I've put on another 800 or so.

The first thing I noticed was a rough idle, and backfires or popping on decel.  My first thought was that the previous owner put on the new pipes and air filter without changing the ECM.  I noticed that the bike had a Power Commander III USB installed also.  After a few hundred miles I noticed that I had to stop and fill up a lot.  The fuel light would come on at between 110 and 115 miles, and after about 3 more tanks the gas mileage remained at about 27 mpg.

I hooked my computer to the power commander, and found that it was programmed with the M807-194 map (103, vance hines exhaust, arlen ness air filter).  That program sounded like it should be about right.  I finished that tank of gas (again getting the fuel light at 111 miles).
Just as an experiment I loaded up a "zero" map to see what would happen.  I was watching everything very closely to avoid overheating or whatever, but the bike actually seemed to run a bit better and backfire less.

I filled up with gas, and after running 100 miles, my tank is still half full and the bike runs great!  Is this perhaps a case of the dealer installing the pipes and stage 1, and reprogramming the ECM and then the previous owner trying to improve on that with the pc?  Thoughts?

[Midnight Rider]

Your last sentence is probably a correct assumption.  PCIII is a good device, but it really needs to have a Dyno Tune by a competent tuner and not just stick a canned map in it.  At 27mpg on a 103, you're obviously running very, very rich.  On my '06 SEUC with a 103, the ECM was flashed by the dealer when I got the bike, as I had added the SE air cleaner, and SE slip ons...ran fine.  I later put Rinehart True Duals on, so got a PCIII and had it tuned by an independent shop local to my area. Ran like a top, got up to 44mpg, and the lowest was 35mpg riding hard loaded with a BSR and gear.

[grc]

Back in those days the dealers would download what was called the "Stage 1 Race" calibration directly to the ECM when doing the stage 1 upgrades.  It's very likely that is what you have, and the PC map was for a stock calibration 103, not for one with the dealer download.

If you want to know for sure, a dealer can hook up his equipment to your ECM and pull up exactly what calibration is installed.  Rather than waste the money, however, I think it would be best to apply that money to a dyno tune.  Neither the Harley download nor a canned map from the PC folks is likely to be optimum for performance, mileage, or driveability, much less for things like exhaust popping.  At least that was my experience.


Jerry

[Twolanerider]

Jerry pointing out the difference in base calibrations is an important distinction for the Power Commander and also a potential cause for the problems you experienced.  The Power Commander makes its changes on top of whatever is the current calibration in the ECM.

What that means is the Power Commander map you saw loaded in your PCIII would make the bike behave completely differently if it were running over the top of a stock ECM versus running over the top of an ECM with a Stage I download.  If, for example, the Stage I download added more fuel to match the requirements of changes to the engines and then the PCIII map did the same thing you'd be effectively adding fuel twice.  That's a simplistic rendering of what might have been going on but will hopefully explain it a bit.

[Midnight Rider]

Both better explanations of what I was trying to say in my post.   

[jchamb]

Thanks for all the comments!  Sounds like I was on the right track.

As I purchased it used (from a Harley dealer), I don't know it's service history.  I'm waiting a few hundred more miles until I get about 19,500, then I'll take it in for a complete 20000 mile service and a dyno tune.  Hopefully it should come back like new!

[Midnight Rider]

Thanks for all the comments!  Sounds like I was on the right track.

As I purchased it used (from a Harley dealer), I don't know it's service history.  I'm waiting a few hundred more miles until I get about 19,500, then I'll take it in for a complete 20000 mile service and a dyno tune.  Hopefully it should come back like new!

At 20K, you might want to entertain the thought of having the cam chain tensioners checked...it's probably early, but wear on them is sort of unpredictable.  Those are one of the few weak links on the earlier TC motors, and it's pretty easy to check them.

You've got one of the classic CVO's...enjoy it!

[Heatwave]

At 20K, you might want to entertain the thought of having the cam chain tensioners checked...it's probably early, but wear on them is sort of unpredictable.  Those are one of the few weak links on the earlier TC motors, and it's pretty easy to check them.

You've got one of the classic CVO's...enjoy it!

+1       Checking the OE cam tensioner shoes on a 2003 SE RK with 18,000 miles! Don't wait!