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[eztigersmc]

Hey everyone,

Looking for a little help here.  I have been looking over the forums to find out a solution to my problem.  I have an '03 FXSTDSE with V&H Big Shot Staggered exhaust, with Big City Thunder baffles.  SERT that was dynoed by Latus here in Portland by Mike Stegmann.  I bought the bike used recently and did some digging around to find out a little history on the bike.  Mike was kind enough to give me a copy of the SERT file.  Anyway, the issue that I am having is that my bike has a pretty consistent miss during steady throttle at any speed.  Another symptom that I am having is that while traveling at slow speed, my bike is trying to lunge ahead.  Realizing that I shouldn't lug the motor, it happens even while I am slowing down for a stop sign and riding through downtown.  I have also noticed that my MPG's are really lousy.  I put 92 octane fuel in last night.  4.1 gallons with 110 miles on the odometer.  That's 26.8mpg.  Realizing that most of my last tank of fuel was in town, I expect a dip in mileage, but that seems extreme to me. 

So, after poking around on the forums, I found some other people having similar issues.  I am hoping to come up with a list of items to check.  One thing to note, I am planning on changing the baffles out per Mike Stegmann to help with a torque dip I am experiencing.  That being said, I will dyno the bike again.  It unfortunately has to wait until after the holidays.  So here's the beginning of the list, could others help add to this?

Intake leaks
Fuel injectors dirty
EFI Map needs adjustment
Connections to injectors need attention - This one seems common
ECM faulty - Noticed after looking at the file Mike gave me, my ECM has been replaced with one from a Fat Boy at some point in time.
Fuel line leak

Thank you,

Sam

[T-Hawk]

While I didn't have the exact same issue... at any speed, after I had installed the Gunships my me ch made the necessary adjustments to the TTS tune.

Problem was, there's not a canned map for the Gunships and he found what he thought was the best solution.

The problem appeared while riding with the cruise set in 6th gear.  Shifting down to gain rpms solved the immediate problem, but it would come back if I reset the cruise at that particular rpm range.  Then I noticed I could induce the problem in any gear, so long as I was in that target rpm range.

Solution:  My mechanic assumed I had baffles (of some kind) in the Gunships, which I did not.  So, he remapped the TTS tune using a "Racing Exhaust" as a template, thereby telling the computers on the engine that there was less backpressure, than the previous tune.  After the latest tune, the bike has never again developed a 'miss'.

Have the tune on your bike looked at again, and make sure at minimum, that the Intake and Exhaust numbers are appropriate for your setup and I'm certain it too will remedy your problem.   

[eztigersmc]

Thanks for the response.  I am hoping that my tune will take care of this.

[grc]

I wouldn't suggest starting your diagnostic routine at the tuning stage.  If you have an intake leak, an ignition problem, etc, you might be able to cover that up temporarily with a change to the tune but your problem won't be fixed and it will likely return.  I'd suggest performing a complete and logical diagnostic routine, starting with the basics of mechanical condition (have you checked compression and leak down for instance), air leaks, ignition system performance, etc.  The shotgun approach can accidentally hit on the root cause of a problem sometimes, but often that approach just means wasting a lot of money and not actually fixing the root cause.  Verify all the basic stuff first, then have the tune checked and corrected if necessary.

JMHO - Jerry

[T-Hawk]

I wouldn't suggest starting your diagnostic routine at the tuning stage.  If you have an intake leak, an ignition problem, etc, you might be able to cover that up temporarily with a change to the tune but your problem won't be fixed and it will likely return.  I'd suggest performing a complete and logical diagnostic routine, starting with the basics of mechanical condition (have you checked compression and leak down for instance), air leaks, ignition system performance, etc.  The shotgun approach can accidentally hit on the root cause of a problem sometimes, but often that approach just means wasting a lot of money and not actually fixing the root cause.  Verify all the basic stuff first, then have the tune checked and corrected if necessary.

JMHO - Jerry

What Jerry said...  my bike was fine right up until the tune for the new pipes.   Haven't experienced any of the other possibilities, and I'm hoping that I don't.  I'm just glad my mechanic takes responsibility, even if it was a simple error, and nothing major came out of it.  From reading your post, it sounded like what I had happen, so my first thought was the tune.   

[eztigersmc]

Agreed as well with Jerry.  I was hoping that others would add to the list of things to check.  This is my first Harley, but not my first time around the engine.    I find that the forums are a great place to gather information when you are getting ready to dive into something.  There's lots of people on here that have been there, done that I'm sure.  I very much appreciate anyone and everyone that chimes in.