First, the set up. I have Vance & Hines high output slip ons attached to Vance & Hines dresser duels headers. I have an Arlen Ness stage one air cleaner & T-man 555 cams with a screaming eagle race tuner and I had a dyno after the engine modification.

On a recent trip that brought me to elevations over 6500 feet, there was a significant amount of hesitation in the engine only at elevation. Meaning, when I was at elevation and I will got on the throttle, there was very little throttle response until I let off the throttle a bit and slowly got back on it. When I had the engine work done on the bike I had a Dino tune done at my local Harley shop. The only other time I've had a similar hesitation in the engine also when I was at elevation at a different time . I'm very sure the technician that did the tuning was competent.

My question is this… am I better off getting a new fuel management system that can autotune real-time taking into consideration temperature and oxygen levels, or having the bike retuned to try to address the problem. There's only a difference of a couple hundred dollars the between the two scenarios. If I change the fuel management system I'm considering the PowerVision with the autotune option or the ThunderMax.

I'm still not sure that the engine hesitation was due to the tuning on the bike, but the fact that the hesitation only happens when I'm at elevation is a pretty good indicator that something is going on that was not anticipated.

Any thoughts, recommendations, comparisons or better ideas you have at this point would be very helpful. Thanks.

 

I haven't had that problem, but my experience of getting my bike dyno tuned was that the operator was quick to find a couple of things that weren't quite right and fix them. I don't believe that any auto-tune will fix your symptom, so my suggestion is to visit your tuning shop. Talking things through with them may identify the problem, before running your bike on the dyno - if that is necessary.

 

I certainly wouldn't have the bike "retuned" specifically to address an issue that only occurs when you are over 1 mile high in elevation, unless the bike spends most of it's time there.

If you are experiencing significant "hesitation" or noticeable power loss at altitude, for sure the engine is pretty "fat" in that range. What fuel economy are you seeing at lower altitudes? Any noticeable hesitation/stumble/bog or power loss anywhere in the load/speed range other than near 7000' or so?


I've been at altitude numerous times with non-CCC trucks, cars and HD's that I've owned and never had that issue, but they were also in perfect tune for the DA that I use them in 99.9 percent of the time.


I did experience noticeable power loss with them up past about 7000' or so, which is to be expected as N/A applications aren't cylinder filling nearly as well as they do at lower altitudes.


I had the PV on my 2012 Ultra Limited, and spent a lot of time with it custom tuning that engine. There are big gains to be had in the "normal" operating range and custom tuning any area of the MAP is only seconds, so a good tool if you head up into the mountains and want to get the most out of the engine while your up there.......Cliff

 

I thought EFI automatically compensated for air density. You may be running ok with your tune but it isn't right and the symptoms show up at altitude.


I don't know anything about the SERT, but I imagine it can handle altitude if the tune is correct to start with.

 

I thought the EFI would also compensate for air density, but that must be true only if you change the map on the bike if the tuner does not automatically learn on the fly like the PowerVision with the auto tune option or the ThunderMax. The problem is when I'm at home I'm at about 300 feet in elevation not 10,000 or 11,000 like I will be the summer. I'm planning a trip to the Beartooth and Teton mountains through Yellowstone this coming summer. I want to make sure not to have that same problem when I go nearly twice as high and elevation as it was last summer.

 

Ordinarily EFI does indeed compensate for altitude, just as it does for cold and heat, wet and dry. I suspect there is something that needs fixing on Cheesehead's bike, possibly unrelated to his EFI.

 

And don't forget that you lose a ton of power due to the thinner air at altitude. Run in a lower gear and see if the bike does better before spending more money trying to fix something that may not be wrong.

 

We live at about 5700 feet and we ride from 1,500' to 14,000', (Mt Evans Colorado) and the ECM does a great job compensating for the changes. I did notice I needed to downshift a little sooner going up Vail Pass at 10,000 ' at 85 mph I know there are some folks who would take there PV along and auto tune and swap out maps but I haven't found the need to do it.

And what do you have against the North West?

 

Are your O2 Sensors plugged in? If not are they supposed to be? Is the SERT a open loop or closed loop tuner? Also with closed loop tuners you still dyno tune them open (sensors disconnected) to establish your ideal baseline and then add your sensors back into the mix.

Nothing beats a Dyno session with a tuner that knows their stuff to establish your baseline map.

Some tuners like the Power commander 5 are called open loop tuners that means the O2 sensor signals are not used after tuning either, they stay disconnected. The ECM will not know if it is rich, lean or ideal stoichiometric. That means as your altitude rises your going to get richer and richer. All it knows is that x throttle opening at y rpm add z amount of fuel and it adds the same amount at 20ft below or 14,000 above sea level.

You've also had cams done, If it makes power further up in the RPM range it sacrifices lower down. Even a modest cam can have big change on your power band

With that being said I used a power commander 5 on my 13, tuned at 760 feet ASL. Last summer we rode NM and Colorado 2 up with full bags and went all the way to the top of pikes peak, I could feel the bike was a little anemic but it wasn't all that bad. Keeping it up in it's proper power band it was fine and I never experienced the need to back off the the throttle and then slowly add it back in. (sounds like your bike was trying to flood)

I'm going to guess that the SERT is either a open loop tuner or if it is a closed loop system your tuning shop forgot to plug the sensors back in.

 

Stolen from another Forum, not in the Internet Brands family so I won't link it.

By Doc 1

"Gentleman here are five questions you can ask your tuner to see what his skill level is without being conspicuous. These are 5 simple questions that a good experienced tuner can and will be able to spit out the answers correctly and without a great deal of thought and the whole time your asking them the questions it will seem like a general conversation of you getting a little knowledge of the tuning procedures from him. If your tuner can't answer all, or any, of these questions it's time for you to search out another shop.

1) How long will my bike be on the Dyno to tune the SERT?
(answer) 4 to 5 hours

2) How many Dyno runs will you have to make to finish a tune?
(answer) 50 to 70 on a average

3) What are people talking about when they say you have to SYNCHRONIZE the VE tables?
(answer) By Synchronizing the VE Table to the Fuel Table your telling the ECM the new air flow through the motor from the mods you made.

4) I heard something about a Step Test, can you tell me what that is?
(answer) The Step Test is a program in the winPEP 7 software (Dyno Software) that allows us to sample the AFR longer for a better reading at 2%, 5%, 7%, 10%, and 15% Throttle Position. This is where the bike lives so we want a good AFR sample to make our edits.

5) Do you change the AFR Table to one value as you tune?
(answer) Yes, 13.2. This makes it easier to synchronize the VE Table.

If your tuner can answer these simple questions chances are (99%) you will get a good tune. I hope this will give you all a better idea who your trusting your $20,000.00 investment with.

Just trying to help!
Doc

PS. If they don't answer all of the questions correctly, PLEASE give them my phone number for training - it's in my signature. "