Get the right Dynotune!

[Rogue1970]

Since, I've been adding mods to my quad, I've been looking into dyno tunes and trying to find somebody that will tune it right. I'm not an expert, but I'm learning more and more every day.

Electronic Fuel Injection (EFI) motors are not dynotuned the same way carbureted motors are dynotuned. Yes, they both try to make sure that the Air Fuel Ratio (AFR) is optimal for engine longevity and power output.

When you are tuning a carburetor, you change the Pilot Jet, Main Jet, Needle and/or Needle height. There are only a few items you can change to control the fuel curve.

05/20/08 Edit - I just found this post on how a carburetor works... great info!
http://forum.nebraskaatv.net/viewtopic.php?f=7&t=14

Carb motor dynotune process:

1. Strap down quad to machine
2. Insert AFR probe into exhaust
3. Press button to start the dyno & open throttle to 100% open
4. Release throttle after max RPM achieved
5. Save run

Start changing jets, needles, intakes, cams, etc... and repeat dynotune. Change, repeat, change, repeat until you get the best TQ / HP / AFR curve. Done.

This same process should not be applied to an EFI dyno tune.

It takes mutiple dyno runs at each of the 9 throttle positions make adjustments thru the HP curve to get the ideal AFR. Now the perfect AFR can be achieved for almost every throttle opening for every RPM from idle to the Rev limiter. This is the advantage of EFI.

The dyno operator should tune each of the 9 possible Throttle Openings one at a time.

Here is an example of what could/should be changed at a 0% Throttle opening (Idle)

Here I adjusted 1500 thru 3000 RPM, but the only Actual RPM that needs to be changed is your idle RPM.

Once that is set correctly, then the dyno operator would tune for the 2% Throttle opening (Just off idle)

2% Throttle opening will let the engine rev a little higher then idle (obviously).

Next step up is 5% Throttle Opening (a little more throttle then 2% Throttle Opening)

Each step up the Throttle Openings, the engine will rev higher and the fuel map should reflect this.

The operator, will go thru each of the 9 possible Throttle Openings (0%, 2%, 5%, 10%, 20%, 40%, 60%, 80%, 100%) to get the AFR correct.

Dynotuning this way will yield a complete map. This takes time and will cost some money. Tuning for each of the 9 Throttle Openings can only (accurately) be tuned with the Tuning Link software addition on the Dynojet dyno. A Dynojet is not required, but it makes tuning very accurate (Throttle Openings). If the Tuning Link software is not available, then the operator should be able to tune for say 0%, 20%, 60%, 80%, & 100% Throttle Openings. Or at least 0%, 50%, and 100% Throttle Settings (still better then 100% only tune.)

Some shops are dynotuning the correct way. Here is a quote from one shop "Gone are the days of wide-open throttle tuning. You get all-throttle, all-condition tuning." from http://www.lews-cycle.com/dyno_tuning.html at least this shop is doing "all-throttle" tuning.

Sorry, I paid $112 to get a wide open (100% Throttle Opening) tune. I would not of taken my quad to this shop if I known they would only tune this way. Hopefully this information will be helpful to others. Call up a shop, ask questions to see just how they plan to dynotune your Fuel Injected machine.

Edit 5/22/2008 I found another good tidbit of info
Problems with Inertia dyno test procedure and fuel injected vehicles: A Sweep Test (hold throttle wide open and sweep from low rpm to high rpm) will often trigger the Acceleration Fuel Map, along with the Main Fuel Map, causing the fuel mixture readings to indicate dyno operator that the motor is overly rich. This would cause the tuner to lean out the main fuel map. Of course, in the real world, upper gears, the acceleration rate of the engine is much slower than what they tested, doesn't trigger the Acceleration Fuel Map, and the engine ends up a lot leaner in reality in top gear. It's not that common of a problem, since most people never drive that fast for that long to cause engine damage. Work around: Tune full throttle fueling in real world usage at dragstrip (to best trap speed) or in Steady State Mode on different dyno.

I don't know if this applies to our quads or not, but it is a good piece of info.

Good Luck,
Larry

[topdollr]

great info, should be a sticky note

[offroadhunter]

Great write up...

[shadey]

Good info Bro


I had a complet map done and did some cam timing change on the dyno and by the time we were done we had over 350 runs and it cost $500, but the map was done right.

[topdollr]

<div class='quotetop'>QUOTE (shadey @ Apr 22 2008, 11:49 AM) <{POST_SNAPBACK}></div>

Quote:

Good info Bro


I had a complet map done and did some cam timing change on the dyno and by the time we were done we had over 350 runs and it cost $500, but the map was done right. [/b]

DAMN $$$

[william88]

This is what i like see, great information that will definately help everybody. I myself made some calls to see how shops in my area tune.

[shadey]

<div class='quotetop'>QUOTE (william @ Apr 22 2008, 12:28 PM) <{POST_SNAPBACK}></div>

Quote:

This is what i like see, great information that will definately help everybody. I myself made some calls to see how shops in my area tune.[/b]

[attachment=1023ost_454...07338543.gif] so what did they say

[william88]

<div class='quotetop'>QUOTE (shadey @ Apr 22 2008, 03:34 PM) <{POST_SNAPBACK}></div>

Quote:

[attachment=1023ost_454...07338543.gif] so what did they say[/b]

A couple said they do full throttle tuning, but they specialize in carburated cars, and some otheres said they do a FULL TUNE at all throttle posistions, but they generally cost more to a full tune.

[Rogue1970]

No problem guys, I was looking over at the LTR site too and nobody actually explained the dyno tune on an EFI quad.

Damn Shadey, that is some coin.... but at least you got it done right. I agree to do it right it takes quite a bit of time and many runs... now you just have to be concerned with too many runs in a row causing 'heat soak'.

Also Shadey, if you don't mind would you post the shop name that did your map. Maybe we could/should start another thread with shops that dynotune our EFI quads correctly.

I know that Fuel Customs will be getting the Tuning Link software soon. They are located in Pomona, so that is within 40 minutes of me (as long as no traffic problems ).

[shadey]

On my tune we had other issues to deal with we worked on cam timing and tried to bring the HP curve down about 500 rpm, then we tried different fuel pressures because we were at +20 on the FMIAK and couldn't go any fatter with out getting a bigger injector or raising the fuel pressure, we even tried to raise the limiter to 11k RPN's so we could use more of the top end HP. So to do a full tune on some bolt on upgrades should take around 2 to 3 hundred runs but a build like I did will take much more, and at $75 an hour it adds up very quickly.

<div class='quotetop'>QUOTE </div>

Quote:

Damn Shadey, that is some coin.... but at least you got it done right. I agree to do it right it takes quite a bit of time and many runs... now you just have to be concerned with too many runs in a row causing 'heat soak'.[/b]

The dyno guy that I used had 4 industrial type fans that kept the temps consistent + it took about 5 minutes between each run to do programing changes and most of the runs are done under half throttle.

Hers the guy that did my tune.
he also did my KX500 and my race kart too

Halls Precision Racing Products
5614 N.52nd ave Glendale AZ. 85301

623-931-8132 ask for Jerry Hall