accelerator pump on pc3
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my dyno tune guy is new to harley and were not sure about the accelerator pump for my bike . 2007 electraglide classic fuel moto rush slipons k&n rk-3910 air cleaner .
who here uses the accelerator pump feature ? also how much tweaking did you guys do with your ignition ?[/align]

 

I had the accelerator pump enabled on mine with a canned map, but by MPG were in the mid 30's. DRAGOSBIKEWORKS hooked me up with a great map. Took it out today and was real impressed. No accelerator pump at all. I have a 07 RK with VH ovals, arlen ness big sucker and a PC3. Honestly I don't think the accelerator pump did much of anything except fix a bandaid a fix over wrong values in the map but then mess;s with your gas mileage bad.

 

Does the PC3 have the ability to do data logging? If so, why do you never see any screen shots for questions like this? It is almost impossible to have anyidea how to answer the question. There are ways to map the VE to make AE almost unneeded.

AW

 

The PC III USB has no data logging feature.

 

Can anyone explain when or why you need the Accelerator Pump feature. I asked this on another forum and could not get a clear answer. One guy said you have a stock bike so you don't need it and that was about it. Any one else have a clear handle on this feature. I'm not really dying to try it, just wondering what it is. The Thundermax has an Accel Fuel setting, is that the same thing?

 

I wrote this for a different forum. A few of the names for things are different but all of the concepts still apply. In most if not all of the ECU programers available there are no where near this may things to play with to truely dial in the AE but....

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[size=2]There is a lot of confusion regarding the tuning of Acceleration Enrichment in the MegaSquirt family of programs. Over the last two years I have been involved, to a varying degree, in several of these ways to control AE. It is far easier to tune AE if you under the underling causes and effects.

There are a few that we have to consider. (Hang with me here)

1) You may remember from high school physics that water will boil at close to room temperature if you pull enough vacuum on it. Conversely, if you apply pressure you can raise the boiling temp up to 250F or more.

2) Water on the driveway always evaporated faster on a windy day than it does on a calm day.

3) Water on the driveway always evaporated faster on a hot day than it does on a cool day.

4) If you leave a cold glass of beer on the counter water droplets form on the side of the glass, apparently water from nowhere.

5) Cold air has more oxygen molecules per cubic foot that hot air.

6) A VE table as we in the MegaSquirt world is designed to balance the amount of fuel delivered from the injectors with the air flow. The internal math of the MegaSquirt estimates this airflow and in turn calculates the matching injector pulse width. This airflow calculation is based on intake air temperature, RPM, intake manifold absolute pressure (KPA), and RPM.

7) An intake manifold often has hot water in it. This manifold is attached to hot things and is being blown on by constantly changing amounts of hot air coming off of the radiator and from the exhaust system.

8 ) An intake manifold has a constantly changing amount of air properties and the amount of fuel that can condense on the walls.

9) Fuel in the intake constantly collects on the inside walls of the intake.

10) The amount (thickness) of this layer of fuel is constantly changing.

11) The earlier the fuel is injected in the intake airflow, the more area of the intake wall can get wet.

12) Back pressure on the exhaust, weather caused buy high atmospheric pressure at the end of the exhaust system or by trying to flow too much exhaust through the system causes the motor to need less fuel.

13) The injector delivers fuel only after it has opened. The injector opening time consists of about the first 1.0 millisecond of the pulse width. So if MT reports 10 ms pw1 the injector is only supplying fuel for about 9 ms. This is a big deal if you have a cruse pw of say 4ms and your AE added pw is 6ms. The amount of fuel delivered goes from (4-1) or 3ms of fuel to (4-1)+6 or 9ms or three times the fuel. Plenty of fuel to put out the fire.

14) Way too much fuel feels just like way too little fuel from the driver’s seat.

15) Fuel collecting in the walls and floor of the intake behaves much like the water examples above.


A few definitions.

MAP: Manifold air pressure. The units are KPA. The important part to remember is 100 KPA is close to amount of air the world has at sea level. At 6000 ft elevation you have 80% air or 80 KPA. 15 psi of boost amounts to about 200% air of 200 KPA. Most manifolds have on a steady state motor about 40 KPA at idle and 95 KPA at full throttle assuming normally aspirated.

MAPDot: The calculation of the change of MAP/sec An indication of how fast the MAP is changing. Extra and base BG code uses KPA/Sec where MS2 uses percent/sec MAPDot is normaly a better indication of a need for tempary additional fuel than TPS related schemes.

TPSADC: The location of the Throttle Position Sensor as the Squirt sees it.

TPSDot: The rate of change of the TPSADC/Sec but converted