wannabe
Pro
Posts: 1931
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posted December 02, 2003 10:31 AM
ECU & PCIIIr question (altitude compensation)
OK, so I'm talking to my buddy again, and he mentioned something to me that I didn't know. Since, he was also the same idiot who tried to convince me that my swingarm was not aluminum, I wanted to run this by you guys before I did anything with the info.
He told me that the stock ECM maxes out at 6% mixture compensation. So, if you go too high, you will still end up running rich. Is this true? If so, what altitude does correlates with the 6% maximum? In other words, above what altitude to I need to mess with the map and take some gas away?
Also, does the PCIIIr have this same 6% limit? Obviously, I'm confused.
  
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zx23rr
Expert Class
Mahogany Bomber Pilot
Posts: 242
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posted December 02, 2003 02:59 PM
How can that be? The engine would burn up when using Dry NOS do you not think???
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wannabe
Pro
Posts: 1931
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posted December 02, 2003 03:01 PM
I don't know. That's why I'm asking.
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zx23rr
Expert Class
Mahogany Bomber Pilot
Posts: 242
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posted December 02, 2003 03:11 PM
Well, on average, the ball park, and for the government, or close enough, the mixture enrichens about 3.3 % for every 1000 ft of altitude if the computer does not correct (or Carb jetting). So at 2000 ft, it would have have max compensation according to the 6% rule.
And I did not state the above correctly as that would be effecting the air temp sensor and not the MAP sensor. So if indeed the stock MAP sensor has a max range of 6% correction, then it would indeed be a limiting factor, so to answer your question, 2000 feet and above you would need to start leaning out about 1% for every 300 feet. Then of course you have to throw in humidity, temperature.
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wannabe
Pro
Posts: 1931
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posted December 02, 2003 03:16 PM
Thanks, man. I appreciate it.
Ok, so approx. 2000 feet is the threshold assuming there is a 6% adjustment limit. How do we verify whether or not this limit exists?
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zx23rr
Expert Class
Mahogany Bomber Pilot
Posts: 242
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posted December 02, 2003 03:36 PM
Short of taking the bike into a air chamber, hooking up leads to the sensor and injectors to see if the output changes as the altitude increases (pressure drops) I do not have a clue. I would still like to know all the changes the factory did to the 00's to detune them.....ANYBODY IN the KNOW.
REF: Ricky Gadson's Gainsville debut on the pre-production unit.
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wannabe
Pro
Posts: 1931
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posted December 02, 2003 03:44 PM
Yeah, I've been reading a lot of references to that, but I don't know what happened back then. I got mine in 2002. What times and mph did Ricky run on the pre pro ZX-12?
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zx23rr
Expert Class
Mahogany Bomber Pilot
Posts: 242
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posted December 02, 2003 03:49 PM
if memory serves, 9.52 @ 147-8ish with just lowering and a "stock" pipe.
With the Muzzy 9.48 @ 151ish. mph. I also heard and maybe someone will verify - it was done only in the first 3 gears!
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Whimp
Parking Attendant
Posts: 26
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posted December 02, 2003 08:21 PM
Hi Wannabe. I've had my bike at altitudes of up to 8,000ft a couple of times this summer and it actually runs much leaner than it does at sea level to 2000ft. If there is a window or limit to fuel correction at 2000ft plus, I sure didn't find it. If my bike would have run at sea level ( with a Hindle) as well as it ran at 2500 ft+, I would have never bought a PC3.
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wannabe
Pro
Posts: 1931
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posted December 02, 2003 08:39 PM
Thanks, Whimp!
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tuusinii
Pro
Posts: 1031
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posted December 02, 2003 11:19 PM
I've had my bike over 3000m(~10000ft) and the bike run well. The idle came little bit down, but otherway it run quite well. I've also changed the original ECU to the "high altitude unit" which was made for the '00 model. After the swap I noticed that the overall mapping was better - also in sealevel. The bike compensated also better for altitude, but on extreme altitudes it still needed some idle adjustment. And if I don't remember wrong the service manual gives voltages from airpressure sensor up to 3000-4000m - someone could check it. So I'd say he's not talking of actual information...
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psycho1122
Pro
Posts: 1608
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posted December 03, 2003 06:33 AM
The range of the Atmospheric Pressure Sensor on the ZX12 is 0-9000ft. (0-2.8m)
This and many other sensors..(Crank, cam, Throttle Position, Inlet Air Pressure, Water temp., Inlet Air Temp., Gear position) play a part in how the ECU sends fuel and spark to the engine. With the PC being between the ECU and the Injector Rail (Stick Coils on the IIIr), It will add or subtract from the constantly varying signals from the ECU depending on your map.
No matter what your PC map is, the ECU still compensates for your conditions.
Keep in mind that the Atmospheric Pressure Sensor has Dual purposes. It helps the ECU in conjunction with the Intake Pressure Sensor to determine how much fuel to give you at high speed. That is why it is located in the Tail section of the bike. The faster you go, the more the pressure dropps in the tail (Low pressure zone). Hence, "Creating your own Atmosphere".
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You say PSYCHO like it's a BAD thing!!
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pdb1964
Zone Head
Posts: 536
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posted December 11, 2003 11:17 AM
Good job with the info Psycho. I was wondering the same thing about altitude compensation since I live in BC. I knew the bike had all the these sensors but it is nice to know what the limits are.
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Pauly
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted December 12, 2003 06:27 PM
Having an O2 sensor on the bike you would be able to monitor the realtime voltage of the o2 and watch changes in a/f ratio.
If i had any doubt about the ECU's ability to remove enough fuel under 10,000+ or whatever altitudes then i'd install an o2.
I find it hard to believe that the Baro sensor is limited to 2000 ft altitude compensation. The algorythems might be less accurate on the 2000 zx12rs so they might not be optimized as well at higher altitudes, but I'd put money on it that the ecu will compensate for 10,000 ft.
But i dunno. Never looked into it.
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Y2KZX12R
CompetitionCNC.com
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