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Buell Forum » 1125R Superbike Board » Archives 001 » Archive through June 12, 2008 » Inproper installation of baro sensor causing low speed surge « Previous Next »

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Archive through June 04, 2008Thurstonbuell30 06-04-08  08:00 am
         

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Jpfive
Posted on Wednesday, June 04, 2008 - 08:00 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Delighted to hear that you're seeing improvement, Zac. Seems to confirm my hunch. I still think that a 'nominal' bike will show AFV's of 100 at any altitude, and that the barostat will make the changes necessary for elevation. AFV's less than 100 (or more - anybody seen these..?) not necessarily bad if they are correcting properly for some other condition. Bottom line is that this just results in a +/- correction to the duration of the injector pulse.

Jack

(Message edited by jpfive on June 04, 2008)
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Zac4mac
Posted on Wednesday, June 04, 2008 - 08:31 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I unplugged the baro sensor and stuck some small wires in the socket then re-connected the plug.
I wanted to check the output and make sure the sensor wasn't stuck and don't have a "break-out box".

Checked the voltages to ground then monitored the Brown/blue and Black/white while I GENTLY applied pressure and suction.
Wide range of voltage, 2.5-4 volts or so, the sensor is working.
Reconnected everything minus the "tap" wires and went for a little ride.

I'll take her to work today and see if yesterday was a fluke, or if she's running tops again.

I wish ODIS had an altitude read-out too.

Z
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Cataract2
Posted on Wednesday, June 04, 2008 - 09:05 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)


I wish ODIS had an altitude read-out too.


Maybe ECMspy will soon be able to work with the 1125R with this functionality in it.
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Spectrum
Posted on Wednesday, June 04, 2008 - 11:31 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Jack is it possible that gas mix could be impacting the AFV? I run 93 octane as there is no 91 available in my area. I ask because I had the bike run real bad last week when I bought a tank of gas at a different station than normal. May have just been bad gas, but the station is a BP and has a decent reputation. I fill my car from that station and never had a problem with bad gas.
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Id073897
Posted on Wednesday, June 04, 2008 - 12:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Assumably Bosch absolute pressure sensor, 10 kPa @ 0.40V - 115 kPa @ 4.65V (cp. 0 261 230 052)

EEPROM Sensor Data (ADC 8bit vs. pressure kPa):

102 - 56
153 - 78
204 - 100
237 - 115

Uout = 5.0 * ADC/255

EEPROM Baro Correction Table (pressure kPa vs. fuel %)

53 - 60
61 - 67
69 - 74
79 - 82
89 - 91
101 - 100
106 - 105

Regards,
Gunter
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Jpfive
Posted on Wednesday, June 04, 2008 - 02:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Spectrum, I am not an authority on the system - just have been thinking hard about it, and applying some experience with other EFI bikes, including one Rotax. Here is what I think: The bike will correct itself, in closed loop, for any condition that causes the combustion result (measured by the O2 sensor) to differ from what is predicted by the map.

In the pre '08 XB's, this would include differences in elevation. In our bikes, however, the ECM is continuously aware of the elevation (due to the barostat), so this particular variable is corrected for separately from a table similar to the one just provided by Gunter.

If I am correct, then the system will correct for differences/deficiencies in fuel quality, as well as differences in fuel pump output, fuel injector output, intake and exhaust variations, and probably some other stuff, the maps assuming these variables to be 'nominal'.

Thanks, Gunter, for sharing the baro info.

Jack
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Chevycummins
Posted on Thursday, June 05, 2008 - 02:55 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Baro sensor readings on my bike today.

96% humidity
73 degrees
29.848 barometric pressure today
baro sensor 3.9V
MAP 3.9V not running

Looks ok to me.
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