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, Mon, 5 Nov 2012 15:29:34
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Giga,
I used to rely on measurements and understanding - others' or mine - of what's going on, rather than experience and public wisdom (like 'those o2 sensors are prone to giving troubles, replace yours and you'll be fine' in response to decreased top speed complain; if it doesn't work, you'll be advised to replace the fuel pump and the next thing to go will most probably be the MAF sensor - because 30% have replaced those things and success rate is 40% - definitely not 100%, but more than 10%, which happened e.g. when they tried using more premium gas).
You can go replacing parts and units on your car according to public wisdom and known failure rates and symptoms and your chances will correlate to those known rates and stats you get from the public wisdom. It's like to slaughter a virgin: sometimes it works, but sometimes (which is much more often) it doesn't.
Or you can try carrying out the troubleshooting procedure to find out what's really happening there. You already have ordered and received your own copy of Bentley, haven't you? Use it to trace that very wire (home work: learn what potential is triggering that shift-up light on and trigger it on manually from the LH ECU connector having that connector unplugged off the ECU and by running an external wire with appropriate potential to pin #26 of that very un-plugged connector) to check whether LH ECU is really gone crazy or not.
If LH ECU does trigger that shift-up light on at obviously wrong conditions (like very light load at 1500 rpm on a hot engine in the 1st gear), then either LH ECU (fuel computer) is bad or something is fooling it, like RPM input (from EZK ECU) or the temperature sensor or the speedometer sensor. Or maybe it is something between that appropriate sensor and the ECU: the wire. Or maybe that sensor itself is good, but it has a bad ground connection.
If a real pro (like Anders or Jon) finds out that that 686 wire is good, then before trying a good known LH ECU he'll finally check the old one with some diagnostic tools like Tech2 or ISAT to confirm what's happening inside the ECU when it toggles on that shift-up light. The only issue there could be that the ECU terminates the diagnostic session in favour of its primary work (fuel management) if RPM's go further then 1700-2100-2700 RPM depending on the LH ECU generation. But he's a real pro so he already knows it.
The bottom line: it's the average engine load and speed signal which differs when you go in the 1st-2nd gear or in the 3rd-4th gear. The load affects fuel injection timing (and pressure) and ignition timing; I'm not sure, but it should also affect the shift-up map in the LH ECU. The road speed signal is used by the LH ECU for idling adjustments and for the shift-up light.
Good luck,
Zig
posted by 188.134.4...
, Mon, 5 Nov 2012 05:17:43
, Mon, 5 Nov 2012 10:22:03, Mon, 5 Nov 2012 10:36:16
, Mon, 5 Nov 2012 11:07:54, Mon, 5 Nov 2012 08:07:19
, Mon, 5 Nov 2012 09:28:31, Mon, 5 Nov 2012 09:33:36, Mon, 5 Nov 2012 10:54:06
, Tue, 6 Nov 2012 12:35:14, Wed, 7 Nov 2012 06:48:17, Mon, 5 Nov 2012 08:42:54, Mon, 5 Nov 2012 09:19:00, Mon, 5 Nov 2012 09:52:05, Mon, 5 Nov 2012 15:29:34, Mon, 5 Nov 2012 16:58:11, Wed, 7 Nov 2012 22:04:48
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