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Author Topic: Fooling lambda heater circuit on ME7.9.10  (Read 4659 times)
woj
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« on: March 06, 2017, 04:52:04 AM »

Hi,

For experimentation and getting some stats I want to connect my Zeitronix AFR module and plug the wide-band sensor in place of the narrow-band one. The narrow band signal will be emulated by Zeitronix (this always worked for me fine, but the ECUs were much simpler), but I also need to take care of lambda heater diagnosis. Will connecting a high power resistor (25W, 10ohm) would do the trick, or is the ECU (ME7.9.10) more clever and will discover that the resistance is not changing as it should during warm up? If this does now work, what would? (Reprogramming / remapping the ECU as well as welding in an extra bung is for now out of question.)

Woj
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overspeed
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« Reply #1 on: March 06, 2017, 07:58:28 AM »

Just code second lambda off, but the resistor trick will do
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woj
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« Reply #2 on: March 06, 2017, 08:18:58 AM »

(I noticed several language mistakes in my original post, sorry for that, something must had been on my mind in parallel.)

Second? I was thinking first, but can go either way. Aren't AFR readings altered by the cat? If they are, then would not the emulated signal throw the cat diagnosis in the ECU off? As far as I have seen, on a properly working car/cat the two lambda voltage readings are offset by a small value (that's the whole point of having the second lambda, isn't it?). 

(Yes, I know that the first lambda spot maybe too hot for a wide-band, but I do not care much for the actual sensor, it comes from an old project of mine and is 60kkm, and I need it only for quick research).
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overspeed
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« Reply #3 on: March 08, 2017, 06:01:40 AM »

Sorry, I answered quickly and didn´t asked before if you take your Katt Off (it´s usual on my country).

If the Kat in on place you really can´t use on second sensor spot.
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woj
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« Reply #4 on: March 17, 2017, 03:29:38 AM »

So, first experiment executed, and it does and does not work. Fooling the heater circuit with 25W 10 ohm resistor seems to work (no DTCs), although the resistor (despite heat soaking casing) gets really hot (untouchable), not sure if that's right / safe. What works less nice is the ECU not liking the emulated narrow band signal. Despite the fact that I can see it in diagnostics that the signal behaves more erratically and has much higher amplitude, the ECU reports P0130 - Intermittent lambda signal disruption, short to GND. This is either because of the power cut to the Zeitronix module during cranking, or the emulated voltage dropping too low during operation. For what I want to achieve this is not acceptable for now and it seems that I need to weld in an extra bung if I want to have the AFR. The AFR itself was nice and stable during idle.
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prj
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« Reply #5 on: March 17, 2017, 10:18:14 AM »

There is no problem fitting wideband post-cat. It will be somewhat inaccurate when you lift-off dump fuel, but normal cruising it will be enough to tune the car.

Also, stop stupid resistor bullshit - just disable ESKONF entry for front O2 heater.
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