LSU 4.9 to 4.2 compatibility? | AEM
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Yars
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Joined: 10/13/2016 - 09:29
LSU 4.9 to 4.2 compatibility?

Dear AEM team.

Got Volvo 1999 2.5T, Bosch Motronic ME7 management. 

The upstream oxygen sensor in the downpipe is a wideband one from the factory, probably the LSU 4.2, what else Volvo would use at those years...

Recently purchased the AEM 30-0300, but I dont want to drill and weld another bung in the downpipe.

Is it possible to feed the signal from the 4.9 sensor to the ECU that was designed to accept the 4.2 readings?

Or the 30-0300 can simulate the OEM wideband signal?

Thanks a lot! 

AEM_NS
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Last seen: 9 min 57 sec ago
Joined: 06/06/2014 - 09:31
Unfortunately something like

Unfortunately something like this can't be done. UEGO sensors are paired with a controller chip and that chip monitors many operating parameters of the sensor and of the chip itself. It wouldn't be possible to split the signals from one sensor between two controllers as they'd both notice that something is askew with the signals. If you need to maintain your stock 4.2 sensor to keep the ECU happy, then you'll need to add in an extra bung for the 4.9 that goes with the 0300 gauge.

Yars
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Last seen: 3 years 2 months ago
Joined: 10/13/2016 - 09:29
Both the Bosch 4.2 and 4.9

Both the Bosch 4.2 and 4.9 uses calibrated resistor located in the probe plug, and the probe pump current is draining through this resistor. Here both the ECU and Gauge comes in as nothing but a high input resistance voltmeter, and they measure the voltage drop on this resistor, is this correct?
If so, it is just an analog signal, being fed to ECU/Gauge ADC inputs.
Therefore I see no obvious reason why this voltage drop couldn't be monitored by two devices simultaneously, as they doesn't interfere to each other..
Please correct me if I'm fundamentally wrong.

 

AEM_NS
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Last seen: 9 min 57 sec ago
Joined: 06/06/2014 - 09:31
Your point is valid for the

Your point is valid for the pump current measurement only of an analog controller. Two problems - Bosch UEGO controller chip monitors every circuit in the sensor and will detect absence of other circuits outside of measurement of pump current for Lambda value. So, you could potentially have a Lambda value being read but ECU will assume sensor is in error and you'll have CEL at a minimum and loss of closed loop fueling and possibly other problems. Other problem is that 0300 uses digital control process without a Bosch chipset with suppression of noise being a specific design construct and it would not be smart to degrade any signals for the sake of not having to add in a second O2 sensor bung.

Perjian
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Joined: 03/03/2020 - 02:17
The 5 volt output at the AEM

The 5 volt output at the AEM controller isn't useable as a signal for the ecm?

AEM_HB
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Joined: 11/07/2016 - 09:22
@perjian that is dependent on

@perjian that is dependent on the ecu being used and the signal the ecu is set up to receive. In this case the OP is referencing an OEM ecu rather than a programmable standalone.