phsyo

Can anyone help me find out why my AFR recorded on an ECU Explorer datalog is so high?

When decelerating it goes up as high as 24.

The lambda reading at a recent MOT alerted me as it was 1.029.

What do I need to check - MAF, Rear Lambda, Injectors etc? (Front lambda is new Denso one).

Thanks in advance.

Phsyo

phsyo

Sorry car is 2003 WRX with stage 1 remap.
Thanks

Andaru

When you decelerate the engine is turning with the momentum from the wheels and the injectors essentially 'shut off' so all the engine is doing is sucking air in and out, with the absence of fuel in the exhaust gases the wideband can't pick up an AFR.

However the lambda reading of 1.029 points to a fault as the legal limit is 1.030. Do you smell fuel at all? as there is a possibility of a leaky injector, but it is much more likely to be an O2 sensor or MAF.

phsyo

Thanks Andaru I really appreciate your help.

No I can't smell any fuel, from what I can see the ECU is compensating massively (The long term fuel trim says bank 3 -28% on my obd scantool).

Has anyone tested lambda sensors as described in this post:
https://www.scoobynet.com/general-te...da-sensor.html

Regards
Darren

Andaru

Usually when I have sensor issues I take it along to my garage who plug it into one of their super duper computers that gives the voltage and signal from specific sensors and you can usually work out what's wrong from that.

The problem with using OBD AFR is that it uses the narrowband or 'commanded lambda' - which is only really good for saying yay or nay to being stoich and closed loop, outside that they're not accurate. I have a Prosport wideband and the narrowband on my ultraguage, when my WB says 11.5 my NB 'estimate' says 9.8.

jura11

iTrader: (7)

Hi Darren

I would check fuel pump and MAF or even Lambda sensor

Yours AFR is bit rich,assume you are running Wideband ?

As above when you off throttle for few seconds yours Lambda reading will be off(22-24 AFR),just what I would check is,partial throttle or when you driving on motorway,what is yours AFR

OE Lambda as above is narrowband and narrowband only reads rich or lean,nothing between

Thanks,Jura

phsyo

Cheers guys

I think I can check the voltages from the lambda sensors using Ecu Edit Logger,
does anyone know what voltages to expect from the front and rear sensors either when idle or driving?

Regards

Darren