I have had pretty well the identical fault (The scope readings could well be mine)
After an MOT fail, The customer had fitted a "Universal" 4 wire lambda and it was stuck at 0.8 volt (with an occasional low switch) with the live data reading 0.6v and "Lean".
(Unfortunatly the custmoer had replaced several componants so I never was really sure what the cause of the original MOT fail was though the MAF was pretty poor before I replaced it)
With a new Bosch, vehicle specific, sensor, the sensor was switching OK with a high of 1.2 volt and the live data reading 0.8-0.2 and "Rich/lean" switching.
Anybody else had this experianc?
Is there something wierd about how the Lambda works on the corsa setup or how the ECU interprets the lambda signal??
My only concern is that the idle switching is a little slow and "occasionly" it sort of hiccoughs at idle and goes rich/lean bigtime (on the exhaust gasses) for a minuite or so before settling down again.
It is Much_better than when I started but I am still concerned that it is "Not quite right" IYSWIM.
I know that the EGR is a possible problem, initially it was throwing codes and the feedback was over 2V at idle/KOEO owing to being clogged up with gunge. Cleaning it has got this down to 1.7V and it no longer throws codes but this is still nearly a volt higher than the feedback signal from a new EGR valve under the same idle/KOEO conditions.
I am lothe to add a new EGR unless I really have to, the guy has already spent a load of dosh on EBAY crap + what I had to fit to get it right and it is still only an old corsa.
But we shall see....
On a more general note, I dont think this is "Just" a scan-tool issue.
Using the scope the "Universal" Lambda gave a "Good" signal, it just wasnt enough to get the ECU to switch. The ECU needed the 1.2V signal from the Genuine(ish) sensor! So what is going on there then?? Is there a shottky diode incorperated in the genuine sensor or something to bump up the output over that which one would normally expect or something??
I am of the opinion that the 1.2v you mentioned earlier is a little high. Whats the earth reading like on the HO2 sensor? I might be tempted to stuff it to battery earth just to see if that brings the voltage down a bit. Am now expecting someone to come on and mention "floating earths"!
it is a floating earth and I expect the universal sensor is earthed at the body of the sensor and not using the ecu earth, try an ohms test on the universal and see.
on April 6, 2010, 6:12 pm, in reply to "