- Vauhall Corsa B 1000cc (3 cylinder) X10XE M1.5.5 Archived Message
Posted by Dave Hill
on September 12, 2007, 11:25 pm
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Thinking caps on again I am afraid! This Corsa B, Year 2000, 3 cylinder (X10XE) has come in as an MOT emissions failure. It has already had a new 02 sensor fitted by a previous guy. The emissions are not miles out & will probably scrape through with a new cat, but a scan & scope have revealed an underlying issue. It has recently had a new (cheap) cat fitted, which suggests that someone has been here before. No codes are present & live data looks good, although the scope shows the O2 sensor is reading a tendency toward rich. Looking at the capture over a few minutes when hot, it is clear that it rarely shifts below 500mv. After a while it became apparent that the scan tool was displaying a different version of events. As an example, the scope will display an O2 reading of 600mv & the scan-tool will show 400mv. At fast idle & tick over the scope figures will show a rhythmic switch between 900mv & 500mv whilst the scan-tool gives the impression that a rich to lean switch is occurring with figures from 600mv to 000mv. The scanner is showing..... Closed loop yes I have fitted another test MAF (Bosch) & another O2 sensor. Fuel pressure = 45 psi (3 bar) (slightly low according to autodata) The EGR has been removed & checked (& cleaned). The breather pipe from the cam cover has been cleared. Throttle body cleaned. A new earth connection to the grey wire fitted. Adaptations (O2 leaning slopes) have bean reset. I have tried a different ECU from a donor vehicle & it's no better. I have even soldered two new wires onto the rear of the ECU pins & directly to the signal & earth wires of the lambda sensor. I have generated a simulated voltage down the O2 signal wire & still I see a lesser figure on the scan-tool. Basically, you name it & I have done it, yet still I am seeing a lower O2 voltage on the scanner than is actually present. I have even tried another scanner & it confirms what I am seeing. Yes I have confirmed the scope reading with a good DVOM. I have run the same tests on the donor car too & it displays data, as I would expect. O2 sensor voltages on the scanner, match the scope. This should be a straightforward one to sort, yet the fix is eluding me. Any Ideas?? Cheers for now Dave (Hill) Oh yes, the captures!
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nearly forgot.
