Help - my lambda probe won't work
Posted: Fri Mar 30, 2012 9:31 pm
After months of smooth running my V6 petrol (not LPG converted) has develped a rough idle and mis-firing. All smooth when started from cold, but starts to mis-fire as soon as it warms up. Also fine under power (over 2-3 k revs) but drop down to idle and the mis-fires kick in again. Everything points to a lean running problem (a short squirt of carburettor cleaner on the air intake settles it down for a short time, but then back to mis-fires again afterwards.
Thought this might point to the lambda probe, so changed it for a universal 2-wire probe (spliced wires white to white and black to blue). No improvement, and have now had it checked by a mobile tuning service. Confirms the new probe isn't working (shows almost zero volts), neither is the old one which I took off. A spare 4 wire probe he had on the van still only got to about 0.24 volts output when the mix was really rich.
With no proper input from the lambda probe the ECU seems to be lost, most of the time it defaults to running lean on idle, causing sporadic mis-fires on most of the cylinders (chug, chug, chug out of the exhaust ). Once we seemed to flip it into feeding rich, at which point the running was of course smooth, but emissions went when way over the top. In either condition none of the lambda probes fitted were giving the correct level of output.
Stuck for ideas now. As the lambda probe is a two wire sensor is it possible that it's not getting hot enough ? (Could be the universal sensor I bought new needs a higher temperature than the Mazda original ?) My engineer's only suggestion was to fit a four wire sensor and connect the heater feeds to a 12 volt supply - a solution he has used in the past successfully on Mx5's that would not pass the emissions test. Any ideas would be very welcome at this stage as I am going mad with frustraion after 5 hours on it this afternoon ! She used to run so smoothly before this too!
PS. Diagnostic revealed one fault code "Variable resonance induction system (VIRS) solenoid #1 malfunction" but I have no clue what this refers to, or whether it has any relevance to the lean running condition.
Thought this might point to the lambda probe, so changed it for a universal 2-wire probe (spliced wires white to white and black to blue). No improvement, and have now had it checked by a mobile tuning service. Confirms the new probe isn't working (shows almost zero volts), neither is the old one which I took off. A spare 4 wire probe he had on the van still only got to about 0.24 volts output when the mix was really rich.
With no proper input from the lambda probe the ECU seems to be lost, most of the time it defaults to running lean on idle, causing sporadic mis-fires on most of the cylinders (chug, chug, chug out of the exhaust ). Once we seemed to flip it into feeding rich, at which point the running was of course smooth, but emissions went when way over the top. In either condition none of the lambda probes fitted were giving the correct level of output.
Stuck for ideas now. As the lambda probe is a two wire sensor is it possible that it's not getting hot enough ? (Could be the universal sensor I bought new needs a higher temperature than the Mazda original ?) My engineer's only suggestion was to fit a four wire sensor and connect the heater feeds to a 12 volt supply - a solution he has used in the past successfully on Mx5's that would not pass the emissions test. Any ideas would be very welcome at this stage as I am going mad with frustraion after 5 hours on it this afternoon ! She used to run so smoothly before this too!
PS. Diagnostic revealed one fault code "Variable resonance induction system (VIRS) solenoid #1 malfunction" but I have no clue what this refers to, or whether it has any relevance to the lean running condition.
valve was goosed when i tested it, replaced it, it then worked but did it solve my problem ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Ive had my van for a fair few years now and have had some intimite times 