Lamda Sensor/s

[Millsey]

Hi everyone

Sorry if being thick but could someone please let me know where the lamda sensor/s is/are locoted on the VR4.

I guess it will behind some of the heat shields but didn't want to be taking stuff off looking for it unnecessarily.

My car has just failed MOT on emmissions a couple of days ago, after it had not been used for a couple of months, the CO figure was a bit too high so been driving it around since and went for a second check earlier when the CO figure was very low but the lamda reading was slightly high which I was told shows it was running lean?

I was hoping to clean the lamda/air sensor/s to see if that is the cause as on the first attempt the lamda reading was spot on.

The only other thing I can think of is that I got the engine/exhaust nice and hot and maybe it was too hot making it read lean?

Any help appreciated.

Cheers in advance :beerbang:

Phil

[Nick Mann]

Normally the cat needs to be roasting hot to get good emissions. Not nice and warm, ***Roasting Hot*** !!!

The sensor is at the end of the downpipes just before the cat.

[Millsey]

Thanks Nick

The CO and HC figures were very low, so that was good, but the lamda figure read high signifying it was too lean I was told.

Phil

[Gly]

the factory sensor is narrow band, and not good for true AFR ratio's,

for that your need a wideband.

[Nick Mann]

It should be good enough to hold the car at stoich for the mot test though.
I understand that a small leak in the exhaust can mess up the readings too.

[Millsey]

Just a quick update to say that I went back this morning after a more leisurely run around and this time lamda was back to normal so passed the emissions test no problems. Didn't touch/clean/change anything at all in the end.

I think they had been having trouble getting the RPM sensor thingy to work right yesterday and had recalibrated their kit this morning before I got there so thought the readings from yesterday may have been suspect rather than the car!!!

Thanks for the replies though.