EFI fault - Is it a Lambda sensor?

[s3dave]

Yesterday after driving over an hour mostly on the motorway, I was only a few hundred metres from my home doing 30mph when I had a EFI fault on the dashboard and the engine stuttered badly. I limped it home. I stopped the engine and started it again and the fault did not reappear. At the time I was displaying live data on my RSiAJP app through my IPad - no faults were shown. There are no obvious loose wires in the engine bay. I have now plugged in my laptop with the MBE Tool and run the engine, again I can not reproduce the fault. Below are 3 screenshots of the live data while stationary in my garage. The only thing I can see strange is my 2 Lambda sensors are reacting slightly differently. I assume this is why my Adaptive trace for banks 1 and 2 are also different.

My question is: do you think it is a Lambda sensor that caused the EFI fault and if so which one?

[Dalamar]

The lambdas don't look too bad to me. Maybe lambda 2 is a bit lazy. I like to see sharp rises and falls with the traces.

Here is a pic of a recent lambda 1 change. New lambda is a Walker 250-23802 which gets you an NTK item.

[s3dave]

Thanks for the advice and sight of your trace. I must admit I expected both lambda traces to be very similar, so perhaps it's not a Lambda issue after all. Don't know what else it could be, I will connect the laptop up again and take the car out this week to see if the EFI fault comes back.

[Basil Brush]

Dalamar said:

The lambdas don't look too bad to me. Maybe lambda 2 is a bit lazy. I like to see sharp rises and falls with the traces.

Here is a pic of a recent lambda 1 change. New lambda is a Walker 250-23802 which gets you an NTK item.

How are you getting on with the alternative NTK Lambdas you fitted? Would be good to know there's an alternative quality part for the early cars.

[s3dave]

Good news (I think). This week I cleaned the connections to the Lambda sensors and ambient air sensor although none looked dirty. I also cleaned all earth points (including the one behind the battery). Today the car drove a faultless 120 Miles. I just hope my EFI issue was a one off :-)

[Dalamar]

Basil Brush said:

How are you getting on with the alternative NTK Lambdas you fitted? Would be good to know there's an alternative quality part for the early cars.

Still looking good after about 1,000 miles. Managed to fire up the MBE software this week and here's a screenshot. Nice and sharp traces for both lambdas.



Here's a pic of the box from Motaclan. I was told by the distributor who sells these to Motaclan it's actually an NGK item that is bought in batches. When I phoned up he said are you after one for a disco or a TVR? I guess others have found this source of sensors before. Anyway, still happy with this replacement part.