The V8 Owners Forum -

Hi All

Rebuild continues, RR is a 1989 flapper, found this exhaust sensor already fitted. Possible that the exhaust is a later addition. Any suggestions as to whether this is a wideband or narrowband sensor?

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There'd be no point in using a wideband with any of the Lucas injection systems. The O2 sensor was just to keep the mixture at stoich to avoid damage to the cat. Wideband are of more use on an aftermarket injection like MegaSquirt, etc, with no cat. They allow those to self tune to a pre-determined AFR map - or just show you what the actual mixture is doing at a point in time to take away the guesswork. Which is also a good idea with carbs.

I can't remember if the flapper ever had a Lambda sensor option. I think it might have done in some export markets. But presuming it is a UK market system, then the sensor must be an aftermarket one, most likely wideband.

Chris.

Obviously that sensor is scrap anyway, and given it had only 4 wires, it is not a wideband sensor.

I should have provided more detail. Flapper has an adjustable ECU, two separate rotary knobs, each marked W - R. I would guess that one is for idle and the other for WFO. Engine also has supercharger.

It is possible that the engine has never run with the supercharger other than idling and running round the lock-up yard (I bought it as a non-runner), therefore I need to ensure that the AFR is somewhere near correct fairly soon. I have some monitoring kit used in a non-automotive application that will measure output from a lambda sensor, hopefully the boss is suitable to receive a wideband sensor. Not closing off the option of stand alone sensor and display.

You're wasting your time reading off a narrowband sensor.

Most sensors are standard M18x1.5, and that photo looks the same.

just buy a wideband kit, they're ridiculously cheap at £150 and give valuable information.

ChrisJC wrote:I can't remember if the flapper ever had a Lambda sensor option. I think it might have done in some export markets. But presuming it is a UK market system, then the sensor must be an aftermarket one, most likely wideband.

Chris.

Yes they did. The forerunner of the UK flapper was the NAS SD1 which had lambda sensors. If you look inside a UK flapper ECU there is quite a large part of the PCB unpopulated - that's where the sensor electronics go.