Air/Fuel Ratio gauge worth it?

[ventureforth]

I have the set of for duostyling gauges that I'm going to put in my '82 Rabbit 1.6NA.  I have the senders and everything I need to hook up oil pressure, oil temp, and voltmeter.  The fourth gauge is A/F Ratio, but uses an oxygen sensor off the exhaust which, of course, I don't have.  Is it worth paying an exhaust shop to install an 02 sensor to use this gauge, or is it really not worth it and I should just put it up on clist or ebay or whatever and just use the other three?

Thoughts?

[the caveman]

You could put it in for fun, but on a diesel ,it doesn't really apply. The AFR bounces all the way from very lean to rich in normal mode. Better to use the spot to install an EGT gauge, which is useful in determining fueling in a diesel, esp. if you are running a turbo.

[R.O.R-2.0]

would a Gasser A/F gauge even function properly in a diesel? i bet it would just stay pegged at lean the whole time. diesels dont have an air throttle, they suck the full amount of air they can get every time the valve opens..

[Vincent Waldon]

Yeah, there's no magic 15:1 air/fuel ratio on a diesel like there is on a gasser... so your O2 sensor and nice Dustyling gauge would be forever looking for something that doesn't exist.  

On the other hand, Dustyling gauges have a pretty fair resale value towards the much more meaningful gauge for your diesel (assuming you're planning to play with the pump)... as already mentioned... EGT.  

[745 turbogreasel]

I think they put wideband  AFR sensors on some of the new diesels, and some do use them for datalogging.
A narrowband will be useless.
O2 bungs cost less than $6, and take all of 5 min to weld in.

[bajacalal]

I would use the hole wherever the air/fuel ratio meter is supposed to be mounted to install a pyrometer instead. It will give you much more valuable information for the operation of your diesel engine.

A gas air fuel ratio meter would probably be meaningless on an old VW diesel. One of the great things about diesels is that they don't, as mentioned, require a specific air fuel ratio to run. When it's idling, it just gets enough fuel to keep it turning over and when you accelerate, you increase the amount of fuel injected but the amount of air entering stays the same for any given engine speed...

Since the engine is always getting as much air as it possibly can, your gauge will consistently show a very lean condition, even under load, as there will usually be plenty of leftover oxygen.

[R.O.R-2.0]

i read somewhere that the o2 sensor in a gasser kinda functions like a pyrometer?

rich = cool

lean = hot

[VWCaddy]

I would use the hole wherever the air/fuel ratio meter is supposed to be mounted to install a pyrometer instead. It will give you much more valuable information for the operation of your diesel engine.

That is what I did on my dual downpipe manifold, drilled and tapped the O2 sensor hole for the EGT probe: