Thread: V8 Exhaust Gas CO%

Anyone know what the CO% exhaust gas reading should be for a 3.9 at idle?

The Haynes manual says 0.5 - 1.0 % but that's for the UK model with cats which I thought was lower than the Aust non cat D1s.

Hmm, my 4.6 Rover SD1 with a 4 barrel Eldebrock has an AEM wideband in it and that idles at 13.5:1 AFR which equates to 2.7% CO. But that's carb not EFI of course.

I set the Disco up to read the same using a Gunson Gas Tester sniffer pipe up the exhaust and it idles very smoothly and accelerates strongly for a 3.9. That's with the distributor ignition advanced to 12 degrees BTDC.

Might try winding the MAF screw back to see how it likes 2% or even 1.5 in the interests of greater economy. That would bring the AFR down to almost 14:1. I guess it's all a bit of a trade off.

Incidentally at 2.7% CO the MAF is reading 0.045 volts ignition on/engine off.