Okee dokee David. I'll let it be for now :)

Mind you, I have a mate for that gauge somewhere, if I can find it I'll compare the gauges.

cheers

alistair

On 2013-07-24, at 9:37 AM, David Beierl wrote:

> At 12:03 PM 7/24/2013, Alistair Bell wrote:
>> Well, it is a USG (US Gauge) pressure gauge. You can't be doubting those readings can you?
> 
> You'd be amazed at my ability to doubt gauges.  I've got a lovely little chromed-brass vacuum gauge made by USG for Gomco, the (at one time anyway) pre-eminent maker of medical suction devices.  It's pretty, readable, responsive, and irritatingly far off.
> 
>> Yup, Bentley gives value in Bar and psi. 2.5 Bar = 36.25 psi. Leaving aside gauge error, I was just wondering if the extra 2psi would be enough to enrichen things beyond the O2 sensor's control ability.
> 
> Hollow laughter, since the ECU has the demonstrated ability to follow a shorted sender down into super-rich will-barely-idle hell.  But remember that the system should operate (except for emissions) perfectly with sensor and CAT removed.  My California-spec '84 was delivered that way in Germany and didn't get its CAT and lambda sensor until it arrived in the US in 1991.
> 
> So lessee...stoichiometric mixture is 14.7:1.  Best economy mixture is about 16.7:1, best power mixture is about 13.3:1.  If the system is aiming for stoich at 2.5 bar, 38 psi will bring it rich by 4%, to about 14:1.  I don't think you have a worry.  And of course the feedback system will get its sticky fingers in there, mis-read the misfiring cylinder as lean and screw your mixture up completely.
> 
> Yours,
> David