[urq] EFI + MAC-14 maxing ataround 5k RPM

[Cody Forbes]

Ben Swann wrote:
> I think I noted a sudden leanout on O2 meter while driving it today
> when problem
> happened, which gives some credence to the lack of fuel.  I just
> don't understand why
> this would be happening when the injectors are supposed to be capable
> of something over
> 300HP and I'm probably doing about half that.
>
> I need to get some fresh logs before enquiring from the motorgeek and
> megasquirt forums.
>
> Ben
>

Wait just a sec before you jump to conclusions on that lean reading. Any 
ignition failures will peg an O2 sensor (wideband or not) in full lean 
because of the unburnt oxygen that gets pumped into the exhaust. A fouled 
plug from an overly rich condition will always trick you by false lean 
readings of the O2 sensor.

Don't forget that an O2 sensor, again wideband or otherwise, doesn't rean 
fuel mixtures. It reads the percentage of oxygen in the exhaust stream. Lean 
conditions cause an incomplete burn which sends oxygen into the exhaust, 
rich conditions snuff out the oxygen with hydrocarbons. Even a momentary 
misfire is enough to put a ton of raw oxygen in the exhaust and fool the 
person reading the sensor.

-Cody Forbes
http://www.5000tq.com
'87 5ktq - Fast.
'87 5ktq QLCC'd plus some
'86 5ktqCD
'86 5k
'86 5k