extreme lean condition at high boost.

[John Cody Forbes]

Grant Lenahan wrote:
> Yea, but if all the other systems are delivering fuel, somewhat
> proportionately to airflow, why would it go "off the scale lean"
> suddenly? It sounds as if something is either reducing fuel delivery
> or abruptly stopping it at a certain rate.
>


Don't forget that a missfire shows up as a lean condition to an O2 sensor 
due to the excess of un-burned oxygen. If you have a bad spark plug that 
can't deliver spark at extra high pressure levels that hole  would go dead 
under load and pump a ton of raw oxygen into the exhaust, tricking the 
sensor into thinking you are lean.

-Cody Forbes
http://www.5000tq.com
'86 5k noT noQ
'86 5k noT noQ - Parting Out
'87 5ktq
'87 5ktq - Fast. Really Fast.