Re: STILL running a little rich...??

["Harold McElraft" <hmcelraft@xxxx>]

> my only complaints NOW are:
> 1. i'm barely getting 12 mpg in town (mostly on city streets, not 
much 
> highway). i have a manual and i don't abuse it. any ideas? 
> 2. when i start the car cold in the morning and don't let it warm 
up, the car 
> starts to sputter around 2500-3000 RPM no matter what gear you are 
in. this 
> continues for only 2 or 3 blocks. extremely short lived problem, 
but happens 
> almost every time. why?

I think you have two problems based on what you say about everything 
appearing to be working.

First, the hesitation - the vacuum delay valve at the fuel pressure 
regulator is probably dropping vacuum too fast. This valve causes 
the cold engine fuel spike when it holds a vacuum long enough. If it 
leaks down vacuum too fast you get too little fuel and the engine 
stumbles. When the engine warms up the vacuum to the valve is turned 
off. The best way to test it is to take it off and time the leak-
down with a manual vacuum pump. The specs are in the shop manual.

Second, the low fuel mileage is probably the o2 sensor not working 
or, the WOT switch is stuck closed. Since the lambda system is an 
enrichment system, if it does not work at all (including the 
frequency valve) the system goes lean. But, if the system is 
working, when the o2 sensor fails the system defaults to an enriched 
condition. The same is true for the WOT switch - when the switch is 
depressed, the system goes to an enriched mode. If the o2 sensor is 
less than a year old I would suspect the WOT switch, but be sure to 
check the wire to the o2 sensor. The WOT switch is at the throttle 
spool and the wiring is on top at the main harness. It is a normally 
open switch - no continuity. Activated should show continuity. If in 
doubt just disconnect it.

Harold McElraft - 3354