[mdlug-discuss] [TECH SUPPORT REQ] OBD-II typical readings

[Robert Meier]

Aaron,

Thanks for your suggestions.

> Perhaps your Mass Air Flow sensor is reading high
> (engine computer thinks more air is coming in than
> actually is, and thus directs for more fuel than is needed).

OBD Gauge does not include that measurement (or my car is unequipped).

> By different means, a dirty air filter can also cause
> an overly rich mixture.

Air filter looks clean and was just changed less than 3Kmi ago.

> 75,000 miles is getting up there.

Two of my prior cars were at 120Kmi and 140Kmi when they
were totalled by collision.

> When was the last time the following services were performed:

> Fuel Filter Replacement
1Kmi after start of problem, and 1Kmi before now

> Spark Plugs Clean and Re-gap OR Replace and re-gap
> Spark Plug Wires Replace
> PCV valve Clean or Replace

60Kmi (15Kmi ago)

> Throttle Body Clean

unknown

> Air Filter Replace

72Kmi (3Kmi ago)

> Spark plugs are cheap ($2 each), so I replace those ever
> 12-24 months. Aging spark plug wires can result in weak
> ignition, even if you don't have any misfiring.

Unfortunately the Saturn plugs are difficult to get at to replace.

> A gummed up PCV valve allows the inside of the engine block
> to hold high pressure gases (and also lots of nasty stuff
> that you don't want in your oil).

> Fuel filter... it's amazing how a used up fuel filter can
> rob you of both mileage and power. I'm not sure if it could
> cause overly rich readings, however.

As this was actually overdue for replacement,
it was replaced first,
but I would expect a clogged fuel filter to restrict fuel flow
and behave like a "fuel starvation" lean injection.

Still investigating,
-- 
Robert Meier
tel:+1.248.650.9488 (voicemail)
mailto:eaglecoach at wwnet.com

 "Destruction is *easy*. Even stupid people and weather formations can
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	      -- Ray Ingles 1997