Re: Fuel economy (was Re: Pressure Acummulator Discoveries)

[zm@mhcnet.att.com (Zafer Mehmood [209])]

> 
> 	By the way, what kind of "tune-up" could one do on these cars
> 	('85 5000ST)?  I've put in new (Bosch Platinum) plugs and an new
> 	filter (it may have been easy for some folks, but it was a real
> 	pain in mine ..) but I can't think of anything else that I could
> 	easily do.  If it ain't broke ... etc., I suppose.
> 
> 

The Audi-recommended Bosch triple-electrode spark plugs are clearly
better than the Bosch Platinums, especially for Audi turbo cars.
Many list members have attested to this fact - smoother idle, better
acceleration.

Other tune-up items:

- Have you checked the condition of the spark plug wires, distributor
cap and rotor? On a 9 year old car, they probably need replacement if
they haven't been replaced already. I usually find a black deposit on the
cap and rotor electrodes (oxidation?) that can act as an insulator and
reduce the amount of spark. Easily scraped off with a utility knife
and cleaned with fine emory paper. I usually do this every 15 to 20K miles.
The cap and rotor need replacement if the electrodes are pitted or worn
down. Bosch replacement parts recommended.

- A post on this list not too long ago mentioned that fuel filter replacement
gives the most "bang for the buck" in terms of tune-up of the Bosch FI 
systems. So, if the filter hasn't been replaced in a while, go for it.
I think the replacement interval is 60K miles. I replaced the fuel filter
on my '87 5000 TQ recently but didn't see any noticeable improvement (50K+
miles since last change).

- A good fuel injector cleaner like Chevron's Techron in the gas tank every
six months has been recommended by many.

On the topic of fuel economy, if you have an automatic expect significantly
lesser mileage than a 5 speed of the same model/year. If I'm not mistaken,
early Audi automatics were 3 speeds (no overdrive) -> poor mileage. A manual 5
speed Audi has better fuel economy for two reasons - less transmission
losses and "deceleration fuel cutoff" (shuts off injectors when the car
is in gear, clutch not pressed and throttle closed). I know for a fact that
the CIS equipped 86-88 turbo 5000 cars have the deceleration fuel cutoff
feature, but I'm note sure about others.

Zafer
zm@mhcnet.att.com