fabric

Care to elucidate? Mine reads 1/4 low all the time.

bd0nalds0n

I was getting consistently around 13mpg in my 928 combined city/hwy until I swapped for a rebuilt LH. Fuel economy has improved, but I haven't driven the car enough to establish a consistent new baseline.

BTW, according to my air fuel ratio meter, before the car was only rich at idle, or coming off-throttle while cruising, but that was enough to adversely affect my fuel economy by, I'm sure, a few MPG.

CMW

On my trip from San Pedro to Bakersfield to Lancaster and back I was averaging about 20-22 MPG city and high way. Since I have been back I have been averaging about 20mpg in LA traffic (unless stop and go).
I have acheived aprox 95 miles on 1st qtr tank of gas. After several such trips I am absolutely convinsed the S/C has decreased fuel consumption at crusing speeds, but increased it at boost or acceleration.
I know this to be true because before (SC instal) the computer would tell me I was averaging 24-28 MPG crusing 65-75mph, and now it shows between 30-32MPG at the same speed.

PorKen

I can never get over 20.5mpg on the highway.

13 or 14 in the city.

Imo000

That’s because now you have larger injectors and the computer counts the injector cycles to calculate the MPG estimate. Since the computer is pre set to calculate for the smaller injectors, it will not know that the volume is actually higher. Larger injectors open less frequently but flow a larger volume of fuel than the smaller ones. This causes the reading to become inaccurate. Your computer, unfortunately, doesn’t know this and is giving you a false reading.

Shark_gts

'93 GTS country mixed driving 14 liters/100km. GTRSS button costs me 0.5L/100 as I leap from first once or twice per drive.

90S4 Same roads, but driver tends to adhere to speed limits, 12.5 L/100km

Checked the computer with actual. Very accurate to within 0.1L/100.

Paul
www.jageng.com

Schocki

Did you follow your wife in the Honda or did they follow you?

TeufelHei

I used engine speed vice speedo since my speedo/odo are unreliable data. Setting the needle at 3000 RPM (80 MPH) between Tucson and Phoenix and back (approx 260 miles) and filling up before and afterward on 91 Octane Chevron gas yeilded a little better than 22 MPG.

My 81 L-jet car got about 25 MPG between Wilmington and Jacksonville, NC. Similar gear ratios, same test.

Admittedly, my Euro is running lean. The inside of my exhaust manifolds are some of the cleanest I've ever seen! I'll tune the car properly and try again, but I suspect that it will be about the same.

I have to say that I am VERY impressed that a car with this displacement engine, ancient fuel injection, and without the benefits of variable cams is putting down this kind of power with relatively low fuel consumption.

Oh, and I've only got half the valves too!

Bill Coleman

a) I was using a 'borrowed' license plate and really didn't want to get stopped.
b) My wife hates driving on interstates. And she's got our 22 mo old daughter in the back seat. Not to mention were driving back on the day of her birthday. That's right - she put off celebrating her birthday so we could drive from Michigan to Virginia (1000+ mile round trip) to buy me a new toy. I was trying really hard not to do anything that would make her the least bit mad! Oh - and I did offer her the chance to drive the 928 while I drove the Honda, which she declined. In retrospect I probably overdid it - my wife told me afterwards that she kept wondering when I was going to 'open it up'.

RDS928S

Something must be wrong then with my 86S 32 valver.
I have been filling up routinely with 17 gallons each time. Commuting in stop and go to work I can only get 13 mpg at best.
The engine runs smooth and pulls strong. I do admit when traffic clears I put the hammer down.

RDS

Colin Emerson

My 89 S4(the one Malcolm was talking about originally) consistently gets on average 10L/100Km. At 100Kph, just light on the throttle I have seen it dip to the low 9L/100Km. I am very happy with that performance. I heard somewhere that the newest vettte can get just over 7L/100k travelling at a modest 100kph, very impressive but when is that ever going to happen. The funny part on these cars with computers is watching the fuel consumption in that first kilometer if you keep the speeds low(ie driving on gravel) my comp will report something like 55L/100km, as soon as I pick up some speed it drops significantly. 20mpg seems good enough to me!
Colin

CMW

IMO,

I was wondering why the computer was showing such a hugh jump on MPG calculations but the actual fuel consumption was only getting slightly better MPG by distance.

the flyin' scotsman

Hi Colin..................welcome to the gong show.

As Garth mentioned earlier how far do we trust the computer read outs? Its probably up there with the volt meter, fuel guage............sun dial in the dark at pagan rituals.

Then again I've an old fashioned 928 without the fancy modern read out technology

CWO4Mann

Kick me for saying this since this thought was the first thing you did probable ..... did you check for leaks both with engine running and not running?

The leak (if there is one) could be a pressure leak (

I caught on my 1976 Datsun 280Z that way after a few hours of dicking aount under car. I spread newspapers and then did run and no run. There was a pinhole hole in the fuel line. It sprayed a fine mist under pressure.

Regards

RDS928S

Dave,

The car did have a bad fuel leak from a previous owner repair where the fuel filter was overtorqued onto the fuel pump causing the fuel pump to crack.
Also currently my gas tank leaks about a cup of fuel on the ground just after filling up.
I think there is a rusted out section at the filler neck/tube. Once I drive a little and use up some gas the leak stops.
I had the engine completly serviced when I purchased the car. There are no leaks at the motor end.


RDS