Gr8godbob

I saw a thread where somebody asked about a mpg gauge in the 928.

I found this picture.

Seems like it was only in early 1980's cars.

Dutch 928 fan

I have one on my 1984 S2 euro. (Litres/100km)
Although instrument clusters can be swapped, I believe mine fits the model year as the rev counter corresponds with the twin dizzy ignition.

Leo

dlagerstrom

My 82 has one. Not a working one, but it has it.

h011yw00d

Jeez, and I thought the downshift light was annoyingly guilt-ridden.

docmirror

It's a vacuum gauge calibrated in fuel consumption.

17prospective buyer

So in other words, not very accurate?

brealytrent

Yeah, not really. If you give the car a little throttle from a stop and while it's accelerating and the revs pick up, it'll go all the way to 25 l/100km. I think it's only good when you're cruising. Mine reads on average 10 l/100km, or about 23 mpg.

Dave928S

On a K Jet the consumption gauge reads a rheostat linked to the fuel plunger in the control head .. so it's fairly accurate.

Tom in Austin

Interesting, I thought it was vacuum-driven, like so many other companies did in the 80s for a fast and cheap 'economy' indication

jeff spahn

Come on, this is Porsche. When would they do it easy or cheap?

bordin34

The 944 has the same gauge. On the 944 at least it is not a vacuum gauge. It measures the injector duty cycle and the speed of the car to get MPG. At idle or 0mph it switches to the other map which is in light grey that reads GPH.

docmirror

Interesting. I thought all of them were vacuum driven. Looks like many of them are sourced from other means.

dr bob

I was thinking that a ported vacuum gauge would do the trick, but neither that nor the plunger LVDT method directly take into account the speed of the car. With just the LVDT sensor, the car would get great mileage sitting still. Is there more to it than just the airflow door position sensor? Since the speedo is driven by pulse inputs. it wouldn't be a stretch to include wheel speed in the electronic gauge smarts.

My only exposure to this gauge has been on the '85Euro project car. I spent time under the hood, not so much in the driver's seat, so didn't pay attention to how it actually responded to load and speed changes.

PorKen

I have a ROW version in my '86.5 auto. (From a euro S4, '85-'88 can share tachs - 944 too.)

The consumption 'computer' circuitry is analog, unlike CASIS, which uses a digital computer, the same type used in EZF and LH2.2 boxes.

(thread)

depami

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