18 MPG!

In message , Simon Dean writes

Lambda sensor?

Hole in the fuel tank??

I think your driving and Hummer!

Heavy Right Foot?

It's always been heavy, but I've usually got more out of my tank than that!

Cya Simon

According to all readings, it's switching fine. Someone did say it was cross threaded though, and there is a hint of a rumour it could be a bit leaky in that area.

Cya Simon

What's the performance like?

Could it be running 'cold' all the time (i.e. rich mixture because the temp sender has gone kaput?)

Perforance is questionnable. It was really rough a while back, I could hardly accelerate onto the motoway, but cruising at 70mph (ahem) is fine... I just lack the get up and go so to speak.

But I actually reset the learning on the computer and it seems good now.

The temp sender looks fine. I hooked it up to my blazt cable and everything checks out... speed... rpm... temperature, o2 sensor, egr egr, timing (although timing is a bit lumpy - even in base idle adjust mode).

The only things Im not sure about is the injectors. I have the results of my tests, but Im not quite sure how to interpret them. I gather though that they work pretty well in that they're only triggered for a short piece of time, ie, they're not constantly running... something like injector pulse. Looks pretty "conservative" to me.

So Im stumped!

Cya Simon

Sometimes I wonder. In that, even yesterday, I was driving around having only used an 1/8th of a tank... constant.... 7/8ths left according to the fuel gauge.

I pull away this morning and quickly the guage crashes down to quarter of a tank. It picks up a little by the time I actually get into work...

Ta Simon

That was going to be my next question - how are you measuring the consumption?

If the gauge is potentially dodgy the best way is to fill it to the brim (so you can see the surface of the petrol through the hole), drive a distance -

Petrol gauges aren't the most accurate (or linear) devices around even on new cars...

Sounds like either its out by a tooth or two on the cams or the cat / exhaust is partially blocked??

Tim..

My Escort tends to stand firm telling me it has such and such in for long parts of journeys. I was driving 60 miles a day and it wouldn't move. Until the next morning when I heated it up again.

Or on hauls from Lancs to London, it wouold hardly move until everything settled down and the next day I started it up again. Odd sensors, seem temperamental but the temperament can be judged to some extent.

-- Billy H

Tell me about it. The one on the wife's Proton Satria is all over the shop, she has to zero the trip counter and fill up when she hits 200 miles because she can't rely on the gauge. I'm assuming the most likely culprit is the float-based sender unit in the tank.

Quite believable if short town journeys.

Depends on the car. The one in my BMW is very good - but it uses twin floats of some description. The OBC gives a 'miles to running out' figure which is uncannily accurate.

Maybe it is, but IMO it's only real value is as a guide, when driving conditions are relatively consistant, because it is a running figure based on the rate of fuel consumption, and speed up to that point. If you meet heavy traffic after a relatively free run, or vice versa, the figure will change to reflect the different mpg because of the altered driving conditions. Frinstance. When I started a 30 mile trip a few weeks ago, it said I had enough fuel for 98 miles. When I reached my destination, it said I had enough fuel left for 104 miles. Obviously the 98 miles was based on how I'd been driving, prior to the 30 mile trip, which was done on a clear road, with no holdups at an easy 70-80 mph. IIRC when I got home, it said I still had enough fuel for 78 miles. Mike.

You want to get one of those gas guzzling 4x4's it would work out cheaper in the long run AND you can help destroy the planet!.

I may add that I say this in jest as my 57, 109 only does 20 ish MPG,

Hence:

"I just put some fuel in my car today as an experiment.

OK yeah, 10 miles through traffic... still... I used to get a bit more out than that, and even then it was questionnable.

I guess I should test it on some nighttime motorway driving... with that, I can almost get 400 miles out of a tank.

Cya Simon