Crazy fuel consumption readings?!?

[DT-P38]

Has anyone ever seen figures in the 40's?

The Mrs "new" P38 is throwing some mad figures and even when I re-set and it does a recalculation it starts off at high 40's... and then steadily decreases as km's covered increase.

As soon as the vehicle comes to a stop, it just starts climbing again... and at a pretty ridiculous rate. I am assuming its not actually using this level of fuel, although i might have to do a manual check and calc just to be sure.

Anybody got any ideas or experience with this sort of thing?

[p38arover]

Fuel consumption vs zero km travelled will give very high readings. What does the handbook say about how the system works?

What figures do you get if you do a reset whilst travelling on the highway? It takes 1km to get a new reading so it won't take you long.

[Eevo]

drive 100km and see what it says

[Keithy P38]

Not too sure on year/spec your P38 is, but mine will do it's calculation over 1km and at 60kmh it'll normally come back around 10L/100km and if traveling at 100kmh it normally comes back around 11.5L/100km. Depending on acceleration/coasting that will change a little but normally on flat-ish ground at steady speed that's what I'll get from a reset.

Cheers
Keithy

[blindin]

Fill it up, run it for a bit, and then refill, and work out that way.
I live in the hills, if I do short trips, I'm up at about 20ltr/100km
I get about 16ltr/100km on longer runs. I have a 98 gems.
Driving harder will obliviously increase fuel use.
But I would work it out manually to get an idea first.

[daf11e]

I also have worked it out manually and suburban trips with no crazy acceleration gives 18.5ltr/100.......I do believe this is pretty normal for a Bosch 2000

[DT-P38]

Fuel consumption vs zero km travelled will give very high readings. What does the handbook say about how the system works?

What figures do you get if you do a reset whilst travelling on the highway? It takes 1km to get a new reading so it won't take you long.

It doesn't really matter at what speed, the figures are mad, crazy high in comparison to what I am used to with mine (mine is a '95 gems and the Mrs is a 97 gems). Had a look under the bonnet and underneath and hers (the crazy one) has pre-cat oxygen sensors where mine doesn't... everything else looks exactly the same. I will do some examples runs tomorrow, (suburbs, highway slow and high way fast) and take photo's to share the experience! Funny thing tonight... when I filled up (carefully and slowly to overflowing) to get ready for a manual calculation over the next few days it only showed as 7/8 full on the gauge.

The craziness I am seeing includes:

1. The gauge seems inaccurate.
2. It seems to "re-set" the fuel gobbling rate to "mad high" at every start up.
3. It then proceeds to wind down the L/100KM figure as the km's increase... but very, very, quickly - as in - it can drop from 40+ to high 20's in a very short trip of less than 3 km's.

The PO used a Faultmate MSV2 (which I have yet to familiarise myself with) and I am thinking that some "dabbling" with fuel mapping or engine management protocols might have occurred.

Is it even possible to do this sort of thing to make a P38 react like this is?

[DT-P38]

drive 100km and see what it says

We have two P38's... and the first we have had for 10+ years... If I thought taking it for a spin would help, I wouldn't be asking questions here... I would be out driving!

But seriously, I have had it for a while, and put a few KM's on it already just getting stuff done for RWC. On a couple of 50 km trips a week or so ago it did settle to a reasonable rate (high teens) but still jumped back into mad-crazy territory at next start up.

Might have to start checking out how to use that Faultmate!

[DT-P38]

Not too sure on year/spec your P38 is, but mine will do it's calculation over 1km and at 60kmh it'll normally come back around 10L/100km and if traveling at 100kmh it normally comes back around 11.5L/100km. Depending on acceleration/coasting that will change a little but normally on flat-ish ground at steady speed that's what I'll get from a reset.

Cheers
Keithy

My original P38 has never come down to that sort of economy - but has returned close variations on the theme you lay out. It's on gas and so I have never even bothered worrying about if it's a little rich or maybe even overfuelling (which I do not think it is).

The experience with this second one and skimming some of the OBD threads going on at the moment are prompting me to try and get a better handle on it all. 'As if' I am really interested though... sometimes I think we all have a little too much knowledge of the deep dark secrets of these P38's!

[TheTree]

Have you reset the adaptive values in the ECU ?

Steve

[Tikka7mm08]

Mine did the same (2002) when I replaced the MAF. I was having a sweating fit parked at the lights watching L/100km rising steadily. Eventually with more driving it came right.

[DT-P38]

Its still showing quite high in comparison to the other one... avg after close to a tank of approx. 22 L/100KM around town. NOT where I want it to be and definitely out of step with responses here indicate it should be doing. The exhaust also has that running rich smell and a very dark charcoal (but thankfully dry) look about it...

Have not had a chance to drive it for a while, will take it out tomorrow and see where things are at.

[DT-P38]

Very thirsty pig!

[Tikka7mm08]

Swap the MAF out.

[Pedro_The_Swift]

or at least test it,,;)

[Keithy P38]

Any updates?