Weird fuel economy

[axton.marinschek330i]

Hi guys, im new to this forum,but I bought a e46 330i 2003 auto and its been giving my weird fuel consuption readings,like in the city it gives about 20-22 L/100km and when on the highway, and you have to see it to believe it, it gives 4,3 L/100km when at 120km/h. I know that the readings is correct because if you compare it to the kilos done and the fuel used out of the tank it gives the right numbers. Is there somebody that can tell me if this is normal or is something not set up right.One extra thought is that i know somebody did a ecu remapping before i had the car and it has been services recently. Also if you owned a 330i or a e46 of the some model, please tell me about your experinces and your thoughts about it.

 

[JustNN]

Ok so 4.3L/100, what was the distance.

Best i did with mine was 6,2 on a 25km stretch and worst 18.9 in town

When last was service done and whats the millage

 

[Ralf*]

Hiya, and welcome to the forums

1) before replying, maybe introduce yourself with a photo or two of your ride

2) Both fuel consumptions seem to be way out when compared to what myself and from I have read others get on similar models
3) Town driving even with a heavy heavy right foot, should not get much beyond 16/18l per 100km, a normal town driving style should realize something in the 11/12l per 100km
4) Open road it would be realistic to achieve around 7/8l per 100km, not even the best diesels get that far down, proabaly closer to 5/6l per 100km


so I would say that there is problem in the indicating of your fuel consumption

I might have it wrong, but the ECON or CONSUMPTION indicator on your clock, just below the rev counter, is actually directly linked to the vacumm pipes, and thus how much vacumm is being generated in the intake system, so first point is to check for possible vacumm leaks and/or blockages.
somehow these reading from your vacumm system, are then used by the cars computor to generate a digital consumption readout, based on average vacumm readings for a fix amount of time.
toegether with the float chamber fuel tank volume readings it then also computes a "Range" based on the average vaumm experienced and fuel quantity in the tank.

I am sure that my understanding (basic) is not far wrong, but some serious "guru's" on BMW's might add or correct me, and possibly also give you better advice.

 

[Philip Foglar]

Welcome to the forum. Yes, an introductory thread is a good start.

But in terms of your fuel consumption query, it doesn't sound right in both cases. It is using way too much fuel in town and dare I say using too little fuel on the open road. Almost as if it is running very (possibly dangerously) lean when cruising. What is your typical tank range and the overall economy when filling up, based on what you are seeing?

 

[axton.marinschek330i]

Thanks all of you for the replies, Im already loving it on this forum. I never thought that the range and consumption is calculated by a vacuum, I always thought it was by a flow sensor of some kind, but you learn something new everyday. I just want to add that could it be that the vacuum given to the consumption sensor, is the same vacuum given to the exuast flap,because I first saw they took off the vacuum pipe this weekend off of the exaust flaps vacuum camber. P.S I dont know all about this car and im only 18 years old but i still want my car to be in a tiptop condition.Here is a few photos of it.

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Can someone just tell me how to add a photo on a tablet,please?

 

[Blomhj]

Welcome !!

This readings is it taken directly after you reset your AVG consumption or is it driving for a while ( a few days at least ) without resetting your consumption .?

 

[axton.marinschek330i]

Ive reset it about 3days ago

 

[Blomhj]

It should stay constant between 12.5 and 17.5 depending how you drive unless you floor it the whole time. What you can do is check your Cluster's secret OBD functions , under test 6 it gives you the fuel capacity in tank , write it down drive 100km or so and take another reading , compare km traveled to fuel usage to get your avg ....

 

[axton.marinschek330i]

I'll try that for a bit but im going to send something i think some people will be scared of.

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Thats the avg L/100km and ive never floored it before because im checking the consumption as I drive.

 

[axton.marinschek330i]

Hi guys sorry for the late update, but I found the problem, it was something I would never thought of , the small grid filter that is on the end of the intake side of the petrol pump that is submerged in the tank, was bent up, and on the beginning I never drove the car with a full tank, so what I think happened is that is made bubbles get stuck or something in the filter and got sucked by the pump, because agter fixing that, even after driving until empty, the consumption went from 25L/100km to 11-17L/100km.

 

[Solo Man]

Welcome to the Forum. Just my 2 cents. The economy meter is not linked with a vacuum pipe as all is nowadays done by sensors, etc. Glad you found the problem!