Ridiculous 14 MPG Help!!

Technical questions and answers about the Mazda Bongo

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bo-luke-duke

Ridiculous 14 MPG Help!!

Post by bo-luke-duke » Mon Nov 09, 2009 1:51 pm

Can anyone make any suggestions as to why our bongo has suddenly decided to do 14 miles to the gallon??!!

It was doing around 22 mpg on short runs and 31 on long runs up until the past week.

Just about to change the fuel filter as thought that might be a contributor, cant spot any obvious diesel leaks.

So where do I go from here? Cant carry on like this as there is no way can afford to run it like this!!!!

Always problems!! :(
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mikeonb4c
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Re: Ridiculous 14 MPG Help!!

Post by mikeonb4c » Mon Nov 09, 2009 2:16 pm

Is there any difference in the way it is running? Now that the mornings have got colder, the autobox will take longer to warm up and allow changing to higher gears (its designed like that). Are you doing very short runs and have you noticed if revs are staying higher for given mph?

Things like old/blocked air filter might contribute but the onset shouldn't be sudden.

Just to be eliminate it, is yours a twin battery 'winter pack' Bongo as these have a preheating switch that recirculates hot exhaust gas into the engine (I think) to help cold running. I blieve this ups fuel consumption a lot if knocked on, but it should also make the car run obviously worse too.

Other than that, a phone call and/or visit to a Bongo specialist like Discount Trucks in Newbury would seem a good idea.

Good luck - keep us posted 8)
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Re: Ridiculous 14 MPG Help!!

Post by haydn callow » Mon Nov 09, 2009 3:33 pm

Mike could well be on the case...do you have a switch with a "engine" logo on it.......???
This shuts a "valve" in the exaust and if not switched off ..about 14 MPG would be right....
As Mike says...I would also expect it to run "rough"
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bo-luke-duke

Re: Ridiculous 14 MPG Help!!

Post by bo-luke-duke » Mon Nov 09, 2009 5:18 pm

Thanks for the replies guys.

There is no switch like you described. Air filter is clean and was changed a couple of months ago.

Havent noticed high revs but not all that observant to be honest :oops:
Will take it out for a run later to check out the revs.
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Re: Ridiculous 14 MPG Help!!

Post by Doone » Mon Nov 09, 2009 5:21 pm

You say this has happened 'suddenly' and I'm asking the obvious, but did you do anything to the bongo, just before this problem appeared? :)
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Re: Ridiculous 14 MPG Help!!

Post by rita » Mon Nov 09, 2009 5:30 pm

Hi,how do you check your fuel consumption.

If you check it by the fuel gauge and trip your gauge might be acting up.
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Re: Ridiculous 14 MPG Help!!

Post by scanner » Mon Nov 09, 2009 5:34 pm

rita wrote:Hi,how do you check your fuel consumption.

If you check it by the fuel gauge and trip your gauge might be acting up.
Yes - Unless you check it precisely from top up to top up, recording every mile you do and every litre you put in, you won't get an accurate mpg figure.
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Re: Ridiculous 14 MPG Help!!

Post by beachbongo » Mon Nov 09, 2009 6:44 pm

what about the fact fuel has gone up in price and your going to get less miles for your buck
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Re: Ridiculous 14 MPG Help!!

Post by mikeonb4c » Mon Nov 09, 2009 6:48 pm

beachbongo wrote:what about the fact fuel has gone up in price and your going to get less miles for your buck
:?

Didn't know the ECU had a parameter for picking that up from a wireless link to the pumps :lol:

Its possible though. Either that or a plastic bag could have got sucked into the air intake (actually - have we covered that outside possibility above?) :roll:
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Re: Ridiculous 14 MPG Help!!

Post by bo-luke-duke » Mon Nov 09, 2009 10:19 pm

I havent been just looking at how much money's worth of diesel I made sure I knew how litres were going in. After filling up last the needle is now in the white & it is working out to be 14mpg. Dont know what motorway mpg is at the moment.
The previous figures were worked out on full tanks, 1st around locally & 2nd on motorway driving,

Towed the caravan back from Exeter last Saturday so perhaps that has a bearing on this. The fuel gauge seemed to go down so quickly whilst towing but I wasnt expecting it to be normal fuel consumption.

Will have a check to see if the fuel guage is faulty. I am sure there must be some place on here where there are some instructions for finding out how to do it.

Revs seem to be normal.
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Re: Ridiculous 14 MPG Help!!

Post by missfixit70 » Mon Nov 09, 2009 10:22 pm

You can't polish a turd - but you can roll it in glitter.
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Re: Ridiculous 14 MPG Help!!

Post by mister munkey » Mon Nov 09, 2009 10:33 pm

How many miles do you get from fill up to empty on the guage & how many litres to refill?
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Re: Ridiculous 14 MPG Help!!

Post by scanner » Mon Nov 09, 2009 10:47 pm

bo-luke-duke wrote:I havent been just looking at how much money's worth of diesel I made sure I knew how litres were going in. After filling up last the needle is now in the white & it is working out to be 14mpg. Dont know what motorway mpg is at the moment.
The previous figures were worked out on full tanks, 1st around locally & 2nd on motorway driving,

Towed the caravan back from Exeter last Saturday so perhaps that has a bearing on this. The fuel gauge seemed to go down so quickly whilst towing but I wasnt expecting it to be normal fuel consumption.

Will have a check to see if the fuel guage is faulty. I am sure there must be some place on here where there are some instructions for finding out how to do it.

Revs seem to be normal.
If you've been calculating MPG by counting miles and litres then the fuel gauge accuracy is totally irrelevant - but towing a caravan isn't - however 14mpg is still a bit low.
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Re: Ridiculous 14 MPG Help!!

Post by bo-luke-duke » Mon Nov 09, 2009 10:51 pm

mister munkey wrote:How many miles do you get from fill up to empty on the guage & how many litres to refill?
Filled up when just above empty with just over 56 litres. Just on empty & 335km (approx 208 miles)

Didnt count when towing the caravan in with the mpg as filled up day after towing.

Thanks for the link Kirsty
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Re: Ridiculous 14 MPG Help!!

Post by missfixit70 » Mon Nov 09, 2009 11:38 pm

Now you need to refill to get exact figure for the fuel used for the mileage.
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