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OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
I have a '98 E36 328is with an M52 (M52TUB28 I think) auto. I've always wanted one since I was about 16, around the time the final evolution of that shape was introduced.

Anyway, problem is for the last 12 months or so I have been battling with its high, very high fuel consumption, it was never like this when I bought it in 2008.

I always fill up with between 20 or 30 litres of V Power, and I used to get a good 90-100 miles for my 30 litres depending on how I drove, more miles on the motorway of course refuelling on reserve light. Now I'll get around 50 and that’s on a good week, the worst ever was 38! Refuelling and driving off the forecourt, the Range will countdown instantly, by the time I’m off the forecourt I’ll have ‘lost’ around 4-6 miles already – but the Range will stay static while the car is stationary confused

I've had it serviced - inspection 2 TWICE with engine flush, changed the MAF, ran engine cleaners through it (Forte Fuel Treatment), pumped up the wheels to 44psi, tried different petrol stations, emptied the tank and refilled up to 20 litres until empty again to check fuel gage for faults, checked emissions numerous times, reset the ECU, flashed the ECU, checked for air leaks (no rough idle btw) changed numerous filters and other little things like checking brakes aren’t sticking, accelerator isn’t weighed by mats. Nothing has made a difference, cold or hot it’s the same. Furthermore, performance is laboured from take-off and acceleration at any speeds; it takes ages to pick up revs, however! Occasionally it’s perfectly fine, quick, sounds smooth and prompt and fuel consumption stabilises. After a restart it'll go back to being lazy and gulping down the fuel.

No sign of leaks or smells of petrol.

Any ideas what so ever on how to resolve this would be greatly appreciated.

Many thanks
OptiManc!

mackie1

7,219 posts

113 months

[news] 
Wednesday 25th April 2012 quote quote all
You're seriously only getting 8mpg? TBH I don't know what could be causing it beyond the usual fueling, air leak, collapsed cat, ignition etc problems. Does it throw up any OBD codes?


Edited by mackie1 on Wednesday 25th April 16:06

OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
Give or take yes, circa 8mpg. No error codes, it did flag up th MAF about 4 months ago which I replaced but it didnt make any difference.

Could you elaborate on the issues you mentioned please?

steve_bmw

1,328 posts

55 months

[news] 
Wednesday 25th April 2012 quote quote all
Do your injectors sound louder than usual? If so it may be your cam sensor that's at fault, these dont always show up on the scan, your symptoms sound like cam sensor to me.

OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
steve_bmw said:
Do your injectors sound louder than usual? If so it may be your cam sensor that's at fault, these dont always show up on the scan, your symptoms sound like cam sensor to me.
Nothing unusual tbh from the injectors and the injectors have been cleaned too using an Injector Cleaning fluid by running it through the fuel system. I'll look into the cam sensor, didnt expect it not to show up on the scan.

Thanks for the lead steve_bmw!
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mackie1

7,219 posts

113 months

[news] 
Wednesday 25th April 2012 quote quote all
Leaving the injectors open too long and running really rich?

OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
mackie1 said:
Leaving the injectors open too long and running really rich?
Wouldn’t that mean the emissions test would identify this if the fuel was too rich?

mackie1

7,219 posts

113 months

[news] 
Wednesday 25th April 2012 quote quote all
You'd think, but the fuel must be going somewhere, and if he's not driving at full throttle anywhere then it's either leaking out or it's running rich.

steve_bmw

1,328 posts

55 months

[news] 
Wednesday 25th April 2012 quote quote all
If the cam sensor is faulty it will cause batch firing of the injectors, ie every stroke they would fire instead of only when needed, if this is at fault your exhaust fumes would smell of strong over fuelling, take it with a warm engine to any mot place and just ask them to check emissions for you, if is high I would try replacing that sensor first.

OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
steve_bmw said:
If the cam sensor is faulty it will cause batch firing of the injectors, ie every stroke they would fire instead of only when needed, if this is at fault your exhaust fumes would smell of strong over fuelling, take it with a warm engine to any mot place and just ask them to check emissions for you, if is high I would try replacing that sensor first.
I've had multiple emissions tests and they've all been well within the legal ranges and similar to mot tests before the problem developed.

Would cleaning out or replace the EGR vavle help, does this engine one or are they only on diesels?

steve_bmw

1,328 posts

55 months

[news] 
Wednesday 25th April 2012 quote quote all
Mmmmm well if the emissions are ok then it can't be over fuelling, stumped really, if you had a leak you would see it as you seem to be using a lot of petrol.

Andy665

1,247 posts

108 months

[news] 
Wednesday 25th April 2012 quote quote all
You said that you used to get 90 - 100 miles for your 30 litres before the problems started - I'd suggest that 13 - 14mpg was already a major problem

Had a 328i Sport for 3 years and never drops below 23 on local runs and an easy 29-30 on a motorway

OptiManc

Original Poster:

156 posts

118 months

[news] 
Wednesday 25th April 2012 quote quote all
Thanks for that Andy, so it seems its been a problem that's been progressively getting worse. Cam sensor change this weekend is planned.

B17NNS

11,730 posts

127 months

[news] 
Thursday 26th April 2012 quote quote all
I ran a 1997 328 auto for a year or so. I averaged low 20's with around 28 achievable on a run.

No idea what your problem may be unfortunately but hope you get it sorted.

helix402

373 posts

62 months

[news] 
Thursday 26th April 2012 quote quote all
It might be worth calculating your mpg by brimming the tank to guide an accurate figure, then you will have a reliable base figure to start with.

Frances The Mute

1,341 posts

121 months

[news] 
Thursday 26th April 2012 quote quote all
helix402 said:
It might be worth calculating your mpg by brimming the tank to guide an accurate figure, then you will have a reliable base figure to start with.
Exactly.

Forget partial fills and reviewing the OBC - fill the car properly and work it out from there.

There is a 'serious' issue if you're genuinely getting less 8mpg; certainly more than a duff sensor or injector would give.
My 328 touring would regularly get me over 35mpg on a run and closer to 28 around town from a tank with the occasional bit of lead-footedness thrown in. Sub-10mpg is very wrong.

OptiManc

Original Poster:

156 posts

118 months

[news] 
Thursday 26th April 2012 quote quote all
helix402 said:
It might be worth calculating your mpg by brimming the tank to guide an accurate figure, then you will have a reliable base figure to start with.
I have done this 3 times, twice unplanned as the car cut out once the tank was dry and same results each time, once i filled the tank and let it run dry.

Slurms

1,143 posts

84 months

[news] 
Thursday 26th April 2012 quote quote all
That sounds really low to begin with - my 330ci used to run around 29mpg regardless of how I drove it..

Are you sure it isn't overfueling or leaking - I can't believe you could get it to run at 8mpg without it going somewhere.

Ozone

2,396 posts

67 months

[news] 
Thursday 26th April 2012 quote quote all
I noticed on another thread recently about old spark plugs reducing mpg (not to your levels though) and i wondered if faulty coil packs (if it has them) could cause the problem.

OptiManc

Original Poster:

156 posts

118 months

[news] 
Thursday 26th April 2012 quote quote all
Ozone said:
I noticed on another thread recently about old spark plugs reducing mpg (not to your levels though) and i wondered if faulty coil packs (if it has them) could cause the problem.
Sparks have been replaced twice since I've had it serviced twice Inspection 2 both times.

Does anyone know if there is an EGR valve on this engine and if so where it might be located?
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