E36 328is Crazy high fuel consumption
Discussion
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
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!
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
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!
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!
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?
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. 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?
Slurms said:
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.
No leaks, no smells. I have placed white sheets under the car in the garage and driven backwards and forwards and left it to sit for a weekend. Checked afterwards some dust and bit of water but signs of oil or petrol and again, no smell of petrol at all!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.
Would cleaning the EGR valve be an idea, excuse my ignorance but does a petrol car have an EGR valve?
vsonix said:
When taking off hard in second gear, does the car feel heavy/sluggish until you hit around 3.5k revs whereupon all of a sudden it feels like a lead weight's been thrown out the window as the car suddenly finds its power and surges forward?
Pretty much yes, the revs are very lazy getting up to 3k-ish. There is onely 1 pre and 1 post cat sensor as far as i am aware. My 540i had 2 of each!
vsonix said:
Mmm, this is what mine was doing until I had the camshaft position sensor changed. It's a common fault and apparently they don't always throw a fault code until they're properly dead. Cost me about £120 parts & labour from my local indie BMW specialist. Car is now pulling like a champ all the way through the revs and returning the sort of figures you would expect.
Ooh! Exciting that is! Changing my cam sensor this weekend, sunday most likely - i wont be sleeping now!seismic22 said:
15 mins to change cam sensor - take oil filter cap off for better access and just stick a sandwich bag over the filter housing. Get that old viscous 32mm spanner at the ready to undo the vanos solenoid too. Good luck and update us.
Got all my hope on the cam sensor doing the trick...but curses! I've been thwarted by the great British weather! Also found that i only have a 30mm spanner so ventured out to the spares shop, they only stock 30mm max. Halfords and even B&Q also only have 30mm! Will attempt again tomorrow once I've found the tools and hopefully the rain and wind will clear.E30M3SE said:
Thanks but my local store does have any. I have however just bought an adjustable one up to 33mm from bnq...watch this space!Well I've changed the sensor and although its early days I have noticed an improvement! The obc figures are fluctuating so I am waitibg at least a week to see if there is a real change. I am also considering an ecu reset after a week of 'normal' driving.
Interesting to see the experiances of others in the community.
Interesting to see the experiances of others in the community.
vsonix said:
I think I remember reading or hearing somewhere CPU reset after CPS change is a good thing, but can't remember where. Ah yeah, it was at a meet I was at the other day, chap said "after changing the sensor you must remember to also do X which many people don't". Can't remember what X was exactly but it might have been resetting the ECU. Not very helpful I'm afraid lol
On the contrary, it’s given me some confidence, I may even do the reset sooner, the price at the pump went up today so the sooner the savings start the better!Well it has been a good number of days since i changed the cam sensor and 2 days later i reset the ECU by disconnecting the battery for a short while.
Verdict, i think the problem has been resolved partly. performance has recovered, now its great from standstill, doesn’t seem or sound laboured and is prompt as it used to be around a year ago. However, fuel consumption has improved also but still fluctuates. My driving style has changed since the issue became apparent, so i rely on the Range on the OBC, and that seems be to more stable than counting down the miles like a stopwatch like it used to. However, it is temporal so i think the problem is only half resolved. I am going to change the o2 sensors too (after pay day) and monitor again.
Like for like driving with the issue and now partially resolved, i would summarise to say we're nearly there.
Thank you to everyone for their contribution, knowledge sharing and support in this thread, your input has been very much appreciated.
I'll update again after changing the o2 sensors.
Verdict, i think the problem has been resolved partly. performance has recovered, now its great from standstill, doesn’t seem or sound laboured and is prompt as it used to be around a year ago. However, fuel consumption has improved also but still fluctuates. My driving style has changed since the issue became apparent, so i rely on the Range on the OBC, and that seems be to more stable than counting down the miles like a stopwatch like it used to. However, it is temporal so i think the problem is only half resolved. I am going to change the o2 sensors too (after pay day) and monitor again.
Like for like driving with the issue and now partially resolved, i would summarise to say we're nearly there.
Thank you to everyone for their contribution, knowledge sharing and support in this thread, your input has been very much appreciated.
I'll update again after changing the o2 sensors.
OldSkoolRS said:
FWIW I replaced a faulty exhaust camshaft sensor on my Z3 3.0 with the M54 engine. I reset the ECU using INPA software and cable (same as I used to find the fault in the first place). There were no lights on the dash to warn of this sensor issue either (despite 83 recorded error codes for it). It was the only error code recorded on the car, apart from a one off code for the throttle switch/pot. INPA records the number of times the error occurs, so it's easier to spot a one off glitch verses a regular problem. Plus you can clear the codes and check again after a drive to see if codes reoccur quickly as my camshaft sensor code did (3 errors in one afternoon).
Like you I've found the car feels much more lively (especially in higher gears, so less need to change down unless really moice lightstoring). I've seen a small increase in mpg, but I've been using the extra power. Reseting the OBC and driving less briskly soon sees it reading around 32mpg, which I don't think is bad for a 3 litre.
I read another thing on a Z3 forums about how some BMWs seem to lose power as the service lights mean that the car is near to needing a service. Some claim that doing nothing more than reseting the lights brings the performance back up to scratch. Haven't tried this myself as I haven't had the car long and still have 4 lights on the SI at the moment, but I'll keep an eye on the mpg figures as it approaches the service to see if mine 'drops off'.
I've heard the same about service lights so i tried it when the issue first vecame apparent but it didnt make any difference. Like you I've found the car feels much more lively (especially in higher gears, so less need to change down unless really moice lightstoring). I've seen a small increase in mpg, but I've been using the extra power. Reseting the OBC and driving less briskly soon sees it reading around 32mpg, which I don't think is bad for a 3 litre.
I read another thing on a Z3 forums about how some BMWs seem to lose power as the service lights mean that the car is near to needing a service. Some claim that doing nothing more than reseting the lights brings the performance back up to scratch. Haven't tried this myself as I haven't had the car long and still have 4 lights on the SI at the moment, but I'll keep an eye on the mpg figures as it approaches the service to see if mine 'drops off'.
I'll lookinto getting own software and cable now, perhaps with its age and milage its worth having a set.
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