E36 328is Crazy high fuel consumption
Discussion
sidpinup said:
Great, glad you have made some progress. Also dont forget there are two cam sensors so doing both will make sure you have that area sorted. It was the input cam on mine which is a fiddle to do but I changed out both to be sure. I think I have a spare exhaust sensor if you need one? I know it's an obvious one but have you checked the spark plugs? If not it's worth popping a new set in.
2 cam sensors? Where is the other one positioned? i changed the one to the front of the engine next to the VANOS solenoid.Thanks for the offer its very kind but i've already bought the O2 sensors.
Plugs have been changed 3 times, once myself then again on Inspection 2 and again on Inspection 2 - desperate times!
sidpinup said:
It's in the same position but on the other side of he head. As you look at the front of the car it's on the left of the engine just by the radiator or is on the 7 series. There is a lead into it so you should be able to spot it. It's likely to be gone also as there is more heat on he exhaust side. It's a different configuration of sensor to the input one you have replaced but easier as the cable plugs in rather than being attached.
Cant spot it, i see one going into the radiator and plenty of leads around the engine bay but nothing on the lfft of it that looks like a sensor fitting...can you offer any more clues? We are talking about an M52 straigh 6 right?
E30M3SE said:
Are you refering to the crank sensor as per #9..
?
Nice diagram! Yes exactly that, i replaced it over a week ago and its made some improvements to performance and help improved fuel consumption but only yesterday and today o've noticed its gone downhill again, performance and mpg.?
E30M3SE said:
..and you've read codes,
Any coming up?
Had codes checked a few times by mechanic on his computer. Only MAF sensor so replaced that but still nothing.Any coming up?
Besides O2, radiator temp, cam position sensor which other engine sensors are there that are involved with fuel, combusion and exhaust? perhaps its worth changing them all?
kavman0 said:
Sorry I haven't read the whole thread but I did read this recently. Worth a try maybe.
http://forum.bmw5.co.uk/topic/65604-poor-starting-...
Very helpful kavman, thanks. The temp sensor was suggested to me at the start of the thread but the cam sensor carried more momentum so i went for swap on that, will try and get atemp sensor sorted for teh weekend.http://forum.bmw5.co.uk/topic/65604-poor-starting-...
E30M3SE said:
On the underside of the inlet manifold.
Part #14
Which sensor have you replaced to date, the cam or crank?
The sensor in the diagram I posted previously is the crank sensor, the cam sensor is located in the rhs of the head, part #17
Great diagrams, thanks. To date I have changed the cam sensor, Part #17 only, is crank work a go too? I am planning on changing the O2 pre and post this weekend weather permitting and now possible the AIT sensor if i can get hold of one before the shops close. Part #14
Which sensor have you replaced to date, the cam or crank?
The sensor in the diagram I posted previously is the crank sensor, the cam sensor is located in the rhs of the head, part #17
Edited by E30M3SE on Friday 11th May 15:18
E30M3SE said:
How many miles are on this car?
I just find it somewhat strange that if all these sensors on your car are 'goosed' it does not bring up any fault codes..............
Your way of actually measuring fuel consumption leaves lots of room for errors, have you actually filled the tank to the brim run the car until almost empty, refilled then calculated your mpg over the distance covered?
Exactly! It has passed the MOT with flying colours and I've had the emission tested numerous times. I just find it somewhat strange that if all these sensors on your car are 'goosed' it does not bring up any fault codes..............
Your way of actually measuring fuel consumption leaves lots of room for errors, have you actually filled the tank to the brim run the car until almost empty, refilled then calculated your mpg over the distance covered?
I have filled it from empty, i mean from being stranded in the middle of a junction to i think 65ish litres or more until it would taje no more. Casual driving with some motorway, to empty again and stranded again at the same junction.
Mostly I keep the Range on the OBD and even when driving like a good boy its still counting down in big jumps, sometimes i've looked at the guage while stationary and the finger is on say 1/4 of tank, as i've moved off its clearly past the 1/4 mark! Since changing the cam sensor it began to improve but last night and now today its gone back to exactly how it was, although performance hasnt been affected as dramatically.
E30M3SE said:
So how many miles did you get on the '65ish' litres?
If memory serves me correct...187 or 193. This was with no unnecessary weight in the boot, after an Inspect 2 and MOT and i think tyres were pumped upto 35 with nitro in an attempt to reduce friction as much as possible.
sidpinup said:
Just a thought but are you 100% that the new cam sensor is working? Try disconnecting it to see if there is a difference. I have heard that some aftermarket sensors are poor quality.
Not keen on unplugging it because its such a tight squeez but worth a try I think, will give it a go tonight and test drive till friday. O2 sensors were not changed over the weekend so that's still pending too.
vsonix said:
+1 the aftermarket ones have a very bad rep vs OEM
the price between an oem and after market was on £8 so i went for an oem.Today on my drive into work i averaged 22.8 and the range went from 29 from leave the house, to 27 to work, as i do work only around 2 miles from home and i drove the same way as i always do at that time in the morning, steady flow. but yesterday, driving home again the range was ticking down 2-3 miles a minute and mpg when i got home the average was 13! the only variable being the today is wednesday and the air temp!
Johnboy Mac said:
Op, will you do yourself & everybody here that's trying to assist you with the problem a favour? Go and fill the tank, I mean fill the tank to the top of the neck (it may take a couple of minutes to allow all the air to escape), reset your trip meter and drive as normal for say 150 miles and then refill the tank in the exact same manner. Forget the OBC read out, work the mpg out from the trip meter and then report back. Oh, and inflate the tyres to the correct pressure too.
Alright then Johnboy, i'll do it but with the way its fluctuating currently i doubt it will provide anything conclusive but its a fair point and worth trying...watch this space!E30M3SE said:
Sounds like your journeys to and from work are on constant cold start cycles, doing only 2 miles.
That won't be helping your average fuel consumption one little bit.
No you're right it wont, but i am a consultant and often work in different locations, today and till Friday i will be going to my own office but normally i can be traveling for between 5-20 miles and odd occasions loner journeys, but i dont only use the car for work, its personal use too during the day and evening and its the same inconsistency.That won't be helping your average fuel consumption one little bit.
Well, the results are in from my, empty tank, full tank, empty tank trial.
But first, I’d like to respond to some of the comments added lately, not all my journeys are around 2 miles and its virtually impossible not turn the engine off until you’ve got a good few miles and temp under your belt, but from occasion I will only go from the house to the office and back. I do a few fair miles each day and obviously drive the car in the morning, afternoon and evening.
Secondly, its defiantly not the ODBC, as it does indicate the correct Range and I am confident the correct MPG too. I am sure of this since having ran out of fuel on two previous occasions the range figures have descended to the ‘- - -’ marks then within a few minutes the engine has juddered and conked out! Also, refills are far too common and full tanks have gone into the 60 odd litre mark so the ODBC is in my opinion accurate enough.
Thirdly, I’ve noticed the warm weather has made a positive difference to performance initially, from start up its more prompt, less laboured as though its gained an extra 20 odd Nm of torque! But within a few miles or so the performance drop returns, so I am assuming the coolant temperature sensor may also be at fault. Anew one is ready to be picked later tonight for £22.
Now then, the empty tank test. I tried to carry out the test as scientifically as possible;
- Ran until completely empty (conked out first time at the car wash so got the lads to push me to the service station! second time 2ft from my drive way and got towed to the service station by my dad’s cab – thanks dad!)
- No extra weight which meant no passengers or extra bags etc
- Consistent fuel supply, Shell unleaded (now at £132.9p happy days!)
- Drove like a saint
- Kept tyre pressure at 32 and 38psi as recommended (although it obviously fluctuated during the day)
- And kept air con off no matter what
The result from empty to full to empty to full, was on average ***16.3MPG*** including around 20 miles of motorway driving and I managed to squeeze in just shy of 65 litres (64.1 and 646) each time.
So now the plan is to swap the coolant temp sensor, test and then eventually fit the O2 sensors which will need more time and effort so jubilee weekend!
Any ideas or points on the above?
But first, I’d like to respond to some of the comments added lately, not all my journeys are around 2 miles and its virtually impossible not turn the engine off until you’ve got a good few miles and temp under your belt, but from occasion I will only go from the house to the office and back. I do a few fair miles each day and obviously drive the car in the morning, afternoon and evening.
Secondly, its defiantly not the ODBC, as it does indicate the correct Range and I am confident the correct MPG too. I am sure of this since having ran out of fuel on two previous occasions the range figures have descended to the ‘- - -’ marks then within a few minutes the engine has juddered and conked out! Also, refills are far too common and full tanks have gone into the 60 odd litre mark so the ODBC is in my opinion accurate enough.
Thirdly, I’ve noticed the warm weather has made a positive difference to performance initially, from start up its more prompt, less laboured as though its gained an extra 20 odd Nm of torque! But within a few miles or so the performance drop returns, so I am assuming the coolant temperature sensor may also be at fault. Anew one is ready to be picked later tonight for £22.
Now then, the empty tank test. I tried to carry out the test as scientifically as possible;
- Ran until completely empty (conked out first time at the car wash so got the lads to push me to the service station! second time 2ft from my drive way and got towed to the service station by my dad’s cab – thanks dad!)
- No extra weight which meant no passengers or extra bags etc
- Consistent fuel supply, Shell unleaded (now at £132.9p happy days!)
- Drove like a saint
- Kept tyre pressure at 32 and 38psi as recommended (although it obviously fluctuated during the day)
- And kept air con off no matter what
The result from empty to full to empty to full, was on average ***16.3MPG*** including around 20 miles of motorway driving and I managed to squeeze in just shy of 65 litres (64.1 and 646) each time.
So now the plan is to swap the coolant temp sensor, test and then eventually fit the O2 sensors which will need more time and effort so jubilee weekend!
Any ideas or points on the above?
E30M3SE said:
Do the coolant temp sensor, if no joy there then do the air temp sensor, before you do the O2's, it's cheaper and easier.
Does your temp gauge sit in the correct position, i.e. vertical?
Yep, dead on 12 o'clock!Does your temp gauge sit in the correct position, i.e. vertical?
OK, will look into the air temp after the coolant, any ideas where the air temp sensor goes?
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