HELP! mpg extra low.

[MrBMW78]

HEEEEEEELLLLLLLLLLLPPPPPPPP!!

Hello everyone. My car now does on average 160 miles per full tank (approx Ԛ£40 spent to fill up)

I have been going through a process of elimination to rectify the problem.
The car is serviced regulary, last full service done 2months ago.

I have checked the pipes, made sure they are all sitting tight and not leaking.

I can not smell any petrol form the engine bay, but there is a slight vapor smell of petrol which doesnt seem to be strong enough to be classed as a problem.

I have also changed my airflow meter hoping this would rectify the high fuel consumption. The new airflow meter was fitted on friday gone, its now tuesday. I filled my tank on the friday and from there till now i have done 69miles and my fuel is at half tank.

As you can all imagine that is way too much on petrol for a 316i auto e30.
If any one can help with ideass of what it could be?

Regards.

[Steviec]

Thats about the same im getting from my 325i.

Not good for the wallet!

[MrBMW78]

you know what i mean! i'm sure that it is also low mpg for a 325i.
What makes it worse is mine is a 316i.

[Steviec]

It is low fuel econ, ive only had the car a little while but as soon as ive got some spare cash, I giving the car to a BMW specialist (cheap but he knows his stuff). Gonna get him to change the cam belt, head gasket, inlet manifold gasket, do the tappetts and give the car a thorough going over and give me a list of jobs that need doing.
I just know is going to be a long list!

[Danstable]

It's a long shot but my 325 has started gulping the fuel and I've been advised that it could be the blue temp sender that sends its signal to the ECU. Basically if it's broken then the car will always be on choke I think. Thing is, it might not be blue on a 316, someone else will have to give you a pointer.

My car can be difficult to start when warm, I think this is another symptom.

[oze30]

if it is blue temp sensor.. how hard is it to change?

[Mops]

it's not hard to change.
to test it for proper operation:
. start the car and let it warm up to full operating temp normally. then with the car idling disconnect the sensor. the revs should go significantly up.

[Simon13]

leaking fule tank? many are rusty now. All E30's rust on the filler neck too

[phil-r]

ye im suffering from the same thing i checked my filler neck thingy today and found that it was not rusted, i got a 320i auto. and all my fuel lines are sharp but i did notice that the car does rev a little high.

if that blue wire is faulty how do we fix it?

[Mops]

you cant fix blue temp sensor. inspect that all wireing is ok, if it is it means sensor's stuffed and needs replacing.

[oze30]

Right.. so if you disconnect the sensor and the revs drop .. what the hell does that mean??

[Steviec]

Right.. so if you disconnect the sensor and the revs drop .. what the hell does that mean??

Some one correct me if im wrong but,
If the revs stay the same or drop = Sensor knackered
If the revs go up = Sensor is working well

Thats how I understand it.

[Steviec]

Which would mean that mines knackered!

Does anyone know how much these cost and how difficult they are to fit?

[oze30]

steve,

AFAIK, it should be working fine going what what was posted.. BUT.. nothing has been said about the revs dropping when you disconnect. It actually ran better with no temp sensor.. WTF??

[Mops]

steve,

AFAIK, it should be working fine going what what was posted.. BUT.. nothing has been said about the revs dropping when you disconnect. It actually ran better with no temp sensor.. WTF??

clearly it's getting wrong reading hence it's stuffed.

[Mops]

measure resistance across it's terminals.
at full operating temp it should be around 300 ohms.
on stone cold I dont remember, but i think about 5K ohms ?

[oze30]

i have tro get it up to working temp first!

So when you remove the sensor, the revs are sposed to change full stop?? Or just go up??

[MrBMW78]

Any ideas for why mine is drinking so much petrol?

[bedema]

hi...mine is sucking gas too...can someone tell me where this blue temp sensor is?
mine is 325i
thx

[kam-325i]

hi...mine is sucking gas too...can someone tell me where this blue temp sensor is?
mine is 325i
thx

Near the brown one on the thremo housing......

[Steviec]

Its a bugger to remove as you cant get your fingers in there!

I had to use a couple of screwdrivers.

[jonbuoy]

Any ideas for why mine is drinking so much petrol?

Are you having trouble with the idle?
Have you done anything to the car? (ANYTHING!)
What else have you done to rectify it?

Cheer's
Jon

P.s PM me your reply

[oze30]

Right. Filled up today after almost runnign to the E line.. Ԛ£38 at 86.9p. Which to my calculations means that i only have a 55 or so litre tank?? I've got a 325 G reg touring.. I thought it was sposed to have the larger 75 ish tank?

Also, on a trip to bristol (Thanks Jonb) I managed 16.66 Litres for almost 80 miles. Does anyone know how many MPG this is??

[gareth]

that's about 24.5 mpg by my rough calcs.

if it's of any use to anyone, my 325i tourer manages about 20mpg average.

however, my old MK2 escort RS2000 did 7mpg if i was careful and when ragging it, i could burn a 40 litre tank in 25 mins round town!!! it could be driven down as low as 3mpg! an smooth motorway run at 60mph would just pip 17mpg! it was rather quick though... 180 bhp full rally spec 2.1 pinto on 45's

[dsio]

I have a 318i M10 that has just been brought back to life after being flooded for 5 months and unable to start.

If I start it, it takes a fair bit of time, and feathering the throttle to get it to take.

If I pull the fuel pump relay and try to start it, it will start and try to run several times, then nothing (assuming fuel is gone from the injection system).

Then If I start it after that, it will start first turn of the key.

Now, I'm assuming this temperature sender is triggering the cold start injector to dump arseloads of fuel into the manifold. I have checked the cold start valve, and its dumping an incredible rate of fuel in a continuous stream, and though I havn't seen it spraying while the car is running, I suspect it may be what is flooding the M10.

This problem is a pain in the arse, and has lead to me wiring a fuel pump relay bypass switch under the dash for when it floods.

Given my problem, would you suggest the temp sender is the problem, or the cold start injector, or something else?

[Grantley]

The blue temp sensor is easy to fit (just done mine), I took out the brown one first then that gave me enough room to get a 19 mm ring spanner over it. The whole job takes about 10 - 15 min, the sensor cost me Ԛ£11.75 inc VAT and a bit of anti freeze to top the system back up.

[gareth]

i hasd trhis exact same problem a while ago on my 2.5 M20, however this was within a month of fitting a new temp sender!

i'm just careful now when starting it and it's not done it again

[dsio]

So does this problem with the temp sender apply to the M10 engine as well as the M20? And is it a possible cause of flooding?

[gareth]

i belive it does, as well as a lot of other german cars (i've heard).

the online ETK has the same part number for the sender on M10 and M20 engines.

[dsio]

I just disconnected the cold start injector and all of a sudden its working perfectly. 3 starts in a row now, two cold, 1 hot, all starting as soon as the key turns.