E30 Zone

Hi all,

Ive read somewhere that a 325 should produce around 30mpg (if driven sensibly). Mine seems to struggle 20 ish.

Is this usual? what does yours do? Any suggestion to increase the MPG, apart from recon injectors (its already on my list)

Thanks, J

will,

I recently changed mine to NGK 7811 BP6ES. Slightly different reference and without the 'R' Have i bought the right ones? I mentioned in in another thread i am suffering from slight shunting.

The R stands for resistor - the element introduced into the plug to act as a suppressor.

I got roughly 32-34 from mine, driving like a bit of an old man, hooning it every now and then.

Right then, when it stops raining ill have a look into air leaks etc.

How do i 'Check that the blue ECU temp sensor is reading properly at operating temp and that the throttle position sensor is set and working correctly and Get the AFM set for correct CO readings' ?????

Appreciate the help!!

I second the above and too would like to know.

If I believe my OBC, I'm getting anyting between 5.9 -16mpg! The needle instrument on the dash tells different. Since it recently did 240 miles on 48 litres this is nearer 22mpg (but this was mainly on a run). Around town I'm reaching just under 200 with a similar amount. Once I've replaced the fuel filter, cleaned out the throttle body and checked the blue ECU temp thingy, I'll be getting the injectors cleaned - £10 per injector @ http://www.injectortune.co.uk

Lucky these are still in my favourites...

You can check your blue temp sensor by unplugging the cable and measuring the resistance across the two pins inside. Do it at cold and then when the engine is up to temperature. Readings should be as

http://www.e30zone.net/modules.php?name ... 01#1554501

When you've done this you should plug the cable back in and check the resistance at the ecu to to make sure the signal is getting there ok as described here...

http://www.e30zone.net/modules.php?name ... e+ecu+pins

To set up the AFM for the correct CO readings you need a specialist bit of kit they stick in the exhaust pipe and then adjust to suit the read out. You'll probably have to take it to a garage to have this done.

32-34?? In my dreams! I just got 31 on a long run and that was much higher than my previous best of about 27. Normally get 25-26 and less in the winter. 325i are supposed to get 25 combined for the manual so much less than that without constant foot to the floor suggests somethings not right

So, is the MPG needle on the inst. cluster an accurate measure? Because, contrary to all the "normal" MPG's, at a cruising speed, and in 5th, I can keep a steady 40-45 mpg, and any kind of grade in my favor jumps it right up and past 50mpg...

But, if i step on it, I can sink it down to about 10 mpg too!

Econometer is not a precision measuring instrument, but it gives a reasonably accurate instantaneous indication of fuel consumption, ASSUMING the fuel injectors and pressure regulator are working as they should. It assumes that for a certain injector pulse width the injectors flow a certain amount of fuel, which, after, 100,000 + miles, might be an inaccurate assumption!

any 325i driven with an eye on the fuel guage should be capable of 31-33 Mpg, my Mrs runs an auto 325 touring and gets no worse than 31, even averaging out the last 3 months , same figure.

check all the usual suspects , then perhaps look @ the way you drive, run the engine to peak torque( you should feel it) and change up just after, should achive the best MPG this way.

FYI I have done a lean cruise chip, the part load maps are set V lean, 25% leaner than OEM, no affect to higher openings, as thats a different map. 36 Mpg in testing with no "bucking" on light throttle openings, M20 does not have to be juicy.

My old 325i used to turn in around 25mpg no matter how i drove it. Remains to be seen what my new one will do!

you own a 20 year old 325i with a straight 6, 2.5 litre engine and worry about fuel ?


just add more when it gets near the red bit !

im getting 80 miles to £20 of fuel does that sound bout right?

redror wrote:im getting 80 miles to £20 of fuel does that sound bout right?

Thats like 21mpg. Its too much.

redror wrote:im getting 80 miles to £20 of fuel does that sound bout right?

Depends what conditions your 80 miles were done, on the motorway I managed 39 MPG at a steady 65/70, around town doing 30/40 with a bit of stick now and again more like 27.

MPG means nothing when your stuck in traffic,or dashing between traffic lights, it should be GPH or gallons per hour ! Incidentally, the OBC has 3 different fuel consumption measurements- built in- they are ; (afaik) US mpg, Uk mpg, and ltres per kilometre. (which is the most exacting way to measure it) Surprisingly perhaps, the American gallon is very roughly about .75ltrs less than the UK gallon, so if you are set on US gallons the reading will be false. Ipersonally budget for 22-28 mpg. Driving economically is quite a skill in itself, much easier in a Fiat Punto than a 20 yr old 2.5 ltr straight six

my 325i sport does 50 miles to £20 any slight accelaration and the mpg gauge goes down to 12 which is roughly what its doing i had a sniffer put up the exhaust and the co was about right put you can smell it rich,i checked the blue sensor and that changes readings from cold to hot,anyone got any ideas
30 mpg is just a dream !!!!!

e30topless wrote:you own a 20 year old 325i with a straight 6, 2.5 litre engine and worry about fuel ?


just add more when it gets near the red bit !

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

he's right

just please bear in mind that when these cars were new fuel was a damb sight cheaper than it is now

if you worry about fuel economy then go buy a e90 320d (or 318d).

the engine in my sport has had a few "tweaks" to spice it up a bit ( ) & around town i can just about get 25mpg & just under 30mpg on a run, but i don't sit there witha north eye on the fuel gauge ( i used to till i got a new level sender in the tank) untill it gets close to the red,

there are no hard & fast figures for the mpg of a m20b25 as nearly all of them are in different states of tune/neglect so it varies from car to car.

give it a full service (all filters & fluids) & then see if it changes (for the better?).

i drove 250 miles this weekend on £40 in my 2.7. with a mixture of 'around town' and 'motorway' with both steady driving and putting the boot down every now and then.. my calculation works it out to be about 33mpg.. which going by the above posts makes me well impressed

I always get massive mpg, driving downhill with the wind behind me

redror wrote:im getting 80 miles to £20 of fuel does that sound bout right?

yeah

Barx325i wrote:

redror wrote:im getting 80 miles to £20 of fuel does that sound bout right?

yeah

.25p per mile @ £6 per gallon = 24 mpg. I don't know the price in the uk

It,s around 6 euro pg here.

uk price at the mo is about 114p a litre where i am, i always tell myself to go steady on the next £20 but it never happens.