M30 - overfuelling

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winx
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Post Wed Jan 28, 2009 2:22 pm

My m30 conversion has been in and running for a few weeks now but the mpg has been aweful!
Engine is standard apart from a shrick cam.
I have a chipped ECU and a Standard one which both overfuel on tickover.
On the standard ecu it also hunts a lot once it is warm.

I've put it on the co meter and it reads between 7-8% at tickover!
I have tried to alter this by using the adjustment screw underneath the airflow meter but it makes next to no difference whether it is all the way out or all the way in!

I have checked the fault memory on the ecu and it has logged no faults.
Unplugging the airflow meter means it runs fine on tickover but as soon as you add some throttle it dies, leading me to think that the afm is not buggered... :?
Have also done the valve clearances to .25mm as Shrick suggest.

Has anyone got any ideas as to why this may be happening and a solution as its starting to drive me up the wall! :)
Thanks
Henry
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MJJ_ZX6RR
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Post Wed Jan 28, 2009 3:59 pm

Blue engine temp sensor perhaps, engine thinks it is cold all the time and overfuels?

Martin.
----------------------------------------------------
Lots of bikes, the odd modern BMW, and now an 88 e30 335i Cab project with E32 running gear
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winx
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Post Wed Jan 28, 2009 4:59 pm

Could be a possibility, although it was showing up fine on the diagnostics. Although not sure if it is the blue or brown that the diag machine reads from...
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MJJ_ZX6RR
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Post Wed Jan 28, 2009 7:35 pm

My understanding is blue tells the ECU coolant temp, brown feeds the dash gauge. No idea whether diag would pick this up.

I'd be tempted to unplug the blue sensor, and see if the engine runs any differently. If it makes no difference, I think you'd be safe to assume a faulty blue sensor. Alternative, and probably more scientific approach, is to measure the resistance at the blue sensor pins when engine is hot, and also when stone cold. I'm sure I have seen the proper specs on the zone somewhere.

I'm thinking your symptom of bogging down with the AFM unplugged is important, but I cannot think what that would point to :roll:

Martin.
----------------------------------------------------
Lots of bikes, the odd modern BMW, and now an 88 e30 335i Cab project with E32 running gear
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winx
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Joined: Wed Jul 30, 2008 11:00 pm
Location: almost certainly not working on my E30...

Post Wed Jan 28, 2009 8:06 pm

these look like the values I am looking for:
http://www.e30zone.net/modules.php?name ... resistance

Just been out and tested it. Temp gauge sitting just under half it is 280ohm and is reducing slowly as the car gets hotter. (no viscous fan and electric comes in at about 95 degrees)

Seems to be in the right area!
When blue sensor is unplugged the revs drop for 2 seconds then come back up. When revving it from idle with the plug disconnected the engine bogs down and then flares to the revs you would expect...
When plugged in the car revs up as normal.
Thanks for your ideas so far, will hopefully sort it eventually as currently doing 12mpg when I use it to commute!
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Theo
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Post Wed Jan 28, 2009 8:08 pm

12mpg!!!!!!!

It did about 8-10mpg going round the 'Ring!
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winx
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Post Wed Jan 28, 2009 8:10 pm

I'm guessing you were 'utilising the performance' somewhat more than I do on the way to work!
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Theo
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Post Wed Jan 28, 2009 8:17 pm

Unless your commute is incredibly fast and exciting!
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winx
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Post Wed Jan 28, 2009 8:22 pm

just looking at some pictures of the screens on the modic I snapped on the phone another thing:
Image

Oxygen sensor control: OFF
Image

Oxygen sensor voltage: 0.456
Image

LMM signal Up/Uv: 0.011
Image


Is this the standard default value for the oxygen sensor?
Even though it says control is off does it still use the 0.456 figure?
And what is LMM signal?
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winx
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Post Wed Jan 28, 2009 8:23 pm

Theo325 wrote:Unless your commute is incredibly fast and exciting!
Nope 7 minutes of town roads, with the occasional 'play' when following one of the lads at work :P
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Gunni
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Post Wed Jan 28, 2009 9:05 pm

LMM signal is the AFM , I´m 90% sure on that.
With great challenges comes great engineering.

Gunni
@ 2012 VEMS group buy !!
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winx
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Post Wed Jan 28, 2009 9:13 pm

Nice one thanks for that Gunni. Think you are right according to this:
http://cuttingedgeautomotivesolutions.c ... ronyms.txt
Will put the diag on again tomorrow and see what the readings do.
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