rough idle 2

[bob53]

Hi
can anyone tell which fuse is for the fuel pump on the m40 engine, I want to change the fuel filter and need to depressurise the system.
I have cleaned ICV and MAF, and the crank sensor but it still runs like a pig for a while on startup.
Just thought of something else, is there a cold start device on this engine, if so where.

PS has anyone got a copy of the owners handbook that can be emailed?

Bob

[Martinaston]

Fuse 11 for the pump
And cleaning the inside of the throttle boy will help.
The cold start is controlled by the ecu and all it does is inject more fuel until it reaches working temp.

[bob53]

Hi Martin
Thanks for fuse number
as for the cold start,it must have a sensor somewhere.
just been searching could it be the blue temp sensor?

[Martinaston]

the temp sensor will give you trouble weather it's hot or cold
Clean the inside of the throttle first as that will cause running problems if the ecu is not recieving a closed throttle signal.
You may want to get the co checked to tell if it's running rich or lean, You can sometimes tell from the condition of the plugs but it's not that reliable.

[bob53]

I have cleaned the throttle and gone for a spin but there is still something wrong.
when it is warm and I blip the throttle it hesitates before picking up as if its sucking air before fuel. Iwill get the fuel filter tomorrow and see what happens then.
Another question, does it matter where the induction lead fitted to a spark lead goes, that is which lead?

Bob
http://img.villagephotos.com/p/2005-8/1060578/bmw1.jpg

[Martinaston]

It's only for the diagnostic plug and not used by th ecu but it normally goes on number 1.

Does the throttle position switch make a click as it moves from the closed position ?
It should click as you open the butterfly by 0.5mm. It tells the ecu that the throttle is starting to open and injects more fuel on take up to prevent lagg.

[bob53]

Definately got a click.

[Martinaston]

You may need to check it with a multi meter as the switch gets full of oil that runs down the throttle spindle and fills up the switch.

Have a look
http://www.totalbmwmag.com/HandsOn/TechMar01.PDF

[bob53]

Thanks Martin I'll give that ago tomorrow.

Bob

[bob53]

Today I fitted a new fuel filter and removed and cleaned the throttle body and ICV, just the same. maybe the fuel pressure regulator or injectors although it has had 2 bottles of cleaner through.
last night I took of the crank position sensor and it needed cleaning,it is more than 1 mm from crank but I can't see how to get it any closer because there is only the one allen screw holding on.

So what next?????

Bob

[bob53]

Just been out for a blast,the exhaust is blowing at the middle joint would this affect the running(as in back pressure)
Also the car seems to be going a lot faster than the speedo shows. it could just be me.

Bob

[Martinaston]

Are you trying to cure the rough idle or poor running problems ?

Have you changed the air filter and what condition are the plugs in?

[bob53]

both
filter new
plugs new
MAF cleaned
ICV cleaned
Throttle body cleaned
fuel filter new
plug leads new
dizzy cap new
rotor good
new stainless exhaust with cat found to be blowing from joint.
2 bottles injector cleaner
Bob

[bob53]

I bought this car cheap thinking I could fix something as simple( on normal cars) a bad idle from cold!!!!!!
the previous owner had spent nearly 1grand including the ss exhaust to try and fix this problem.
Maybe its just a BMW thing as I also have some problems with my seven that BMW can't seem to solve.

[Bob_S]

I mine hunted quite badly at idle shaking the car I found a loose vacuum pipe that peeps told me should have a bung in it so I did, it might be this



above, I have blocked mine with some gaffa tape but will get a screw next time I venture into the garage

[rickk]

Altough mentioned before in this thread, I don't see the tempsensor in your checklist. Would really check that if I were you.

If that's not it, get the exhaust gases analyzed so you at least know if it's running rich or lean, and maybe it's just fixed by an idle mixture adjustment.

[Martinaston]

For a poor idle you will need to check the system for air leaks and maybe reset the mixture screw (as the other bob mentioned)

If you have problems with hesitation then again it could be an air leak,
But if it's a lack of power as you accelerate to the point where the engine boggs down and almost dies then it could well be the temp sensor.

[AlpineCab]

Just a thought, have you gone round and checked / tightened all the air hoses?

Could it be inlet manifold leak?

[bob53]

all hose's have been ckecked

Martin where is the temp sensor? is it the blue topped one under throttle body?

[Martinaston]

Yep blue one, can be a pain to get to.

[bob53]

thanks I'll take the throttle off again then it is easy to get to.