E34 540iA 95 rough idle for first couple of minutes then all fine!!

[daycm1]

Hi,

Just wondered if anyone can help with this problem.

When starting from cold it seems to run really rough for a minute or so then runs beautifully as it starts to warm up.

I have had both Lambda sensors replaced as they were showing a fault code but still the problem is there, granted much better but still causing probs.
Sometimes it starts fine from cold no problems but most the time it runs rough for a couple of minutes.

Once the car is warm it starts fine everytime.

Does anyone know what this might be or had similar experiences with their 540's?

Thanks and appreciate any help you can give me.

Damon.

[BMW525]

Ok im not that expert in these things.. so you gotta be patient with me!

but it happened with me once and it turned out that there is an air pipe or hose ---> exactly above the manifold with a leak in it!

it may be that! do u hear a sound in the engine!>? like a wisiling sound or an air leak?!

[daycm1]

Hi, thanks for the reply.

I have checked everywhere and there doesn't seem to be a leak or any whistling, but just saw a tip online about the maf sensor and unplugging to see if it runs better without the sensor connected and hey presto it does!!

Now when I reconnect it it runs ok, but not as sweet as when you unplug it.
Also when I bought the car the last owner fitted a sports induction kit to it and now the filter is pretty black (which was once red!) so going to replace that first and see if it makes any difference, if not then looks like the maf is at fault and will be replacing that too!!

Any ideas where I could get one cheaper than the £218.00 I've been quoted? Anyone??

Thanks for your help tho buddy, I do appreciate that.

Cheers,
Damon.

[marti5]

I wouldnt rush out yet and buy a MAF, 1st change the filter and give the maf a clean with either break cleaner or meths, be careful not to break the thin wires you can see inside, I always go the brake cleaner way, from Halfords in an aerosol.

If you still require a new MAF....Ebay, but only buy a BOSCH do not get a cheap one.

[daycm1]

Yes, cleaned the filter as it was a washable type and used cleaner on the maf sensor today but then had to go to work so will see in the morning if it has cured the problem.

Thanks for all your help guys, will let you know how I get on.

[daycm1]

Hi well, when starting this morning it still runs a bit rough i.e shaking around for about 10 or so seconds and then calms down and runs fine. Is it supposed to do that or is there still a problem somewhere?

I'm going to get it serviced next month so hopefully if that sorts it then great but if not I guess I will have to try the new maf sensor route!!

If anyone has any other suggestions then they would be greatly appreciated.

Cheers,

Damon

[jimoreno]

You might have an intake manifold leak. Spray carburator cleaner around the intake manifold area and if the engine runs better you have found the area of your leak. These engines do need gaskets changed as a service item eventually.