Engine management light

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jonzee
Joined: Fri 16 May, 2014 15:24
Posts: 68

  Z3 roadster 1.9

Engine management light

Post by jonzee » Wed 11 Nov, 2015 10:21

Hi all
Would a leaking (albeit slightly) valve cover gasket cause the engine management light to come on? I am thinking of unmetered air entering the engine.
My car is a 1999 1.9 m43.
occasionaly the light does go out on its own but usually after a 15/20 mile run if you have to stop at traffic lights etc it comes back on again.
I have cleaned the maff, idle control valve, replaced all the vacuum hoses, air filter, valve cover breather hose (very spongy) crankcase vent valve (absolutely knacked).
I have had a diagnostic done by my local gargage and it did throw up vacuum problems but since its pretty well all covered by the repairs stated above that were done after the diagnostic i am fast running out of potential problem areas.
I do get the occasional whiff of oil in the cabin and have seen oil smoke from the rear of the engine where i guess its leaking from the top and dropping on the exhaust but it is very minor.
cheers
simon

andy & fonz
Joined: Tue 28 Jul, 2015 18:35
Posts: 47

  Z3 roadster 2.2i

Re: Engine management light

Post by andy & fonz » Wed 11 Nov, 2015 10:31

hi
nice to know I am not the only one with this problem see my story under engine emission warning light, running my 2.2 on 99octane fuel seams to help as per the hand book, having said that just moved the car around the driveway in and out of the garage and the light came back on, but there was a misfire on number 2 so think its just unhappy not being taken for a run

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2122

  Z3 roadster 1.9

Re: Engine management light

Post by Del » Wed 11 Nov, 2015 11:38

In my experience, when everything else has been checked/renewed a likely candidate is the MAF sensor. They are complex little sensors and notoriously hard to pinpoint as a fault, as often they cause indirect symptoms like a "lean mixture". I've not found that cleaning them helps once they fail. If you're lucky you can pick up a decent 2nd hand one from a breaker and swap it over to see if it makes any difference - your outlay on a speculative fix is therefore minimised.

In my own experience, the items that can cause a "lean error code" that tends to pop up intermittently, often after a long run, is either a faulty crankcase valve or MAF sensor - you've fixed the former.

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: Engine management light

Post by deni2s » Wed 11 Nov, 2015 12:26

Did you read errors ECU is throwing? You should do that first. Without that it's just a speculation...

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 10008

  Z3 roadster 1.9
Location: Cheshire

Re: Engine management light

Post by Robert T » Wed 11 Nov, 2015 12:35

If oil is coming out of the gasket, then it is unlikely that air is going in, as if it were, it would be sucking the oil in rather than weeping it out. If air were getting into the cylinders via this route, you would have much bigger problems, as the valve guides would be very worn, so it would be burning oil as well.

I assume you already know this, but for anyone else reading this, a common mistake is to confuse the warning lights.

The Engine Management Light on a UK car is a little engine symbol like this:

Image

As opposed to the EML (Electronic engine output control) light:

Image

More details in the knowledgebase here: http://www.zroadster.net/forum/viewtopi ... 18&t=35657

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

jonzee
Joined: Fri 16 May, 2014 15:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee » Wed 11 Nov, 2015 15:22

Hi
Thanks for the info.
definately the engine management light.
When using the car it drives superbly, no hesitation or power loss, it is nice and stable when at idle.
The code that came up was p0170.
would using a higher octane fuel be beneficial to my car?

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: Engine management light

Post by BladeRunner919 » Wed 11 Nov, 2015 15:36

Different octane fuel won't help the code. Code is suggestive of an air leak, faulty maf or faulty O2 sensor. What did you clean the maf with?

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 582

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Engine management light

Post by colb » Wed 11 Nov, 2015 17:51

Concur with Robert and Bladerunner on this, if you have eliminated any air leaks it's likely to be a bad Maf or Lambda sensor in the exhaust, in my experience the Maf is the more likely issue. Either get a known good used Maf from a breaker or bite the bullet and buy an OEM one do not use cheap pattern parts, been there myself and lesson learnt.

Colb
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

jonzee
Joined: Fri 16 May, 2014 15:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee » Wed 11 Nov, 2015 19:35

Hi
I cleaned the Maf with an electric contact cleaner. just sprayed on and left it too dry naturally, no poking about with cotton buds or anything like that.
Take on board the sub standard cheap maf as i have read enough on the pitfalls of buying non BMW parts.


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colb
Joined: Sat 05 May, 2012 23:46
Posts: 582

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Engine management light

Post by colb » Thu 12 Nov, 2015 12:18

Interesting content in the link, exactly the same circumstances I went through when I had an EML problem, mine was the Maf as well.

Colb
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

jonzee
Joined: Fri 16 May, 2014 15:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee » Fri 13 Nov, 2015 10:25

New maf on order.
Thanks for all the help its been most appreciated

jonzee
Joined: Fri 16 May, 2014 15:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee » Mon 16 Nov, 2015 10:11

Will the fitting of a new maf automatically turn the eml off or do i need to get it switched off at my local garage.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2122

  Z3 roadster 1.9

Re: Engine management light

Post by Del » Mon 16 Nov, 2015 11:10

Generally with cars, once a new sensor is fitted it is usual for three, trouble-free, start and stop drive cycles to cause the fault light to go out by itself. Alternatively, the fault can be deleted by a suitable, plug-in diagnostic device.

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