Engine management light

UK forum for general and technical discussion about the Z3 roadster
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jonzee
Joined: Fri 16 May, 2014 14:24
Posts: 68

  Z3 roadster 1.9

Engine management light

Post by jonzee »

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 17:35
Posts: 71

  Z3 roadster 2.2i

Re: Engine management light

Post by andy & fonz »

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: 2136

  Z3 roadster 1.9

Re: Engine management light

Post by Del »

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: 761

  Z3 roadster 2.8

Re: Engine management light

Post by deni2s »

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 10:35
Posts: 10170

  Z3 roadster 1.9
Location: Cheshire

Re: Engine management light

Post by Robert T »

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 14:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee »

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: 2225

  Z3 roadster 1.9

Re: Engine management light

Post by BladeRunner919 »

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 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Engine management light

Post by colb »

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
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
jonzee
Joined: Fri 16 May, 2014 14:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee »

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 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Engine management light

Post by colb »

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
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
jonzee
Joined: Fri 16 May, 2014 14:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee »

New maf on order.
Thanks for all the help its been most appreciated
jonzee
Joined: Fri 16 May, 2014 14:24
Posts: 68

  Z3 roadster 1.9

Re: Engine management light

Post by jonzee »

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: 2136

  Z3 roadster 1.9

Re: Engine management light

Post by Del »

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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