Help rouge cold start again

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Hammer
Joined: Wed 13 Feb, 2013 16:30
Posts: 36

  Z3 roadster 1.9

Help rouge cold start again

Post by Hammer » Fri 20 Sep, 2013 07:20

Hi guys changed my oil in may and the rouge cold start stopted now it's back miss firing for 30 seconds then its ok thinking of an engine flush is that ok to do ? Thanks Steve :head:

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

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Del » Fri 20 Sep, 2013 08:09

I would definitely suspect sticky oil residue and go ahead with another change when the oil is good and hot. Views differ on engine flushes - some like them and others avoid. Personally, I've seen my son use it (Wynns) in a dirty engine (neglected oil servicing) and I was impressed with the clean-up it did.

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

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by BladeRunner919 » Fri 20 Sep, 2013 08:12

What oil grade did you use? I'd suspect the problem recurring is linked to the start of the colder weather and the fact that the oil is a bit 'thicker' in the mornings.

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
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  Z3 roadster 3.0i
Location: Johannesburg

Re: Help rouge cold start again

Post by Southernboy » Fri 20 Sep, 2013 08:29

I am under the impression that the Z3's like all BMW's have a cold start phase controlled by the ECU. The issue should not be related to fuel or ignition. Back firing or even "front" firing can be attributed to valves, valve guides, and also the engine pressure regulating valve. I cannot say if the 1.9's have such a pressure regulating valve, but I have had to replace that item on my 2.8 around a week ago... On my car, it is situated below the intake manifold, and controls the internal engine pressure between the upper cylinder (Head) area and the crankcase. It has two rubber hoses which connect to the cylinder head at top, and the oil dipstick tube right at the bottom...
This is a pic of my old unit which essentially was "blown up" when I attempted to start my car first thing in the morning...as you can see, the one face of the plastic cover has been blasted off by a "front (back) fire. This means the engine ignited, and the gasses were expelled out via the intake manifold vs the exhaust as in a "back" fire....

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If the issue is in the cylinder head and valve related, I could recommend you fill up with 98+ octane and add some STP valve / ignition cleaner to the fuel, as well as a decent engine flush such as Wynns...do the engine flush thing by driving the recommended mileage vs the alternative of running the motor at an idle for 10 mins...driving applies higher revs and stresses / pressures inside the motor than just idling...after the mileage is covered, drain and replace with clean oil of the correct specifications for your car.
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Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
Posts: 1991

  Z3 roadster 2.8
Location: Daglan, France

Re: Help rouge cold start again

Post by Mike Fishwick » Fri 20 Sep, 2013 10:43

It took me a while to realise that we are talking about a ROUGH cold start! I must be getting slow on the uptake, but after all, today is my 69th birthday . . .

My bet is air being drawn into the inlet manifold by a failure of the crankcase breather valve/cyclone filter, the resultant unmetered air making the mixture weaker than it should be, and being more noticable on a cold engine. At the current not-really-cold ambient temperatures the cold start mmixture will not be highly enriched, so making it even more noticable than would be the case at lower temperatures.

As a firststep, take the filter unit off, clean it out, and check for air leaks. A new one is not that expensive.
A Z3 is not just for Christmas - it's for life!

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Brian H
Joined: Tue 16 Dec, 2008 19:55
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  Z3 roadster 3.0i

Re: Help rouge cold start again

Post by Brian H » Fri 20 Sep, 2013 11:25

Mike Fishwick wrote:today is my 69th birthday . . .
OT I know but Happy Birthday.

Hammer
Joined: Wed 13 Feb, 2013 16:30
Posts: 36

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Hammer » Fri 20 Sep, 2013 11:49

Hi guys thanks for geting back to me last year I had this for 6ths months changed pipes and maf sensor when I changed the oil in may it was fine until now put in Fuchs oil recommend for my z3 1.9 m44 :head: thanks steve

DC
Joined: Tue 15 Sep, 2009 18:31
Posts: 562

  Z3 roadster 1.9
Location: Inverness-shire

Re: Help rouge cold start again

Post by DC » Fri 20 Sep, 2013 19:54

Mike Fishwick wrote:It took me a while to realise that we are talking about a ROUGH cold start!
Well done, I didn't get it at all and I'm only 67!
Happy Birthday.

Dave.
Dave. 1998 Arctic Silver Z3 M44 1.9 Automatic

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OXO
Joined: Wed 31 Mar, 2010 09:32
Posts: 566

  Z3 roadster 2.2i
Location: France

Re: Help rouge cold start again

Post by OXO » Fri 20 Sep, 2013 20:04

Many happy mike.

Maybe a mod could edit the thread title, cos it's not at all obvious what it means..

Rafolian
Joined: Wed 27 Feb, 2013 08:41
Posts: 547

  Z3 roadster 2.8

Re: Help rouge cold start again

Post by Rafolian » Fri 20 Sep, 2013 21:37

Happy birthday Mike, I thought it was ROGUE!

RichP
Joined: Wed 20 Feb, 2013 00:47
Posts: 190

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by RichP » Sat 21 Sep, 2013 01:39

Mike Fishwick wrote:My bet is air being drawn into the inlet manifold by a failure of the crankcase breather valve/cyclone filter, the resultant unmetered air making the mixture weaker than it should be, and being more noticable on a cold engine. At the current not-really-cold ambient temperatures the cold start mmixture will not be highly enriched, so making it even more noticable than would be the case at lower temperatures.

As a firststep, take the filter unit off, clean it out, and check for air leaks. A new one is not that expensive.
Sorry to go back to basics, but where is the crankcase breather valve located on the M44? i also have cold start issues when it gets really cold (around 0 degrees C), needs a load of accelerator to eventually chug to life. Although it was ok last year, and i've been running it solely on 98 or 99 octane fuel for a year.
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RichP
Joined: Wed 20 Feb, 2013 00:47
Posts: 190

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by RichP » Sat 21 Sep, 2013 01:50

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not to worry. i answered my own question. :D part 16 8-)
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"I spent a lot of money on booze, birds and fast cars. The rest I just squandered." George Best

Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
Posts: 1991

  Z3 roadster 2.8
Location: Daglan, France

Re: Help rouge cold start again

Post by Mike Fishwick » Sat 21 Sep, 2013 07:39

Look at hose 13 and the valve 16 - and its junction with the inlet manifold. Also check the oil filler cap, and make sure it is not leaking air into the engine - is the rubber seal in good condition?.

If it all looks OK, remove the valve from the manifold, and plug the hole. Now try a cold start and see if there is any difference.

If the roughness has gone, put your finger over the exit hole of the valve, and see if a steady flow of air is coming out - it should not, unless the crankcase is pressurising - most likely due to an air leak into it.

If this does not show up the problem, look for air leaks from the airflow sensor to the inlet manifold and associated pipework, and try spraying WD-40 over the joints - in case of air being drawn into the manifold the idle speed will increase as the engine burns the WD-40. Favourite places are the rubber trunking between the airflow sensor and throttle body, the joint faces between the throttle body and manifold, and those between the manifold and the DISA valve actuator, and the manifold to cylinder head.
A Z3 is not just for Christmas - it's for life!

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

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Del » Sat 21 Sep, 2013 11:34

I can understand why Mike is following the vacuum leak line of enquiry. The general expert/mechanical view is that rough starts, isolated only to cold starts, point to a vacuum leak. When I bought my car in 2011 I spent eight months actively “chasing” a cold start problem and following the vacuum leak line of enquiry.

My “cold start” was rough in the summer, got rougher towards the autumn and on one or two frosty winter mornings the engine coughed and actually refused to start at all. I replaced the crankcase valve (16) and replaced nearly all vacuum pipework. I removed the upper intake manifold, replaced the steel gaskets and removed, inspected and thoroughly cleaned the throttle body. I moved to the sensors changing the camshaft position, coolant and air temperature. I bought new spark plugs, a spare 2nd hand MAF for £15, checked the HT leads and coil pack. The car was now running beautifully when warmed up but was still having rough starts & throwing random, non-specific piston misfire codes.

Reading loads of US and UK forums I stumbled on the fact that oil changes had improved this situation specifically for the M44 engine with sticking hydraulic valve lifters. I hadn’t suspected mine as it had been changed (by a large drive in chain) shortly before I got the car. I did a change using Mobil 0W-40 which had a reputation for being nice and runny/thin and replaced the filter and three rubber o-rings. As if my magic the situation was immediately cured. I have since done a quick succession of good oil changes and have had no reoccurrence.

I have never encountered any other car or engine (BMW or otherwise) that has been so fussy about oil changes and sticking hydraulic valve lifters. I can only assume there is a slight design fault with oil circulation in this area for the M44.

RichP
Joined: Wed 20 Feb, 2013 00:47
Posts: 190

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by RichP » Sat 21 Sep, 2013 13:57

I think in the past I've just used mid range 10w 40 oil. I plan on changing before the weather gets too horrible, so I'll try the 0w 40. Thanks!

I hope all this helps hammers original problem, otherwise I've just commandeered his thread! :)
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Hammer
Joined: Wed 13 Feb, 2013 16:30
Posts: 36

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Hammer » Sat 21 Sep, 2013 14:08

Thanks guys I think the oil change is the way to go. When I changed it in may it went away and has just started again this time I will do an engine flush will let you know how i get on :head:

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

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Del » Sat 21 Sep, 2013 14:27

Yep - I don't think the problem is directly the oil itself, but the build up of "gummy deposits" left in nooks and crannies from oil in the past that has not been changed frequently enough - lots of short journeys and strict observance of the green service lights. Frequent oil changes, or a flush, should have the effect of washing these away.

Hammer
Joined: Wed 13 Feb, 2013 16:30
Posts: 36

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Hammer » Mon 23 Sep, 2013 08:24

Hi guys just an up date have not changed the oil yet . It has been warm here and the first start of the day ha been fine :colourful:

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

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Del » Mon 23 Sep, 2013 09:06

If it gets noticeable worse as temperatures fall then I reckon you can be more certain it is an oil problem as a vacuum leak issue would not be that temperature-sensitive.

Hammer
Joined: Wed 13 Feb, 2013 16:30
Posts: 36

  Z3 roadster 1.9

Re: Help rouge cold start again

Post by Hammer » Thu 21 Nov, 2013 07:34

Hi guys up date on the rough start changed the oil about 8 weeks ago with a engine flush and has been fine thanks for all your help :colourful:

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