Rough cold starting issue help needed.

UK forum for general and technical discussion about the Z3 roadster
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Tibs
Joined: Sun 05 Jul, 2009 16:38
Posts: 25

  Z3 roadster 1.9
Location: Cleveland

Rough cold starting issue help needed.

Post by Tibs »

Afternoon all!

Hoping that we are all well, quite a while since I was on here.

Looking for advice and help with a little problem that we have with the Z3 currently.

Starting from cold, the car seems to be running on less than all cylinders, coughs and splutters all over the place. Once warm, she runs like a dream and cannot be faulted really.

'97 1.9 if it helps?

Had been putting it down to the cold and damp weather, but worried I could be missing something now?

Any help welcome :-)
alan36
Joined: Wed 17 Aug, 2011 19:57
Posts: 68

  Z3 roadster 1.9
Location: Macclesfield

Post by alan36 »

Hi mate,

This happened to me after fitting a new thermostat. I think it is the cam sensor at fault and they cost around £75 from BMW. I would get it checked with one of them testers to be sure though.
Tibs
Joined: Sun 05 Jul, 2009 16:38
Posts: 25

  Z3 roadster 1.9
Location: Cleveland

Post by Tibs »

Thanks for the response.

Will have that looked at and see.
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Post by Del »

Would be very interested in the outcome. Have a very similar problem on my Z3 1998 (1.9) M44 engine. I intend to next work my way through the vacuum hose system replacing various bits and pieces, but have not got to the bottom of the problem yet.

So far have changed plugs, checked HT leads and coil, changed noisey DISA valve, changed stuck/cold thermostat, changed CVV, coolant temperature sensor, cleaned MAF and ICV.
Fender2004
Joined: Fri 14 Aug, 2009 10:24
Posts: 907

  Z3 roadster 2.8
Location: Houghton-Le-Spring

Post by Fender2004 »

Del wrote:Would be very interested in the outcome. Have a very similar problem on my Z3 1998 (1.9) M44 engine. I intend to next work my way through the vacuum hose system replacing various bits and pieces, but have not got to the bottom of the problem yet.

So far have changed plugs, checked HT leads and coil, changed noisey DISA valve, changed stuck/cold thermostat, changed CVV, coolant temperature sensor, cleaned MAF and ICV.
HI Del

Just a thought, have a good look at all your rubber pipework, inspect it all for holes or splits. :)
Image
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Post by Del »

Update for Tibs and any other interested members with the 1.9 M44 engine. I have been puzzling over a very rough idle (only on the first cold start of the day, for approx. 1-2 minutes) since acquiring the car last June. Warm idle is fine. Diagnostic equipment was just giving a vague misfire code on all cylinders. It was getting worse in the colder weather with a very hard start, failing to hold idle without stalling, firing on what seemed just two cylinders and strong smell of un-burnt fuel from the exhaust during this problem start-up period. The textbook cause was a vacuum leak, but I had checked and replaced most likely items. I decided to check the last rubber vacuum hose I hadn’t checked/replaced which was the 4 branch injector air distribution hose situated under the upper manifold on the M44 engine - part number 13531739618 (£24.11 from local BMW dealer). My hose was the original 1998 one and had hardened with a half inch long split through the wall of the hose to the injector on number one cylinder. Replacement made the car run smoother with more torque at low revs e.g. climbing inclines. However, the rough, cold start still persisted and on one recent frosty morning the car would not fire up at all.

After hours of reading online motoring forums, just one or two postings by people with the M44 engine hinted at it possibly being the camshaft position sensor (CPS). I decided on speculative replacement of the CPS (only one on the M44 engine). The cost from BMW was £94.50 plus £0.83 for a new O-ring. After fitting, the next morning the car burst into life with the first flick of the key and the accelerator pedal felt much more responsive. On a quick test drive down my local dual carriageway (I thought my fairy godmother had transplanted an M engine overnight) the car seemed eager to accelerate to 70mph despite a lighter touch on the pedal.

I hope this experience helps other Z3 owners with similar 1.9 engines who might be experiencing similar problems.
:)
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