Hi new member with fuel comsumption fault

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JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Hi new member with fuel comsumption fault

Post by JeZ3 » Wed 09 Mar, 2016 13:33

Hi

New member looking for some advice.

I have a 1.9 M44 Z3 Automatic it needs a few jobs, just went through the MOT with no advisory’s so that was a relief, love driving the car, can’t wait to get the roof down once the weather gets better.

My 1.9 M44 Zed has very poor fuel consumption currently getting 20mpg, general driving although short trips of around 15/20mins of 10 miles, no faults on diagnostic reader done by local garage, car gets up to temperature sits dead centre, start up when cold outside is very difficult once car has been started once it starts on the button every time until following morning if its been cold less than 2 Celsius then takes an age to start.

There does not appear to be any vacuum leaks, o2 sensor and breather replaced within 12 months and it was serviced last Sept less than 4000 miles ago and there doesn’t appear to be any petrol leaks.

Having had a look about on the forum I think the best place to start maybe replacing the cam position sensor, does this sound like the best course of action?

I’m in need of some help as getting this mileage is killing me, once this is sorted my next job is to clean and treat the roof as its looking a little mouldy.

Looking forward to joining in on the forum. Will post some pic up once it stops raining and the car has had a good clean I'll get some pics up.

Jez

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

  Z3 roadster 2.8

Re: Hi new member with fuel comsumption fault

Post by deni2s » Wed 09 Mar, 2016 18:30

When engine is cold o2 sensors are not in a play. Fuel is enriched until engine is at it's normal working temp. And cam position sensor should throw an error. Maybe sticking idle valve or something like that?

Wookee
Joined: Thu 10 Dec, 2015 19:45
Posts: 166

  Z3 roadster 1.9i
Location: Herts

Re: Hi new member with fuel comsumption fault

Post by Wookee » Wed 09 Mar, 2016 19:22

Hmmm... I've been chasing a very similar problem for the past couple of months and think I may have sorted it, but I won't be sure until I've driven mine for a bit....I just haven't had the time to drive it :(. Essentially it often comes down to air- too much of it in the wrong place making the sensors think it's running lean and then over fuelling. First thing to do is to take off any rubber hoses or boots you have between the airbox and throttle body. Look for cracks or splits or ill-fitting connections.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2120

  Z3 roadster 1.9

Re: Hi new member with fuel comsumption fault

Post by Del » Wed 09 Mar, 2016 23:11

I agree with Wookee. I would ensure that your engine is in tip-top condition in terms of vacuum leaks. As mentioned, the rubber bellows between the MAF sensor and throttle body can develop cracks – very common BMW issue. The M44 engine also has a little “tree” of rubber pipes that branch off this bellows to feed air to the 4 injectors (helps fuel atomisation) – these are under the intake manifold top plenum which needs to be removed.

Obviously plugs and air filter – it has been known for the plugs in low mileage Z3s to get left in for far too many years causing them to deteriorate with age.

Automatics of this generation of car tend to give slightly worse fuel consumption. However, I’ve often seen transmission fluid changes forgotten on these older BMWs and a change of fluid has caused some owners to report “crisper” performance, gear changes and slightly better economy.

HT leads can break down with age. I’ve changed mine as one lead (not the longest) was giving a higher resistance reading on my multi-meter.

I would check to see if the ECU has logged any error codes before replacing sensors.

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Fri 11 Mar, 2016 14:15

Thanks for the replies.

I had 10 minutes spare so whipped the bellows off, they appear to be good and free from cracks, hopefully I'll get a chance to check other bits over the weekend.

Wookee you put me too shame with the amount of work you have done to Cinders in a short space of time. Keep up the good work.

Wookee
Joined: Thu 10 Dec, 2015 19:45
Posts: 166

  Z3 roadster 1.9i
Location: Herts

Re: Hi new member with fuel comsumption fault

Post by Wookee » Fri 11 Mar, 2016 15:09

JeZ3 wrote:Thanks for the replies.

I had 10 minutes spare so whipped the bellows off, they appear to be good and free from cracks, hopefully I'll get a chance to check other bits over the weekend.

Wookee you put me too shame with the amount of work you have done to Cinders in a short space of time. Keep up the good work.
Gee thanks :oops:

I drove mine to and from work last night and can still see the needle almost visibly moving...though I did spend a lot of time over 4000 revs :lol:. My next port of call is to look at the injector/vacuum hoses :rtm:

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Sun 13 Mar, 2016 12:42

I have now done a full check for vacuum leaks, I flooded the engine bay with propane around all pipes especially under the intake where the 4 branch of rubber pipes feeds the injectors and there was no difference in the engine idle speed.

I have discovered that the air intake tube that causes the ram effect has perished so I've ordered up so 3 inch tube to replace it. I was going to follow this modification

http://bmwz3diys.weebly.com/fogged-air- ... 9-m44.html

I may have some pipe left over has anyone tried opening another hole in the airbox and running a secondary pipe from the other side of the grill to increase airflow?

Other than that not sure as still had a problem starting from cold this morning but I'm not sure that have a ram air effect would effect starting the car.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2120

  Z3 roadster 1.9

Re: Hi new member with fuel comsumption fault

Post by Del » Sun 13 Mar, 2016 14:56

Problems starting from cold only, on the M44 engine is often "sticky valve lifters" caused by slightly dirty or slightly too thick engine oil - the M44 engine is a bit susceptible to this - as mine was when I first got it.

http://www.zroadster.net/forum/viewtopi ... aa#p365861
http://www.zroadster.net/forum/viewtopi ... hlight=m44
http://www.zroadster.net/forum/viewtopi ... 72#p340572
http://www.zroadster.net/forum/viewtopi ... 94#p343594

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Mon 14 Mar, 2016 12:54

Thanks Del I'm going to change the oil at the weekend will do plugs and air filter whilst I'm at it. If it is that easy I'll kick myself but it seems quite a common fault.

Is there any benefit to using 0w40 oil over the 5w40 that's recommended?

Does the M44 engine cope with an engine flush, or am I better running the thinner oil and changing it in 3 months?

Finally can anyone advise me who's doing the best deals on service parts?

Thanks

Jez

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2120

  Z3 roadster 1.9

Re: Hi new member with fuel comsumption fault

Post by Del » Mon 14 Mar, 2016 13:53

I wouldn't get too hung-up on the brand with these older engines as long as it is fully synthetic. Personally, I had quite a bad cold misfire problem and spent six months chasing/changing stuff. For me Mobil 1 0W-40 worked instantly. It has a superb reputation for being a nice thin oil that gets around engine crevices cleaning and lubricating - even from cold. Like many, I get my servicing parts from http://www.carparts4less.co.uk/?gclid=C ... tAodpB8AEw which is the mail order arm of EuroCar parts. :)

The wholesale warehouse Costco often sells Mobil 1 0W-40 cheap.

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Tue 22 Mar, 2016 15:58

Service completed starts on the button first time seems to be running smoother using 0W40 oil. the oil that came out was quite dirty so I think 4,000 miles or a 6 month change is in order to keep the engine clean.

I've run a new pipe to the air feed and brimmed the tank, I'll keep an eye on the mpg.

Wookee
Joined: Thu 10 Dec, 2015 19:45
Posts: 166

  Z3 roadster 1.9i
Location: Herts

Re: Hi new member with fuel comsumption fault

Post by Wookee » Tue 22 Mar, 2016 21:04

I'll be watching for your results..... :rtm:

I've had a terraclean done on mine and went on a long journey on Sunday but I'm not too sure the clean has solved my issues :head:. Fortunately, the long journey took me to a Z3 meet where someone more knowledgeable than I has suggested having a look at my injectors/rail. :shrug

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Sat 09 Apr, 2016 13:47

Its not great news.

I've not been driving the Z3 much and not filled it up to calculate MPG but its only done 96 mile to 1/2 a tank, you can watch the fuel gauge go down as you drive.

I'm at a bit of a loss I thought a good service would sort it, anybody got any ideas?

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2120

  Z3 roadster 1.9

Re: Hi new member with fuel comsumption fault

Post by Del » Sat 09 Apr, 2016 15:46

The tank holds 51 litres - just over 11 UK gallons. I would plug in an OBD code reader to check in any error codes are being logged. Do you suspect a binding brake - wheel normally gets hot - do the wheels spin freely?

Around town these cars are not that good with the manual 1.9 capable of dipping below 30 MPG in heavy traffic. Redex will clean dirty injectors https://www.youtube.com/watch?v=WQN-0zvZNbY

The main sensor controlling fuel air mixture (the MAF) if faulty, can push up fuel consumption but as they are expensive I would not change one speculatively without first doing a fault code check.

JeZ3
Joined: Sun 24 Jan, 2016 16:14
Posts: 15

  Z3 roadster 1.9
Location: Milton Keynes

Re: Hi new member with fuel comsumption fault

Post by JeZ3 » Sat 16 Apr, 2016 20:44

I just brimmed the tank, I'm getting 25.4 MPG.

Most of my trips are less than 10 miles so I suppose I can't complain.

Brakes are not binding I took them to a local fast fit station that were doing a free brake check, although the rear discs are not in the best condition.

Next step I think is to get myself an OBD reader, are any better than others?

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