Front strut brace & rough cold idle 1998 Z3 M44 (72k mil

UK forum for general and technical discussion about the Z3 roadster
Post Reply
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Front strut brace & rough cold idle 1998 Z3 M44 (72k mil

Post by Del »

Hi I am a newbie member having picked up my Z3 this spring as an early retirement hobby/toy. I am gradually working my way through a small list of little imperfections and I am a bit stuck on fixing two. Firstly what seems to be the fairly common problem of a rough idle on cold start only, for around 30 seconds - after this it now runs beautifully across the rev range and idles fine (have replaced plugs NGK BKR6EK/oil/air filter/DISA valve/thermostat/fuel regulator vac pipe/ MAF rubber boot & substituted MAF for another + cleaned it) all to no avail. I am pulling out what little hair I have left over this one.

Second problem is tram-lining which is a little unpleasant on the inside lane of motorways (lorry ruts) particularly if it is also a bit windy. This seems to have become a bit more pronounced since I had 2 new front shocks fitted two months ago and tracking was re-done. Do any experienced members have a view on whether a front strut brace would help?
User avatar
Jonttt
Z Register member
Joined: Sun 28 Dec, 2008 16:32
Posts: 6554

  M roadster S54
Location: Liverpool

Post by Jonttt »

Hi Del, welcome on board.

I don't think a front strut would really help with tramlining as they are designed to stiffen up the handling mid corner ie with forces much greater than tramlining would create on the suspension.

You more likely to see a differnece experimenting with tyre pressures as the Z3's are prone to be sensitive to tyre pressure depending on setup and tyre choice.

Re the rough idel from cold have you tried to see if your throttle is sticking when under auto choke ? Its pretty common for the throttle cable to get stiff over the years and need adjusting (which is pretty easy to do) or replacing. It could be as simple as your cable is sticking at a certain point under choke ?
Happiness is not around the corner........happiness is the corner
Image Video or Journal Garage: 2015 FFRR Black Edition, Porsche Boxster GTS, 1997 Porsche Carrara C4S, Ex 2001 BMW S54 Z3m Roadster
r37
Joined: Tue 01 Nov, 2011 18:38
Posts: 22

  Z3 roadster 2.8

Post by r37 »

Im no mechanic so i cant help on the rough start but the tramlining i can help with. With wide tyres with low profiles they tend to bridge the ruts in the road left on the most common path and want to stay in the dip. A strut brace wont help to remove the tramlining as its a tyre/suspension based issue (not much anyway). A strut brace stiffens the front of the car and improves handling no end (if you dont have one you should pick one up from ebay, well worth fitting imo). The best solution to tramlining would be to get some good tyres, Falken 452's seem to be the most popular on the forum and are what i have fitted to my z3 all round and i can say i very rarely tramline and only really notice it one one particular corner which is often taken at speed (not by me) and has a deep rut on the outside edge of it.

EDIT: johntt beat me to it :)
User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2505

  Z3 roadster 3.0i

Post by Brian H »

I can really echo the other two posts but I found that my 1.9 M44 was really sensitive to tyre pressure. I had 17" alloys on the car and ran on 225/55/17 falken 452 tyres but if there was the slightest bit of difference in tyre pressure the car would tramline something rotton. IIRC I had my tyre pressures at 32psi all round, it seemed to suit both the car and me, this of course costs no money to try and you might be supprised at the results.
Trevsky
Joined: Tue 26 Jul, 2011 21:57
Posts: 140

  Z3 roadster 1.9
Location: Leeds

Post by Trevsky »

I had similar concerns when I bought my 1.9 last year. The idling was a bit rough, I'd call it hunting, but this when warm. I thought a service would cure it. I changed the usual stuff including air filter thinking it could be blocked and fuel filter and a new set of plugs. None of this made a great deal of difference. I was buying normal unleaded from Sainsbury's because it was about the cheapest and most convenient. One day I was passing Tesco and filled up with their regular unleaded. I noticed a difference immediately, much less of a roughness at tick over. On another visit to the pumps I decided to try the Super Unleaded. The tick over now is almost perfect and it might be my imagination but the performance seems so much better, it really goes now compared with the mediocre performance when I first got it. I wouldn't run it on anything else now but Super Unleaded, maybe a little dearer but in my opinion well worth it.
As for the tramlining this really suprised my for this type of car, I expected a BMW sports cars handling to be spot on. From reading posts on here I realise it is a common feature brought about by the wide tyres. I must agree that tyre pressures do seem to make a difference though because when I set my tyres to the recommended 2 bar the tramlinning was quite pronounced, I haven't reset the pressures for some time and I have noticed that the car handles much better. It is either me getting used to it but I suspect it is because the tyres are gradually losing pressure and becoming more flexible.
Post Reply