MOT woes, and where to buy parts

[Rodent]

Hi all,
My z3 2.2 sport failed the mot today. I’ve been putting off a few jobs but todays news means I need to bite the bullet and gets a few jobs done. Other than needing new sill covers, I also need suspension arms for all four corners, and probably front ARB drop links too. Can anyone recommend where I can get reasonably priced replacements? The car has 140k on the clock so I can’t justify genuine parts? I see an eBay site selling full front wishbone kits for £118, has anyone tried these, the feedback seems ok on ebay? (It seems like parts for the 4 cyl cars are everywhere, but the 2.2 6-cyl not so easy to find parts?)

Another concern is that the car also failed mot for ‘exhaust lambda reading after 2nd fast idle outside specified limits’. I don’t see any exhaust leaks, but I do sometimes feel a slight misfire, and a local garage said these engines are prone to misfiring due to sticky hydraulic tappets. Has anyone come across this? I was hoping a new air filter, spark plugs, cat cleaner and an oil additive might be enough for now?
Thanks in advance,
Will

[bowei001]

There is no reason not to use these kits as they are made to a standard and should be OK (Febi & Meyle ones are a bit dearer). If you have access to a press you can use your old front arms and press in new ball joints which are available quite cheaply from some well-known manufacturers. If you go down the press-in route it is worth fitting Z3M rubber mounts to the wishbone brackets as they don't have slots in the rubber and give better stability (I think that they are only available from BMW). The rear arm rubber kits from the likes of Febi or Mahle work OK. If you are having to do the rear beam bushes, Febi are OK but these bushes are a bit of a fight to get out and replace without taking the beam out. Make sure you use a rubber lubricant that hardens when it dries (like P-80 THIX) when pushing in rubber bushes. As far as I can see from looking at RealOEM, all these suspension parts are the same for all models of Z3 (and some bits fit other models as well).
I used a Meyle kit but pushed in Z3M bushes at the front and dropped the beam and used either Febi or Meyle(can't remember which) at the back and everything has been OK since 2018.

[Rodent]

Thanks bowei001 that’s a good shout, I didn’t know that Febi and meyle offered these parts. I don’t have a press so I think I’ll change the whole arm on both sides for Febi or meyle.
The rear trailing arms seem hard to find (unless going for super expensive bmw oem. It looks like people often shot blast and repaint the trailing arms and just fit new rubber parts?
I probably need to refurb my diff casing and rear beam too, but maybe that can wait until winter.
I’ve ordered plugs, air filter and Cataclean to try and address the emissions issue. Bit worried about the misfire though….
I’m hoping to get the old sill covers off this weekend, to check how the actual sills look, before I order any new panels.
Thanks,
will

[bowei001]

Hi Will,
Yes, I had our trailing arms sand blasted and then fitted new rubbers and they were fine. Whilst I had the rear beam out I had a cam adjustment kit welded onto it so that I could adjust toe-in and camber if needed. If you take the diff out it might be worth replacing its rubber bush whilst you are at it.
It is all do-able (if you have a local sand blaster) but just takes a bit of time.
Good luck with it.
Ian

[Rodent]

So I thought a new set of spark plugs, air filter and Cataclean would fix the high lambda reading (1.13, when range is 0.97-1.03). Readings were the same at idle as at the 2500-3000rpm test. CO and HC readings were low 0% and 3ppm so I’m think it’s running lean.
So it’s now failed the MOT retest !
I checked the exhaust and there is possibly a tiny hole in the seam weld of the exhaust back box, but it really is a tiny leak. When I stuffed rags up the twin tailpipes there was also a bit of a blow where the twin pipe end-pieces fit onto the back box, but I thought that’s just blowing back when pipes are stuffed with rags?
A local tyre/exhaust specialist has quoted me £395 for a supply and fit of a new stainless back box.
Before I go and spend this, is there anything else I should check?
I replaced the rubber hose between air box and engine a couple of years go and it appears to be in good condition. I do have INPA software on an old laptop somewhere…does INPA read/check Lambda sensors (I think the 2.2 M54 engine has 4 of these sensors, 2 either side of the CAT.

When I changed the plugs I also found the valve cover gasket was leaking oil into 2 spark plug wells so I’ve put a new gasket set in (again)
Any help most appreciated.
Thanks, Will

[bowei001]

You can check the lambda probe readings using INPA live data. That might tell you whether one is way out. As far as I can see from RealOEM, you do seen to have 4 lambdas, 2 on each bank. They seem to be in different positions compared with our 1999 2.0 and look to be easier to get to.
If you have to buy new I suggest that you go to a Bosch agent - you will get the same sensor but at a lower price than from BMW (at least that was what I found when I replaced ours quite a few years ago).
Are you sure that your intake manifold or any of the other intake bits are not letting in air? Do you have a local garage that can do a smoke test to check?
Good luck with sorting it out.
Ian

[Rodent]

Thanks Ian, i'll see if i can get my INPA running to check the sensors. (INPA software/computer stuff always a bit of a challenge for me). good idea about the smoke test, i think i might invest in a smoke tester as i do enjoy buying tools!
will post up how i get on...
cheers,Will