My midlife crisis purchase; E86 BMW Z4 Coupe

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Gallons Per Mile said:

It'll fun fine with the MAF unplugged because the ECU will be using a default map rather than live data

Cool, I was just wondering.

You were right re the vacuum leak it just wasn’t from where I expected. Just need to get rid of the bloody check engine light.

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jasonrobertson86 said:

Ah thats a shame, have you driven a coupe with standard shocks and springs for comparison? Interested if it is an 'improvement' with B4's / eibach.

I haven’t driven a stock coupe but I wouldn’t describe mine as soft. It’s just on the acceptable side of form if I’m honest.

It makes my wife’s 330i feel like an absolute pudding and that’s on the same suspension!

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In celebration of getting the car working (other than the check engine light), I gave it a clean to remove this week’s dust and bird poo collection.

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jasonrobertson86 said:

Loving your work, looks great. Wish I had your patience for tinkering!

Thanks. It’s fair to say my patience has been tested a bit this week! Albeit it was user error.

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Gallons Per Mile said:

If you're working in my area in the near future and driving here then I can clear it for you

Cheers, I’m on site again next week but will be training it because it’s so easy.

My cheap Creator 410 arrived this morning courtesy of Amazon and I’ve cleared the codes and the check engine light seems to have gone. Hopefully it’ll say that way.

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Earthdweller said:

It’s absolutely an improvement *

I’ve B4’s on mine which replaced the OEM set and they are much better giving more control and seemingly more suppleness in the ride, of course upgrading the top and bottom mounts also will have helped

• Caveat being that when replaced the original suspension was a bit tired so it’s not a comparison of “new v new”’ if that makes sense

Personally though I’d recommend the B4’s for general road use

I’d free with that; for normal use the B4’s are indeed a really good buy. I’ve not been disappointed with them on any of the cars that I’ve fitted them to.

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Earthdweller said:

I’ve enjoyed reading this thread and I have to admit the gold wheels are growing on me

Cheers.

I love them; they look better in the flesh than in pictures to be honest.

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jasonrobertson86 said:

Super. I will get ordering shocks and brakes. Any more specifics on mounts you moved too please? (I am going to order soon as I can)

I’d get on RealOEM and order some of the bolts / nuts too. Depending on the age of your car, some might be a bit crusty and be better replaced.

How many miles has your car done? Might be worth doing the RTAB while your replacing stuff and it saves paying for another alignment.

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And the check engine light has made a reappearance….

I’m left with four codes that all relate to the Lambda sensors. If I clear the codes and start the car the light stays off but if I clear them and leave the car for a while the light comes back with the codes. The car is driving fine.

What are the chances of all four sensors dying at the same time?

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So, after some googling, it looks like the chances of all four O2 sensors stting themselves at the same time are skim to none. Which is good, my wallet can breathe a sight of relief.

One thing that did come up was the possibility for a blown fuse. There are a couple of fuse boxes in my Z4 but annoyingly only the main one in the glove box has a diagram and there seems to be limited information online about the one others but I did find a website and pulled fuse number four in the engine bay box…



This responsible for crankcase heating and all four O2 sensors.

Annoyingly, I’ve not got a spare 30A fuse but will grab one tomorrow and see what happens.

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Gallons Per Mile said:

Awesome, come say hi if you're about, I'm around in the afternoons next week!

Will do.

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Gallons Per Mile said:

Brilliant! Looks like you've found the culprit to the lambda codes giving you the eml. New fuse and clear the codes, that should be sorted.

Fingers crossed.

I was thrust all four dying at once seemed a bit odd (the pre-cat ones in my car are at least dead easy to get to). The post cat ones would have been horrible because access to stuff under the Z4 is nasty. Even the diff drain plug is horrible to get at.

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And I still have an intermittent check engine light…

Started the car this morning and there was no light on. Drove to ECP to grab a pack of fuses, started the car and the warning light came back on along with the same four codes.



The car seems to drive just fine other than a slightly lumpy cold start idle; it doesn’t feel down on power and economy is as expected.

I’m trying to find a local indy who can have a look but the nearest guys are booked until 23rd July.

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d_a_n1979 said:

Bloody hell Sam; can the codes be cleared? Or do they clear and then come back?

Codes will clear but come back.

I cleared them last night (again). It’ll start with no warning light but it’ll make an appearance as soon as I next start it.

The indy that I spoke to mentioned that it sounds like a possible issue with try air / fuel mixture due to a vacuum leak after the MAF. I can’t see anything by eye and am struggling to find someone to look at it.

I wish I’d just lived with the oil consumption now.

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I’ve just checked the fuse that I replaced yesterday and it’s blown again.

I’m starting to wonder if the oil separator that I fitted is a dud and the electrical connections are shorting out to blow the fuse.

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JakeT said:

Unplug all of the heaters for the hoses and valve under the inlet and then try it. All they serve to do is stop the hoses freezing and splitting, snd we’ve little chance of that for a while.

Good call….I might do them one by one to see if I can isolate which one is causing me grief.

On another forum, some mentioned the pins getting bent in the power box because they’re small and you’re plugging them in my feel. I’ll check that if I need to pull the manifold again. Luckily the power box is dead cheap and available separately if there is a bent connection pin or two.

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InitialDave said:

Have you tried AutoTechnik in Lutterworth? Though they'll likely be just as booked up as anyone else.

I haven’t no. They’re on the list because they’re not too far away.

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I forgot to say that the fuse in question has been changed before because it is different to the other ones installed. I’m wondering if a previous owner has had similar issues?

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So, I did some more faffing with this car at lunchtime.

I might have found the vacuum leak. This part of the sound generator hadn’t been out back together fully.



Getting the raise sort inside of the hose to seat properly in the groove on the bracket took some doing. So it looks like user error on my behalf; I hadn’t really considered how integral the sound generator is to the vacuum system.

I’ve also unplugged the CCV heater plug to see if the fuse blows again. I’ll be really cross if it’s that that’s blowing the fuse because it’s a new part and a pain in the bum to get to. If it’s either of the pipes, I’ll be less fussed because at least one of them can easily be changed without touching the manifold. I might be able to do the return pipe with the manifold in situ but I think I’ll be better off just loose it off.

I’m on the school run at 3pm so it’ll be interesting to see if the idle is solid now and if the bloody check engine light makes a reappearance.

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Idle is much better although still flutters ever so slightly.

The bloody EML is back on though, so I’m guess true fuse has blown again.

I’ll swap the fuse again tonight, plug the new CCV connector back in and unplug the next one down!