My midlife crisis purchase; E86 BMW Z4 Coupe

[Court_S]

pmorg4 said:

The MAF is almost certainly a red herring as you've discovered. Most likely a vacuum leak, with the MAF connected it's fuelling based on the measure quantity of air and thus getting it wrong due to the leak after the MAF. With the MAF disconnected the ECU falls back onto a pre calculated map based on things like manifold absolute pressure, throttle position and RPM.

I had a very similar situation on my E46 330i years back, ran like a dog with the MAF plugged in, but perfectly smooth without it. Turned out it had a large tear in the intake boot that was very difficult to spot without removing it. Once that was sorted it ran perfectly on the original MAF.

Good luck getting it sorted. These faults can be a pig to trace, if you have access to a smoke tester it could make it a lot easier to find the culprit, although as you've just done some work it's almost certainly a hose or gasket not seating properly.

I’ve checked the boots etc that I’ve removed and they all look good.

Hopefully a mate can pop over later with a code reader which might shed some light on whats going on. I’ve checked my coil connections in case I’ve knocked one etc but they all seem OK. Definitely feeling at a bit of a loss right now especially given that it should have been an easy bit of work.

[Court_S]

So, new development….

I put the sound generator pipework in that comes off try air intake and it’s running fine. Idled smoother that’s pre-CCV change but I still have the engine management light on.

[Craikeybaby]

Could the EML be a historic code. Have you tried clearing them?

[pmorg4]

If it's running smoothly with the MAF plugged in then you've sorted the air leak. The engine management light will probably clear itself after a few cycles of it running well, it doesn't go off immediately when tripped by things like an air leak.

[Court_S]

Craikeybaby said:

Could the EML be a historic code. Have you tried clearing them?

My Carly app is being a dick. It reads the codes to 90% and then crashes so I’m not able to clear them.

But it is progress.

[Court_S]

pmorg4 said:

If it's running smoothly with the MAF plugged in then you've sorted the air leak. The engine management light will probably clear itself after a few cycles of it running well, it doesn't go off immediately when tripped by things like an air leak.

I’m hoping that’s the case. It was idling nicely this morning with everything plugged in. I just need to put a few brackets etc back in place then I’m going to take it for a quick drive (locally).

[d_a_n1979]

Good to hear Sam; hopefully that's the end of the issues!

[cerb4.5lee]

Fingers crossed that it is now playing ball for you Sam.

[Court_S]

Just been for a drive and it’s absolutely fine; pulls well, idles fine etc.

And just need to get the engine management light off. Hoping that clearing the codes will sort that bit. Does feel like I’m nearly there.

It was a vacuum leak that was causing the issue by the looks of it, it just wasn’t were I’d assume it was from and it looks like the car needs the sound generator box in place to run nicely.

Are the creator code readers any good? Was thinking about buying one given that Carly is hopeless for me.

[InitialDave]

If it's a generic code, have you tried just using the Torque app?

[jasonrobertson86]

Court_S said:

Just been for a drive and it’s absolutely fine; pulls well, idles fine etc.

And just need to get the engine management light off. Hoping that clearing the codes will sort that bit. Does feel like I’m nearly there.

It was a vacuum leak that was causing the issue by the looks of it, it just wasn’t were I’d assume it was from and it looks like the car needs the sound generator box in place to run nicely.

Are the creator code readers any good? Was thinking about buying one given that Carly is hopeless for me.

Sorry, if this is a repeat, but have you upgraded the brakes and was it worth it?

[Court_S]

jasonrobertson86 said:

Sorry, if this is a repeat, but have you upgraded the brakes and was it worth it?

Only in the same that I’ve fitted ceramic brake pads to cut down on dust (which is well worth it).

I’m still running stock callipers and rotor sizes.

[jasonrobertson86]

Court_S said:

Only in the same that I’ve fitted ceramic brake pads to cut down on dust (which is well worth it).

I’m still running stock callipers and rotor sizes.

Thanks, which brand?
I see quite a few opinions here: https://z4-forum.com/forum/viewtopic.php?t=98616

[Court_S]

jasonrobertson86 said:

Thanks, which brand?
I see quite a few opinions here: https://z4-forum.com/forum/viewtopic.php?t=98616

I’ve got ATE Powerdiscs on the front with normal ATE discs on the rear and ATE ceramic pads.

I’ve used ATE ceramic pads on a few cars now and can’t fault them to be honest.

[jasonrobertson86]

Court_S said:

I’ve got ATE Powerdiscs on the front with normal ATE discs on the rear and ATE ceramic pads.

I’ve used ATE ceramic pads on a few cars now and can’t fault them to be honest.

Perfect, thank you. Has suspension been done also? Sorry if this has all been covered? I have seen posts where people have moved to b12 or whatever and found it too harsh but the boggo shocks/springs are quite soft in IMO

[Court_S]

jasonrobertson86 said:

Perfect, thank you. Has suspension been done also? Sorry if this has all been covered? I have seen posts where people have moved to b12 or whatever and found it too harsh but the boggo shocks/springs are quite soft in IMO

Yes. The previous owner fitted B4 dampers with Eibach springs.

I think the B12 kit is quite harsh albeit my only experience is in a friends 125i on 17 inch wheels.

I’ve fitted Powerflex RTAB bushes and front ARB bushes.

[jasonrobertson86]

Court_S said:

Yes. The previous owner fitted B4 dampers with Eibach springs.

I think the B12 kit is quite harsh albeit my only experience is in a friends 125i on 17 inch wheels.

I’ve fitted Powerflex RTAB bushes and front ARB bushes.

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.

[Gallons Per Mile]

Court_S said:

I suspect it’s the return pipe.

The other two have clicked into place really nicely and are side to remove, but that return pipe….

I’m going to pop the old one back in and see if it works.

Any idea why it runs with the MAF unplugged?

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

[Court_S]

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.

[Court_S]

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!