My midlife crisis purchase; E86 BMW Z4 Coupe
Discussion
Some good work there Sam but that's a bugger about the starting and stalling!
I would have thought if it was the MAF it'd run but just not as smoothly as it should be
Wondering if it's more of a vac leak/running lean that's causing it...
It looks as faffy a job as the CCV is on the M54s; with them a lot of it's buried, so best way is intake mani off so you don't snap anything (and refresh the intake mani gaskets at the same time)!
I would have thought if it was the MAF it'd run but just not as smoothly as it should be
Wondering if it's more of a vac leak/running lean that's causing it...
It looks as faffy a job as the CCV is on the M54s; with them a lot of it's buried, so best way is intake mani off so you don't snap anything (and refresh the intake mani gaskets at the same time)!
d_a_n1979 said:
Some good work there Sam but that's a bugger about the starting and stalling!
I would have thought if it was the MAF it'd run but just not as smoothly as it should be
Wondering if it's more of a vac leak/running lean that's causing it...
It looks as faffy a job as the CCV is on the M54s; with them a lot of it's buried, so best way is intake mani off so you don't snap anything (and refresh the intake mani gaskets at the same time)!
Yeah, it’s really odd. I’ll try the 330 MAF and see if that works.I would have thought if it was the MAF it'd run but just not as smoothly as it should be
Wondering if it's more of a vac leak/running lean that's causing it...
It looks as faffy a job as the CCV is on the M54s; with them a lot of it's buried, so best way is intake mani off so you don't snap anything (and refresh the intake mani gaskets at the same time)!
If not, I’m suspecting the oil return pipe from the CCV. I had a really battle to get it to seat properly on the sump and I’m not 100% convinced by the CCV connection. If the other MAF doesn’t work, I’ll try refitting the old return pipe and see if that solves it.
The manifold gaskets are all new.
Gallons Per Mile said:
d_a_n1979 said:
It looks as faffy a job as the CCV is on the M54s; with them a lot of it's buried, so best way is intake mani off so you don't snap anything (and refresh the intake mani gaskets at the same time)!
Check my E46 thread for M54 CCV change! I've just done it 
And TBH peace of mind too with new Elring intake gaskets for c£35\
First time I tried it on my 1st E39 530i with the mani in place; snapped 2 of the connections... Learned the hard way after that
Gallons Per Mile said:
It's 100% an air leak. Probably something on the CCV pipework isn't quite home tight and sealed. Classic air leak symptoms.
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?
The old oil return pipe has been fitted and this snapped into place nicely and feels really firm.
But the act will still only start / run with the MAF unplugged. I’ve just checked the other CCV hose connections and they all seem good and solid.
My last resort to fix it has to be the MAF from the 330i.
But the act will still only start / run with the MAF unplugged. I’ve just checked the other CCV hose connections and they all seem good and solid.
My last resort to fix it has to be the MAF from the 330i.
I can’t swap the MAF’s between the cars because despite what the various websites are telling me, the MAF’s are completely different.
The one in the 330i is really thin and only has two pins whereas the Z4 one is much fatter with five pins.
I’m still no further forward with the Z4 at the moment. I’m tempted to buy a new MAF and see what happens. I can’t see any leaks anywhere and all the connectors look good.
The one in the 330i is really thin and only has two pins whereas the Z4 one is much fatter with five pins.
I’m still no further forward with the Z4 at the moment. I’m tempted to buy a new MAF and see what happens. I can’t see any leaks anywhere and all the connectors look good.
InitialDave said:
With no signal it'll probably default to a safe baseline, then when you plug jn the MAF and it gets a bad signal it thinks is good, it all goes to s
t?
Is there any information available for bench testing the MAF, resistances or voltage across certain pins, anything like that?
Basically yeah. t?Is there any information available for bench testing the MAF, resistances or voltage across certain pins, anything like that?
I think the MAF can be tested with INPA or ISTA which I don’t have.
I’m tempted to buy a new own from ECP tomorrow just to see if that works. If that doesn’t work, looks like I’m taking the manifold off again tomorrow night.
Still not really any further forward.
I spent a few hours poking around under the manifold this evening and I noticed that the vacuum line at the front of the manifold from the throttle body was quite easy to pull off whereas the other night it was a total bd to remove.
Off came the manifold (again) and the little vacuum line. Looking at the manifold, it can only clip in one way and with some effort I managed to get it seated fully.
Popped it all back together and it’ll runs, but rough as fk whereas yesterday it would stall almost instantly. I tried a new MAF but to no avail. I still can’t get Carly to finish a code read. I’ve fitted the OE hoses in case the Febi ones are a bit st. I’m tempted to stick the old CCV unit back in tomorrow to see what happens.
Very confused and cheesed off right now.
I spent a few hours poking around under the manifold this evening and I noticed that the vacuum line at the front of the manifold from the throttle body was quite easy to pull off whereas the other night it was a total b
d to remove. Off came the manifold (again) and the little vacuum line. Looking at the manifold, it can only clip in one way and with some effort I managed to get it seated fully.
Popped it all back together and it’ll runs, but rough as f
k whereas yesterday it would stall almost instantly. I tried a new MAF but to no avail. I still can’t get Carly to finish a code read. I’ve fitted the OE hoses in case the Febi ones are a bit st. I’m tempted to stick the old CCV unit back in tomorrow to see what happens.Very confused and cheesed off right now.
What a faff this is turning out to be...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 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.
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