2003 2.2 Z4 hunting/missfire issues (video)

D

Dalmahoy

Member
Hoping to get the Z4 back on the road this week but this hunting/missfire issue is giving me grief.
No fault codes, replaced all plugs and coils this week which has made an improvement but its still not 100%.
Here's footage of it starting from cold:-

https://youtu.be/uudQZL7wFOc
 
Probably a daft question, but are you absolutely sure there are no codes? What code reader are you using?
It could be a number of different things but that is exactly what mine did after I overhauled the vanos. It was the inlet solenoid valve sticking slightly in its bore as it had been sat without oil for a while. You seem to suggest your car has been laid up for a while, so that's why I wondered about it. However, my Autophix 5900 showed exactly where the problem was.
Check the inlet pipe for splits.
Make sure the filler cap is on tight and sealed.
Dipstick fully in and sealed.
Check all the ccv pipes for splits or leaks.
Filled up with fresh fuel?
MAF properly connected and clean?
 
My experience of hunting like that is

1) MAF
2) vacuum leak on the brake servo side

Just my 4 penneth and I’ve had 3 cars do that
 
Thanks for the replies.
100% sure there are no fault codes - it was scanned using the latest snap on code reader.
I ordered a new MAF sensor last night, it's wasn't too pricey at all.
Admit I have looked all over the inlet manifold side but no once at the brake vacuum side so I'll try the propane test on that tonight.
Then move onto the Vanos side of things.
And feedback my findings.
Cheers
 
Dalmahoy said:
Thanks for the replies.
100% sure there are no fault codes - it was scanned using the latest snap on code reader.
I ordered a new MAF sensor last night, it's wasn't too pricey at all.
Admit I have looked all over the inlet manifold side but no once at the brake vacuum side so I'll try the propane test on that tonight.
Then move onto the Vanos side of things.
And feedback my findings.
Cheers
Click to expand...

Watching with interest as mine started doing this today and I suspect the MAF has gone, tried cleaning and no better.
 
I have had similar problem. Eventually traced it to a vacuum leak on the brake servo.
I have replaced servo and problem is resolved.
 
New MAF fitted and it's no better.
Below 2k rpm it's running pretty bad with the car lurching.
Above 2k it's running as sweet as
It's booked in for it's MOT today so will see how that goes.
I am planning to pressurise the inlet manifold system this weekend and listen for leaks.
 
Managed to get a couple fault codes to pop up on the way back from the MOT.
PO151 and PO154 which very much is pointing to a vacuum leak.
Hope to try a smoke test on it this weekend.
 
Smoke test is the way to go, should reveal leaks that can't be traced visually, all BMW engines require a completly sealed vaccum system to run correctly, air leaks will play havoc with fuel trims and cause running problems.
 
Just carried out a compression test.
All 6 cylinders reading 210psi.
Appreciate its an old tester but the cylinders reading exactly the same rules out a cylinder down.
 
Smoke test complete and nothing!
Motor is so well sealed I was surprised how much pressure it could take.
Hand pump almost became solid and the first thing to show an issue was oil leaking out the crankcase/dipstick tube seal but it took quite an effort.
 
You must log in or register to reply here.
Back
Top Bottom