Low revs when stopped and occasionally cuts out out

Shaun T

Member
Hi all. I have recently brought a lovely 2011 Z4 s drive, 23i which has been great till yesterday. I stopped at a junction and the car shuddered and cut out, I started it back up and drove home with no issues but the revs are low when stationary at around 500 to 600 rpm. On the way to work this morning exactly the same thing, the engine warning lights is on and still low revs....any ideas?
 
Really need a fault code reader to determine what may be happening..
 
I'm trying to get it booked in...looks like a slow drive home from work today. I have a cheap reader that I tried last night and it came up with p22aa which just belive is the nox sensor, p0000 ECU? And b2a00 ECM?
But there were no engine management light on last night, this came on at lunch time today after I drove 21 miles to work.
 
Shaun T said:
I'm trying to get it booked in...looks like a slow drive home from work today. I have a cheap reader that I tried last night and it came up with p22aa which just belive is the nox sensor, p0000 ECU? And b2a00 ECM?
But there were no engine management light on last night, this came on at lunch time today after I drove 21 miles to work.

There is no nox sensor on the N52 in the UK..

Those fault codes could point to many issues including bus communication failure and other ECU and sensor issues ….you’re probably going to need a full bmw diagnostics system to bottom that out..
 
Thanks for the update, I know very little about these things so just waiting to see when I can get it booked in
 
Had the car checked and had this report sent to me, been quoted £3500 to change the timing belt etc....I am not sure which way to go with it
 

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Shaun T said:
Had the car checked and had this report sent to me, been quoted £3500 to change the timing belt etc....I am not sure which way to go with it

Strange suggesting the timing belt as there is no timing belt..however it does have a cam chain ..I’d suggest you take it somewhere else for a second opinion…just doesn’t sound like a together plan..
 
When I drove it there last night it was really smooth, the engine management light was on and the oil light came on 2 minutes from the garage. The revs were still low but that was it
 
Shaun T said:
When I drove it there last night it was really smooth, the engine management light was on and the oil light came on 2 minutes from the garage. The revs were still low but that was it

I’d certainly not be driving any more than you can ..but I’d want a second opinion…oil pump failure on N52 is very very rare…clogged / collapsed oil filter more probable..
 
I only live 3 miles from the garage and then it will be left alone, it's a beautiful car so I'm very upset and don't know which way to go. I said to the garage if it was the timing chain then surely the engine wouldn't be so smooth when running..
 
Well drove it home and engine light was on, no oil warning light but car did cut out when I stopped as it warmed up. I asked the guy at the garage if it was a timing chain issue would it run smoothly and only change when the engine starts getting warm. He said he was surprised how smooth it sounds when ticking over but did say there was a small rattle when he started it . Told me again £3500 to change the chain then investigate the faults more when it's replaced
 
When my car had problem low revs it was the cam cover was bowed, oil in no. 4 spark plug hole.
Fitted new cam cover all sorted.
That was about 92 k miles.
 
Hiya, i am at a loss with it. It is such a beautiful car in fantastic condition and to good to scrap but I don't know which garage can be trusted to sort it out and get rid of the faults. It's done 95k miles and runs perfect when started from cold, all the roof mechanism has been serviced, alloys all done and is a head turner. To be quoted £3500 to replace the chain etc as a min to me seems a rip off. Then they saidnthey would look at the codes and what ever else needs replacing
 
Shaun T said:
runs perfect when started from cold

Firstly, this 'garage' sound shite. Stop going there. If you don't have your own code reader yet, get one; I use an Autophix 7910, it does most of the things you could need it to and can just sit in the glovebox.

If the chain was that bad it needed replacement the car would be a bag of nails all the time, if it started at all.

My thoughts are this points to the VANOS solenoid, so a free test would be to swap intake and exhaust over then clear the codes and see if the fault moves.

The oil pressure is a concern but wouldn't cause it to cut out. Easy to take the filter off and check it.
 
Thank you so much for your help on this it has really stressed us out. If I replace the Vanos unit then hopefully it will sort it out. The previous owner hardly used the car so sat for quite a while with occasional drive around the block.
Not sure what the codes meant from the garage tbh..
 
When was the last time you checked the oil level and when was it last changed, the codes do seem to indicate a problem with the timing solenoid valves.
 
Hi, i will have to check when I get home. I only brought the car last week, the oil.level is smack in the middle but I will have a look when it was last changed.
 
Shaun T said:
Thank you so much for your help on this it has really stressed us out. If I replace the Vanos unit then hopefully it will sort it out. The previous owner hardly used the car so sat for quite a while with occasional drive around the block.
Not sure what the codes meant from the garage tbh..
You're welcome.

For the VANOS solenoids it is possible to clean them but faults usually come back, so replacement is the best course. Buy OE from BMW though, the knock offs don't last.

But I would suggest just swapping them over for now (easy DIY though access might be a little tight) just to see if the fault moves. Though you'll need a code reader. Getting one is a good investment rather than keep paying garages when you change battery etc.

If the oil has sat for a while it could be sludgy. Where are you located, maybe a friendly member could help you do a DIY oil change for some beer tokens?
 
Thanks again for all your help, I'm located in Birmingham, just.off junction 2 of the M5.
So desperate to get it running right again but cannot find a trustworthy garage near me..
 
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