Z4 stalling/timing chain/unknown issue

Hi

My son impulse bought a 2006 Z4 2.5L automatic. Trying to help him out figuring what's wrong.

It started having intermittent power loss, stalling at low speed and engine light coming on. He went to a small local garage who hooked up and produced codes. This was some months ago and he’s now lost the code printout! From memory, it referred to the following:

P0171 – this one we remember
Oil leak – sounded minor
Something to do with banks
Vanos issue

The garage said they weren’t knowledgeable enough on this car but replaced spark plugs and ignition coil. Then they sent him to a BMW specialist.

BMW specialist thought it might be camshaft positioning sensors or the timing chain but dismissed Vanos. They replaced the sensors and said if that didn’t fix it then it must be the timing chain and that would cost £3500 to replace which sounds way off the going rate. And “thinking” it might be timing chain doesn’t reassure me, especially charging that amount.

The engine light comes on intermittently and It has occasionally stalled at crawling speed. He says there’s a ticking sound but not rattling.

I’ve been reading about how unlikely it is to be timing chain but other possibilities - timing chain tensioners being a known fault and wonder if it could be that. Also read about timing chain guides potentially being problematic. Don’t know how easy to fix though.

I know lack of codes isn’t helpful for figuring this out but to my mind he needs to take this to a Z4 specialist who doesn’t “think” the problem can be solved with a fix that costs as much as the car. Any input would be really appreciated, including any great garages that really know their stuff on the Z4s - somewhere around London or over to Bristol.

Thanks

You really need to code read it again or find a member on here who can code read it. Camshaft and Crank sensors can be a cause of stalling and long crank is a symptom if they are bad. Bank refers to the sets of cylinders and usually come up as codes referring to fuel trim issues either running rich or lean and these are usually caused by air leaks in the cars intake and vacuum system that develop splits and holes. Other causes can be a bad Maf sensor or bad exhaust lambda sensors. You need the codes to point you in the right direction for a fix.
I am down in Newport South Wales and run our Zedshed Whats App Group with members across South Wales and Bristol and beyond. We help each other out with jobs on our Z3 and Z4's owners supply parts oil filters etc and job gets done at my home garage known as the Shed. Donation to the Shed is usually made by owners that goes towards running costs and consumables, don't charge for my time.
If your down Bristol way your welcome to cross the Bridge and pay a visit for a scan.

As to the code you remember a quick Google shows this
BMW code P0171, also known as "System Too Lean Bank 1," indicates that the engine's air-fuel mixture is too lean, meaning there's not enough fuel relative to the amount of air being drawn into the cylinders. This code is triggered when the oxygen sensor detects excess oxygen in the exhaust, signalling that the engine is running lean.
Possible Causes:
Vacuum Leaks:
A vacuum leak can introduce unmetered air into the intake, causing the engine to run lean.
Mass Airflow (MAF) Sensor Issues:
A faulty or dirty MAF sensor can misread the amount of air entering the engine, leading to an incorrect fuel mixture.
Fuel System Issues:
A plugged fuel filter, a weak fuel pump, or faulty fuel injectors can restrict fuel delivery, resulting in a lean condition.
Oxygen Sensor Problems:
A malfunctioning upstream oxygen sensor can send incorrect readings to the ECU, causing it to adjust the fuel mixture incorrectly.
Dirty Throttle Body:
A dirty throttle body can affect airflow and contribute to a lean condition.
Crankcase Ventilation Valve:
A faulty crankcase ventilation valve can also introduce unmetered air.
Symptoms:
Check Engine Light: The P0171 code will trigger the check engine light.
Reduced Engine Performance: The car may have trouble accelerating or reaching its peak horsepower.
Rough Idling or Engine Stalling: The engine may idle erratically or stall at times.
Poor Fuel Economy: The engine's efficiency may be affected, leading to lower fuel economy.
Whistling or Clicking Sounds: In some cases, a vacuum leak can cause a whistling or clicking sound.
Troubleshooting and Repair:
Check for Vacuum Leaks: Inspect all intake hoses, vacuum lines, and seals for cracks or leaks.
Clean or Replace the MAF Sensor: A dirty MAF sensor can be cleaned, while a faulty one may need replacement.
Check the Fuel System: Inspect the fuel filter, fuel pump, and fuel injectors for any issues.
Test the Oxygen Sensor: Ensure the upstream oxygen sensor is functioning correctly.
Clean or Replace the Throttle Body: A dirty throttle body can be cleaned or replaced as needed.
Inspect the Crankcase Ventilation Valve: Check for any damage or issues with the crankcase ventilation valve.

[ref]ash1212[/ref], you need to get the codes read properly. Any of the members on this list can help you, although it would have been helpful if your “bmw specialist” had told you.

Alternatively, purchase a Creator 310+ on line (not expensive) and do it yourself. You will receive much more targeted help and advice on this forum if you know the codes.

colb said:

You really need to code read it again or find a member on here who can code read it

Click to expand...

Hi Colb

Thanks for your detailed reply. I'm trying to help my son as he's quite green around cars. That said, i bought my share of rust heaps at his age. Neither of us know much about cars and he doesn't seem to be getting good advice and the 3k quote sounds way too much?

I remember some of the codes indicated potential problems with perished pipes. Sounds like we need a scanner though to check again.

He is in Bristol and actually going to the Gower - i think this weekend. The thing is though, it sounds like you are a community of people helping each other and my son has zero car skills so couldn't contribute in the spirit of that community. He's a junior doctor so he could tell you what's wrong with you but that's about it!

Thanks

ash1212 said:

colb said:

You really need to code read it again or find a member on here who can code read it

Click to expand...

Hi Colb

Thanks for your detailed reply. I'm trying to help my son as he's quite green around cars. That said, i bought my share of rust heaps at his age. Neither of us know much about cars and he doesn't seem to be getting good advice and the 3k quote sounds way too much?

I remember some of the codes indicated potential problems with perished pipes. Sounds like we need a scanner though to check again.

He is in Bristol and actually going to the Gower - i think this weekend. The thing is though, it sounds like you are a community of people helping each other and my son has zero car skills so couldn't contribute in the spirit of that community. He's a junior doctor so he could tell you what's wrong with you but that's about it!

Thanks

Click to expand...

Get him to buy his own code reader, it will pay for itself in one go. Creator 310+ or Autophix 7910.

I am away Saturday at a car show in Evesham but home Sunday if he is passing Newport, he could pop in and I can scan the car for codes and give it the once over. He doesn't need to be mechanically minded quite a few of our members know nothing about deeper maintaining their cars, hence the Zedshed Cymru.

That's a nice offer

Hi

Thanks for your help and kind offer Colb

He went and got a code check and its 2A87 which Google says is VANOS exhaust – stiff; jammed mechanically. I've watched youtube vids and i reckon this is within my capabilities to fix. I see some vids saying you can try cleaning the solenoid first but if that doesn't work then i need to source a new solenoid. I'm finding it quite hard to figure our what part number and where to buy it from without going to BMW (£££!)- if you have any suggestions that would be appreciated.

Thanks

ash1212 said:

I'm finding it quite hard to figure our what part number

Click to expand...

Use realoem. Put in the last 7 of your VIN and have a rummage, it will start to make more sense as you use it more. You can also search on the site.
Another option is to call or visit a dealer and ask the parts department.

ash1212 said:

where to buy it from without going to BMW (£££!)

Click to expand...

Once you have the part number you can google it. If you've asked the dealer then get a price while you're there as that sets the ceiling.

For me (double check on your car) the VANOS solenoid part number is 11367585425. Both are identical.

OE RRP is now about £ 150! But they will last.

ML performance are £ 132.98 delivered.

I would avoid generic copies but might consider decent OEMs though I don't know who makes the originals.

If you want to try and confirm it is the solenoid before stumping up the cash then swap over the inlet and exhaust and see if the fault follows.

Hi

So things have moved on slowly with this. He got a code read out at local garage that suggested exhaust vanos solenoid was the problem. Even though teh code said exhaust, the garage guy said it could be either so my son came to see me and we were going to swap that for a new Febi one. We did a test of both existing ones and could see both moved when hooked up to battery so with that and garage telling him the code meant it could be either solenoid be decided to do the inlet one.

He drove about 600 miles but then it nearly stalled again. So he bought another Febi solenoid and installed on exhaust position. Since we had seen oil pooling on engine casing he also bought a Febi oil cap. Worth mentioning it does seem quite oil thirsty.

Then almost immediately it's worse with lots of near stalling. I asked if he's sure he got the exhaust vanos solenoid installed correctly, remembered to get the old O ring out, securely tightened etc. He's sure he did. My logic is that if it was kind of ok before those two changes then one of them was responsible for making it worse.

Meanwhile I borrowed a cheap code reader and sent it to him. After installing new solenoid and oil cap he gets the following two codes:

P1553
P0015 B Camshaft Position Timing Over-Retarded Bank 1

So the first is pointing at exhaust vanos solenoid which was the original issue (2A87). This kind of indicates either the new Febi solenoid is dead or installer error since there was a big change after installing that (multiple near stalling).

Second issue looks like a £40 fix and as easy to do as the solenoid.

I said he should swap original BMW inlet solenoid back to where it was and put first new Febi solenoid in exhaust position. We know original BMW ok and we know first new Febi ok or would get an inlet vanos solenoid code. I think this logic is sound?

Both these issues though also point at a possible timing chain issue so he's wondering if anything will ever be fixed and if he just needs to cut his losses and get rid before MOT runs out to WBAC who are offering peanuts. His GF is also not impressed and wants it gone.

Thanks