2.5si N52 - ignition coil & vanos solenoids

[EVM]

Hi all

So this is my first proper post after introducing myself, hope I don’t bore anyone with it

I have recently picked up my first Z4 roadster, it’s a post facelift 2.5si sport, has done around 110k and seems to have a pretty good service history. In the 2 or so months and 3000 miles since I bought it, I’ve had no issues apart from the oil needing topping up (twice!).

Driving home one evening I had some open roads and decided to really let it run, not bouncing off the limiter but getting revs nice and high out of a few roundabouts. On the exit of one roundabout the amber EML light illuminated and it started to misfire quite heavily.
Having previously owned a 325i Touring with the same N52 engine which presented the same issue, I immediately thought it was an ignition coil.
However when I used the OBD reader to confirm which cylinder was the culprit, it showed the two fault codes below.

• 2A98 Crankshaft – inlet camshaft, correlation
• 29CD Combustion misfires, cylinder 1

Z4 OBD reader coil failure.jpg (121.5 KiB) Viewed 1081 times

So I’m looking for help on two topics;
1. Ignition coil specification to be used.
2. Action to be taken for the inlet camshaft correlation issue.

For the coil story I swapped cylinder 1 with 2 and confirmed it was the coil and not the spark plug, but my problem relates to which coil to replace it with.
All of the coils installed are Bosch items with P/N 0 221 504 467, correlating with a BMW OEM P/N 12137551049.
From what I assume to be the date of manufacture (12 August 2006) stamped on the side of the coils, all 6 appear to be original from the cars manufacture (Oct 2006). I know the date seems wrong but I have seen another of these coils with the figure 12-06-23, so assume the dates are reversed.

Z4 failed coil - manuf date.jpg (82.49 KiB) Viewed 1081 times

From my research (on this forum, several other forums, REALOEM and the Bosch website), I’ve established that this coil type is discontinued and has been through development iterations by Bosch and to make things more interesting BMW have superseded the Bosch Items with a Delphi item.

Installed Bosch 0221 504 467 (BMW 12 13 7 551 049)
Revised Bosch 0221 504 470 (BMW 12 13 7 594 937)
Realoem Delphi GN10571-12B1 (BMW 12 12 8 616 153)

So I want to canvas other people’s opinion with regards to coil replacement in the N52, do I replace one Bosch like for (improved) like and then hope that no more fail?
Or as all 6 appear to have been in there for 11 years/110k miles, with the aim of preventative maintenance, replace the whole lot in one go, with either the new Bosch or the new Delphi? Cost difference between the both is just a few euros, Bosch €21,42 & Delphi €24,11.

For the camshaft correlation issue, after clearing the fault code it hasn’t returned whereas the coil fault code returned immediately, but I suspect that it will return after the coil problems are fixed.
So (again) after trawling this forum and others for information I believe that the Vanos solenoids could be a little clogged with dirty old oil
I’m planning on doing a full inspection 1 service soon (in the next few thousand miles), is it worth cleaning out the solenoids before or after?
Or do I go the whole hog and run a bottle of fuel system cleaner through the car, drain the oil, replace the oil filter mounting gasket, clean the solenoids and replace the oil?

Thanks in advance for any help,
Sion

[Chris1981]

Bit of poor luck for both at the same time!

Personally I'd change all 6 coil packs at the same time that way you know all 6 should be working equally! I have no opinion on whether Bosch or Delphi would be best, you'd like to think they are almost identical... However I stand to be corrected on this in case anyone here has horror stories from using either of them!?

I'd clean out the solenoid now if i were you as it's a pretty quick and easy job, I'd probably swap them around too! If it errors again you can verify it is in fact the solenoid to blame as the code would then reference exhaust camshaft?

[Magicarcher]

I'd clean out the solenoid now if I were you as it's a pretty quick and easy job, I'd probably swap them around too! If it errors again you can verify it is in fact the solenoid to blame as the code would then reference exhaust camshaft?

Fully agree with this, I did exactly this on my mini with dual vanos, was getting misfiring and stalling intermittently at 80k, the ISTA-D code was suggesting inlet camshaft alignment errors at, so took both solenoids out (at same time as changing the oil), cleaned them up and swapped them over (on mini they are same part number). A couple of weeks later it started misfiring again, so I connected up ISTA and the error code had changed to exhaust camshaft alignment errors. Replaced the faulty solenoid and all was fine.

Simple check to make which is easy to do and fairly conclusively establishes if it is the solenoid.

[Lance]

I have a 2003 2.5 and had a coil failure recently, I got a replacement from ECP for £17, which has been in there for a few months without issue. Now carry a spare coil in the boot just in case another fails.

I personally wouldn't change them all just because of one failure.

Cheers

[ph001]

I'd be changing all 6 coils out for the revised Bosch items and cleaning those solenoids out as a first port of call.