Close call MoT Solved!

[Roberltd2]

Hi everyone,
The Zed scraped through it’s MoT today.
Usually it flies through on the emmisions but the boys really had to fight to get the figures low enough to pass this time round.
I’d noticed a couple of weeks ago when leaving work on a particularly damp and drizzly day that the idling was eratic, the engine was revving on the over run as well as making a screeching noise (a bit like when a fanbelt needs tightening) also on the over run.
The Creator 110 gave me 2A2E / 2A2F DME Mixture control codes as well as a 2A38 DME Valvetronic, sluggish movement code.
After Googling the 2A2E code I followed up a suggestion by one chap on another BM forum by cleaning up the contacts on the MAF sensor, and lo & behold that seemed to do the trick…..
…..Until last Saturday when I thought I would put in a new set of plugs ahead of the MoT test today. I noticed that all six of the old plugs had a healthy looking light brown tan colour on them.
Anyway, as soon as I started the car up again, the rough idle returned although it did seem to have cleared itself after a round trip of about 25 miles to Morrisons Saturday evening.
It was fine yesterday but as I pulled into the drive tonight the EM light came on and the engine cut out, so clearly things are not getting better.
I noticed when changing the plugs that there was a bit of oil pooling at the bases of tubes 2,3 & 4 (mostly) and the exhaust side of the block looked quite oily which I’d not noticed before.
So having done a bit of research online, tomorrow I’ll check to see the state of the connection to the eccentric shaft sensor as I’m led to believe that if that fills up with oil it will eventually seep into the sensor itself and destroy it.

I’m also wondering if the Valvetronic fault codes and the mixture codes are somehow interrelated or just coincidental.
My mechanic is not a BMW specialist but he ran a diagnostic which also came up with 2A2E/F, 2A38 as well as 2A32, 2A47 and 2A37, the last four all being Valvetronic related.
His advice was that I should do a bit of research and consult the experts. So this is where I'm at!
Thanks in advance for any advice as to what should be my best course of action.
Cheers,
Robert.

Just had the car back today from the indy.
Turns out the diagnosis of a perished rocker cover gasket was correct – thanks ColB – although it also transpired that the diaphragm / membrane in the PCV (crankcase ventilation) had also split resulting in oil ingress into the cylinders & black smoke on starting up etc.
Although replacement diaphragms are available, my mechanic was advised by a BM specialist that it would be more advisable to buy a complete new rocker cover with the PCV membrane already fitted as this would have a lesser probability of causing further problems in the future. Not cheap but this is the option I went for. Febi / Bilstein.
I also bought a new eccentric shaft sensor (£145.52 ex VAT I think) & seal from Autodoc because of the fault codes thrown up, VDO make, OEM quality so hopefully that will work for a few years to come.
My mechanic tested the car for emissions & said that they are “spot on” again now.
He does think though that the actuator / stator on the eccentric shaft is a bit lazy and I’m also thinking that the throttle response seems a bit “delayed” on application and on the over run. Any comments about that would be welcome.
Really, I’m just glad to get the Zed back again after having to use a Toyota Aygo to get to work for the last couple of weeks (thank you Border Garage, Welshpool). I wish I could get the same fuel economy out of the Zed!

 

[colb]

Sounds like you have a classic case of the cam cover gasket failing if you have oil in the spark plug wells and on the exhaust side of the cover. Failed gasket will also be letting air into the vaccum system as well as leaking oil. This will mess your fuel trims up as the exhaust sensors will be pivcking up more air that has been measured by the Maf. Seeing this makes the car think its running lean and commands more fuel at the injectors to richen the mixture up. It will add up o 20% more fuel as it tries to rectyfy the supposed lean condition. It eventually gives up and sets the EML to draw attention to the fault.
You need a full cam, cover gasket set which includes the main cover gasket and the two centre plug well gaskets, always advisable to put new round rubber seals that sit under the cover bolts, these like the main gaskets go hard and brittle with age and repeated heat cycles, these also need to be compressable to ensure a good seal when the bolts are done up.
I use Elring brand gaskets but got the 15 round seals for the bolts from BMW.
Use some Hylomar gasket sealant only around the half moon shapes at the front and back of the cover where the gasket changes direction, no need for sealant on the rest of the gasket, its a ribbed gasket and compresses on the long side runs well enough to provide an oil and airtight seal.
Fix the gaskets before throwing money at other parts, once buttoned up scan and clear codes then rescan to see if anything else comes back or returns. A smoke test will find any other air leaks you may have.

 

[Roberltd2]

Thank you Colb. It's the kind of explanation I was hoping for to make sense of what's going on here. Thanks for the specific advice on things needed as well.
Assuming I do find that the Eccentric Valvetronic sensor is filled up with oil on the connector side, would you advise fitting a new one anyway when I'll be replacing the valve cover gaskets. They're expensive I know but.... And then of course replacing the EV sensor seal as well.
The other long overdue replacement is the water pump. The car's over a 100K miles still on the original so would putting a new one in now mean not having to go through all the same dismantling / reassembly procedure again maybe?
Robert.

 

[colb]

If it is filled up with oil pobably best to replace, it will never clean up once contaminated.
Probably best to do it to avoid having to dismantle it all again and ruin the cam cover gaskets if a second strip down needs to happen.
As to water pump at your milage it would certainly be prudent to put a new one in, also check all the hoses and filler tank as the tanks are known to split with age. Also check out the drive belt tensioner and idlers replace any that run rough when spun. New Belt would complete the job. Whilst your in there a new thermostat would be a good idea then you know what you have in there. Got to be worth doing these jobs if your going to keep the car, gives some peace of mind knowing there are new parts in there.

 

[Roberltd2]

Hi Colb, would you happen to remember what the product number is for the round rubber seals for the bolts?
I've gone ahead and ordered new gaskets, seals and screws and also an OEM eccentric shaft sensor for good measure. At first the connector looked OK but on closer inspection I could see there was oil in there and it took a few cotton buds to wipe it up.
There was also a lot of oil around the Valvetronic gasket, especially around the RHS.
Engine still runs erratically though.
Read somewhere that the MAF sensor can be disconnected and the engine will then run with reference to static codes and use the throttle body rather than the Valvetronic system. Would this be a workable temporary fix?

 

[Roberltd2]

Just had the car back today from the indy.
Turns out the diagnosis of a perished rocker cover gasket was correct – thanks ColB – although it also transpired that the diaphragm / membrane in the PCV (crankcase ventilation) had also split resulting in oil ingress into the cylinders & black smoke on starting up etc.
Although replacement diaphragms are available, my mechanic was advised by a BM specialist that it would be more advisable to buy a complete new rocker cover with the PCV membrane already fitted as this would have a lesser probability of causing further problems in the future. Not cheap but this is the option I went for. Febi / Bilstein.
I also bought a new eccentric shaft sensor (£145.52 ex VAT I think) & seal from Autodoc because of the fault codes thrown up, VDO make, OEM quality so hopefully that will work for a few years to come.
My mechanic tested the car for emissions & said that they are “spot on” again now.
He does think though that the actuator / stator on the eccentric shaft is a bit lazy and I’m also thinking that the throttle response seems a bit “delayed” on application and on the over run. Any comments about that would be welcome.
Really, I’m just glad to get the Zed back again after having to use a Toyota Aygo to get to work for the last couple of weeks (thank you Border Garage, Welshpool). I wish I could get the same fuel economy out of the Zed!
One final note:
I did a search for sluggish throttle response and dropped lucky with a post on this Forum by Argenta (thank you) who advised trying a throttle re-set.
I thought what the H., gave it a go and lo & behold it worked!
The Zed is now back to its old self at last.
Cheers,
Robert.

 

[dgmx5]

Sounds like you have a classic case of the cam cover gasket failing if you have oil in the spark plug wells and on the exhaust side of the cover. Failed gasket will also be letting air into the vaccum system as well as leaking oil. This will mess your fuel trims up as the exhaust sensors will be pivcking up more air that has been measured by the Maf. Seeing this makes the car think its running lean and commands more fuel at the injectors to richen the mixture up. It will add up o 20% more fuel as it tries to rectyfy the supposed lean condition. It eventually gives up and sets the EML to draw attention to the fault.
You need a full cam, cover gasket set which includes the main cover gasket and the two centre plug well gaskets, always advisable to put new round rubber seals that sit under the cover bolts, these like the main gaskets go hard and brittle with age and repeated heat cycles, these also need to be compressable to ensure a good seal when the bolts are done up.
I use Elring brand gaskets but got the 15 round seals for the bolts from BMW.
Use some Hylomar gasket sealant only around the half moon shapes at the front and back of the cover where the gasket changes direction, no need for sealant on the rest of the gasket, its a ribbed gasket and compresses on the long side runs well enough to provide an oil and airtight seal.
Fix the gaskets before throwing money at other parts, once buttoned up scan and clear codes then rescan to see if anything else comes back or returns. A smoke test will find any other air leaks you may have.

Hi colb, I am looking at these Victor Reinz bolts on onlinecarparts.co.uk (https://www.onlinecarparts.co.uk/reinz-7440478.html)

Do you know what the part number is for the circular rubber seals? Thanks

 

[colb]

Real oem parts site for your 2.5si 2007 here
https://www.realoem.com/bmw/enUS/showparts?id=BU32-EUR-06-2007-E85-BMW-Z4_25si&diagId=11_3737
Its fitted with an assortment of bolt sizes and threads, all alloy so ythey should be replaced when the cover is replaced.
Worth checking BMW for prices and compare with that Victor Reinz kit.
Can't see any round rubber sealing washers for those bolts, check if indeed you have these on yours. They may have only been used on the 2.5i E85 earlier cars. Looks like the bolt kits come with the seals on them.