BMW Z4 2.0 E85 2007 Misfire

GuidedFlower

New member
I have read quite a few you guys helpful posts and I'm hoping that someone may be able to help me please?

Ok sorry this may be a long one but I'll try to give you as much information as I can. So my story started like this....

I left home, petrol light was on so I stopped of at the petrol station and half filled the tank (not sure if relevant).
After driving for about 15 minutes I felt the car judder and a few lights flashed up on the dash but went off instantly (too quick to see what they were). This happened again a few minutes down the road.
After another few minutes when pulling off at junctions the car was very juddery but no lights were present.
I continued to drive the car as I had an appointment I needed to attend which was about another 30 minutes away.
During the drive the car continued to feel like it was loosing power when I was trying to gain speed, although seemed to cruise fine at around 60/70MPH.
I then had the lights appear on the dash (ESP, ABS, Tyre pressures + brake light), I pulled over turned the car off and when I turned the car back on the lights were still on.

I parked the car in the car park which is located up a slope, when driving back down later the brake pedal was juddering like crazy when I was braking (which I have been told was the ABS kicking in).
I drove for a short while longer and the speedo pin was all over the place, when it finally settled on a speed it was not accurate to what I was doing.

Concerned I may be doing more damage to the car by driving it I pulled over and called my breakdown company which came on towed the car to a garage.
They plugged the car into the computer and found a code relating to the N/S/R ABS sensor. Upon checking they could see that the ABS ring had rusted and pushed up against the sensor wearing the end of the sensor off.
Luckily they managed to remove the old ABS ring, clean up the shaft and fit a new ring and sensor.
This issue has now been sorted, no lights or codes showing.

However.....

When the mechanic was driving the car to check it was ok to come back to me he noticed a misfire rendering the car pretty much undriveable.
He plugged it back into the computer and no codes or anything are showing up.
He seems to think this is completely unrelated to the ABS issue however I find it very strange how these things seems to happen almost the exact same time.
I'm assuming the loss of power I felt when driving it was the misfire.
The mechanic not wanting me to waste my money on something that may not be the issue has not advised on anything specific at the moment to replace but I have searched everything I can find online to do with Z4 misfires and from the information provided I have requested for the spark plugs, coil packs and vanos solenoids to be replaced but the misfire is still present.
The mechanic has said it does seem slightly better now and instead of the misfire being present all of the time it now only seems to be in low gears and drives with no problems in 5th and 6th gear.

If your still reading this and I haven't bored you long ago then thank you.
Literally any information you can provide would be gratefully received, after owning the car for less than a year and it being over 3 weeks since it went into the garage I'm so desperate to sort it.
All the nice summer weather is coming and I'm missing out on all the joy of owner a convertible.

Thank you,
Amy
 
Where are you? A local member might have INPA which might be better at reading codes - could even be something as simple as an old battery or iffy fuel.

There should be plenty of tips from people on here who have tried something and it worked.
 
Thanks for the reply guys, it has now been noted that there is oil in the coolant header tank (possible cause of engine issue?).
The mechanic has said this could be the head gasket however a compression test has come back fine.
He's stated this could still be a head gasket issue but isn't 100%.
I have no idea what to do next, I'm tempted to take it to the BMW dealer but they want £96 per hour diagnostic, with it being at the current garage for nearly a month I'm worried about how much I'm going to end up paying to BMW just for diagnostic and I can imagine and over the top repair cost too.
 
GuidedFlower said:
Thanks for the reply guys, it has now been noted that there is oil in the coolant header tank (possible cause of engine issue?).
The mechanic has said this could be the head gasket however a compression test has come back fine.
He's stated this could still be a head gasket issue but isn't 100%.
I have no idea what to do next, I'm tempted to take it to the BMW dealer but they want £96 per hour diagnostic, with it being at the current garage for nearly a month I'm worried about how much I'm going to end up paying to BMW just for diagnostic and I can imagine and over the top repair cost too.


If you need any parts let me know, currently breaking a 2.0
 
Oil in the coolant header tank certainly would point to a head gasket issue. It depends where the gasket fails exactly to be able to see it on a compression test (low compression basically means the gasket has failed around the cylinder, and this is the most common, but they can also fail between oil and coolant galleries which means the two mix). I'm not sure if there is an oil / coolant heat exchanger on the front of the engine on the 2.0 which would be well worth eliminating as a problem there could result in oil and coolant mixing.

Whether a head gasket problem would be worth fixing or not would come down to the age / condition / mileage on the car.

oil_water heat exchanger.jpg
 
I have attached a picture of my engine, I think the part I've circled is the same as yours.
Do you know if these can be tested or whether its another thing I'm going to have to replace and hope for the best please?
Thank you

20190424_0828491.jpg
 
Yep, that's the one. Don't think there is a reliable way to test. I would also note that although it may be responsible for the oil and coolant mixing, I've never heard of one failing before and I don't really see how it can be related to your misfire so hope it's not too expensive.
 
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