Lumpy Idle - Starting Problems ....

[teamemmenracing]

Been reading a few threads recently about lumpy idle, starting problems and iffy low throttle response ......

Been having the same, and rather than dive in at the deep end and get all complicated, first job I did was replace the
front 2 Lambda sensors with new items ( choked on the price ) .....

Engine now runs like a sewing machine at idle, low throttle response is crisp and sharp, exhaust note funnily enough at
low throttle sounds sharper too ....... starts on the button.

Just for info ......... seen a few suggestions about MAF sensors and crank position sensors and re mapping ........ sometimes
the simple fix works best

 

[AndyBeech]

Good info How much did the lambda's set you back out of interest (plus fitting)?

 

[mr wilks]

Nice gamble , what info made you take the lamda route ?

 

[teamemmenracing]

440 quid for the pair from BMW ........ looked online at various suppliers ( 200 quid the pair ) who all without exception told me that the Z4M is fitted with 5 pin plugs ...... they are not, they have 6 pins. Stealer seemed like the safe option.

Fitted them myself, easy enough if you are a bit spanner savvy ........

Bitter experience in the past with a multitude of old motors ....... have spent many hours trying to fix problems only to find out that the O2 sensors were on their way out.
Now I do the simple things first lololol ........

 

[mr wilks]

Fair do's for grabbing the bull's horn's , what year/miles is your car on ? Also interested in what kind of miles you do ? Decent daily commute or odd weekend run out ?

 

[pvr]

Expensive gamble but at least it paid off.

 

[TomK]

440 quid for the pair from BMW ........ looked online at various suppliers ( 200 quid the pair ) who all without exception told me that the Z4M is fitted with 5 pin plugs ...... they are not, they have 6 pins.

Yep correct, they're not like the e46m3 ones sadly, they have an additional sensor reading if i understand it correctly. I want to get mine changed too, I pretty sure it's only one of them that 'may' be not be heating up correctly (though i have no fault codes), ergo giving me a lumpy cold start, however once you've got to the buggers it makes sense to do both even at that price. £440

 

[Beedub]

440 quid is painful but needed!! Well done OP for doing this yourself, you have probably another 300 quid by doing so. The front ones don't look to bad, the rear ones are a PITA as the hole exhaust needs to come down. Im guessing the front ones have sufficient access from the underside??

 

[teamemmenracing]

Fair do's for grabbing the bull's horn's , what year/miles is your car on ? Also interested in what kind of miles you do ? Decent daily commute or odd weekend run out ?

66K on a 2006 plate ...... used to be my daily drive, now its just for fun.
Fun being trips like Edinburgh to Trondheim via Holland / Germany / Denmark / Sweden lololol

 

[AndyBeech]

Just to confirm this was the pre-cat sensors right? The post cat ones rarely seem to have issues......

 

[mr wilks]

Fair do's for grabbing the bull's horn's , what year/miles is your car on ? Also interested in what kind of miles you do ? Decent daily commute or odd weekend run out ?

66K on a 2006 plate ...... used to be my daily drive, now its just for fun.
Fun being trips like Edinburgh to Trondheim via Holland / Germany / Denmark / Sweden lololol

Im sure its treated right & warmed thoroughly but it helps as a reference for others

 

[teamemmenracing]

Just to confirm this was the pre-cat sensors right? The post cat ones rarely seem to have issues......

yup, the front ones mounted in the exhaust manifold ...........
quite a few threads on here about them needing replacing regularly

 

[AndyBeech]

Just to confirm this was the pre-cat sensors right? The post cat ones rarely seem to have issues......

yup, the front ones mounted in the exhaust manifold ...........
quite a few threads on here about them needing replacing regularly

Thanks for that, from what I've seen around 60k seems to be a pretty good mileage to consider a change if your having issues especially, as you've said though it's an expensive change, almost a whole Inspection 1! Depends on the petrol you use as well so told, regular unleaded can foul them up quicker than Super/V-Power does, maybe that's just an urban myth though.
It's a difficult one though as they don't seem to throw fault codes until completely fubar, INPA reading's don't really give much of a clue either unless you know what normal readings should look like.

 

[teamemmenracing]

Lambda sensors are probably the most stressed item on the car constantly going through a cold to extreme heat cycle, its not surprising that they fail.

When they fail you will get an engine management warning light, when they are starting to fail ........ probably not.

One thing I forgot to mention, I just did a return trip Edinburgh / Aberdeen ..... and I noticed it cost me about 10 pounds more in fuel than usual ........ and indication that the fuel mix has changed.

 

[teamemmenracing]

Just a latest update ........
several hundred miles completed since the job .......
Car has never been so smooth ...... I mean really, got a smile on my face a mile wide

 

[pvr]

How is the fuel consumption now?

 

[AndyBeech]

Bugger, just checked my service history paperwork, BMW changed one of the sensors at 37000 miles due to EML.
So that means I've got one sensor that's done around 33000 miles and one that's done 70000 miles, that can't be ideal!
I think a change for both is on the way, open wallet

 

[teamemmenracing]

How is the fuel consumption now?

if I knew how to reset the gauge I would tell you lolol ..........
The Aberdeen trip was easy, used to cost around 42 quid return, the last trip was 49 quid and petrol is cheaper.

 

[Scooba_Steve]

Are the lambdas the same on M's as others? Check the part numbers with the Bosch catalogue I'm sure the equivalent part minus the BMW stamp can be found cheaper somewhere

 

[teamemmenracing]

I'm convinced they could be bought cheaper elsewhere ......
I just got conflicting information from various suppliers about how many pins in the connector ........ and I believe the length of the wire is specific for the Z4 .....
I used the stealers because the had them in stock and ...... if they didn't fit I could drive back there in 10 mins and get them changed.

I reckon I could have got then for about half the price ...... if I had had the time and patience ....