Faulty 02 Sensors - TECHNICAL UPDATE!! (pg.5)

[StevenH72]

Mine was doing exactly as you describe Steven and then the exhaust emission light came on. I thought coil pack, idle-control valve or TPS but they diagnosed the wiring for the O2 sensor had rubbed through against the engine block on bank 2 (pre-cat I think?) and the sensor had failed. They replaced under warranty and the car is now faultless since. Aren't there two pre-cat and post-cat sensors? Could it be your other pre-cat one has failed too?

Quite possibly, it was bank 2 showing the fault. It's going back in again today so hopefully it can get sorted.

The below is a quote from Sniffer on page 10 of the hesitation thread. Almost exactly the same symptoms as mine, so maybe if the O2 sensors don't sort it, a DME update will?

If you did not clean anything else up and only worked on the idle control valve, that must be the actual root cause of this issue.

I was unsure because I cleaned up everything including the ends of the fuel injectors so although I thought it could have been the idle control valve I could not be 100 percent sure this was the ultimate cause.

What is this rough running issue? Mine had a cold running issue which made the car behave nastily until the coolant temperature was up above 50 degrees c. (I can see this through my Intravee). Coolant gets to 50 degrees c within two or three minutes, so quite quick and then the issue would go away.

Mine was like a jerkiness misfire kangaroo type feeling when being in gear and on the throttle accelerating. This was resolved for me by the DME update I did.

I subsequently stumbled upon a BMW PUMA case for the S54 Z4M which was about poor cold running and the fix was DME software update.

 

[StevenH72]

Here's another post looking at the issue from a thread entitled "Engine Light on - Z4M". So perhaps it could still be a coil pack? Either way hopefully it gets resolved quickly.

Morning.
My engine light has been on for about a week, orange colour. Symptons when stationary are a rough idle.
When driving at low speed and a light throttle, there is sometimes a hestitatation on throttle pick up and some engine surging, car seems to miss a beat then picks up.

Less noticeable at cruising speed. Earlier the orange light came on about a month ago, I hoped it was just bad fuel. Symptons the same as now but the light went out by itself a few days later and driveability improved.

Will be heading to the dealers next week, just wondered is there anything I can check out myself or fix,such as cleaning sensors?

Problem turned out to be both a coil & an O2 sensor, pre CAT. Car was in for nearly a week as they wired the sensor up incorrectly which started throwing out more error codes. Yikes! I had visions that everything electronic on the car would be changed and charged, before final identification of the problem.

Got a few other minor things sorted such as brake fluid changed, wipers, bill was £740. (discounted by £100 due to hassle). Think I might start going to a non BMW dealership for servicing work in future, the amount they charged for diagnosis, recoding etc just feels as though they are in right up to the elbow.

 

[jimmybell]

What garage did you take it to??

I'd be pretty pissy if i'd driven off and had the problem within 2 miles again - they clearly didn't test it very thoroughly.

If they're just guessing at the problem - consider taking it to ML or CPCPE for a better troubleshooting skillset.

Hope it all works out for the best.

 

[StevenH72]

Yeh, I've already decided that I won't allow BMW to perform an "investigative diagnostic" works.

They did say yesterday, that they'll replace one, if it works great, but the post-cat sensor did also show a fault code. Will phone them shortly to see what they say.

Interestingly the car drove perfectly again this morning (but light still on). The rough running has only happened twice (once after I'd detailed the car all day and the other time yesterday). On both occassions the car would have experienced numerous cold starts, so I'm wondering that could be the contributing factor?

Will keep everybody updated.

 

[Oakandacorns]

Something breaking or something blocked but not completely? And on an 'investigative diagnostics' what is that compared to when a mechanic says 'xx is giving a fault code'?

 

[StevenH72]

Something breaking or something blocked but not completely? And on an 'investigative diagnostics' what is that compared to when a mechanic says 'xx is giving a fault code'?

Basically, if there are no more fault codes, but the car is still running oddly they'll just start changing things out....could get very costly, so I won't be doing that with BMW. As Jimmy suggested, if I take it to a decent Indy they'll have a better idea of what's causing the issue and can be more precise / cost effective in the repairs.

I wonder if it's the Idle Control Valve or throttle Position Sensor / Throttle Actuators that are causing the lumpy running. It's only happened twice in a year though and only for 3 minutes before the engine warms up. Will monitor it and see what happens.

 

[andysat]

Something breaking or something blocked but not completely? And on an 'investigative diagnostics' what is that compared to when a mechanic says 'xx is giving a fault code'?

Basically, if there are no more fault codes, but the car is still running oddly they'll just start changing things out....could get very costly, so I won't be doing that with BMW. As Jimmy suggested, if I take it to a decent Indy they'll have a better idea of what's causing the issue and can be more precise / cost effective in the repairs.

I wonder if it's the Idle Control Valve or throttle Position Sensor / Throttle Actuators that are causing the lumpy running. It's only happened twice in a year though and only for 3 minutes before the engine warms up. Will monitor it and see what happens.

I wouldnt be so sure my indy were following the stealers process of elimination.

 

[StevenH72]

possibly, at least Indy's labour rates are lower than the stealers though.

What was the issue with yours Andy?

 

[jimmybell]

I've had dirty idle control valve issues with an old vauxhall astra, it would bounce around at idle +/- 500rpm.

 

[StevenH72]

The first one that went on mine had gone due to an inlet manifold air leak,so dont leave it too long to sort out or you could be looking at a holed piston in the worst case scenario.

Just heard from BMW, the post-cat sensor also needs replacing, which they will do in the morning.

They have said that the diagnostics have shown that there may also be an air leak, but that after having a look (FOC) they couldn't find any.

They have suggested that they may have to have a look under the manifold to locate the leak if replacing the post-cat sensor doesn't resolve the issue.

I have asked if they know what has caused the sensors to fail, which they are going to come back to me on with an answer.

The two sensors have failed on bank 2, I'm pretty clueless mechanically, but would that correlate with the inlet manifold? What sort of cost did you incur to fix the manifold goon?

 

[jimmybell]

If there is an air leak, then that's three independent components failing? How are they sure the first sensor was screwed?

I'm always paranoid about paying for BMW to learn about their own products and figure out what's wrong with a car they should be already able to fix.

 

[StevenH72]

As i read it Goon suggested that an air leak was the root cause of his 02 sensor failing?

Could it be the same for me, i.e. an air leak that has caused issues for the sensors, so whilst three units have failed it's the fault of only one original issue?

We'll see, if changing the post-cat sensor (only £240, so £260 cheaper than the pre-cat), doesn't clear the warning light, I'll be taking the car elsewhere for a more thorough investigation.

Where did you take yours for your issue Jimmy? I like ML but it's a 120 mile round trip for me, somewhere easier to get to would be ideal.

 

[Z8Cookie]

Yes, I’ve had 3 X Z4M’s & all three have had this problem. Just had one replaced (front bank) while I had my inspection 1 & MOT done, think it cost about £270. Quite a relief really as I told them the one to replace after using a code reader, so far so good! I tried for months to find one with an ebay search or on google shopping with the part number & they just don’t come up, so it’s a BMW job at BMW prices.

 

[jimmybell]

CPC Performance Engineering, they're in Amersham. probably ~40 miles from you? they open really early (~7am), and finish early (~3), so you can drop the car off before work, then catch the train/tube to the city. It may not be that much easier to get to, it's more m25 dependent. Definitely where all my non logbook-stamped works are going to be done.

Phil @ CPC PE is pretty damn good, as is his team. Best to call them first thing i found, by the end of the day they get swamped and are busier.

When comparing ML and CPCPE (both very good and reputable), i found Stuart @ ML was initially helpful on the phone but never called back in the end, CPC were responsive, and able to squeeze me in around my schedule knowing i needed the car asap. CPC also do VANOS rebuilds, rather than replacements, hinting at deeper engine-internals knowledge, so they could immediately rule that out as the cause - saving me ~£1500.

 

[Beedub]

Everyone should check these points , the can be seated poorly and rub away on certain parts of the gearbox/ engine ..... Funnily enough one of mine was rubbing on the gearbox nut...

Sent from my iPhone using Tapatalk

 

[Mike8080]

Beedub, Whereabouts in the engine bay are we looking in that photo?

 

[goon]

The manifold was ok,they did a smoke test and found a split in a small rubber pipe,total cost was about £340 inc new sensor I think.

 

[StevenH72]

The manifold was ok,they did a smoke test and found a split in a small rubber pipe,total cost was about £340 inc new sensor I think.

Ah OK, fair enough. Once the new sensor is fitted, i'll get down to an Indy for confirmation of any leaks. Don't want BMW playing with her anymore (not sure they know what they're doing really).

 

[Ninarvana]

CPC Performance Engineering, they're in Amersham. probably ~40 miles from you? they open really early (~7am), and finish early (~3), so you can drop the car off before work, then catch the train/tube to the city. It may not be that much easier to get to, it's more m25 dependent. Definitely where all my non logbook-stamped works are going to be done.

Phil @ CPC PE is pretty damn good, as is his team. Best to call them first thing i found, by the end of the day they get swamped and are busier.

When comparing ML and CPCPE (both very good and reputable), i found Stuart @ ML was initially helpful on the phone but never called back in the end, CPC were responsive, and able to squeeze me in around my schedule knowing i needed the car asap. CPC also do VANOS rebuilds, rather than replacements, hinting at deeper engine-internals knowledge, so they could immediately rule that out as the cause - saving me ~£1500.

ML have been a bit short handed this year however they have just taken on a new chap in parts so I'm confident any delay in receiving phone calls will have been taken care of now as Stuart will have his hands a little freer. They are a really knowledgable outfit down there

 

[andysat]

possibly, at least Indy's labour rates are lower than the stealers though.

What was the issue with yours Andy?

Mine is not an m tho-just the emission light coming on-4 years down the line still no nearer a solution-looking at 1/3 series coupes now, shame really like I have said if someone could give me a cast iron solution I would pay and get on with my life.