Exhaust emission values have deteriorated

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mich
Joined: Wed 16 Feb, 2005 05:53
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  Z3 roadster 3.0i
Location: King Country
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Exhaust emission values have deteriorated

Post by mich »

While taking the Z3 for its annual WOF my wife had a warning light come so I have checked handbook and it said, “Exhaust emission values have deteriorated” I should explain that the car spends most of the year in the garage and last year traveled only 250k. I have not yet driven the z myself and just wondered if this is serious or common?
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137699
Joined: Wed 04 Mar, 2020 21:40
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  M coupe S50

Re: Exhaust emission values have deteriorated

Post by 137699 »

May just mean a lambda sensor has failed.
But could be something more sinister like it's burning oil.

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mich
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  Z3 roadster 3.0i
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Re: Exhaust emission values have deteriorated

Post by mich »

Thanks 137699 not burning oil, I have not had a chance to go for a spin yet will get back and post when I have.
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
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Re: Exhaust emission values have deteriorated

Post by colb »

First thing to do is put a code reader on it to see what codes have been set, bound to be some as the dash light has come on. Reading the codes might lead you in the right direction to what is at fault. Also check all the rubber inlet pipes and vaccum syatem pipes for splits or holes. Extra unmetered air that the Maf has not seen will be picked up by exhaust sensors and lead the car to think its running lean and it will add more fuel to the injectors to richen the mixture. If you have diagnostics that can look at live data look at thefuel trims if they are high then that is a good indication that you have air leak(s).
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V

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mich
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Re: Exhaust emission values have deteriorated

Post by mich »

I do have it booked in for checking on monday and hope to have a run in it over the week end unfortunately we do not have a BMW dealer local so will entrust it to the local Ford man.
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Gazza
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Re: Exhaust emission values have deteriorated

Post by Gazza »

colb wrote:
Wed 09 Dec, 2020 23:56
First thing to do is put a code reader on it to see what codes have been set, bound to be some as the dash light has come on. Reading the codes might lead you in the right direction to what is at fault. Also check all the rubber inlet pipes and vaccum syatem pipes for splits or holes. Extra unmetered air that the Maf has not seen will be picked up by exhaust sensors and lead the car to think its running lean and it will add more fuel to the injectors to richen the mixture. If you have diagnostics that can look at live data look at thefuel trims if they are high then that is a good indication that you have air leak(s).

Great advice.

Another thing to try is going for a drive, blow the cobwebs off so to speak.
Gazza

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

Z3 S54 M roadster Image, BMW Z1, BMW M3 CSL, Z4M Coupe
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mich
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Re: Exhaust emission values have deteriorated

Post by mich »

Just had a run and the Z behaved OK no misfiring on hard acceleration or when maintaining a steady 100kph (our limit) also no vibrations from engine, idle seems a bit rougher than normal but does not stall as it did when it had vanos problems at 5000k it has now done 52.000 k. Warning light still on.
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colb
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Re: Exhaust emission values have deteriorated

Post by colb »

Be interested to hear what codes it has set to get to the bottom of the fault(s) it has recorded when you get it scanned. I would hazard a guess its going to be an air leak either at the rubber inlet bellows after the Maf and before the throttle body which are the usual places. Leaks are the common cause for the fuel trims to go high and evntually set the EML when it reaches the maximum it can get to to correct what it sees as a weak mixture thats down to the extra air seen by the exhaust sensors that exceed the amount registered as passing through the Maf.
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V

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mich
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Re: Exhaust emission values have deteriorated

Post by mich »

It seem that it was an air leak as predicted by everyone, have only done short runs so time will tell. Thank you all for the help and advise. :D
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