MOT failure-Lambda reading- Need a new exhaust??

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Pierrick
Joined: Fri 31 Aug, 2012 23:47
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  Z3 roadster 1.9

MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 25 Mar, 2014 19:44

Hi everyone, some of might have seen my other post:
http://www.zroadster.net/forum/viewtopi ... =5&t=40190

I'll try to resume, I went twice through the MOT and the lambda reading was twice out of the limits.

After the first MOT I changed:
Lambda sensor (bosch, as original).
DISA valve, or intake adjusting unit as they call it.
New air filter
Chechecked and cleaned the plugs. They were really clean as I changed them a year ago.
And put some injector cleaner in the tank.

Second MOT... no change.
I have to change the back box and the pipe which goes with it as everything has rusted away and there actually quite a big leak.

So does the leak change the reading?? My lambda sensor is just after the catalitic convertor and then before the leak but at the MOT they take the reading right at the back of the car...

So what should I do???
Stainless steel back cat exhaust if not too expensive or steel if you give me a good adress?
And the catalitic converter then... do I really need to change it... here is the real question!!
Or can it be "fixed"?

I really need help there!

Thanks in advance for your help!

Del
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Del » Tue 25 Mar, 2014 20:11

My guess would be an exhaust leak. My understanding (as a DIY non-expert) is that pulses/waves of exhaust gases are pumped down the exhaust which at any stage can "suck in" air from quite small leaks - which would influence a reading at the tailpipe.

Several aftermarket rear sections for the M44 on ebay at around £100-£120. Stainless is around £350 and BMW OE around £600 :shock:

littlefeller
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by littlefeller » Tue 25 Mar, 2014 21:07

ooops just posted in the other thread (we need a face palm smiley). my guess is leaking exhaust like mine, though im working on a sticky lifter idea on mine. does yours have an odd cold start issue?

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 25 Mar, 2014 21:28

no cold start issue!

by the way here are my readings for the 2nd MOT:

1st fast idle
CO=0,032, max is 0.300 pass
HC=0, max limite is 200 pass
Lambda= 1.049, should be between 0,970 and 1,030 fail

2nd fast idle
CO=0,013, max is 0.300 pass
HC=0, max limite is 200 pass
Lambda= 1.090, should be between 0,970 and 1,030 fail

Natural idle
CO=0, max limit is 0,500 pass

Can't find the readings from the first MOT!

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wildeboy
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by wildeboy » Tue 25 Mar, 2014 22:56

Pierrick wrote:
wildeboy wrote:My zed has just failed its MOT with a leaking exhaust and my emissions test was very similar to yours with CO and HC passing and lambda barely scraping through.

Another pointer towards your exhaust leaking, or maybe my lambda sensors are kaput too!
Wildeboy, did you change you exhaust then? and nothing else? this cured the problem with the lambda reading?
No not yet, it only failed today, but I am hoping so.
1997 Z3 2.8 in Montreal Blue, only 130k on the clock!
OEM Roll Hoops
M50B25 Inlet manifold
BMC CDA Induction kit
Beige roof

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 25 Mar, 2014 23:15

Ok, well don't do like me spending money on others parts... try to fix the exhaust leak first!

My exhaust is so bad is so bad I'll change it, there is no point at pluging the hole!

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wildeboy
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by wildeboy » Tue 25 Mar, 2014 23:33

The tester offered to remove the front baffle box and replace with a pipe to fix the hole for £100, I have known him for years though and reccomended I take it away and get a ss one made as it would only go again somewhere else. It is still an option to keep it going another few years.
1997 Z3 2.8 in Montreal Blue, only 130k on the clock!
OEM Roll Hoops
M50B25 Inlet manifold
BMC CDA Induction kit
Beige roof

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Thu 27 Mar, 2014 00:25

Ok, so here are my options:

exhaust from euro car parts (reg is R447CGJ) at 185£:
http://www.eurocarparts.com/exhaust-parts

Or e-bay at around 110£:
http://www.ebay.co.uk/sch/i.html?_sacat ... &_udhi=200

and this:
http://www.ebay.co.uk/itm/BMW-Z3-Custom ... 232d991d86

Seems to be very cheap!
Does anyone knows them?

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Althulas
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Althulas » Thu 27 Mar, 2014 03:34

If your looking at keeping your car I would go for the last link and have a complete stainless system done while your at it never having to worry about corrosion again, also you can have it made to give what sound you want. There are lots of companies for you to google but even if your doing just the back box you might as well treat your zed to something nice http://zroadster.org/forum/threads/bmw- ... usts.4251/ . The cheaper euro car part will just be a short term fix looking in the long term, but if the purse strings are a bit tight have you considered contacting http://m.ebay.co.uk/itm/160922991419?nav=SEARCH
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Del
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Del » Thu 27 Mar, 2014 09:57

I'd be wary of the ebay ones. The stainless one only mentions a "rear box" and not a rear section that contains 3X hanger brackets, 2X boxes and a joining flange to the front section. I've always been happy with the premium (not budget) brand options from Euro Car parts and GSF. The former seems to be offering a Klarius exhaust which looks like a decent firm http://www.klarius.eu/klarius-Emission-Control/.

GSF use the manufacturer Bosal who claim to be OE quality. I have had an aftermarket Bosal exhaust fitted to another car (not the Z3) and it was not budget quality. It was heavy, well made and has not rusted. Theirs is £210 for the 1.9 Z3 but I have found they will negotiate a bit over prices and possibly match their arch enemy Euro Car Parts. :D

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stu
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by stu » Thu 27 Mar, 2014 13:35

Had a similar problem last year, very slight exhaust leak, causing very slight fail, like yours.

Very experienced MOT tested suggested, correctly, stuffing a sock in the tail pipe to increase back pressure = result!!!

WIll be expecting a new centre section to the required this year, so might be time to thoroughly upgrade the exhaust. Not bad for a 15 year old car!

Let us know how you get on please.
someone in a minority once wrote:I know I'm in a minority
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Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Thu 27 Mar, 2014 22:12

Thanks for the links athulas but cobra and longlife are definitly too expensive for me! I don't know about roar power but I think it will be too expensive too!
And I can't just replace the back box as the rear section is so badly corroded!
I think the only way I could get a stainless steel exhaust is to find a second hand one! But I can't wait as I don't have another car!

Del, as you said I'm not very confident about buying an exhaust from e-bay.
So I now have to choose between GSF and euro car parts.
I'll give a ring to GSF to negociate tomorrow and see how it goes.

But if someone knows where to find a second hand stainless one...

Del
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Del » Thu 27 Mar, 2014 22:25


Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Fri 28 Mar, 2014 18:29

Exhaust bought from euro car parts.
I called GSF and because they had to order specially for me they didn't want to do anything about the price!

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wildeboy
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  Z3 roadster 2.8
Location: Leeds

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by wildeboy » Fri 28 Mar, 2014 22:39

Had a new stainless cat back exhaust fitted yesterday, took it back for a retest and it failed again on emissions. Same as before HC and CO zero and lambda high at 1.179. So the new exhaust didn't fix it, sounds nice though!

Engine was running rough, especially at idle when cold, it was 'hunting' and cutting out, and was popping and spluttering on overrun. The garage suggested it was a weak mixture, I was thinking it was the O2 sensor. The symptoms were familiar though, I just couldn't remember why.

I started thinking maybe the MAF and was just opening the bonnet when it struck me, it had done it before when one of the intake manifold pipes worked loose, too much air getting in after the MAF so weak mixture. A quick look at the rubber pipe/boot after the MAF and there was a huge hole!

Ordered a new one from BMW which will be there tommorrow morning, but I couldn't wait that long so stuck some tape on it and took it back to test! An easy pass. The retest they did yesterday didn't go through the system so today was the official retest, and they didn't even charge me for that! The benefit of a friendly garage and being a rugular customer!
1997 Z3 2.8 in Montreal Blue, only 130k on the clock!
OEM Roll Hoops
M50B25 Inlet manifold
BMC CDA Induction kit
Beige roof

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Fri 28 Mar, 2014 23:09

Good for you! You are ok for one more year!

Where did you get you exhaust? SS?

t-tony
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by t-tony » Fri 28 Mar, 2014 23:12

You are entitled to 1(one) free retest within 10 working days ( 2 weeks as Saturday is not counted as a working day). They could have counted your 1st try as your free retest so that's good. Shame the tester didn't notice the problem first time around. All's well that ends well I guess. Would have saved you some money!
"Knowledge and experience are not always the same"

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 01 Apr, 2014 19:44

Recieved my exhaust today.
Fitted this evening!

But there is a problem. When I put the middle rubber mounting the exhaust is touching the underneath of the car. Can it be a failure for the MOT???

If I don't put the rubber on the exhaust doesn't touch and the exhaust is well supported (according to me!) but that won't be enough for the MOT as last time they sait "exhaust not properly supported" because the bracket for the rubber has snapped from the exhaust!

need help!!!

Del
Joined: Sat 19 Nov, 2011 18:35
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Del » Tue 01 Apr, 2014 20:10

The 1.9 exhaust always passes very close to that chassis point. The OE exhaust had a flattened section to clear it - did the new one have that flattened section? I recall forum member Bladerunner919 saying that he had fitted an aftermarket exhaust and he made the point that this middle bracket is adjustable (slides up & down) and so can be adjusted to allow the exhaust to clear the chassis. Failing this, there are generic brackets and hangers that can be used.
http://www.carbuildersolutions.com/uk/exhaust-hanger

http://www.powerflex.co.uk/road-series/ ... 618/1.html

Pierrick
Joined: Fri 31 Aug, 2012 23:47
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 01 Apr, 2014 20:36

The bracket is as low as it can be! I'll have a look at the others fittings, or probably get a second hand one.

But the question remains... will it pass the MOT like this???

quite like this:
http://www.carbuildersolutions.com/uk/exhaust-hanger

littlefeller
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by littlefeller » Tue 01 Apr, 2014 20:53

this is interesting, mine failed the emissions too, best I check out the intake. :)

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Tue 01 Apr, 2014 23:00

Ok,so tony told me the car should pass the MOT... well should, not 100%, but we will see tomorrow!


Anyway, I'll have to buy ar make a different mounting, so, do anyone have a suggestion? appart from the one given by Del?

gookah
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by gookah » Wed 02 Apr, 2014 11:14

Pierrick wrote:Ok,so tony told me the car should pass the MOT... well should, not 100%, but we will see tomorrow!


Anyway, I'll have to buy ar make a different mounting, so, do anyone have a suggestion? appart from the one given by Del?
how about a little adjustment to the exhaust to replicate the flattened section using a mallet?
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BladeRunner919
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by BladeRunner919 » Wed 02 Apr, 2014 14:03

Del wrote: I recall forum member Bladerunner919 saying that he had fitted an aftermarket exhaust and he made the point that this middle bracket is adjustable (slides up & down) and so can be adjusted to allow the exhaust to clear the chassis.
Good memory! I was just about to mention this! :D

Pierrick
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  Z3 roadster 1.9

Re: MOT failure-Lambda reading- Need a new exhaust??

Post by Pierrick » Wed 02 Apr, 2014 17:21

Hi guys. MOT has passed!!!! Soooooooooo happy!

So, i'll have a new lambda sensor to resell... has done 10 miles on my car!

The problem was the exhaust and not the lambda sensor.

And I bought the bracket which appear on the firsl link del gave me. So it should be fine, no need of a hammer!

henrycrun
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Re: MOT failure-Lambda reading- Need a new exhaust??

Post by henrycrun » Wed 16 Apr, 2014 14:05

Does anyone have experience of exhausts made by Eberspaecher ?

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