MOT FAILURE today

Stuart B

Stuart B

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I put the original stage 1 map on first.

Seized handbrake adjuster on rear caliper (I knew about this) but it has meant the handbrake cable fell off under the lever.
Leaking brake fluid on other rear caliper - probably the flexi hose
no brake lights - brake light switch?

those I expect I can rectify but it failed on 2 emissions tests, is this likely to be because of my assumed oil burning? tester said he reckons it is misfiring slightly. I need to decide what to do with this car - before I do anything with this I suppose I will do a leak down test to try and figure out whether the engine is shot.

its also making that dry sound from the rear (haldex) on engine braking, which it didn't before it was parked up in June.
 
Current Failure
  • Exhaust emissions Lambda reading after 2nd fast idle outside specified limits (7.3.D.3)
  • Exhaust emissions carbon monoxide content after 2nd fast idle excessive (7.3.D.3)
Interestingly when checking "mot history" they were this in 2014?

  • Exhaust emissions carbon monoxide content at idle excessive (7.3.D.4)
  • Exhaust emissions carbon monoxide content after 2nd fast idle excessive (7.3.D.3)
  • Exhaust emissions Lambda reading after 2nd fast idle outside specified limits (7.3.D.3)

is it possible to check the readings on the drive with VCDS etc?
 
You can do lambda... given its mapped I am not sure what the value being reported is or what the target value should be as stock a wideband S3 should do lambda 1 until it needs to protect itself... mapped fuelling will run a bit richer depending on mapping, coolant temperature that the reading was taken (lambda control kicks in quite late on stock maps) and load generated at the test rpm... you can log request vs actual in VCDS to see if the AFR is in spec... if the request is the value you failed at then it will need a tweak of lamfa (assuming you are at 90 deg coolant temps etc)

CO can't be logged in VCDS as there is no sensor for this

CAT state won't effect AFR but will effect CO... unless ECU emissions readiness is compromised by an unplugged valve or sensor (N249, rear lambda etc)

<tuffty/>
 
I'm no expert on the impact of mapping but usually high CO is either a very rich mixture or more likely cat not doing its job. High lambda (in an MOT emissions context) is commonly an exhaust leak - exhaust pulses actually sucking in air. I've always understood that the "lambda" (oxygen) tested at MOTs is not related to the so called "lambda sensors" in the exhaust that tweak the combustion mix.
 
Retroman said:
I'm no expert on the impact of mapping but usually high CO is either a very rich mixture or more likely cat not doing its job. High lambda (in an MOT emissions context) is commonly an exhaust leak - exhaust pulses actually sucking in air. I've always understood that the "lambda" (oxygen) tested at MOTs is not related to the so called "lambda sensors" in the exhaust that tweak the combustion mix.
Click to expand...

An exhaust leak will trick the lambda into thinking the mixture is lean and the ECU will enrichen accordingly... this in turn will give a richer reading out the back of the exhaust while the AFR the ECU sees will appear to be correct...

An ECU like the ME7.5 will attempt to bring AFR to requested value... requested value will vary depending on what the ECU is seeing from other sensors so the map may have an initial request of lambda 1 but knock, EGT and IAT events will add a factor to the final AFR so could be richer than the base map suggests..

Lambda at MOT tests is still an AFR reading... this will be controlled by the ECU via what it sees from the lambda sensor... if there is an exhaust leak (plausible as I believe Stuart has a relentless manifold) then this could well be a contributory factor

<tuffty/>
 
I can put on a standard BAM map - but the 243 MAP I have is pretty conservative 1 all the way to 95% Throttle.
pretty sure the readings were > 1 pointing to being lean. if I have an exhaust leak it is after the post cat sensor on the other side of the centre box.

if the engine was burning oil would that be the failure - I do have a sports cat and last year we needed to heat up the cat and get the car through.

I am a paranoid person, but I am sure I have too much blow by - it is blowing out of the dipstick - when I was having difficulties with the pipes popping off the intercooler the engine bay was sprayed with oil - all since I checked my oil after a misfire (related to coil) and it was below the minimum. The garage said check the engine breathers but there is 2 isn't there? and both the cam cover and the oil filter are puffing smoke and the inside of the cam cover through the oil filler cap looks dry.

I only really do about 3-5K a year and expect if the brakes were all good we could have come to some arrangement.
 
leaky pipe..
sports cat and not revving it a lot befor ehand at 3-4krpm to heat it up.. if they did'nt do that it explains the fail
(why did'nt they do that)

as for rest of stuff, you did'nt do a precheck of anything then?!?!
 
Small exhaust leak in rear section won't show on a laptop. Both faults point to exhaust "issues" - in my view on a forum :welcoming::welcoming:
 
so if the middle section has a slight leak would that effect the emissions.

I will have a chat with them - as last year he said the cat needed to be hot to get it through - I am sure he did this again.
 
Well I would say that the problem is likely to be a combination of the sports cat and oil useage. The HC reading will be well out but also the sports cats tend to be quite poor even when new. After another year and especially being coated in oil it's likely that the car will need a decent cat fitting.
Quite often an Italian tune up will help to clear some of the crud from the cat and help it on the MOT.
 
so forgetting about the emissions (I am going to chance the Italian tune up with cataclean)
moving onto the handbrake cable - simple enough to temp lube up the slow return spring and put the cable back on through the ashtray.
brake light switch I sill get to tomorrow

that leaves the fluid leak. - it looked dry - so engine running got my son to press brake and low an behold it is leaking from the top "blanking bolt" so I haven't yet touched it. I want to try and avoid replacing fluid and bleeding etc.

has it simply come loose?
can I tighten it during a brake press?

or should I take the bolt out to see if something is cracked as I am frankly surprised it has started leaking?

Thanks


Leakybrake
 
Doutb you can fix the leak without taking it apart, had same issue myself and it was the crush washers that were the culprit, I would just minimise loss of brake fluid then you can just bleed that corner
 
Thanks - I just backed the bolt up and cleaned the surfaces and nipped it back in - the brake lights worked after removing and refitting the brake light switch and the sorted the handbrake cable out - so fingers crossed the cataclean and a hot catalytic converter will get it through - otherwise I reckon up as a "track / project" on ebay or break off the easy bits and scrap the rest. I am too tired for this - and to be fair it is only really fun to work on, but I am not very good at that bit. :D :D and have no interest in trying to make it look original and polished.
 
well I am taking my car back for a retest this afternoon, decided to clean the MAF and low and behold... no wire? is that just an air temp wire or a key part of this? - I have also seen comments that it isn't even for an S3?



IMAG0925 20171017 105929574


IMAG0924 20171017 105930985
 
Yes... correct sensor for the wideband AMK and BAM S3...

On some MAF sensors (B5 RS4 for example) there is an air temp sensor fitted across those connections... this is not required for the S3 and would not work without calibration anyway..

049 suffix sensor is correct

<tuffty/>
 
Thanks :) I just sprayed contact cleaner into the little end - just in case it's part of the issue.

Really need a sympathetic MOT tester regarding the emissions if they are still high the CO is much too high it is 0.65% instead of 0.3% for idle and 1% instead of 0.3% for fast idle, and the lambda is 1.069 instead of 1.030

but without any test equipment I will end up paying out for MAF, CAT etc etc and re-MOTing after every stupid change. unless of course the snake oil and MAF clean has helped it.

I have disconnected the N75 so I can do an Italian tune up on the way there without breaking the thing or breaking down.
 
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Reactions: <tuffty/>
#winner

it passed and was a definite balancing act of getting the fast idle on long enough to get the CAT working - then not too much up or down on revs - otherwise it moved out of range on either lambda or CO.

at least I can muck about with it until it is properly broken now :D :D :D
 
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Reactions: hydro s3
Yay! Should have put on launch control, that would hold the revs for you haha
 
Good news mate,I knew you wouldn't leave in the lurch,was there an advisory on the MOT sheet about it being the wrong colour?

:yes:
 
he he the colour is fine, they didn't even comment on my flared wheel arches to cover up the crap drivers side - free retest too - I didn't keep the trial map I made as I had not even tested it further than running the engine on the drive (apart from the 2 step launch control) , but tax it after my holiday and see if the intercooler piping holds fast - change the Haldex oil again all this sitting around for months has led to that dry vibration sensation on engine braking.

this car is a shed - it would make a lovely flower pot - but I am gonna make sure I get to play with it before I take the B5 TIP and heat shield off and scrap the rest.
 
I will sell it when the car blows up - my point was its the only decent thing left
 
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