MOT - just scraped through :( any advice?

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sirius-c
Joined: Wed 12 Dec, 2012 22:24
Posts: 499

  Z3 roadster 2.8
Location: Eeh ba gum lad, 'ow do?

MOT - just scraped through :( any advice?

Post by sirius-c »

The 'ol Z just scraped through its MOT yesterday, the potential problem being emissions, but only marginally,

Just wondering if anyone has any advice on where to start and try rectify this?
I know I'm asking a lot of questions, but I dont want to start throwing money where its not needed.

Here's all the info I can muster which may help with any advice anyone could give:-
I drove 10 miles to MOT tester waited 10 mins with engine off before starting MOT, then let car idle for 5 mins before the probe went in the tail pipe,
I was asked to rev at constant 2000rpm which brought the values down to passable levels.

1)
my 1997 2.8 Auto (M52) has done 57k, I use premium unleaded at all times, it only has 1x pre-cat sensor, there are no OBD related error codes stored nor has there ever been any.
I'm assuming the MAF and Lambda sensors are ok because there are no codes but there is a strong smell of fuel from the exhaust on a cold start up, and a lesser smell of fuel when up to temperature but still noticeable when stood behind it.
There's no smoke whatsoever other than cold start condensation and sometimes small amounts of water dripping out from the tail pipes, it idles fine when warm, doesn't stutter, its a very steady +700'ish. There is no hesitation or stutters under acceleration either.

1st question...
should i replace the maf and lambda sensors?

There is no OBD indication that they need replacing, I ask this question only because I'm guessing its running rich because of the exhaust smell
MPG is anything from 17 ('I've been paid' Driving style) to 22 ('I'm skint' driving style), the most I ever squeezed out of it was 24.8 ('annoying other road users' driving style).
I think these are acceptable figures for a 2.8 Auto but I have no comparison.




2)
I had a stainless steel exhaust system fitted between Mots last year.
The S.S system begins just after the precat sensor/downpipe and includes a sports cat and rear muffler, there is no mid box.

2nd question...
Is the sports cat likely to be the culprit here? and if you think so, why? surely they are designed to be MOT compliant...or do i need a re-map?

I will go back to Tony Banks in Leeds who fitted it if theres a chance it could be a dud, it has a lifetime warranty




3)
3rd question...
I've been running a Simota carbon filter, do you think this could be a contributing problem?





4)
I've been on NGK UK's web site and it recommends BKR6EK for BMW M52 engines up to 08/1999, (mine is a 1997) and BKR6EQUP for 08/1999 >up.
But, if you go to NGK U.S web site or Euro car parts BKR6EQUP are recommended for my 1997

4th question...
I currently have BKR6EQUP installed, should I replace them with BKR6EK or the upgraded BKR6EIX?


One of the main differences between these plugs other than the obvious number of electrodes is that BKR6EK has an interference suppression of 1KOhm and BKR6EQUP are 5KOhm, I have no idea what this means or how it would affect a car.


I removed the plugs today for inspection and this is what they looked like after 2657 miles (Installed on 17/12/2012), I have no idea if these are good or bad.

1st plug (front)
Image

2nd plug
Image

3rd plug
Image

4th plug
Image

5th plug
Image

6th plug (Rear)
Image




Other Notes/Questions:-
I've checked for intake/vacuum leaks and found none.
One thing i noticed today is that there is no vacuum hiss when my fuel cap is removed...should there be?
The rubber o-ring on the cap does looks a little cracked, maybe replace this?
Should i start using regular unleaded instead of Premium?
Thermostat, thermostat housing and water pump have all been replaced in the last 2 years, engine temps seem fine. I have not replaced the coolant sensor.
I've cleaned the MAF in the past using Servisol IPA 170 Isopropyl Alcohol electronic cleaning solvent, i didn't touch the sensors, i just sprayed liberally, should I have not used this?
Product info:
Servisol IPA 170 Isopropyl Alcohol is a powerful electronic cleaning solvent, which conforms to BS1595, ASTM D770 and DIN 53245 specifications.
The solvent forms an azeotrope with water for effective removal of moisture from parts and components.
The solvent evaporates after use, leaving no residues.
Ideal for cleaning tape heads, disc drives, photocopier drums, PCBs, optical equipment, lenses, precision instruments and delicate components.




or is there anything else I should be looking at that I may have over looked?
Last edited by sirius-c on Sat 18 Apr, 2015 18:13, edited 1 time in total.
Designed or not designed, that is the question.
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: MOT - just scraped through :( any advice?

Post by Del »

What particular gas readings were causing the problem? A high CO reading (for example) can denote a failing/failed CAT, some "sports cats" can be a bit borderline in this respect. Things like mixture formulation and/or exhaust leaks can have an influence on CO and the other gas readings. However, the new exhaust provides a possible clue in a forum context :nerd:

I've had a failed Cat (after just one year) when everything else was perfect - high CO. The MOT inspector and garage where I bought the exhaust system, pinpointed the Cat because the pre-cat lambda (which was also new & in perfect condition) was not reacting to any imperfect mixture being caused upstream e.g. MAF - because the mixture was not at fault.

High lambda (oxygen) is usually an exhaust leak and the final gas (can't remember name) is often mixture/ignition.
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sirius-c
Joined: Wed 12 Dec, 2012 22:24
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  Z3 roadster 2.8
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Re: MOT - just scraped through :( any advice?

Post by sirius-c »

Thank you for your reply Del.
for some strange reason i didn't receive an emissions print out with this MOT like I did last year.
I remember looking at the screen and watching in anticipation for the values to turn green. I'm pretty sure HC was the real problem but i know CO just scraped through too.
It looks like i may have a few things contributing here, I think it might be a good idea to check for exhaust leaks too.
Designed or not designed, that is the question.
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sirius-c
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Re: MOT - just scraped through :( any advice?

Post by sirius-c »

It's just dawned on me that I also had nearly a full tank of fuel that was sat in it since filling on 13/10/2014 (6 months old), that cant be good
Designed or not designed, that is the question.
peter2b
Joined: Sat 01 Nov, 2014 18:47
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  Z3 roadster 2.2i
Location: cheshire

Re: MOT - just scraped through :( any advice?

Post by peter2b »

My z3 2.2 just pased its mot, the emissions were fast idle co2 0.057% hc89ppm vol, natural idle co2 0.077 if this is any help + she has been off road since last april at least with 1/4tank of fuel milage 104452
peter2b
Wolverine_1999
Joined: Mon 15 Feb, 2010 20:07
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Location: Munich

Re: MOT - just scraped through :( any advice?

Post by Wolverine_1999 »

A few points I remember when I failed on this:

- Drive the engine warm and hard beforehand. A 10 mile trickle might not even do it if you are plodding along at 30-40 mph. (e.g I do a 5 min run on the Autobahn doing 200 :D )
- When was the engine oil last changed? What type of oil was used?
- Have the errors been read off of the car? Faulty lambda sensor? (This was where I failed because it was giving a bad reading - sensor replaced - all good)
- I have the same spark plugs, they look fine and are good for 30000 miles as far as I know
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sirius-c
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  Z3 roadster 2.8
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Re: MOT - just scraped through :( any advice?

Post by sirius-c »

Wolverine_1999 wrote: - Drive the engine warm and hard beforehand. A 10 mile trickle might not even do it if you are plodding along at 30-40 mph. (e.g I do a 5 min run on the Autobahn doing 200 :D )
Noted, thank you, the drive was about 40-50MPH.


Wolverine_1999 wrote: - When was the engine oil last changed? What type of oil was used?
The following changed soon after purchasing Z3...
Oil change with 5w40 Fully synthetic & oil Filter on 17/10/2012 mileage was 57014 (Current mileage is 59671)
Fuel filter replaced on 21/11/2012 mileage was 57424
Spark plugs replaced on 17/10/2012 with NGK BKR 6EQUP (Old ones removed were NGK BKR6EK) Mileage was 57014

Wolverine_1999 wrote: - Have the errors been read off of the car?
No none at all, but the car smells to be running rich and as the car is nearly approaching 18 years old, do you think I should replace the MAF and Lambda sensors regardless?
I've no idea how or what to check for via INPA regarding the MAF and Lambda, if someone could advise that would be great

Wolverine_1999 wrote: - I have the same spark plugs, they look fine and are good for 30000 miles as far as I know
Thank you for this confirmation, i'm still convinced by the info on NGK UK that i should be running BKR6EK as mine is the M52 not M52TU, and pre 1999
I'm no plug expert but was worried that they were a little black/sooted tried wiping it off but its baked on, I'm relieved to know they are fine.
Designed or not designed, that is the question.
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stevov
Joined: Sun 21 Dec, 2014 15:56
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Re: MOT - just scraped through :( any advice?

Post by stevov »

2 and a half years since its last oil change. Yearly at the very least. The low mileage makes it worse as your oil is holding the water of 2 1/2 years condensation cycles with the engine probably never run long enough at temperature to evaporate the suspended water. Your sport cat is probably a 200 cell which is half the standard 400 cell unit and despite what the sellers say will always give higher reading and are sometimes depending on tune not enough to pass.
Del
Joined: Sat 19 Nov, 2011 18:35
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  Z3 roadster 1.9

Re: MOT - just scraped through :( any advice?

Post by Del »

When these pre-facelift cars were built, the modern spark plug and the one mentioned in the handbook was the 2-electrode NGK BKR6EK. More recently the modern upgrade (fitted by BMW technicians as well) is the 4-electrode, platinum NGK BKR 6EQUP. I thought that the pictures of your plugs looked fine - nice pale brown colour.
stevov wrote:Your sport cat is probably a 200 cell which is half the standard 400 cell unit and despite what the sellers say will always give higher reading and are sometimes depending on tune not enough to
- I agree.
Wolverine_1999
Joined: Mon 15 Feb, 2010 20:07
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  Z3 roadster 2.0
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Re: MOT - just scraped through :( any advice?

Post by Wolverine_1999 »

Get that oil changed!

I followed Mike Fishwicks guide the last time and did it myself. Don't trust those garage cowboys anymore..
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sirius-c
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Re: MOT - just scraped through :( any advice?

Post by sirius-c »

stevov wrote:2 and a half years since its last oil change. Yearly at the very least. The low mileage makes it worse as your oil is holding the water of 2 1/2 years condensation cycles with the engine probably never run long enough at temperature to evaporate the suspended water.
Wolverine_1999 wrote:Get that oil changed!
Thank you, I didn't know this, in-fact I thought quite the opposite ...IE that the low mileage wouldnt be wearing the oil as quick and given the oil colour still looks almost new.
I'll be doing it immediately and yearly from now on.
5w30 or 5w40?
stevov wrote:Your sport cat is probably a 200 cell which is half the standard 400 cell unit and despite what the sellers say will always give higher reading and are sometimes depending on tune not enough to pass.
Interesting stuff, I guess that everything is pointing to the cat, next year I'll give it a thrash down the motorway just prior to the MOT and see what happens.



Del wrote:When these pre-facelift cars were built, the modern spark plug and the one mentioned in the handbook was the 2-electrode NGK BKR6EK. More recently the modern upgrade (fitted by BMW technicians as well) is the 4-electrode, platinum NGK BKR 6EQUP. I thought that the pictures of your plugs looked fine - nice pale brown colour.
Thanks for the confirmation, appreciated.



I've been reading up on how o2 sensors work and what the ideal values should be, I'll be giving it a go with testing its live data later on.
I think I'm going to buy a MAF regardless as these are becoming quite rare for my Z3.
Designed or not designed, that is the question.
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sirius-c
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Re: MOT - just scraped through :( any advice?

Post by sirius-c »

can anyone recommend any software that can read live oxygen sensor data on the old Z3's (circular port under bonnet)?
INPA shows nothing much.
Ive got the adapter & usb cable.

The voltage on the o2 sensor is 4.8v at idle and barely changes with revs, is this OK?
Designed or not designed, that is the question.
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stevov
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Re: MOT - just scraped through :( any advice?

Post by stevov »

Given the low mileage you do I would go Mobil 1 0w40. IMHO one of the best oils available and the 0W cold rating ensures the fastest possible pressure build up on cold starting. This oil has served me without fail for almost 140,000 miles in a 450/450 evo5. You need to check the voltage under load. It's more than you need but diagnostic equipment like the solus Pro I have in the for sale forum have live data acquisition.
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