Toyota Camry (1987 - 1991) - 91 2.0 Exhaust gas analyser

Honest John Back Room » Technical matters
View Threaded
Mon 14 Dec 2009 15:15
91 2.0 Exhaust gas analyser - Gregory II
Hi
Where can I purchase an exhaust gas analyser? I am looking for a DIY one. Are there any available on the open market?
Greg
Reply | Report as offensive | Link
Mon 14 Dec 2009 15:34
91 2.0 Exhaust gas analyser - Galaxy
Unless you want to spend £'00000's on one then the only one aimed at the DIY market is the Gunsons one, that is, if they still make it.

Update. It would appear they still do:

www.gunson.co.uk/item.aspx?cat=698&item=1835



Reply | Report as offensive | Link
Mon 14 Dec 2009 16:33
91 2.0 Exhaust gas analyser - bathtub tom
I've got one of them (with an analogue meter).

Probably totally useless nowadays.
Reply | Report as offensive | Link
Thu 17 Dec 2009 14:26
91 2.0 Exhaust gas analyser - Gregory II
This seems to be a very impressive system. Are there other manufacturers of this analyser aimed at the DIY market? Also, where can I obtain figures for motorbikes as to their expected CO2/ O2 etc percentages that are deemed to be acceptable? I have never noticed a gas analyser for motorbikes at local garages (only cars seem to require these for MOT time!)

Reply | Report as offensive | Link
Thu 17 Dec 2009 14:49
91 2.0 Exhaust gas analyser - dieselnut
There is no MOT emissions test for motorcycles.
Most new larger bikes now have a cat, although it is usually the first thing the new owner removes in search of even more power.
Usually just a case of checking the colour of the spark plug, should be light brown & not black.
Reply | Report as offensive | Link
Thu 17 Dec 2009 18:13
91 2.0 Exhaust gas analyser - Gregory II
The gas analyser is a nice tool/ toy; also, it means adjustments can be made in theory. I would like something like this for the car as well, but back to basics: i.e. the colour on the plug is a good indicator.
Reply | Report as offensive | Link
Thu 17 Dec 2009 19:23
91 2.0 Exhaust gas analyser - bathtub tom
>>it means adjustments can be made in theory

Are you sure?

Is it carbed or injected?

This is why I said they're probably useless nowadays as there's nothing to adjust.
Reply | Report as offensive | Link
Fri 18 Dec 2009 14:29
91 2.0 Exhaust gas analyser - Gregory II
I see. Motorbikes still run on carbs so can be adjusted. With a car, it is just nice to know how well it is performing: it is a good indicator of perhaps whether sensors and systems in place are all working as they should be perhaps?
Reply | Report as offensive | Link
Fri 18 Dec 2009 14:33
91 2.0 Exhaust gas analyser - WorkshopTech
Probably best to nip down to MoT VTS and pay £10 to put it on their machine and take it from there.
Reply | Report as offensive | Link
Fri 18 Dec 2009 20:35
91 2.0 Exhaust gas analyser - TurboD
Takes me back a few years! How many car fail on CO2 emission?, I am not sure but reckon it to be very few. Most run so lean that they won't fail. What do they fail on?
Well when I took my Mbike down the other week( no emission test) it was handbrakes and minor stuff like that. But as most cars were under ten years old they were not worn out .After en they the uspension start to trigger MOT fails.
I would not worry about CO2, plenty of other things, bearings, joint , disc thickness etc etc
Reply | Report as offensive | Link
Fri 18 Dec 2009 20:58
91 2.0 Exhaust gas analyser - SpamCan61 {P}
Well I've pensioned off my last two bangernomics Vauxhalls on the basis of MOT emissions fails; trouble is emissions is one of the more complex MOT failures to diagnose, most other areas are much more black and white, apart from corrosion anyway; can't remember the last time I had rust issues on an MOT mind you.
Reply | Report as offensive | Link
Fri 18 Dec 2009 21:11
91 2.0 Exhaust gas analyser - bell boy
lots of emmission problems crop up on second hand cars but due diligence usually sorts out easy ones from difficult ones
i try to do my own gas emmission testing prior to taking for the mot,my machine came from the mot station after they upgraded it, sometimes takes an hour to get going on a morning though but is invaluable to sort a problem that a code read or compression test would never identify
if you really want one gregory11 they come up quite often on ebay for a reasonable £100 ish but make sure its not timed out and home to scary mice before you take it home.
(your local motman might still have his round the back under a sheet if you ask nicely,its usually about £90 for the man to come and recommission it for you and turn the timer off so theoretically it will work forever)
Reply | Report as offensive | Link
Thu 3 Feb 2011 13:52
91 2.0 Exhaust gas analyser - Gregory II
With regards to MOT's, what should the values be with regards to CO etc. I have looked online, but I cannot find a diffinitive answer:

I have come up with the following:
Carbon Dioxide (CO2) = The CO2 level at this 14.7:1 ratio is normally around 13.5%
Carbon Monoxide (CO) = The CO level at the 14.7:1 air fuel ratio is normally just under 1%.
Hydrocarbons =
Oxygen = At the correct 14.7:1 air: fuel ratio you should normally expect an O2 reading of less than 0.5%

Can someone in the know confirm this for me?
Thanks
Greg
Reply | Report as offensive | Link
Thu 3 Feb 2011 14:14
91 2.0 Exhaust gas analyser - unthrottled

Those values are about right. You've missed NOx.

NOx is the killer because it is trivially easy to set the mixture just lean of stoichiometric to keep CO and hydrocarbon levels to very low levels-but this will cause NOx levels to soar-and a standard thre way cat has no way of reducing NOx unless:

1.)O2 levels are low (below ~0.5%

2.)There is sufficient CO and HC to reduce the NOx

The maximum values for MOT purposes will depend on which emissions standard (EURO I, II, III, IV, or V) the car is required to conform to. As someone pointed out earlier, CO2 and O2 are not regulated pollutants.

As you get progressively leaner (AFR tends towards 20), combustion quality suffers, and unburned hydrocarbon levels start rising-so you get a mixture with excess O2 AND high HC.

O2 and CO2 levels are useful for fault finding. Especially when investigating misfire or maldistribution of fuel between cylinders. Say one cylinder has lambda=0.9 and another has lambda=1.1 The combined exhaust composition will have high NOx and O2 from the lean cylinder and high CO and HC from the rich one. The catalytic converter can smooth out these fluctuations however. What is it that you're tryingto do?

Reply | Report as offensive | Link
Thu 3 Feb 2011 15:52
91 2.0 Exhaust gas analyser - Gregory II

Thanks for the info.

I have a car converted to run on LPG; it is low on power at medium revs. I am thinking that adjusting the mixture is the best thing to do as this would affect the way it drives. This involves a gas analyser to get the mixture spot on basically!

Greg

Reply | Report as offensive | Link
Thu 3 Feb 2011 18:54
91 2.0 Exhaust gas analyser - unthrottled
Well, with LPG you should have a fairly homogeneous mixture with little cylinder to cylinder variation-so that's one problem you shouldn't have to deal with. How are you going to test the mixture under load? Cleary, A 3000RPM idle isn't the same as 3000 RPM WOT. To be honest, I'd be tempted to look for obvious faults in the system, but I'd leave the mixture alone. I don't know if rich mixtures are used at WOT (there's no in-cylinder evaporative effect to cool components like petrol) so I don't know what fuelling map is used.
Reply | Report as offensive | Link