I pose a question to trained service and repair technicians:
What CO meter would you recommend as an affordable and dependable shop tool to use as reference and/or verification of fuel/air ratio in CIS K and KE-Jetronic applications?

A tool that is available to purchase today

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I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.

There's an English company called Gunson that make equipment like this for the hobby market. Having bought some of their stuff I find it to be over priced for what it is...

...if you must buy a CO meter I'd go for old school 1980s second hand stuff that has been calibrated recently.

Unless you're working as a professional I would argue that this type of equipment is a bit more than is needed. If you have a decent multimeter with a Duty cycle function (and you realise that Mercedes quote their duty cycle values differently from most meters!) you are going to be able to tune the emissions as well as any "shop" - CIS is essentially so simple it all comes down to the oxygen sensor - if you can check that functionality via mulimeters or oscilloscopes then you're 95% of the way there.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Thank you, Stretch. I value your advice based on your experience.

I am aspiring to turn my hobby into a professional level service.

Right now I have a Fluke 83V and Rigol DS1102E as DVOM and oscilloscope respectively. They are robust enough for repeatable data I can depend on.

My interest in monitoring CO is for personal educational purposes. Being an autodidact I like to have all the data in front of me to decide what has the greatest value to make accurate and effective decisions. I doubt the CO monitoring tool will have value to be in my daily routine.

I like the idea of '80's second hand equipment that can still hold a calibration.

I agree the newer diagnostic tools I see others use in general are over-priced gadgetry. If I wanted to play video games I'd buy a console. I'm too old for childs' play.

Coming from the background of non-destructive test equipment manufacturing combined with a brief but informative position in a thermodynamics laboratory I have had an education in what is substantial and what is superfluous.

Admittedly my experience with a CO meter will most likely be brief and it will end up sitting in the cabinet next to an almost museum level collection of archaic obsolete equipment. But then I appreciate a certain responsible level of clutter...

__________________
I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.

I fully advocate filling up shelves with interesting "you never know when" type stuff!

I have have no idea if this example would be any good - but for 50 USD if I were in the US of A I reckon it might be worth a play

https://www.ebay.co.uk/itm/Neotronics-F-E-M-Fuel-Efficiency-Monitor-Combustion-Gas-Analyzer/323661764022?hash=item4b5bbe95b6:g:5dgAAOSwLKhcK7TL

It could be total crap

But if you're friendly with your local indy / garage / dealership you might be able to get them to let you do a simple comparison calibration (i.e. chuck your sensor down the next tail pipe too and compare the readings on your 50 USD piece of horse **** with their multi-thousand dollar gucci gucci - if you're friends with the mechanic I expect they'd find it rather amusing)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Still on my shelf is an old Heathkit engine exhaust analyzer. It was very helpful when jetting dual carbs on old air-cooled VWs. I used to see them on eBay.

What’s the sensitivity of a household CO alarm sensor?

Does MB spec CO as a range or not to exceed value? I don’t recall seeing excessive CO independently of excesive HC. Meaning if you fix one you likely fix the other.

Sixto
98 E320s sedan and wagon
02 C320 wagon

The Gunson meter is barely acceptable for rare hobby use. If you plan on doing this as a business or even a more serious hobby, it won’t do. The Heathkit was well regarded in its day, but who knows where to find one in good shape today.

A home CO detector is very slow acting and not built in any way for stochiometric exhaust measurement. They use non-replaceable chemical sensors, which have a ten year life in air. Exposed to CO-rich exhaust, the detector would be consumed in no time.

I thought as much

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Here is a Heathkit. Seems pricy though.

https://www.ebay.com/itm/VINTAGE-HEATHKIT-MODEL-CI-1080-EXHAUST-GAS-ANALYZER-1974-/132921577917?_trksid=p2349526.m4383.l4275.c4#viTabs_0

If you don't find one, drop me a PM and I will dig mine out. I am well retired and no longer work on air-cooled VWs.

That does look like what I remember seeing in the past. My dads' buddy used to use it for exactly the same purpose; tuning dual carbs on TYPE I's & TYPE II's. I always appreciated the Unysin but I knew there was more to be learned from CO monitoring.

PM sent

__________________
I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.

Unisyn balances airflow, it can’t tell you anything about mixture.

If you don't find one, drop me a PM and I will dig mine out. I am well retired and no longer work on air-cooled VWs.[/QUOTE]

PM sent

__________________
I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.

How you getting on with this?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Forum member TWD and I are working on a deal.

Thank you all for your contributions so far.

Kind Regards,
Scrappy

__________________
I do not 'believe'. I have no use or time for this distraction. A'priori is antiquated furniture that clutters the mind and deteriorates society. Instead I investigate, research, scrutinize then choose from data what best serves as a suitable answer until a new idea or material is presented. Then I start the process again.

I didn't mean to nag (!) I was just interested to see what you come up with - I'm not convinced I want one - yet...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!