Measuring vehicle emissions at home

  1. ibrooks Member

    Messages:
    1,009
    UK Lancashire
    Does anyone know a way to measure the exhaust emissions of a petrol car at home? A semi sensibly priced machine I'm guessing.

    I've got a Gunson gastester but it's always been a bit toffee at the best of times and even then it'll only measure CO and not hydrocarbons and whatever else they measure.

    It's something I've wanted to be able to do for a while but a recent MOT failure on emissions of the Discovery has sort of prompted me to try and look into it again. It's one of the few areas where I can't check the results of my work myself and know that when it rolls back out of the garage it's fixed. I'm going to fix what I think the problem is and then have to take it back to the garage before I find out if I've fixed it or if there's another problem I've got to chase down - a bit more trial and error than I'm happy with. One of the problems with more modern vehicles I suppose (yeah yeah it's 23 years old). It runs fine and there's no visible smoke but I think one of the cats has broken up resulting in the failure.

    I've thought of a lambda sensor and some wiring but they are an oxygen sensor if I remember rightly?
     
  2. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    13,394
    Location:
    East Yorkshire
    Enquire with your local indy’ garages. Wouldn't surprise me if they dont have an old unit sat in a corner. my local was trying to give me one the other day
     
  3. mtt.tr

    mtt.tr Member

    Messages:
    454
    Essex England
    Pretty sure an o2 would give you half a clue.
     
  4. CompoSimmonite Member

    Messages:
    4,109
    Location:
    Werrington, Stoke-on-Trent
    Have you plugged in a OBD tester to see what is at fault ?
     
  5. ibrooks Member

    Messages:
    1,009
    UK Lancashire
    Yeah but big, out of calibration, loads of other functions I'd never use. I have had an idle look on ebay and there are units available all through the price spectrum but they are big floor standing things and surely just to measure the gases it doesn't need to be such an item - or maybe I'm wrong and that's why a hand-held thing to do what I want doesn't exist.

    Maybe - hence my wonderings about a lambda sensor welded into a pipe I could clamp onto the tailpipe of a vehicle I'm looking to measure whilst it's running on the driveway.

    See where I mentioned that the car is 23 years old....... that means no OBD unfortunately. Besides which the lambda sensors are before the cats so if I'm right and the problem is down to the monolith in one of the cats having broken up the cars own sensors aren't going to know about it or show anything unusual. A really modern thing (like sub 20 years old) would possibly have pre and post cat exhaust sensors and would probably have put a warning light on before the MOT showed up a problem and flag a fault code.
     
  6. rtcosic

    rtcosic Member

    I had a little poke about on the internet. I see why the Gunson thing is no use. CO only and +/-0.5%. So vaguely useful for setting up carburetor engines but not for modern ones.

    I found some hand held units in the £1500-£2000 range that might do the job, but I suspect that's more than the vehicle is worth.

    The equipment required is relatively sophisticated and low volume production so expensive.

    A cheap boiler flue gas tester in the sub £500 range only measures CO, but with greater accuracy and precision than the simple Gunson thing. If you know any central heating installers you might be able to borrow one and it may help.

    Otherwise talk nicely to the indy who offered you the old MoT standard tester.
     
  7. Anguz

    Anguz Forum Supporter

    Messages:
    388
    bedfordshire
    wide band lambda and a innovate display would give you a clue as to how rich, if you are prepared to weld a boss on the exhaust before the first cat
     
    Dcal and mtt.tr like this.
  8. Parm

    Parm Metal Tinkerer

    Messages:
    8,263
    Location:
    Towcester
    Good idea but worth checking the operational range, I think the boiler flue analyser won’t go high enough for a car exhaust
     
    mtt.tr likes this.
  9. Kayos

    Kayos Member

    Messages:
    4,456
    Location:
    Yorkshire
    Flue gas analyser will measure into the thousands of ppm co however it will kill the cells. Anything over 500 I pull the probe (and turn boiler off)
     
    Parm likes this.
  10. CompoSimmonite Member

    Messages:
    4,109
    Location:
    Werrington, Stoke-on-Trent
    I assume it's a Disco 1 as Disco 2 had OBD.
    Quick search finds this -

    For a Disco 1(none US market) the OBD socket will only allow access to the 10AS Alarm ECU. The socket, a 16 pin item, is at the bottom edge of the dash panel.

    The engine management system, called hotwire, uses a 14CUX ECU and is not OBD compliant. The socket is behind the panel on the outside of the RHS footwell. Diagnostic access can be achieved by units such as Rovacom or Autologic. There may be other economic systems that claim compatibility but these two do work.

    You might find an independant Land Rover specialist will have Rovacom or Autologic diagnostics.
     
  11. CompoSimmonite Member

    Messages:
    4,109
    Location:
    Werrington, Stoke-on-Trent
    I've got a Gunsons tester and agree - brilliant for carb engines but useless for modern units.
     
    rikrobson likes this.
  12. Robotstar5

    Robotstar5 Casanunda Staff Member

    Messages:
    17,624
    Location:
    Birmingham
    When I had emissions problems on my 3.9 Disco 1 I took it to an independent and they plugged in somewhere behind the dash to read the sensors, turned out a previous owner had gutted the cats so I traded it in before the MOT ran out.
     
    Parm likes this.
  13. minimutly Member

    Messages:
    277
    Location:
    Pembrokeshire Wales
    Whatever you do don't buy an old mot testing machine - you can have mine if you want. It won't be any use for you since the callibration has expired and locked everyone out. The thing is useless, no good for anything. And they all do it, probably by law.
     
  14. earthman Member

    Messages:
    632
    I have one too, haven't used it for years now though.
     
  15. M.F. Member

    Messages:
    30
    Location:
    Lancashire
    Not sure about the latest machines (because I’m no longer in the garage equipment trade) but certainly Crypton 290 4 gas analysers had 8 dip switches located under a panel on the rear of the unit-switching on number 8 would override the calibration lockout feature. There has to be a way of getting live readings off a machine, even when the calibration is expired because UKAS calibrations require ‘before’ & ‘after’ readings to be entered on the calibration certificate
     
    earthman and minimutly like this.
  16. minimutly Member

    Messages:
    277
    Location:
    Pembrokeshire Wales
    Ha, I'll have a look, but previous searches failed to find a workaround, it would be great to find the answer here though - Should maybe have asked?
     
  17. ibrooks Member

    Messages:
    1,009
    UK Lancashire
    Yeah it's a Disco 1 but as said the cars own Lambda sensors are before the cats so if as I suspect it's one of the cats that's at fault the sensors aren't going to see anything unusual.

    I've been googling some stuff since and it would appear that you can get handheld testers that will test multiple gases including HC from alibaba in the range of $250. Most just have the sensors in the front of the hand unit and need a supplemental pump and cover to be fitted/attached to draw gas from an exhaust. For the moment I'm partway through fitting a new set of downpipes with cats and I'll ask the MOT place to shove the probe up the exhaust and give it a sniff to see if it's fixed the problem before the log it on and start an actual test when I go back. For other cars in the future I'll keep chasing these cheapanese testers and see if there's something that I'm willing to take a punt on.
     
  18. ibrooks Member

    Messages:
    1,009
    UK Lancashire
    What emissions problems did you have if not at an MOT? Or at least how were you aware of them if it wasn't shown up by an MOT?
     
  19. Robotstar5

    Robotstar5 Casanunda Staff Member

    Messages:
    17,624
    Location:
    Birmingham
    I had the car given a good service soon after I bought it and the guy said it looked like the cats had been cut and welded so I took it to my local MOT garage just to see what it was kicking out, they said it would never pass an MOT as the readings were well over the limit.
     
  20. ibrooks Member

    Messages:
    1,009
    UK Lancashire
    I've looked and a lambda only measures O2 so no good for what I'm after as it's specifically HC that I'm trying to measure on this occasion. I'm also looking for something that would be useful on other cars in the future.[/QUOTE]
     
    Anguz likes this.
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