Indirect follow on from another thread where my 205 GTI recently went through it's MOT. Car uses much the same Bosch injection set up as a lot of MK2's, so thought it may be relevant. Got a Gunson Gastester a few years back (highly recommended) and they advertise them as having a +/- error of 0.5 CO, to let you can make allowances in case it indicates a level that's a borderline fail. Previous MOT I got 1.3% on the Gunson, the test center got 1.320. For todays MOT the Gunson gave me 1.5%, the test center got 1.530 ... so pretty accurate. Down side of the Gunson is it only tests for CO and not HC's. Is there a correlation between CO and HC? For example if one goes up does the other drop? Ask because last years test center results were CO 1.320 and HC 153 ppm (at idle) Todays were CO 1.530 and HC 214.0 (at idle) It's just something I'd like to understand better!
HC s is unburnt fuel, crank case gases etc. If you have an air leak for example the HCs can be way high
Few ancient posts on the 205GTIDrivers forum seem to suggest Peugeot originally recommended 1.0% CO as ideal, but engines with some miles on them (I'd imagine they must all be now) it's suggested between 1% and 2% is to be aimed for. Between 100 and 200 ppm for the HC's is also mentioned as a target. Don't know if any of that is accurate or otherwise. If it's close, looks like the car's sitting where is should with those figures. Have sussed the CO adjustment, but if the HC went off target would be good to know how to try and sort it. Thanks for replys.
