Holding back at lights

Hi all, I have a 1991 GTi, DX engine cabriolet and I took it for an MOT last week and the co2 has high, so the MOT station lowered them to the correct reading of his emissions machine and passed the co levels. Now when I move from a standstill position eg traffic lights etc it holds back before moving off. I checked the timing which is correct at 0 degrees advance but am I right saying it should be 6 degrees advance and if so what else should I check so it stops holding back. Thanks in advance for all responses.

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The CO should of course be checked before adjusting the idle mixture. According to the Haynes manual, ignition at idle should be between 5 and 7 deg before TDC with the distributor vacuum advance hose disconnected

Hi the co was checked and as it was high it was adjusted to meet the required co level, I ll adjust the timing to 6 degrees and take it from there. Thanks for the info

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I don't know what the max CO level is for a 1991 car but for my 1983 one it's somewhere around 5% I think, it seems to run best somewhere between 1.5% and 2%,.
Check the max for yours, the MOT tester could have got it wrong and it could be a simple fix, you don't want to run it too weak.

The MOT emissions limits are:

Cars registered before 1 Aug 1975 (N suffix and before): Not tested

Cars registered from 1 Aug 1975 and before 1 Aug 1986 (P suffix to
C prefix): 4.5 % CO, 1,200 ppm HC

Cars registered from 1 Aug 1986 and before 1 Aug 1992 (D prefix to J prefix): 3.5% CO, 1,200 ppm HC

For cars registered from 1 Aug 1992 and before 1 Aug 1995 (K prefix to M prefix), the rules are more complex, Basically, if the car was originally equipped with a catalyst, a much more stringent emissions test applies, but if not, the previous limits of 3.5 % CO and 1,200 ppm HC apply.

In my experience, most MOT testers are unaware of these transitional rules for non-cat K, L and M prefix cars, so may apply the more stringent catalyst emissions test, which includes an idle CO limit of 0.3% CO and HC limit of 200 ppm, as well as a test at fast idle speed. Could this have happened with your car?

I won't think so as the MOT tester has been working on cars for a very long time maybe 40 plus years and is very clued up. The co was showing 6.2 at idle that is when he told me it needs to be brought down which we did, I can't remember what we brought it down to but as close as we could get it

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A time-served MOT tester should hopefully have the common sense to know that all but the very last Mk1 Golfs were non-cat cars, and apply the correct limits. However, because non-cat K, L and M- reg cars are extremely rare, for many testers, it will be the first time they have seen one.

I have been incorrectly told in no uncertain terms by an ex-police vehicle examiner/agency MOT tester that my L-reg Scirocco will fail its MOT if it doesn't have a catalyst, with the car initially failed due to emissions test not carried out, but passed on retest after giving the test station manager a copy of the flow chart from the MOT inspection manual. He now always briefs any new tester at the beginning of the test, so they don't make the same mistake.

I once took the car for an MOT and like yours the CO was between 6 and 7, I had missed plugging the connector back in the warm up regulator.