Help Hi Hc Emissions
Posted 18 October 2019 - 08:31 AM
Mini I’m talking about is a 1982 mini 1000 only mod is a cone air filter
Hope someone can help I’ve recently decided to get my mini back on the road I’ve changed her head gasket and taken her for an MOT where she failed on high co emissions so I brought her home about 2 miles from the garage and turnt the adjuster a couple of turns to make her run a bit leaner.
I then took her for a re-test and the co is now ok but the hc emissions have jumped from 500ish to 6000 I’ve tried adjusting the carb but it’s made no difference and the guy at the local garage is at a loss. Any ideas of what this could be would be greatly appreciated.
Many thanks in advance
Posted 18 October 2019 - 09:07 AM
Check the plugs. They may have fouled up due to running rich and could now be misfiring.
Posted 18 October 2019 - 09:12 AM
Posted 18 October 2019 - 09:15 AM
Have cleaned them and no improvement..: could it be the valve clearances or timing have slipped?
Neither will cause high HC and timing is on a chain, if that's slipped you'd have bigger problems.
A couple of turns of adjustment is too much. You should do it quarter or half turn at a time with the emissions reader attached to the car. If the MOT station is reasonable they should let you spend a few mins getting it right.
Also make sure your idle speed is correct, I've had a couple of incidents where a marginal car has passed by tweaking the idle down a few RPM where it was a little high.
Edited by Icey, 18 October 2019 - 09:16 AM.
Posted 18 October 2019 - 09:21 AM
Posted 18 October 2019 - 09:30 AM
It's possible for the ignition timing to slip if the distributor clamp is loose. Anything that causes a misfire will raise the HC emissions quite substantially. I'd be suspecting something to do with the ignition system if the carb idle mixture is ok.
Posted 18 October 2019 - 09:35 AM
Have tried adjusting carb at the garage while on the emissions machine but can get the co to 3.5% but the hc is still around 6000. Took her for a run to warm her up and she feels low on power that’s why I wondered if the distributor had moved or the valve clearances had altered
Apologies, you're quiet right, I was thinking cam timing not ignition timing for some odd reason. So yes it's possible an ignition timing change may throw emissions out. First is simple checks like vacuum advance is connected/no leaks and then to use a gun to check the static timing.
Posted 18 October 2019 - 09:55 AM
Is it still on points or have you fitted an electronic kit - at £40 ish it's worth fitting if you still have points.
High HC is normally a sign of poor ignition, so plugs, timing, spark, coil are all possibilities.
Posted 18 October 2019 - 10:21 AM
So thats good. Make sure it's timed correctly.
Does it start OK from cold ...just thinking of a way to isolate a coil problem, it it was iffy it might struggle to start?
Did you do a compression check when you put the head gasket on ...dont think it's that but it worth a check if you have a gauge?
Also, did you redo the tappet gaps when you put the head back on ...once again worth a 5 min check.
Posted 18 October 2019 - 11:07 AM
Posted 18 October 2019 - 11:59 AM
Posted 18 October 2019 - 12:09 PM
Strange how the HC reading jumped from 500 to 6000 just from a little drive and a carb tweak. Was anything else touched at the same time?
Posted 18 October 2019 - 03:33 PM
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