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Author: Subject: mini failed mot high hydrocarbons
corrado vr6

posted on 5/8/11 at 09:54 PM Reply With Quote
mini failed mot high hydrocarbons

Hi there, well took my mini for mot today after a total resto and it only failed on emmisions particually hydrocarbons, the maximum limit being 1200ppm and im running at 2248ppm! I have a built up and bored 1330 engine new gaskets exhaust etc so no obvious airleaks basically me and a mechanic mate have worked on it this evening and nothing we tried made alot of difference apart from clamping off housing breathers either side of the engine going to the carb, we did an oil change as i think i put fully synthetic oil in and there was alot of blue smoke the timing is right tappets are set to the manual spec the only thing i can think of is the carb needle which was supplied with the engine or the coil as its from my origional 998 engine. Please please please any help will be much appriciated would be so nice to pass mot for the weekend but running out of ideas! I have read some suggestions of increasing the tappet gap and the spark plug gaps but not sure on this any suggestions? Greg





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PSpirine

posted on 5/8/11 at 10:04 PM Reply With Quote
If you're still using a needle from your original 998 engine your fueling will be miles out!

Trip to a rolling road is essential I reckon.

I'd be worried if you're getting a lot of blue smoke on a freshly built engine - could be valve stem seals, piston rings or crankcase ventilation.

Is it legal in UK to just vent the crankcase breathers to atmosphere instead of into the intake? That might help if you've got excessive crankcase pressure.

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posted on 5/8/11 at 10:05 PM Reply With Quote
Sounds like it burning oil... Blue smoke!

That will most like be the cause of the high HC readings

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Litemoth

posted on 5/8/11 at 10:08 PM Reply With Quote
I agree, high HC's is a sign of oil burning.

Are all the valve seals ok? Piston rings ok?

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corrado vr6

posted on 5/8/11 at 10:10 PM Reply With Quote
This is what we thought with the oil, as i think or am 99.9% sure i put fully synthetic oil in so we changed it for a recomended mineral oil which is supposedly better for sealing properties also changed the oil filter as well not sure if i now need to let it bed in with the fresh oil before next mot but its difficult to bed in when you cant drive it lol





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AdrianH

posted on 5/8/11 at 10:13 PM Reply With Quote
Only a suggestion but if you do not have NGK plugs give them a try.

Adrian





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mark chandler

posted on 5/8/11 at 10:22 PM Reply With Quote
Sounds like it needs canning on the rolling road to bed the rings in... fully synth oil is just to slippery for this to happen.
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austin man

posted on 5/8/11 at 10:48 PM Reply With Quote
the oil is probably a little too thin for the a series lump.





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zetec mike

posted on 5/8/11 at 10:53 PM Reply With Quote
More info needed

More info required, have you got the other gas readings from the test, difficult to work out the cause without knowing the co / co2 / oxygen readings. If the mixtures weak there will be high oxygen low co2. What cam r u running ? are HC's only high at idle, do they drop at 3000 rpm ?
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corrado vr6

posted on 5/8/11 at 11:03 PM Reply With Quote
Co is 3.4% i will look up the cam unsure without looking, yes HC are only high at idle when accelerator is applied they do drop, oil has been changed for 15w/40 mineral but was only done this evening with a new oil filter unsure as to how long to leave it to see of it makes any affect thanks for replies





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hobzy

posted on 5/8/11 at 11:07 PM Reply With Quote
OT, but did you ever finish the Indys?






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corrado vr6

posted on 5/8/11 at 11:11 PM Reply With Quote
quote:
Originally posted by hobzy
OT, but did you ever finish the Indys?


I did just gotta go through IVA ended up getting distracted with this mini made a bet with a mate that i could get it on the road in 6 months i failed but hey its back on the road, once its through mot my attention will be 100% on the indy especially with todays weather, hows yours back on the road yet?





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DRC INDY 7

posted on 6/8/11 at 07:43 AM Reply With Quote
When to do the test
It Is recommended that the engine is tested as soon as possible after driving on the road
.

B. Vehicles first used on or after 1 August 1975

1. Check that the analyser probe can be inserted into the tailpipe.

2. Use a suitable exhaust gas analyser to
determine the proportions of carbon monoxide {CO) and hydrocarbons (HC in the exhaust gas over a period of at least 5 seconds at idle.

Note: Any residual hydrocarbons (ie those indicated by the analyser when it is sampling only clean airj should be deducted from the HC reading obtained from the vehicle.

111.Note: If a vehicle meets the CO requirement at its normal idling speed but fails the HC check, re-check the HC level at a high idle speed of 2000rpm. If the HC reading is 1200 ppm or less, the vehicle will meet both the CO and HC requirements.
. the CO requirement must be met with the engine running at its normal (low) idling speed
. do not use a cold start/cold running mechanism to achieve a high idle speed. Instead, apply light pressure to the throttle pedal.
. HC not applicable to Compressed Natural Gas (CNG) fuelled vehicles.
B. Vehicles first used on or after 1 August 1975

1. The emissions cannot be measured because a tailpipe accessory is fitted which prevents Insertion of the analyser
probe

2. The exhaust gas contains
a. a carbon monoxide content
exceeding the limit for a continuous period of 5 seconds

b. a hydrocarbon content exceeding the limit for a continuous p


Check note 111 above i remember this from the mot maual a long time ago but have not needed to use it yet





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RAYLEE29

posted on 6/8/11 at 07:44 AM Reply With Quote
Hi ignition timing and cam timing can effect hc too worth swinging the dizzy to find a sweet spot for the emissions test.
Ray
sounds a bit rich also





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rusty nuts

posted on 6/8/11 at 07:47 AM Reply With Quote
Tight tappets ,worn valve guides and seals, wrong/misfiring plugs,HT leads, cap,rotor arm , incorrect timing, incorrect carb, settings/needle will all increase hydocarbons. My old Mini pick up running a modified MG Metro lump had hydocarbons less than 200ppm so it should be easy to get yours down. As already suggested old A series engines don't like modern synthetic oils . Might be worth setting the valve clearances to 0.015" as a start and if you are using Champion plugs the best place for them is in the bin try NGK BP6ES or even BP7ES not the BP5ES recommended
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minitici

posted on 6/8/11 at 08:04 AM Reply With Quote
If your 1330 is a new rebore the rings may not have bedded in (especially if you used synthetic oil).
Could also be due to the quality of the cross-hatching or size of the bores.
Have a look at the trials and tribulations of a Hungarian guy re-building an A-Series for his Cox GTM
Gergo
He went through dozens of therories and suggestions before getting it right.

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plentywahalla

posted on 6/8/11 at 08:33 AM Reply With Quote
I know its been said before but the rings will NOT bed in with fully synthetic oil. Always use mineral oil after a rebuild. I think your high hc is just oil breaching the rings.
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Neville Jones

posted on 6/8/11 at 09:30 AM Reply With Quote
The SU carbs are easy enough to adjust the mixture on. My MOT station used to do it during the test.

You're in Winchester, so why not go across to Tom Airey at Cheriton, just a short drive. He's about the best in the country at SU tuning.

http://aireytuning.com/

Cheers,
Nev.

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MikeRJ

posted on 6/8/11 at 11:41 AM Reply With Quote
HC is usually just unburnt fuel in the exhaust which can be a problem if you have a relatively wild cam fitted. I had a 1275 Mini with a Kent 276 cam (completely crap cam BTW the 266 and 286 are both vastly better), and it was a nightmare to get the HC low enough to pass. Opening up the valve clearances significantly and messing around with the ignition timing brought it in, just.

[Edited on 6/8/11 by MikeRJ]

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hobzy

posted on 6/8/11 at 05:34 PM Reply With Quote
quote:
Originally posted by corrado vr6
quote:
Originally posted by hobzy
OT, but did you ever finish the Indys?


I did just gotta go through IVA ended up getting distracted with this mini made a bet with a mate that i could get it on the road in 6 months i failed but hey its back on the road, once its through mot my attention will be 100% on the indy especially with todays weather, hows yours back on the road yet?



Not yet - having problems with the emissions too!






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britishtrident

posted on 6/8/11 at 07:22 PM Reply With Quote
High HC very often down to misfire, check ignition over carefully. also check valve clearances and also to check the condition of the valves do a compression test or cylinder leakdown test.
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