Emissions

Post by **newkid** » Mon Aug 04, 2014 5:38 pm

Took car in for its mot today and if flew everything bar the emissions. Guy even said its one clean example.

Heres the results

Fast idle test

co < 0.300% actual 0.726
hc <200ppm actual 44ppm
lambda 0.970-1.030 actual 1.004

second fast idle test

co < 0.300% actual 0.513
hc <200ppm actual 64ppm
lambda 0.970-1.030 actual 1.015

natural idle test

co <0.500 actual 0.477

Anyone any advice on what needs doing? Guy did mention checking air filter and spark plugs, plugs are like new (only done about 4000 miles) and filter is clean.

Do have the tanabe catback on and did have the type-s airbox if this makes any difference?

Cheers

mercutio · Post by **mercutio** » Mon Aug 04, 2014 5:52 pm

rag the drokk out of it get it good and hot or get it terracleaned or get an new o2 sensor quite a few ways to go

Post by **newkid** » Mon Aug 04, 2014 5:54 pm

Isn't the o2 sensor fine by the readings above?

mercutio · Post by **mercutio** » Mon Aug 04, 2014 6:00 pm

Excessive Crankcase Blowby or PCV Flow

If oil vapours in the engine's crankcase are excessive, or the oil is dirty or contaminated, excessive CO emissions can result. Dirty or contaminated oil is easily rectified by an oil change. Excess crankcase vapour flow can be caused by an incorrect PCV valve or by serious internal engine damage such as worn-out piston rings. Serious internal engine damage can only be remedied by major engine repair or overhaul.

For more info regarding the diagnosis of crankcase vapour control systems, see Crankcase Vapour Control System Testing.

Saturated Evaporative Control System

The charcoal canister stores fuel system vapors until they can be withdrawn and burned in the engine. Under normal circumstances, this should never result in excessive CO for more than a few seconds. It is possible for charcoal canisters to become saturated with fuel. This essentially means that they can never be cleared of HC vapors and need to be replaced.

For more info on how testing for excessive crankcase blow-by gases, see Evaporative Control System Testing.

Rich Air-Fuel Mixture

There are many aspects of the engine's fuel delivery system that may need to be checked when diagnosing a rich air/fuel mixture. That is the main reason that this is listed behind crankcase vapor and evaporative emission control systems-even though they are less likely causes of the problem, they are much easier and quicker to check.

When diagnosing a rich air-fuel mixture, it is important to keep in mind the possibility of a defect in an entirely different area affecting the operation of the fuel delivery system. For example, certain mechanical engine defects may cause abnormally low engine vacuum and result in the fuel system delivering more fuel than is actually needed by the engine. The symptom of excess CO may lead one to think that the defect lies with the fuel system but the problem actually lies elsewhere.

For detailed info regarding the diagnosis of fuel delivery systems, see Fuel System Testing.

Are Other Problems Being Masked?

An additional consideration if your vehicle failed with very high CO emissions is the possibility that it may also have a NOx problem that was masked by the high CO. Sometimes restoring the air/fuel ratio to the proper range uncovers a NOx problem. The NOx defect may have existed previously but wasn't evident because of the lack of oxygen that accompanies a rich mixture.

If possible, the technician should perform a quick check of NOx control systems after identifying the cause of the CO problem. Any problems found should be included in the total repair estimate. However, in these circumstances any NOx related repairs would be a lower priority than the CO related repairs.

At any rate, you should be aware that it is possible that a NOx problem may become evident after a CO problem is repaired.

bb1boy · Post by **bb1boy** » Mon Aug 04, 2014 6:03 pm

Find a friendlier MOT guy

..I hope you sort it mate. Emissions can be a real worry.

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Mon Aug 04, 2014 8:49 pm

Check all the vacuum lines are clean and not leaking, clean out the egr valve etc. Start with basic stuff like that I suggest. Are the plugs properly gapped? I know they're basically all meant to come pre-gapped these days, but worth a check.

Post by **vanzep** » Mon Aug 04, 2014 9:31 pm

quite a difference between first and second test -catbax and type s airbox wont make any difference as you know.
my recent test showed:
co 0.56
hc 195
and thats running rich and no cat etc

what i did notice wa that after adjusting the timing earlier this year the results are major improvement on previous years test

so maybe get the timing gun and check the disti timing
but like i said there is major differences between first and second test and thats got to raise a few questions

i also did an engine flush and oil and filter change which also made a slight improvement

Post by **Thebusofwoe** » Mon Aug 04, 2014 9:50 pm

I personally don't think he had the cat hot enough. The other readings are fine. The co is mostly controlled by what the cat is burning off. We see this alot. Just needs to be revved high for a min then the test done. You see the second time the reading came down, this is because the cat is heating up still. Get it back in and tell him to make sure its hot. I mean real hot.

Post by **vanzep** » Mon Aug 04, 2014 9:53 pm

yeah id go with that conclusion - the readings for co were similar to my reading and as you know i dont have any cat fitted

Post by **RattyMcClelland** » Mon Aug 04, 2014 10:08 pm

Put all the electrics on too like rear windown demister all lights etc etc.
Does help a little