I almost had an MOT today. I couldn't get the car in up the ramp to the garage due to the low ground clearance. The guy pulled out the hose for the gas analyser and let me tinker for a few minutes before hinting that he'd had enough. He didn't charge me but I didn't get the levels just right. The CO was fine, the lambda droped to about 1.04 eventually but the HC ppm didn't get below 550. That was with the idle screws turned in all the way and then out by 1/4 turn.
I'd just driven 9 miles to the test station and reved it a bit. The fan switched on so the engine was hot.

what can I do to get this in for my SVA on Thursday? I could turn the screws in all the way I suppose.

Lambda 1.04, is that too rich or too lean?


[Edited on 26-11-2005 by smart51]

The higher the lambda the leaner it is. Wind the idle screws out a bit (mine were more like half a turn out). I assume you are using some form of air bleed system. This needs to pass air into the system to lean it out. If it is already running lean it cant do anything.

Also make sure you are tested at a fast idle 2500rpm ish. IIRC the test can go up to 3000rpm.

If you are getting a high lambda as an emergency fix I heard that some gaffer tape on the filter will help richen it up.

Best of luck with the test.

How long has the engine been run for?? If you haven't done that many miles on it the high HC could be down to crap still burning off your exhaust system...

I had done 9 miles when this test was carried out, plus plenty of time at idle to bleed the coolant. A couple of days later at SVA and 30 miles from new, I have the same problem. Ithe the mixture settings anywhere from 0.97 to 1.03 lambda the HC PPM wouldn't go below 500.

most of those 30 miles were fairly gentle with only about 3000 RPM although once or twice I had it up to about 11,000, just to see if it had any problems across the range

Sounds like your not far off.

I can only agree about getting the car as stinking hot as possible, it can make all the diference. If the exhaust hasnt had a chance to cure any paste used, the emmissions will be well over. Ive had (car engine) in the past which was a mile out but that was due to the paste burning off which was used in fitting the CAT in an attempt to pass the test!! Took the car for a spirited drive for an hour and it was a completely different beast.

Is the CAT ok? Are you using an elaborate air bleed system or some cuning baffles etc in the pipe.

Keep us posted

Kind Rgds

Rich

I had fitted exhaust sealing paste a couple of days before visiting the MOT test station. It could be the paste curing.

The cat was lent to me by OX. It was new 3 or 4 SVAs ago

I am not using an air bleed system. Marc from MNR has had several R1s though SVA just by adjusting the idle mixture screws. With the mixture just right, the cat SHOULD burn off all the nasties.

Not necessarily. The OEM only loads the cat with enough Platinum to get the emissions below the current legislation. They dont give platinum away for free!!!

Having reshimed the valves on my engine, I went to have an emissions test today. The results were a little better. The hydrocarbons were in the range 250 - 350 ppm which is still a bit high.

The lambda reading was too high and wouldn't come down no matter what I did. It started off at 1.4 something and I got it down to 1.2 something by winding out the mixture screws by 2 turns. At 2 1/4 turns the CO reading went up from 0.03% to about 6%. The mechanic said that he suspects a leak somewhere, as he pulled the probe and tidied away the emissions tester. He suggested using a bit of tube held up to my ear to find it.

The exhaust jount to the cylinder head on No4 cylinder made more of a ticking, fizzing noise than the other cylinders so I tightened this up. the 4-into-1 joint also makes a noise that reduces if I move the tube from between two of the exhaust pipes to piont squarely at 1 pipe only.

Can air leak INTO and exhaust? If so this could explain the high lambda.

Is there more likely to be a problem on the inlet? I checked the spark plugs for tightness and also the rubber joins between the carbs and the head. They were fine. Sqirting WD40 on the joins had no effect.

If an airleak on the exhaust was causing the lambda to be high, could this affect the high HC readings or is this likely to be yet another problem?

how hot are you getting the cat ,,on both my cars i had to get the manifolds to a dim glow.
the only way we could get sheds car through the emissions was to do the test with out the airfilter in,,the air filter looked new,wasnt pure white more of a light grey so it hadnt done that many miles and it didnt stink of fuel.

emissions are to went crazy about them....

i even feel mine failing...

because it smells like hell and in an close room lets say 3 by 2 by 2mtr with only one side open in one minute your clothes get an very nasty smell.

the smell is like fuel..

is this the right discription..of problems comeing up..??

offcourse it has been ages that i have had the engine running, and the exhaust is fairly sure leaking.....also the air filter can be changed..(grey colour..)

Tks

p.s. if on idle you see flames some times what does this mean? to rich? bad sparkplug? bad coil?

most of the time its only 1 cilinder...

when you accelarte to an higher rpm they don't come..but when you let the throtle down they will be there for an split moment...

its on an injection system...

The engine was hot enough that the coolant fan cut in. I couldn't say how hot the cat was as I didn't look.

you need to get the cat cooking... rev the goolies off it up and down to get it hot, then it should improve

OK so revving it hard to roast the cat may reduce the HC, what about the lambda?

it should help that as well

get the lambda about right then roast the cat...

Stuffing an old teatowel ip the tail pipe alowed my to find several exhaust leaks. 1 in the joint between the manifold and the cat, several in the welding either side of the cat (sorry Ox) and a 2.5mm round hole in the side of the can. Liberal aplications of exhust sealant plus a rivet in the can seems to have sorted these out.

Now that I've let the sealant dry, I've tried it agian. With all the other holes plugged, a leak in the 4 into 1 joint can be felt. It seems to be between the 4 pipes.

How can I get to this joint to seal it? I don't want to take it off if I can at all avoid it.

the hole in the cas isn't there for

draining purposes?

i thought my bike cans also had them...

well you can easyly see because it should be an nice hole..


Tks

only two thoughts. Exhaust lagging might help keep the cat temperature high, and aparently silicone sealant can withstand exhaust temperatures in the short term, so could be used to plug holes.

another thing to try is to blank off part of the tail pipe - this keeps the exhaust gas it the system - air can somtimes feed back up the tail pipe and upset the readings. -especially if they are jumping about a bit

quote:

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Originally posted by JoelP
only two thoughts. Exhaust lagging might help keep the cat temperature high, and aparently silicone sealant can withstand exhaust temperatures in the short term, so could be used to plug holes.

---

quote:

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Originally posted by G.Man
[silicone will last about 2 seconds... my exhaust headers were glowing red in my sva test..

---

OK so now I'm depressed. Just had an emissions test at an MOT centre and despite getting the lambda OK the HC jsut won't drop below 600 reliably.

Blocking up the holes in the exhaust has reduced lambda to a sensible level but despite tweeking the fueling for 1/2 an hour it wouldn't go right. Interestingly, when revving up to 2500, lambda would slowly drop from about 1.35 down to 0.9 but then HC would go up from 600 to 1200 or more.

I am really at a loss now. After 1/2 hour in the test booth the cat should be more than hot. what else can I do?

Are you really caning the nuts off it beforehand to get the cat properly hot though? I doubt it would get the red-hot that others have mentioned is required just from sitting idling for half an hour.

There is absolutley no need to get your catalyst 'red' hot. As long as it is above about 300 degrees celcius then it is in the designed operating range.

Your problem is either:

1. Your cat is shagged
2. You are producing far too much HC for the catalyst to oxidise (for example, crap still burning off the exhaust, burning oil, overfueling etc). The catalyst has a specific Pt loading in grams per cubic foot of surface area. If the HC are above a certain limit then you will never pass the MOT test even with a brand new cat


Sounds like you have investigated the fueling but not getting anywhere with that avenue. Is the car using oil? Can you see any visible smoke from the exhaust?

When they test the car is it jacked up or on level ground?

Is your engine at a funny angle in the car so more oil is sitting around the valves?
[Edited on 26/11/05 by R1minimagic]

[Edited on 26/11/05 by R1minimagic]

[Edited on 26/11/05 by R1minimagic]

The engine was hot enough for the cooling fan to cut in. I had revved a few times during the test but no so much that it glowed. Just how had to you have to run it to get it litterally "red hot"?

The engine is installed at the correct angle (I believe). There is a bit of white smoke when the engine is cold. Is this more than just water?

The car is sat on the concrete floor of the garage. Does this make a difference?

If you have some white smoke then i think that could be the problem. Water wont give smoke, it will just drip off the end of the exhaust pipe on startup (unless you are talking about water vapour in cold weather??)

If the car or engine is tipped then you could be getting oil going down past the valve guides and producing smoke.

Went to my local MOT garage with the new cat fitted and with just a little tweaking it has passed the emissions: 160 PPM with 1.01 lambda and 0.01% CO. Birmingham SVA centre weren't answering their phones at 4:45 so I'll try again in the morning. Fingers crossed.

Big thanks to everyone for their help.

hi colin glad the new cat sorted it , just be carefull driving your car around that lean

best regards

marc

nice one m8
sorry the cat had worn out,the only reason i can think that caused it is all the silicone or exhaust paste that has passed through it.glad it's all sorted now tho

Lean? Lambda 1.01 is prety much stoichiometric. Are R1s meant to run a bit rich?
The idle air screws are all turned out by 2 turns more or less. I suppose Haynes does say 2 1/2 turns.

Ah! I have just put all the needles all the way in. maybe that's amde it worse.

[Edited on 6-12-2005 by smart51]