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davev

Exhaust Readings

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davev

hi. i have had the oppurtunity to have a look at my emmisions while my boss was out. and these where the readings.

 

rpm 1262

%vol co 2.545

ppm hc 281

lamda 0.964 (i dont have one as its a non cat car)

%vol co2 12.76

%vol o2 0.93

temp C 7 (i didnt measure)

 

just thought i would put these up as i think its running a little lean. and would like your opinion.

 

by the way its an mi with bike carbs on 8valve management just in case it makes a difference.

 

cheers. dave.

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Alex G

sounds a bit rich for idle.

by the looks of it you are running fast idle and hence warm up enrichment

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Richie-Van-GTi

mine at last test, 1.9 gti was idle at 1000 rpmish and CO % vol was 2.4 which they reckoned was slightly lean. Thats a pre 92 decat model. Not sure if that helps since its similar displacement. He reckoned 3% is right for a decat 1.9.

Could always use a colour tune or something and check that its burning right.

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Rob_the_Sparky

Not that it really matters anyway as idle fuelling is adusted completely seperately from normal running!

 

Have been told in the past that book CO was 1.5%...

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davev

sorry to drag the post back up, i have not been on regulary enough to realise anyone replied. :P

 

so your basicly saying that the idle emmisions dont really indicate how the car is running on the road? if so how do i check if its running lean at high revs?

 

cheers. dave.

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Anthony

Rolling road session with a wideband lambda probe would be the most accurate way of doing it.

 

A somewhat more crude (but free) method would be to drive with the engine at high revs/load for 30-60 seconds or so, quickly pull over and kill the engine, and check the colour of the plugs - whitish is lean, tan is good, and black is rich.

 

As said above, idle mixture is completely independant of running mixture - there's a small allen bolt on the AFM that adjusts idle mixture, and aiming for around 1.5-2.0% CO is about right. Yours isn't too bad though, and well within MOT limits (3.5% CO and 1200ppm HC IIRC)

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davev

looks like i need to get it on the rollers then.

 

the main reason for checking is that when i put the reangle manifold plate on (just before the bike carb conversion) there was alot of fuel soaked carbon around the exhaust ports. and im worried that it might have give a false reading when setting them up.

 

that and the fact it dont seam to pull as hard when you go above 5500rpm.

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simonb

I would just go by the plug colour if you can't get a RR session. What's the economy like?

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davev

fuel econamy? didnt think it existed on these cars :blush: id say about 65 miles to a tenner on the motorway and as little as 45 in town if not less. and thats without giving it loads.

 

i'll try the plug style out when ive got abit of free time.

 

cheers. dave.

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Rob_the_Sparky

You should be aiming for 30mpg or more. With driving to work and back I get 30-35mpg, although 35 is more usually only attained on a long MWay run.

 

If we work on £4.50 a gallon then you are getting ~30mpg on the MWay so not bad at all.

 

Rob

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