tim windmill
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| posted on 19/2/08 at 07:34 PM |
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sva tomorrow and emmision woes
sva tomorrow and had my car back on the machine to try and sort out the emmisions, sadly its not looking good,but i will still take it and get a fail
sheet of items to be put right. So it looks like i will be looking for a bigger cat and car exhaust silencer.
if anyone is has gone bec from cec and want to do a swap for my modified carbon r1 can, (rolled end and 52mm inlet to slip on link pipe)please let me
know
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MkIndy7
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| posted on 19/2/08 at 07:47 PM |
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 Come on Tim, there must be some hope?.
What happens if you run the engine really lean, do the other emissions like the HC suffer?.
Is there no way to run a descent map to the SVA (if its not trailerd) and then put a really lean map that runs crap on for the test?.
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tim windmill
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| posted on 19/2/08 at 08:07 PM |
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its being trailered there so no problems with running a lean map but it buggers up all the other readings when i alter it! and when i run it really
lean it wont register on the machine and melts the probe OMG, ithink i will try a bigger cat on the retest and a cec silencer rather than the r1
can.
somebody out there must have got a blactop through using megasquirt and standard tb and injrctors, how did you do it?
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MkIndy7
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| posted on 19/2/08 at 08:22 PM |
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Mines always been running on the over rich and thus hopefully safe side, and its on the old boat anchor so i've never had to worry about
emissions!.
I can watch mine much closer on the wideband lambda though to know where abouts either side of correct the reading is.
Maybe far too lean is making the other way then, i've never had to set a car up for the HC test but I do gas boilers for work so it should be a
similar preinciple.
I would have thought somebody could give you some pointers as to what to set things to tho, for example we set boilers to:
9-10% Co2
4% O2
This usually gives under 100ppm carbon monoxide. (probably your equivalent is HC's)
If we lean the air off to 2% for example the Co2 reading goes up accordingly and the carbon monoxide goes above 100ppm
Same if we put too much or little gas on that sends the emissions wayward.
There must be some kind of pointer like that for car engines, unless the 14% AFR is the target?.
Your fixed with the incoming air.. so there can only be the required amount of fuel to burn it that needs sorting.
Can you not just set the lambda to run closed loop and manage itself, if its brought slowly upto speed and no wide open throttle movements it should
be ok?
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tim windmill
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| posted on 19/2/08 at 08:34 PM |
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how do i run closed loop, what settings do i need to be looking at? i am sure that if somebody knows what they are doing with the megasquirt it could
be achieved on my existing set up
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MkIndy7
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| posted on 19/2/08 at 08:46 PM |
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I've just looked and there's quite alot of Zetec base maps here: Link
This might be the kind of values I was tring to explain and equate to what we use for gas:
Tuneing for Emissions
Bugger, the closed loop settings might only work with a wideband sencor but here's the info:
Wideband AFR targets
Basically on part throttle and low load cruise it constantly fine tunes itself to give the AFR you request.
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tim windmill
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| posted on 19/2/08 at 08:50 PM |
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the zetec nb is the one that i am using from the link that you gave me. it drives really well but wont pass the emmisions , i have tried leaning the
fuel table and messing about with the timing but dont seem to be getting anywhere with it
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MkIndy7
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| posted on 19/2/08 at 08:59 PM |
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I've just noticed this on the tuneing for emissions page:
"With a converter, emissions would have been best at stoichiometric mixtures and the timing retarded somewhat"
So i'm guessing the cat likes to be warm! although if yours has been melting the testers probe when running lean then its obviousley been pretty
warm.
Other than that i've no idea about cats and how they work, maybe yours isin't big enough, that gas is flowing through it too fast or maybe
something else is amiss.
I would presume that they turn NoX into Co2.
Is the fuel pressure the standard reducing valve for the Zetec, there isin't too little or not enough fuel pressure thats throwing you?.
The chances are that as the fuel table is altered then the ignition table needs altering at the same time (presuming you've not just altered one
and then the other)
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paulf
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| posted on 19/2/08 at 09:55 PM |
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If you set it up to run closed loop with the narrow band sensor you should be able to get it correct at a fast tickover.You need to make sure that the
O2 feedback is active at the idle speed , it is usually set up at a speed above idle to give a steady tickover at richer than stochimetric mixture.
Check the O2 settings and set it active at maybe 500rpm and up the idle speed to a 1000rpm you could then tweak the mixture until the gauge on the
laptop for 02 reads 14.7 This is obviously dependent on the cat working correctly and being hot enough.
Paul.
Paul
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