Emissions what do I need to look at.........

[Herman Toothrot]

Last year = High Lambda, so I thought exhaust leak, I found a leak at downpipe slip joint, sealed it car passed.


This year = High Lambda, so I look at exhaust again, seal up all joints. It initially passed Lambda and Hydrocarbons but fails CO at 4%. I whip out laptop thinking lean it out a touch and we'll be fine, basically didn't make any headway, it would either swap between high lambda or high CO. After 10 minutes playing I couldn't get lambda back passing...

Car is a '97 1.8 Eunos Turbo, with CAT fitted, no narrowband, but does have a wide band fitted in down pipe, pre CAT. I can turn the lambda trim on and off witht he ECU, last year in was running open loop with no sensors.

I'm thinking its still leaking somewhere, as the lambda went to being to high, but no i'm also worried the CAT may not be doing its job withthe high CO, but then it can pass so that makes me think its ok. CAT is one year old sports CAT. I have been running a little on the rich side on boost 11:1 to keep engine safe (cars just a track car, but needs to drive to tracks), it does very few miles per year 3000 maybe.

Any suggestions?

[FWDRacer]

Try oil and air filter change if you were only missing the CO2 by 0.5?

[wildoliver]

Good service, clean plugs, clean or replace air filter, oil and filter.

Italian tune up on way to mot station.

Oh and I suggest finding a more relaxed Mot station!

[350Matt]

Try a bit more spark advance at idle if you can, also how does your sensor compare to the MOT one?

As your sensor may be on the way out?

Matt

[Herman Toothrot]

I calibrated the WB only on the weekend when I had the downpipe off, it cals to free air so should be good. Car certainly runs well, sensor is only about 9 months old. It was showing a variation from the MOT centres, but then his is stuffed up the rather large bore exhaust (another concern of mine is its too big and "sees" atmospheric air possibly) where as my sensor is in the downpipe pre CAT, difference was only about 0.5 AFR.

I'll try increasing the ignition timing, I was only fiddling with the fueling when I had a play at the station. MOT man seems a nice bloke and said he's happy to check emissions first before commencing a test.

[Herman Toothrot]

Well, had the exhaust off again, all joints totally sealed, new studs on manifold and turbo all torqed down nice and tight, new plugs with a slightly wider gap just for the test (need a small gap for on boost), tweaked the mapping so that all cells hit during the test required no more than 1% trim from the wideband to be Stoich....

and it passed Hydrocarbons and Lambda but still failed CO by 0.07% coming in at 0.37%

Must be the CATs been killed running rich for the track.

[That Daddy]

Herman Toothrot said:

Well, had the exhaust off again, all joints totally sealed, new studs on manifold and turbo all torqed down nice and tight, new plugs with a slightly wider gap just for the test (need a small gap for on boost), tweaked the mapping so that all cells hit during the test required no more than 1% trim from the wideband to be Stoich....

and it passed Hydrocarbons and Lambda but still failed CO by 0.07% coming in at 0.37%

Must be the CATs been killed running rich for the track.

That sounds possible as thats about as good as it gets closed loop with no cat running(its clean though)i figure your cats failed it tightens down that last bit of CO.

[anonymous-user]

I've got a 440mm (I think) cat here just around the corner from Jon's if it will help you for MOT time.