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Discussion Starter #1
Ok this is starting to annoy me now. Had my NCT(MOT) today and once again the car failed on emmissions. Last time their was no cat fitted so was kinda chancing my arm. This time round though I fitted new filters, plugs, and a brand new cat. What is strange is with the cat in my C0 readings have more than doubled than before at low idle, the lamda and HC at high idle are also higher, but the C0 at high was lower.
What the heck is going on. Can anyone shed some light on how I can possibly get the car to pass as my insurance company are demanding an NCT and also there is now a 1500euro fine and 3 points for not having one.
Dave.
 

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Discussion Starter #2
Also there have been no modifications made in between tests besides what was stated above. The tester also tried to pass the car as best he could by repeating the test 3 times and even switching to another machine.
 

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Discussion Starter #4
Apexi FC and is still the same map as previous.
Here are the readings if it helps:

old / new
Low Idle: C0 1.04 / 2.29 above 0.5=fail
HC 0ppm / 0ppm above 0ppm=fail

High Idle: Lambda 1.067 / 1.081 above 1.03=fail
C0 0.93/ 0.52 above 0.3=fail
HC 77ppm/ 60ppm above 200=fail

Engine Temp: 85/ 90
 

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Here in England a 1994 R32 would only have to pass a non CAT test.

CO 3.5% Max
HC 1200ppm Max
at low idle


as there is no exact match in the database or in-service emissions book.

With a Lambda of 1.081 your car is running a bit weak.

Phil
 

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Send it over to the UK, we'll MOT it for you and track it a few times and send it back ! LOL
 

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Discussion Starter #8 (Edited)
I'm sure you would Steve, but nahh.
0000 what do you mean by the car is running a bit weak.
Unfotunately over here every car post 94 is tested on low and high idle and they are set emissions values for all cars. What I am trying to understand is why have the emissions doubled with a cat in place it just doesnt make sense.
Will have a look at that acidone or do you mean acetone
 

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Discussion Starter #9
Another thing I forgot that is different from the last time is that the sensor in the cat was disconnected previously, but that only being the egt sensor shouldnt make any difference.
 

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Ideal Lambda (air/fuel mixture) is 1.00 higher than 1.00 is running weak & lower than 1.00 is running rich. Limits for MOT are 0.97-1.03.
Skylines are best run on the rich side.

Your mixture is reading too weak & this needs sorting first, can be many reasons but check your exhaust / manifolds etc.for leaks first. Sometimes the smallest of leaks can throw the readings out.

Good luck.
 

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Discussion Starter #11
Gotya, will get under the car over the weekend. But on the car running lean I wouldnt have thought so and you would probably agree if you caught a wiff of the exhaust and it also likes to pop and bang shooting flames regularly which I thought would also be a sign of a rich mixture.
But hey I am asking for advice so all replies will be noted.
 

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Discussion Starter #12
Another thing to add is the car was left sitting for a few months and the battery had to be replaced, could the map of been lost and running on a base map on the ecu.
 

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check your lamba sensors..you can check them with the power fc, there's a menu to check all sensor voltages. check also if you have actived o2 control in the power fc
 

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Give it a good run before you take it to the test centre, only drove mine half a mile to the test centre and the emissions were sky high gave it a good drive and then the emissions checked again and it was a lot lower!
 

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Discussion Starter #16
Ok what should the voltage readings be for a/f meters and 02 sensors. Currently at idle I am getting measurements of 0.84v and 0.85v for a/f and 1.5v and 1.4v for 02.
Bashman, believe me I went for a good ould drive before hand and sat there with the engine runing and held it at 2000rpm until the tester brought the car in.
 

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i have my retest on tuesday,i failed on emmissions too , i have 2 new o2 sensors to be fitted will post up my results
 

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Failed NCT with a vw vento 2.8 vr6 last week. Had to fit universal CAT, new lambda sensor, and put 15 euros of pure E85 into tank which is available in maxol at the red pump. Because the lambda reading said it was running lean I checked for any air leaks and found one between the MAF and t-body. So fitted a new hose/pipe and took it up to NCT.

NCT tester said there was fresh air coming out the arse of it now and the lambda was half the original reading but a small bit over the limit. I had to argue with him but thankfully he passed it.
 

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I also failed nct miserably on emmissions with my r34 gtr, retest in about 3 weeks time, i have a high flow cat mapped on a apexi pfc, im going to bang in a standard cat, give the car a good run, and hope for the best:thumbsup:
 

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Ok what should the voltage readings be for a/f meters and 02 sensors. Currently at idle I am getting measurements of 0.84v and 0.85v for a/f and 1.5v and 1.4v for 02.
Bashman, believe me I went for a good ould drive before hand and sat there with the engine runing and held it at 2000rpm until the tester brought the car in.
a/f voltage looks about right but O2 is way out. O2 voltage should alternate between 0.2v & 0.8v, 0.8v being rich. Your sensors are reading a rich mixture so the ECU is trying to weaken the mixture, hence lambda being 1.08 - weak.

Take a look at this:-

OXYGEN SENSORS

will explain a lot better than I can.

Phil
 
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