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Discussion Starter #1
Hi,

I have an R33 running a G4, cams and 640 at the hubs.

It's been SORN since last year but I took it to get an MOT and it has failed on emissions.

1st fast idle
CO 4.00% fail
HC 267ppm pass
lambda 0.898 fail

2nd fast idle
CO 3.11% fail
HC 318ppm fail
lambda 1.030 fail

Natural idle
CO 1.84% fail

After having a look the cat has been knocked out so I now have a replacement sports cat to go on, I just wondered whether the above suggests any other problems or would just fitting a cat solve it?

Many thanks,

Matt
 

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Hi,

I have an R33 running a G4, cams and 640 at the hubs.

It's been SORN since last year but I took it to get an MOT and it has failed on emissions.

1st fast idle
CO 4.00% fail
HC 267ppm pass
lambda 0.898 fail

2nd fast idle
CO 3.11% fail
HC 318ppm fail
lambda 1.030 fail

Natural idle
CO 1.84% fail

After having a look the cat has been knocked out so I now have a replacement sports cat to go on, I just wondered whether the above suggests any other problems or would just fitting a cat solve it?

Many thanks,

Matt
Catalyst should solve it mate, I have a sports cat and from what I remember it fails one of the tests and passes the rest resulting in an overall pass.
 

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Other options are playing with cam timing.....reduce overlap.
Also ignition timing and lambda feedback via the ecu.
Also make plugs and ignition system are in top condition. Anything that stops a complete burn of the injected fuel will hurt emissions.
 

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did you pass mot test last year with all this mods without any problem, and this year it failed?
 

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the strange thing is you have lambda 1.03 and co 3.11, with this lambda value you shud have co close to zero
 

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Discussion Starter #9
Thanks, it was all replaced a few years ago and hardly been used since.

I've put a sports cat on it and also suspect it has a low temp thermostat as it's not getting hot enough and running enrichment even after a drive (68 degrees rather than 80) so I'm swapping that out next week and I'll see then
 

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Discussion Starter #10
I've changed the thermostat for a new OEM one, it was an original that was in there from December 1992! (I put a new thermostat in my old engine before it went in for the work and the new build engine seemingly came with this old thermostat)

I've tested the removed one and it's opening early at around 70, so I'm hoping replacing that and the cat will sort it for a new mot
 

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Discussion Starter #11
Just to conclude this, fitting the cat made some difference but nowhere near enough and it failed again.

After various enquiries, the car was remapped remotely through my laptop just for the MOT which got it much nearer and then a little more remote tweaking managed to get it through yesterday on the retest. Thank you for your efforts Garth!
 

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How does the car run now after the tweaks? I am guessing it was running rich? I have had similiar problems with my car even after it was mapped with the Apexi PFC.
 

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You need an ***8220;Italian tune up***8221;.

Get the car bloody hot, a very spirited drive and then get them to re-test the emissions.
 

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Discussion Starter #14
How does the car run now after the tweaks? I am guessing it was running rich? I have had similiar problems with my car even after it was mapped with the Apexi PFC.
Yes was running rich, don't know if it is too rich for the setup but it was blowing out smoke on boost and its got a sooty rear bumper, it seemed to run better afterwards and cleaner.

Just a day after sorting the mot saga it now seems to have a fairly major boost leak so any satisfaction from getting it through the mot was short lived.

Now on to the next problem!
 

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Discussion Starter #15
You need an ***8220;Italian tune up***8221;.

Get the car bloody hot, a very spirited drive and then get them to re-test the emissions.
The mot place was 40 miles away from me so it was nice and hot and they did it as soon as I got there but still not enough, if it was cold though it would definitely have been even worse
 

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I mind mine when I got it 100% stock it struggled to pass, 3 times of out for a thrash clear it out and get nice n hot straight back for emissions and just passed
 

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Yes was running rich, don't know if it is too rich for the setup but it was blowing out smoke on boost and its got a sooty rear bumper, it seemed to run better afterwards and cleaner.

Just a day after sorting the mot saga it now seems to have a fairly major boost leak so any satisfaction from getting it through the mot was short lived.

Now on to the next problem!
The joys of a Gtr :) I made my own boost leak test kit from some plastic bungs I got off ebay. Drilled a hole in the middle of one and fitted a schraeder valve assembly. Took off the afm's put the bungs in the pipes pressurised the system with air from an airline through the schraeder valve. Then sprayed soapy water around the pipe unions and watch for bubbles. I had to put a bolt into one of the pipes coming off the turbos as well. Can take some pics if it will help.
 

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Discussion Starter #18
The joys of a Gtr <img src="http://www.gtr.co.uk/forum/images/smilies/smile.gif" border="0" alt="" title="Smilie" class="inlineimg" /> I made my own boost leak test kit from some plastic bungs I got off ebay. Drilled a hole in the middle of one and fitted a schraeder valve assembly. Took off the afm's put the bungs in the pipes pressurised the system with air from an airline through the schraeder valve. Then sprayed soapy water around the pipe unions and watch for bubbles. I had to put a bolt into one of the pipes coming off the turbos as well. Can take some pics if it will help.
Thanks for the kind offer Tam, I sorted it with a coffee jar blocking off the intake and a brake bleed pressure pump on the boost sensor pipe running 5 psi.

Found a pipe had come loose behind the front bumper. So it lives to fight another day!
 
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