CO emissions failure.

[Nick Mann]

Why would a VR4 pass its emissions on everything except CO? The HC was at the top end, the lambda was spot on, but the CO was 0.7 where the max is 0.2.

I thought CO meant that the engine was running rich, so not enough oxygen in the system to get full combustion, so CO instead of CO2. But surely if the engine is rich the lambda will be out?

[Kieran]

I presume this is your car, Nick?

What state is your cat in?

[shaun1978]

I know it's a stupid question but did you get the cat warm and give it some beans before you put it on the machine?

[Nick Mann]

Yes its my car. The cat was fine last year and hasn't seen much action since! It should have been roasting hot when the emissions were tested - I spent the previous 10 minutes thoroughly enjoying the local countryside lanes!

Would the cat give the problem? I'm not saying it is, but it seems strange that it was okay last year, and apart from eat a spider or two it hasn't done anything since?

[Davezj]

maybe it is the lack of use.

as far as i can remember the cat is a honey comb affair and it will absorbe moistur readily. maybe it could be that and you just need to use it more.

that is just a thought i have nothing to back up my theory.

[shaun1978]

one other thing - I left my GLS stood for a year at one point (had other cars to use) and when I eventually started it up it blew the cat's internals apart.... and this was an OEM cat also....... just a thought mind

[Physician]

I guess it isn't going to help you Nick but .... my cat is sitting on my garage floor if you want to borrow it.

[GalantOnly]

Do you have an aftermarket air filter in it? If so, you should try with factory one...
...Clean one...

[swinks]

CO emission increased may indicate small oil leak into combustion chamber (i.e. piston rings, valve stem seals). Just check spark plugs deposits.
Or just injectors, air intake plenum and throttle body to clean (and new filters). Cat failure is much more than your 0.7% on fast idle.

[Kieran]

CO emission increased may indicate small oil leak into combustion chamber....

You could be onto something here Swinks.... Nick's engine is a bit 'oily' - But normally I thought that pushed up HC levels?

Nick - What does your 02 signal look like in EVOScan? I'm wondering if that's gotten a bit lazy again? Also, is your MAP-ECU upsetting the applecart?

[swinks]

You could be onto something here Swinks.... Nick's engine is a bit 'oily' - But normally I thought that pushed up HC levels?

Not necessary, you have increased HC with common headgasket failure, where coolant and oil mixture is getting into cylinders. If it's only oil thru piston rings or valve stems, and it's not much (let's say, engine drinks 1.5l of oil for 7k miles), with good ignition and compression you can get only CO inreased on emission test.

But, IMO just air intake needs good wash.

[Nick Mann]

I have a pretty clean HKS panel filter in the car.
The MAP2 ECU is in and proably not quite right yet, but 2500 rpm is still closed loop, so you can se the PLX AFR bouncing around 14.7 during the emissions test.
I do burn a bit of oil, especially when idling, so that could be the answer I guess. In which case, I'm going to struggle to put it right before JapFest.

The one option I do have is to remove the ECU lambda feed, and then tune it using the MAP2 at 2500 to run slightly lean. That should reduce the CO a bit? But can I keep the HC and the lambda in spec too.......