Idle CO emmission failier

[router]

My car just failed the MOT with idle co at 4.19 the passmork is 3.50 this seems to be way out can someone advise me how to get this under control..

[paulrwebster]

Presumably it is an SE so no cat to worry about. Have you chipped it? Is the Lambda sensor cream crackered?

[lotuska]

Procedure for adjustment is in the electrical manual (relavent pages attached in zip file).

Also note that there was a upgrade to the ecu to allow the correct adjustment.

[paulrwebster]

Hmm. Reading the engine management manual, I am beginning to think that the Lambda/Oxygen sensor is an S2 improvement.

[ailwyn]

Hmm. Reading the engine management manual, I am beginning to think that the Lambda/Oxygen sensor is an S2 improvement.

I think Enright agrees with you

[router]

your right I do have an se turbo, i dont know if its been chipped as i have only just aquired the car.. Ill take a look at the manual thanks

[router]

how do I check if the Lambda sensor is cream crackered?

[Enright]

Hmm. Reading the engine management manual, I am beginning to think that the Lambda/Oxygen sensor is an S2 improvement.

I think Enright agrees with you

Nod arf pop pickers!
Recently I did Bournemouth to Nottingham in 3 hours - that's 200 miles at an average speed of 66mph (but I was mostly cruising between 80 and 90), and got over 31mpg.

how do I check if the Lambda sensor is cream crackered?

If it's an SE then it's easy - you don't have one.
You need to find the CO potentiometer (which is blue with a yellow cap and usually lives behind the glove box) and turn it down a bit.
If you can borrow a gas-tester while you're doing it then you'll get the best results.

[router]

thanks I found the pot and turned it back 3/4 of a turn, hope thats enough!!!

[John_W]

Router,
Glad you found the CO pot. However, just turning it back 3/4 turn may not have solved your problem

Even if the pot is at its minimum ohm value (which is what will give you minimum CO readings), you can still keep turning the screw anticlockwise - it just doesn't alter the ohm value any more. When you were changing the pot, was the engine running? Did you hear (or measure any other way) any change in idle smoothness or RPMs? If you didn't hear or measure any change, it probably won't have changed the CO pot value.

After the emissions targets were lowered, Lotus brought out a replacement chip (9930) to allow lower CO levels. If you still have the old chip, you may not be able to achieve the necessary CO level, even on the min pot adjustment. You may still be able to get the replacement chip (cheap) from Lotus, or alternatively it's a good excuse to buy a mountain chip as these use the later Lotus chip specs as a base.

When I fitted a mountain chip to replace my old (pre-9930) chip, the idle was very lumpy because the position of the CO pot meant that CO level was now too low.

My pot was set on minimum (270 ohms, fully anticlockwise) so I adjusted it slowly clockwise while listening to how the engine idled. There was a marked change in the first half-turn or so, but after that I heard no further improvement, so half a turn clockwise is where I set it. (For info, there are 21 (twenty-one) turns min to max).

The pot was previously on its extreme low adjustment and now I’m half a turn from the extreme, so presumably that gives me a bit of latitude for the future MOT tests.

Make sure the engine is hot for all adjustments and preferably run ElanScan during the full set-up procedure.

John

[router]

Router,
Glad you found the CO pot. However, just turning it back 3/4 turn may not have solved your problem

Even if the pot is at its minimum ohm value (which is what will give you minimum CO readings), you can still keep turning the screw anticlockwise - it just doesn't alter the ohm value any more. When you were changing the pot, was the engine running? Did you hear (or measure any other way) any change in idle smoothness or RPMs? If you didn't hear or measure any change, it probably won't have changed the CO pot value.

After the emissions targets were lowered, Lotus brought out a replacement chip (9930) to allow lower CO levels. If you still have the old chip, you may not be able to achieve the necessary CO level, even on the min pot adjustment. You may still be able to get the replacement chip (cheap) from Lotus, or alternatively it's a good excuse to buy a mountain chip as these use the later Lotus chip specs as a base.

When I fitted a mountain chip to replace my old (pre-9930) chip, the idle was very lumpy because the position of the CO pot meant that CO level was now too low.

My pot was set on minimum (270 ohms, fully anticlockwise) so I adjusted it slowly clockwise while listening to how the engine idled. There was a marked change in the first half-turn or so, but after that I heard no further improvement, so half a turn clockwise is where I set it. (For info, there are 21 (twenty-one) turns min to max).

The pot was previously on its extreme low adjustment and now I’m half a turn from the extreme, so presumably that gives me a bit of latitude for the future MOT tests.

Make sure the engine is hot for all adjustments and preferably run ElanScan during the full set-up procedure.

John

Thanks for the info John, I was altering the pot with the engine running and this seems to have dropped the idle rpm slightly, I dont have elanscan atm as ive only just bought the car.
Im hoping what ive done will be enough but as I cant test it im not entirely sure this will cure the issue.
It would seem by removing the ECM that the warranty stickers are untouched so I gather I have the old lotus chip still in there ( further investigation required). Im gonna run it back to the mot station to see if theres any difference.

[router]

took it for a mot and it passed, the car doesnt go so well though now and almost kangaroos along while driving slowy, think ill put it back to how it was now...

Thanks for the advice

[John_W]

took it for a mot and it passed

the car doesnt go so well though now and almost kangaroos along while driving slowy, think ill put it back to how it was now...

Alternatively... http://elanchips.com/

John