[sunnyside]

Hi

I'm hoping that someone can help me, I recently put my 1996 Twingo through a Control technique in France (it is the same as the MOT but carried out by independant assessors that cannot do repairs on the vehicle). It failed on excessive CO emissions.

The readings where:

CO idle: 0.3 (needs to be 0.5 to pass)
CO acceleration: 0.36 (needs to be 0.3 to pass)
Lambda: 1.021 (needs to be 0.95 - 1.03 to pass)

For the repeat test I changed the spark plugs, air filter, oil filter, oil and put on a new exhaust silencer. I also used an additive like Red X to clean carbon deposits.

The car failed again but the results where worse.

The results where:

CO idle: 0.46 (so this has improved slightly)
CO acceleration: 0.46 (This is worse)
Lambda: 1.040 (This is worse)

Does anyone one have any advice on what I can do to try and get the car to pass without costing a fortune as at this stage I have to weigh up the cost of the repair to the value of the car.

 

[Recycled Scenic]

Hello and welcome to the Renault Forums

Have you changed the airfilter?

You might find changing the lambda senor might help?

The next thing to do would be change the catalytic converter though thats likely to be expensive!

 

[Colin :)]

i would suggest changing the lambda sensor

 

[Lagdti]

Hello and welcome to the forum.

I would guess that the original problem was a tired cat,with the Lambda reading going up on the second test I would say that there is a slight blow around the joint on the new silencer now adding to the problems.

 

[sunnyside]

Thanks for all your help/suggestions I am going to replace the lambda sensor and see how it gets on. If if fails again then I think it's time to scrap the car as the lambda sensor cost over 130 euro and the next thing possibly to replace would be the Cat but this could mean costing more than car is worth. Thanks again for all suggestions offered. I'll let you know how it gets on on retest.

 

[roby37]

I think you should give some more thought to this. The figures in the first test show both CO and Lambda in spec. The 0.5 % CO is a MAXIMUM and Lambda 1.021 is within the 0.95 to 1.03 spec.I don't know what the CO acceleration means but I do know that Lambda is showing the engine running slightly weak with a suggestion that the cat is not fully operative!

Add:- Incidentally a failed/failing Lambda sensor tends to give a rich mixture.

 

[Recycled Scenic]

Thanks for all your help/suggestions I am going to replace the lambda sensor and see how it gets on.

If you do change the lambda sensor IMO I would buy a universal sensor as they are much cheaper. it will involve cutting off your own plug and crimping it on the wires of the new sensor. I have sucessfully used 3 or 4 of these now.

Yours will probably be a 4 wire sensor?

http://cgi.ebay.co.uk/1x-TOP-QUALIT...arts_Vehicles_CarParts_SM&hash=item19b98e3f63

 

[sunnyside]

Thanks to everyone for the help. After changing the air filter, lambda sensor and sealing all holes in exhaust the emissions got worse not better so it was going to be either the catalytic converter or engine and as they would cost more than car was worth we decided to scrap the car. The guys in the CT Centre (French equivalent to MOT Centre but they only test the car and can't repair it) done their best to help us with possible causes).