Another MOT Failure!

[DuncanM]

2001 R500 with CAT fitted - Lambda sensor in No4 primary, MBE ECU

 

CO - 6.53%

HC Level - 1398ppm

Lambda - 0.79

 

These readings are way off passing. The tester was so shocked by the numbers that they thought the machine was broken and re-calibrated it! I have a number of questions:

 

1) Is it likely that the Lambda sensor is broken - is there any way of testing it?

2) Is it possible to run an MOT friendly map like people do with Emeralds - does anybody have such a map?

 

Thanks

 

Duncan

[oilyhands]

I would try balancing the throttle bodies and ensuring they are flowing 5.5KGs/hr, and then align the throttle pot to give the correct resistance as per the manual (0.45 OHMS across pins 1 & 2), the current calibration should be MOT compliant.

 

Oily

[DuncanM]

I have no way of measuring air flow but just checked the TPS and am getting +0.43V on the centre pin at idle.

 

Duncan

 

Edited by - DuncanM on 4 Apr 2010 18:04:01

[oilyhands]

I would borrow an airflow meter and establish that the TBs are drawing the correct volume of air or you will be stymied.

 

Oily

[Gulf7]

My 2004 R300 failed the emissions last year by a huge amount. I took it back to Caterham south who had supplied it the previous year. They got a pass and said that they had put it on a PC and found some one had set the the Lambda way off and that they had corrected.

 

Once home and cleaning the car I found that they had moved the Lambda sensor down from the exhaust primary to after the collector (a blank already existed). Obviously this gives a more average reading if one cylinder is off.

[shn7]

Duncan,

 

Any update? Has it passed yet?

 

Steve.

Not forgetting Percy the Polar Bear who recommends

Puddle Pet Care

[paul jacobs]

There is another reason why the emmisions could be so high, as I found out when I took my 260 in for this years MoT the other day, which was that the CAT just wasn't hot enough. I was told to take it out for 4-6 miles at fairly high revs, and they put the probe up the exhaust the moment I got back, and it passed well within the limits. I'm lucky in that my regular test station really wants to pass cars if they can, and are prepared to go the extra mile to ensure that if the car is capable of passing, it will.

 

Just a thought 😶‍🌫️

 

Paul J.

 

[DuncanM]

My car does now have an MOT thanks to Minister Power. Throttle position sensor was a bit dodgy so changed that (they are not cheap though ~£70!). Also the connections to the water temp sensor for the ecu were corroded. Apparently the map is set up so if the ecu does not detect any temperature sensor then it assumes by default that the engine is overheating so dumps loads of fuel in.

Depite these fixes there is no replacement for a friendly testing station and a Fiesta parked alongside

[EFA]

"Apparently the map is set up so if the ecu does not detect any temperature sensor then it assumes by default that the engine is overheating so dumps loads of fuel in."

 

It should be set to 80 degrees which would add not extra fueling. Throttle pot position is the cause of your problems. I doubt the sensor itself was faulty, they are pretty reliable.

 

Its critical the sensor is calibrated as per the TPS load site table in the map though. So you need to read the map, set the rpm and TPS voltage all at the same time.

 

Edited by - EFA on 2 May 2010 10:34:37

[shn7]

Good to hear it's all sorted. Hope we'll see you at a local meeting soon then

 

Steve.

Not forgetting Percy the Polar Bear who recommends

Puddle Pet Care