Ford Scorpio Forum - Print Page


    
      
        Ford Scorpio Forum
        (https://www.fordscorpio.co.uk/cgi-bin/yabb/YaBB.pl)
      

        General >> Problems >> MOT Emissions Failure
        
(Message started by: macw on Oct 17^th, 2007, 10:17pm)

Title: MOT Emissions Failure
Post by macw on Oct 17^th, 2007, 10:17pm

My 2.3 167K FSH has failed emissions CO at fast idle is .532/.569 (max is .300) at fast idle. It still is OK at slow idle .182 (max .500). The garage is suggesting a HO2S sensor (sometimes called Lambda) fault. I don't have a OBD cable as yet. Does anyone out there have an idea if the sensor failure is likely before I have one fitted. The engine seems a little unsettled at idle.
Any advice would be appreciated.

Title: Re: MOT Emissions Failure
Post by Highlander on Oct 17^th, 2007, 10:31pm

A decent garage should be able to tell you for definite what the problem is

Title: Re: MOT Emissions Failure
Post by martin_rowe on Oct 18^th, 2007, 10:20am

what are the other readings on your report.

Title: Re: MOT Emissions Failure
Post by macw on Oct 18^th, 2007, 4:33pm

Highlander - Thanks for the advice, however my trusted good garage closed. These are new people to me and not Scoprpio Specialists. They think its the sensor but they said it could be the CAT and I would have to try the Sensor first. The Ford dealer is less knowledgeable.
Martin - It passed all the other with OK readings. I'll dig out the paperwork again and post the exact readings. It might be of interest to have a table of readings people get, but probably complicated to implement.

Title: Re: MOT Emissions Failure
Post by Highlander on Oct 18^th, 2007, 5:07pm

But they can plug in their diagnostics and see what the problem is, dont spend money on a sensor to find out you then need a cat.
Good business though if you can get away with it ;)

Title: Re: MOT Emissions Failure
Post by macw on Nov 1^st, 2007, 6:10pm

Martin and Highlander,
Sorry for the delay it has a new Bosch Lambda sensor and passed the MOT (just). It now has an 800-1000 hunting at about 1-2Hertz when cold. I am going to look at the MAF and the the bypass valve over the weekend. The emiision figures are below, it's only a problem on the Fast Idle Test

Pass MOT

Engine Oil Temp 92C

Fast Idle PASS MOT FAIL MOT LIMIT

Engine Speed Manual Check Manual Check
CO: 0.286% 0.532%/0.569% 0.300%
HC: 92ppm 93/32ppm (2nd run much lower) 200ppm
Lambda: 1.080 1.012/1.005 1.090

Natural Idle

Engine Speed Manual Check
CO: 0.204% 0.182% 0.500%

The fail had two runs

I can't see anything obvious to my inexpert eyes, except the problem is not just the Lambda sensor. It looked as if it was running rich, soot on the old sensor, which might be explained by a dirty MAF. (or is it the other way round?)

Dinners being served go to go.

ODB cable should arrive next week.

Title: Re: MOT Emissions Failure
Post by scorpio_man on Nov 1^st, 2007, 8:29pm

hi there

i've just noticed that the lambda sensor has a fuse (#40, 25amp).

unlikely, but worth a check. :-/

hth

Title: Re: MOT Emissions Failure
Post by martin_rowe on Nov 2^nd, 2007, 8:44am

All ytour llambda readings are over1.000, indicating mixture on the lean side or a small air leak on exhaust system, you failed on rich mixture, more than likley cat not hot enough. a 4 gas test would tell you if exhaust was sucking in air, simple digital multi meter would tell you weather sensor is working.