MOT fail on emissions...where do I start?

[richiemac2]

Hi, My 98 Ex has just failed it's MOT test on high emissions. It has a single point LPG system fitted which brings the engine management light on which when I check / reset the codes it states that it running lean. Have been advised to check the air filter (looks ok) and the plugs (only covered 3-4000 miles since renewal). Reset the light by disconnecting the battery, tried again and failed again. Can anyone advise what the best next step would be? I understand there are 2 lambda sensors and 2 cats. Logic would tell me to try the sensors first, can they be tested or should they just be replaced? Then do I go for one or both cats? Have been quoted £290 for the right one. EEK!!! It's close to being an uneconomical repair if I have to get the lot done...Anyone had any similar issues........any ideas or suggestions ? HELP......:yelexp:

 

[boots]

Your MOT Fail

Hi,

Had a similar problem, my garage just had the test done on petrol = Pass.

Hope this helps

Boots

 

[richiemac2]

Thanks Boots,
I did have the test done on petrol and it still failed. Could it be that I need to do a few miles with the check light out to clear out the cats/sensors?

 

[SB98UKexplorer]

it could be that you dont boot it enough, usaually before goin to the test station i give it a good thrash and passes really well

 

[richiemac2]

Thanks SB, I did take it for run up the motorway with the overdrive switched off before the test but that was with the engine check light on...Would I be right in thinking that if the sensors tell the car it's running lean, the ECU will adjust the mix to make it run richer? Would it help to run only on petrol after resetting the light, take it for a thrash and then try? Are there any other places you can go for an emissions check? I feel the mot place will get the hump if I keep going back every time I've tried something.Are there any DIY tools you can get that do the job?

 

[DuncanOfEngland]

Richiemac2,

Whether or not you can thrash it enough to pass the emissions, the 'check engine' light is there to advise you that there is a problem. Ignore it at your peril, because running on LPG, you risk burning out your exhaust valves if it's not rectified.

Duncan Clarke
Ford Explorer Services and Parts, Aylesbury

 

[richiemac2]

Thanks Duncan,
I assumed the check light and the Lean warning was simply because it was LPG being burned and not petrol and that the sensors were not picking up the usual gases as there were less of them. The light, once reset, stays off until I switch over to LPG. What would you advise? I have a single point LPG conversion with a Bedini system.Would adjusting mixture on that help? I have no idea how do it though and can't seem to find any info on the net.

 

[janolsson]

Hi Richie
If you do a search in the US part of this forum you will probably find how to test Lambda sensors. If not a general web search will show results.
How old is the air filter? This lets the car breath so if in doubt renew it. Also can you get an OBD II reader as this will tell you what fault the engine is throwing up.
As for the cats have you considered used. Justin "explorer uk" on flea bay may have some or there is a guy on there that goes by the name of glastonbury92 that breaks explorers. Personally i would check all other possibilities before the cat. MAF, temp sensors, o rings for the plenum chamber, air filter, plugs and lambda sensors all have an outcome on the fuel mixture.
good luck

 

[janolsson]

Just done a search and found this thread on O2 sensors.
Worth a read and make it to the second page as it tells you how to test the sensor.

http://www.explorerforum.com/forums/showthread.php?t=149917&highlight=test+O2+sensor

regards

 

[richiemac2]

Thanks Janolson,
Interesting info on that link. Have ran it for a while on petrol only with no Mil warning, cleaned the maF( as best I could),checked the plugs, fixed a broken air box and tried a can of 10k boost from halfords which is supposed to de coke and reduce emmisions, boost power etc. Gonna try it again tomorrow before trying to get out the sensors....it does seem to run a little smoother so you never know...fingers crossed!

 

[janolsson]

I think the main point to take from that thread on O2 sensors is that they sense stuff and tell the ecu when something is wrong. this throws a code that you should investigate. Hence find somewhere to read your ecu. It is just a matter of plugging in a reader to a connector and then checking for error messages.
As for cleaning your MAF, what did you use as carb cleaner can damage them.
good luck

 

[richiemac2]

Well, I took it back for re test and although it was slightly better it did fail again.So, changed both cats (bargain priced from cats2u.co.uk) and replaced one of the lambda sensors -because I couldn't get the old to come out of the cat , and she passed! Bit of a mare of a job but hopefully not one I'll have to do again for a while. Hardest part was getting the right lambda sensor , even the main dealer ordered the wrong one in for me. Ended up getting one from euro car parts in the end which was far cheaper that the one from ford. All's well that ends well....