MOT failed lambda emissions too high even with new sensor!

[M@tt_182]

I'm currently having emissions problems with the MOT, it's passing the actual emissions test fine however the lambda reading it still high.

Today they fitted a new Bosch pre CAT lambda but it's made no difference. They also swapped the sensors around in the post CAT fitting and still had no luck.

Where do I go from here? MOT runs out Sunday.

 

[Dan@SJM]

Lambda reading generally indicates a leak somewhere

 

[MarcB]

if the above is pointing to a leak i would be checking the CAT joins as i know that mine is leaking and is blowing badly.

 

[M@tt_182]

They didn't mention is was leaking? The report say 1st idle test 1.07 2nd idle test 1.12 and the limit is 0.97.

 

[Dan519]

What exhaust system do you have. As it's a 182 you'll probably have to stick a wet rag in the tailpipe that the probe isn't in if you have an aftermarket system

 

[M@tt_182]

It's got a Yozza fitted. I'll ask the garage to try that but not sure they will?! The readings don't seem overly high do they?

 

[Dan519]

that's definitely your problem then.

No that's not a long way out. 1.07 is actually lean, indicating an air leak, which having 2 outlets on one pipe effectively is. block one tailpipe and I'll pretty much guarantee it will solve it

 

[M@tt_182]

that's definitely your problem then.

No that's not a long way out. 1.07 is actually lean, indicating an air leak, which having 2 outlets on one pipe effectively is. block one tailpipe and I'll pretty much guarantee it will solve it

Thanks I'll get them to try that on Monday.

 

[MarcB]

What exhaust system do you have. As it's a 182 you'll probably have to stick a wet rag in the tailpipe that the probe isn't in if you have an aftermarket system

It's got a Yozza fitted. I'll ask the garage to try that but not sure they will?! The readings don't seem overly high do they?

I have a yozza also and my mate who done my MOT rammed a rag up a tail pipe after giving it a good drive to warm it up and mine passed with flying colours and readings where spot on.

 

[M@tt_182]

Cheers, I really hope that solves it!

 

[M@tt_182]

Quick update, it's still not passed...

Today they checked for air leaks and it's fine, blocked one of the pipes which gives the same/similar reading, cleaned the throttle body as it was hunting slightly and still no joy.

The co2 is well below the limit however the lower it goes the higher it pushes up the lambda reading? The garage are slowly running out of ideas so I'm not sure what to suggest?

 

[MarcB]

Matt you have a PM

 

[M@tt_182]

Just collected the car from the garage and either the lambda reading is too high or the C0 is too high they can't lower both.

 

[ben lee]

sounds like an air leak(exhaust blow could be a small blow on a join) or a faulty engine sensor is the eml light on? faulty coolant temp sensor is a common one to fail.

if they can do a live test on the lambda sensors is the voltage changing?

 

[Jonny1*2]

Have you checked to see if it might be a dodge new lambda?

 

[M@tt_182]

The lambda must be working as it initially did bring the reading down. They also thoroughly checked the exhaust for air leaks. No EML lights currently on and it seems to run well, averaging 40mpg at 70mph on a long run.

 

[ben lee]

whats the lambda reading at idle? and the co%

what readings are the hc and co% on fast idle?

 

[st3ve]

Could be a knackered CAT?

 

[Jonny1*2]

The lambda must be working as it initially did bring the reading down. They also thoroughly checked the exhaust for air leaks. No EML lights currently on and it seems to run well, averaging 40mpg at 70mph on a long run.

Just a thought mate. Another possible reason for running lean could mate the air filter isn't flowing correctly. Has it been changed recently?

Mines running BTB and has never struggled to pass MOT, both on standard ECU and now EC1. Strange one.

 

[M@tt_182]

Air filters not been changed for a while however it was checked over today and 'looked' clean. Here's the results from the emissions test a couple of days ago, not a lot has changed since.

 

[Dan519]

I think that might genuinely be running lean

 

[ben lee]

how come they didnt connect up the rpm probe? dose look like its genuinely running lean i would try a coolant temp sensor.

 

[Dan@SJM]

Do you have access to stuff like an RSTuner? Live data would be good to see if the lambda sensors are doing what they're supposed to.

 

[Jonny1*2]

Do you have access to stuff like an RSTuner? Live data would be good to see if the lambda sensors are doing what they're supposed to.

I'd do this Matt. There will be someone local to you no doubt. It will also let you check to see if the MAP readings are ok as if the filter isn't flowing correctly it will be slightly high compared to atmosphere. Unless the MAP sensor is on the way out too.

 

[Chip-mk1]

Johnny, if the throttle is at about 10 percent opening to hold at 3krpm with no load do you really think even a dirty filter is going to restrict it? Seems highly unlikely to me, especially given that its speed density mapped not throttle angle based anyway, plus its running lean not rich, which means there is too much air in the mix, rather than not enough.

Is it getting upto temperature enough to enter closed loop control? Rstuner will tell you this. Might be a dodgy coolant temp sender.

 

[Jonny1*2]

Johnny, if the throttle is at about 10 percent opening to hold at 3krpm with no load do you really think even a dirty filter is going to restrict it? Seems highly unlikely to me, especially given that its speed density mapped not throttle angle based anyway, plus its running lean not rich, which means there is too much air in the mix, rather than not enough.

lol. i've just realised I've been reading the thread assuming Rich Yeah no chance it's filter related

 

[M@tt_182]

I sold my RSTuner a couple of weeks ago! It's been getting up to temp like normal and not had any issues with cooling. The MAP sensor was changed aprox 1 year ago.

It's back in the local garage today for one last attempt, shall I ask them to change the coolant temp sensor? If not I'm attempting to book some time off work next week and visit 519 to try and solve the problem.

 

[Chip-mk1]

You could try a new coolant temp sender, but if the ecu is already seeing it get upto temp when you last checked it on your RS2 tuner then it largely rules that out.

These silly emissions laws are such a pain, its not like its making the slightest bit of actual difference to the environment anyway that your car is a tiny bit lean, so frustrating its enough to keep you off the road.

TBH what you really need is a more friendly MOT tester who isnt so fussy about what car he sticks the probe up, lol!

 

[M@tt_182]

You could try a new coolant temp sender, but if the ecu is already seeing it get upto temp when you last checked it on your RS2 tuner then it largely rules that out.

These silly emissions laws are such a pain, its not like its making the slightest bit of actual difference to the environment anyway that your car is a tiny bit lean, so frustrating its enough to keep you off the road.

TBH what you really need is a more friendly MOT tester who isnt so fussy about what car he sticks the probe up, lol!

I could find a friendly tester as I used one in the past for my 106 however I'd really like to solve the problem. All the suggestions so far have been good and worth trying hopefully I'll solve it.

 

[Dan519]

I'd do this Matt. There will be someone local to you no doubt. It will also let you check to see if the MAP readings are ok as if the filter isn't flowing correctly it will be slightly high compared to atmosphere. Unless the MAP sensor is on the way out too.

in response to your 2 posts saying the filter could be blocked/not flowing properly, this would make it RICH, it's LEAN

 

[Jonny1*2]

in response to your 2 posts saying the filter could be blocked/not flowing properly, this would make it RICH, it's LEAN

I know mate, Chip pointed it out. Wasn't reading correctly

 

[M@tt_182]

in response to your 2 posts saying the filter could be blocked/not flowing properly, this would make it RICH, it's LEAN

Dan - I'll try and call later to confirm coming over next week, hopefully I can make it earlier than Friday.

 

[MarcB]

And you say you are worried about emissions

 

[Bowser]

This thread was the first result Google gave me, so thought id add to this instead of making yet another emissions based thread..

So my car (172 ph2) drives fine with no problems, good economy etc. but has just failed MOT for Lambda reading (exactly the same results as Matt posted above)
I worry it wasn't fully up to temp, however after it failed the first emissions test the mechanic wedge the peddle and held it at 3k rpm for some time, and then it still failed. (So should have been hot by then)
After that the dash lights up, Lamba and coolant light on, revs all over the place.
I told him to get on with the rest of the test, although in hindsight, i should have just turned the ignition off and re tried. As since then, the car has been fine.
He started it, moved it out and i drive home with no problems. (miserable git wouldn't retest emissions at the end)

So after researching, it could well be the front Lambda sensor, but the fact it drives fine, and only went crazy when he wedge the peddle open for ten minutes makes me wonder.
Ive got a standard exhaust, and a tiny leak where the back box joins the centre pipe. (Pretty hard to seal metal to metal with just a clamp)
I havent got an OBD reader,but is there any reason it drives fine, but spazzed out at the MOT?
Anything else to try before buying a new sensor?
Or any OBD owners in near Suffolk/Essex border feeling kind.. :smile:

 

[oVerboost.]

I would get any leak sorted as best you can, do you have a print out of the emissions failure info? As the exact part it failed in will tell you what part you need to address.

Sitting at idle revving the engine won't get the engine hot enough, it needs a good hard drive, maybe even add in some redex, it's old school and often joked about, but can work well especially come MOT time. For peace of mind, if you can afford it, just replace the front lambda if you think it's faulty but again, the test results will give a clearer indication of what you need to change etc for the retest.

 

[Bowser]

image uploader

 

[Bowser]

Thanks Boost, results above.
Just noticed he didnt actually do a second test..

Another thing to note, the car has been sat for three months, and oil was not changed (planned to do it after the MOT).
However, this, or exhaust leaks, dont explain why the dash lights and revs went ape whilst he was revving it.
Think i will change oil, sort that little leak, and deliver it red hot for a retest.

 

[oVerboost.]

The funny revs and dash lights could be due to the low battery voltage or a bad earth, more than likely the battery.

3 month old oil should be fine, just make sure it's properly hot before you retest it, so the exhaust and engine is hot not just warm. Maybe even speak to the garage and ask if you can drive the car hard, and bring it in for a certain time so they can do the emissions test there and then without any waiting around. What did the MOT tested have to say? Did he offer any wisdom or just tell you it's failed?

 

[Bowser]

Zero wisdom, just shrugged his shoulders. Time for a new garage i think, the original owner seems to have left two chavs to run it.

If the Lambda is at fault, should i be getting any signs? As i say, it drives fine.

 

[Bowser]

Interesting you mention bad earth. It also failed on one of the lights not working when the indicator is on.
Seeing as its been sat for three months in the winter, it seems to have some earthing issues.