Emissions failure
Discussion
Hi all,
First time on the forum, but have been surfing them for a while and now hoping for some help.
I've got a 4.2 Cebera that has failed its emissions on its MOT. It's the first time I’ve MOT'd it and have not and the car for a full year yet.
It's failing miserably at idle on all counts (3-4 times over the limits) but if you hold it at 3,000rpm + its starts to clear up and pass on Lamba and HC’s and it was just starting to drop on the CO when I dropped the revs due to it getting to over 100+ degs temp, but this was after an lot of reving and time on the gas analyser.
It's the second time it's failed and I've been through everything, I have the software and all is good on adaptives, throttle pots, injector time and the Lambas are switching just fine.
The MOT technician suggested some sort of fueling problem and he thought the CAT's were ok and the obviously passing the Lamba reading I'm assuming with the software showing them good that they are ok too.
We tried it up both exhausts and they were the same. I'm now thinking it could be the fuel pressure regulator causing some over fueling. It is a little rough at low rpm and the plugs are rich in colour.
Any one got any suggestions?
Thanks
First time on the forum, but have been surfing them for a while and now hoping for some help.
I've got a 4.2 Cebera that has failed its emissions on its MOT. It's the first time I’ve MOT'd it and have not and the car for a full year yet.
It's failing miserably at idle on all counts (3-4 times over the limits) but if you hold it at 3,000rpm + its starts to clear up and pass on Lamba and HC’s and it was just starting to drop on the CO when I dropped the revs due to it getting to over 100+ degs temp, but this was after an lot of reving and time on the gas analyser.
It's the second time it's failed and I've been through everything, I have the software and all is good on adaptives, throttle pots, injector time and the Lambas are switching just fine.
The MOT technician suggested some sort of fueling problem and he thought the CAT's were ok and the obviously passing the Lamba reading I'm assuming with the software showing them good that they are ok too.
We tried it up both exhausts and they were the same. I'm now thinking it could be the fuel pressure regulator causing some over fueling. It is a little rough at low rpm and the plugs are rich in colour.
Any one got any suggestions?
Thanks
sonnylad said:
Would also check there using the correct machine settings
Yep the settings are a bit different than for a Eurobox, so info in the thread belowhttp://www.pistonheads.com/gassing/topic.asp?h=0&a...
IIRC the MOT gas analyzer should pull up the limits automatically from the DLVA when the operator enters your plate. There’s a good possibility the DVLC have got it wrong so maybe worth a check? I’m not an expert on the AJP, (S6 owner), but have had some fun getting a V8 Ferrari through in the past.
A pressure test on the rail will tell you if it’s the regulator, but you’ll need to get hold of a test kit. Otherwise, if it’s not an expensive part (?) just change it anyway.
It sounds to me that it’s something common across the whole engine as it’s not specific to a single bank. As a rule, with any kind of issue like this, the first thing I do is give the engine a full service and check the below.
Is the air filter new/clean?
Has it got the correct plugs in?
Are your injectors old / worn?
Has it been filled with super-thin synthetic oil (not good)?
What is the oil and fuel consumption like?
Have you driven it properly lately – e.g. given it an Italian tune-up?
For me I’d book it in at one of the specialists for the MOT, they should know all the tricks needed to get it to through.
Hope this helps.
Julian.
A pressure test on the rail will tell you if it’s the regulator, but you’ll need to get hold of a test kit. Otherwise, if it’s not an expensive part (?) just change it anyway.
It sounds to me that it’s something common across the whole engine as it’s not specific to a single bank. As a rule, with any kind of issue like this, the first thing I do is give the engine a full service and check the below.
Is the air filter new/clean?
Has it got the correct plugs in?
Are your injectors old / worn?
Has it been filled with super-thin synthetic oil (not good)?
What is the oil and fuel consumption like?
Have you driven it properly lately – e.g. given it an Italian tune-up?
For me I’d book it in at one of the specialists for the MOT, they should know all the tricks needed to get it to through.
Hope this helps.
Julian.
Hi,
Thanks for the reply’s so far. I checked the settings on the re-test just to make sure they had the vehicle specifics and yes they were correct as below:
Limits
CO, 0.3
HC, 200
Lamba, 1.2
I haven’t got the reading from the second emissions test but it passed HC and Lamba but failed CO on the 2nd fast idle, think CO was still around 0.5. It failed the idle and the first fast idle on all but the Lamba reading
The readings from the first emissions test showed CO between 1.12 – 2.02 between fast idle test 1 and test 2 and HC between 602 – 2075 respectively, so massively over. Lamba failed first fast idle at 1.227 and passed second one at 1.037. So lamba is there or there abouts but still on the high side
CO at idle was 2.24 on the first test.
I’ve ordered a gauge to check the fuel pressure readings so will check this weekend and have previously put a new set of NGK plugs in and run some CAT cleaner additive through the petrol tank. I’ve not checked the air filter yet but it was only serviced 2k ago by the previous owner so assume its ok, will double check this weekend. Oil and filter change also completed before it went back on the road, filled with Mobil 1 - 10w/60
I’ve done about 70miles trying to get it through the MOT on pre-inspection warm ups so think I’ve given it a good enough run through and as previously stated have check everything on the software all appears within limits. Planning on taking one of the CATs off to check they are not blocked this weekend.
Cheers
Adam
Thanks for the reply’s so far. I checked the settings on the re-test just to make sure they had the vehicle specifics and yes they were correct as below:
Limits
CO, 0.3
HC, 200
Lamba, 1.2
I haven’t got the reading from the second emissions test but it passed HC and Lamba but failed CO on the 2nd fast idle, think CO was still around 0.5. It failed the idle and the first fast idle on all but the Lamba reading
The readings from the first emissions test showed CO between 1.12 – 2.02 between fast idle test 1 and test 2 and HC between 602 – 2075 respectively, so massively over. Lamba failed first fast idle at 1.227 and passed second one at 1.037. So lamba is there or there abouts but still on the high side
CO at idle was 2.24 on the first test.
I’ve ordered a gauge to check the fuel pressure readings so will check this weekend and have previously put a new set of NGK plugs in and run some CAT cleaner additive through the petrol tank. I’ve not checked the air filter yet but it was only serviced 2k ago by the previous owner so assume its ok, will double check this weekend. Oil and filter change also completed before it went back on the road, filled with Mobil 1 - 10w/60
I’ve done about 70miles trying to get it through the MOT on pre-inspection warm ups so think I’ve given it a good enough run through and as previously stated have check everything on the software all appears within limits. Planning on taking one of the CATs off to check they are not blocked this weekend.
Cheers
Adam
Just one thing reading this, you are using the wrong grade of oil, won't effect your MOT but it is far too thick for an AJP which should run a 0/40 or a 5/40 certainly not a 10/60.
www.opieoils.co.uk/pdfs/tech-articles/10w-60-oil.p...
www.opieoils.co.uk/pdfs/tech-articles/10w-60-oil.p...
Edited by gruffalo on Monday 31st March 22:51
If I understand your figures correctly, you finally managed to get the HCs and the Lambda within the limits but that the CO was 0.50%?
If so those readings indicate the cats have failed. When you have a cat reading of 0.50-0.65% on the second fast idle it is a good indicator the cats are not able to clean the emissions effectively.
Try the cat cleaner (Cataclean gets some good reviews but is usually a one-off fix) and fingers crossed. Available at Halfords, Amazon, Ebay etc.
If so those readings indicate the cats have failed. When you have a cat reading of 0.50-0.65% on the second fast idle it is a good indicator the cats are not able to clean the emissions effectively.
Try the cat cleaner (Cataclean gets some good reviews but is usually a one-off fix) and fingers crossed. Available at Halfords, Amazon, Ebay etc.
Unfortunately I don't think there is going to be a specific answer without eliminating one thing at a time.
Check the manifolds for cracks and leaks in the exhaust pre cats, if the car is passing the fast idle it will be sucking in less oxygen and therefore leaning off the lambda less than at idle. If the car has been running with cracked manifolds for any length of time it will also have been over fueling which in turn will have damaged the cats and lead to poor cat performance.
If the ignition side is weak or injectors are over fueling you will also get a poor burn and again similar results.
Check the manifolds for cracks and leaks in the exhaust pre cats, if the car is passing the fast idle it will be sucking in less oxygen and therefore leaning off the lambda less than at idle. If the car has been running with cracked manifolds for any length of time it will also have been over fueling which in turn will have damaged the cats and lead to poor cat performance.
If the ignition side is weak or injectors are over fueling you will also get a poor burn and again similar results.
Thanks Gruffalo,
The oil article was of particular interest and fits with what I’d experienced since changing the oil. The oil pressure was actually lower when cold than when hot which can only be down to viscosity as it struggled through the oil cooler and filter before it goes in to the engine block. I’ll change it this weekend.
Embarrassingly I knew what grade it should have been but got talked in to the thicker by a bloke at Halfords who looked the car up and recommended it based on his car check chart and the fact the car would be older and therefore benefit from a thicker oil, you live and learn
N7GTX
Is that cleaner you put in as an additive to the petrol, as I’ve tried that or can you actually soak the CAT in the cleaner once removed?
I’ll give the exhaust manifolds a good check over as well this weekend
Thanks
The oil article was of particular interest and fits with what I’d experienced since changing the oil. The oil pressure was actually lower when cold than when hot which can only be down to viscosity as it struggled through the oil cooler and filter before it goes in to the engine block. I’ll change it this weekend.
Embarrassingly I knew what grade it should have been but got talked in to the thicker by a bloke at Halfords who looked the car up and recommended it based on his car check chart and the fact the car would be older and therefore benefit from a thicker oil, you live and learn
N7GTX
Is that cleaner you put in as an additive to the petrol, as I’ve tried that or can you actually soak the CAT in the cleaner once removed?
I’ll give the exhaust manifolds a good check over as well this weekend
Thanks
Cataclean goes in the tank.
I can only repeat that if the HC and lambda readings are within limits and the CO on any cat equipped car is reading 0.5-0.65%, it is almost certainly cat failure.
However, in your case, it started very far out and is trying to come back in towards the end so the cat cleaner may just do enough if you are lucky.
As said above, a faulty injector throwing neat fuel into the exhaust and on to the cat(s) will shorten their life very quickly. Likewise a misfire - plug, lead, coil.
I can only repeat that if the HC and lambda readings are within limits and the CO on any cat equipped car is reading 0.5-0.65%, it is almost certainly cat failure.
However, in your case, it started very far out and is trying to come back in towards the end so the cat cleaner may just do enough if you are lucky.
As said above, a faulty injector throwing neat fuel into the exhaust and on to the cat(s) will shorten their life very quickly. Likewise a misfire - plug, lead, coil.
Ok thanks for that, I’ve tried the cat cleaner between MOTs but I will now focus a bit harder on the cats and hopefully take one off this weekend and have a look and see if it is blocked up or showing any other signs of failure.
I have another theory but it’s a long shot, I’ve found a receipt dating back to 2010 for some silenced decats in the service history file and it’s just possible that the previous keeper has left them on the car. The dealer I bought the car from told me the previous owner sold the car direct to him in a hurry due to a divorce, putting the original cats back on may not have been a high priority for him. It’s a long shot and wouldn’t necessarily explain the improving results but worth a look at the weekend. The cat pipes that are on are very nice polished stainless steel which would fit with the £160 receipt I have for silenced decats.
I have another theory but it’s a long shot, I’ve found a receipt dating back to 2010 for some silenced decats in the service history file and it’s just possible that the previous keeper has left them on the car. The dealer I bought the car from told me the previous owner sold the car direct to him in a hurry due to a divorce, putting the original cats back on may not have been a high priority for him. It’s a long shot and wouldn’t necessarily explain the improving results but worth a look at the weekend. The cat pipes that are on are very nice polished stainless steel which would fit with the £160 receipt I have for silenced decats.
Problem solved! I whipped one of the cats off today and the pictures below say it all. They are not Cats at all but silenced decats.. Bit frustrated that the previous keeper didn’t pass this information on but at least I have a solution now, just got to buy a couple of cats
This looks just like a normal cat
But clearly isn't!
Thanks for the help particulary the advise about potential cat failure as I could have been tuning the engine for weeks
This looks just like a normal cat
But clearly isn't!
Thanks for the help particulary the advise about potential cat failure as I could have been tuning the engine for weeks
Thanks for the info, that sounds a good service.. I'm actually interested to see how the car behaves and sounds with cats on, its a bit lumpy at the moment. I cant imagine the cats will change anything apart from reducing noise a fraction and possibly a bit on power and fuel consumption. I've ordered a couple from Ebay for £60 ech. so will be interesting to see the difference.
Edited by Adambul on Monday 7th April 12:19
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