Cav 1.8 Emissions Nightmare
Discussion
Hi
Been failed twice CO (carbon monoxide) at around 0.6-0.7 when maximum is 0.2 on high rev test. Car is always well maintained, always kept in good cond. just changed cat, new temp sensor, oxygen sensor, oil change with flush, fuel flush, fixed slight leak in manifold/downpipe gasket and still failed at same level.
No lights or anything on in dash and car runs very well and uses little fuel. Spoke to an old mechanic I used to work with and he said have you changed plugs/air filter, said no but always keep them clean/never had this issue before. He said doesn't matter the cavs are known for needing plugs/air when CO is high. Not convinced to be honest this is going to fix it.
I will try that but only other thought is the EGR valve. Failing that what other desperate measures could I try (please no pushing it off a cliff comments i'm pretty cross and need some honest advice!)?
Thanks
g
Been failed twice CO (carbon monoxide) at around 0.6-0.7 when maximum is 0.2 on high rev test. Car is always well maintained, always kept in good cond. just changed cat, new temp sensor, oxygen sensor, oil change with flush, fuel flush, fixed slight leak in manifold/downpipe gasket and still failed at same level.
No lights or anything on in dash and car runs very well and uses little fuel. Spoke to an old mechanic I used to work with and he said have you changed plugs/air filter, said no but always keep them clean/never had this issue before. He said doesn't matter the cavs are known for needing plugs/air when CO is high. Not convinced to be honest this is going to fix it.
I will try that but only other thought is the EGR valve. Failing that what other desperate measures could I try (please no pushing it off a cliff comments i'm pretty cross and need some honest advice!)?
Thanks
g
stevieturbo said:
That makes no sense at all. Use different test equipment, and it also is not what I asked.
I asked if the lambda sensor was tested and working correctly.
With such a high CO reading it should be unlikely for the Lambda readings to be within pass range. Even if it had an air leak in the exhaust it would still be unlikely, although not impossible I guess.
As far as I can see the lambda test or check at the test was ok, I even changed it from a new one I got to an older one and it made no difference. I am going to get another emissions test at another garage to get a 2nd opinion and take it from there.I asked if the lambda sensor was tested and working correctly.
With such a high CO reading it should be unlikely for the Lambda readings to be within pass range. Even if it had an air leak in the exhaust it would still be unlikely, although not impossible I guess.
So it failed emissions again on lambda and CO. I know this was asked originally and I thought the lambda passed. I have not tested the sensor either. The lambda sensor is quite new and also changed it back to original one, which made no difference to the test.
When tickover test was done the lambda was too high but CO was ok, when high idle test was done lambda was ok but CO was too high. They tried to balance both readings by taking the revs just up above tickover but no luck.
Just to relist the stuff done:
Top end overhauled, grind valves in/new followers/cam fingers as some were worn, new gaskets all round
Fixed manifold to downpipe leak as bolt was broken and one was missing
New cat
New multipin temp sensor
Air filter
OE plugs
Flush
Fixed servo pipe leak
Fixed leak in other vacuum pipe
Cleaned/inspected EGR valve
So now I am stumped. I bought cataclean and am going for a 2nd opinion at another garage today.
When tickover test was done the lambda was too high but CO was ok, when high idle test was done lambda was ok but CO was too high. They tried to balance both readings by taking the revs just up above tickover but no luck.
Just to relist the stuff done:
Top end overhauled, grind valves in/new followers/cam fingers as some were worn, new gaskets all round
Fixed manifold to downpipe leak as bolt was broken and one was missing
New cat
New multipin temp sensor
Air filter
OE plugs
Flush
Fixed servo pipe leak
Fixed leak in other vacuum pipe
Cleaned/inspected EGR valve
So now I am stumped. I bought cataclean and am going for a 2nd opinion at another garage today.
stevieturbo said:
2nd opinion ?
So what diagnosis did the first mechanic come to when he conducted tests ?
And exactly what were all the readings ?
Still to go for the 2nd opinion later onSo what diagnosis did the first mechanic come to when he conducted tests ?
And exactly what were all the readings ?
First mech didn't diagnose anything. Readings for CO was about 0.40 tickover, 0.60 ish for high idle, and lambda 1180-1200/1050 (ticokver/high idle).
CO should be <= 0.3 and lambda I think is meant to be about 1080.
Someone suggested an air leak if lambda is high at idle?
Sardonicus said:
Have you carried out a vacuum test? this engine uses MAP if I am not mistaken 
even slightly poor Vac readings will be enough to rock the boat and unfortunately the ECU can not make allowances for this scenario as its does not understand 
low vacuum high CO 
enough that the Lambda probe cannot trim/lean 
I just got the 2nd opinion on my emissions and the bloke said he has looked over everything he can think of and can't see, or reasonably suspect, any faults. Pretty much where I am at the moment, lost as to what is causing the issue. even slightly poor Vac readings will be enough to rock the boat and unfortunately the ECU can not make allowances for this scenario as its does not understand low vacuum high CO enough that the Lambda probe cannot trim/lean No haven't carried out a vacuum test and don't have the tools to. I see what you mean about the car using MAP and being upset by a very slight vac leak, although strangely enough fixing the split in the servo hose and pipe on injector body made no measurable difference to emissions.
The guy at the garage recommended getting another injector to try. I have just read about potential leak at pipe going to carbon canister, which is a pipe leading from no return valve on servo hose to bulkhead.
Stumped!
Plan of action firstly is to see a guy I used to work in the trade and see if he can "pass" it for me!!
stevieturbo said:
Basic CAT test, assuming this is the test you have to comply with ( what age etc is your car ?? )
Those numbers are wrong. Yes CO should be less than 0.3
Lambda should be 1 +/- 0.03
Hydrocarbons should be less than 200ppm.
You need factual information to have any chance of diagnosis from afar.
Lambda can never be 1180-1200 etc or whatever you're trying to explain.
So are these mechanics you're taking the car actually performing any tests or measurements at all, or are they just looking at the engine and poking things etc ?
To be honest I have only asked them to test the emissions and haven't asked them to do any other fault finding, so really all they can do is cast a second eye over it and see if they can spot anything. What they would do is more or less do what I have already done except stuff like vac tests. What he said today was that he can't plug this car up to a computer to test anything like a more modern car.Those numbers are wrong. Yes CO should be less than 0.3
Lambda should be 1 +/- 0.03
Hydrocarbons should be less than 200ppm.
You need factual information to have any chance of diagnosis from afar.
Lambda can never be 1180-1200 etc or whatever you're trying to explain.
So are these mechanics you're taking the car actually performing any tests or measurements at all, or are they just looking at the engine and poking things etc ?
Can't comment on specific value for lambda but i'm not going to dispute 2 MOT testers both telling me it is too high.
stevieturbo said:
The lambda figure you have quoted is not high. It is impossible. If the car failed, surely they have given you a sheet listing the failure along with the test results ?
So some facts are getting thrown out the window between testing, and this forum.
And there is no point taking the car to a garage and asking them to test emissions, but undertake no form of diagnostic work whatsoever.
That's like going into a hospital with a broken arm and asking them to look at it, but not actually do anything about it.
As for plugging it in etc...Obviously this mechanic you have taken the car has no clue whatsoever. And that's being polite. Stop to think what mechanics did before cars had some form of self diagnostics ?
Yes, they tested things manually. Computers dont fix cars, competent mechanics do.
But without some proper factual information relating to the problem, nobody anywhere will ever be able to fix it. So either that is relayed correctly so you might have a slim chance of a remote fix, or you find a competent mechanic that can conduct tests and diagnose the car properly. It really shouldnt be rocket science for any decent mechanic.
Or just sell the car.
Well it looks like I missed a decimal point in the values I quoted for lambda. The sheet I have from the original fail sheet is:So some facts are getting thrown out the window between testing, and this forum.
And there is no point taking the car to a garage and asking them to test emissions, but undertake no form of diagnostic work whatsoever.
That's like going into a hospital with a broken arm and asking them to look at it, but not actually do anything about it.
As for plugging it in etc...Obviously this mechanic you have taken the car has no clue whatsoever. And that's being polite. Stop to think what mechanics did before cars had some form of self diagnostics ?
Yes, they tested things manually. Computers dont fix cars, competent mechanics do.
But without some proper factual information relating to the problem, nobody anywhere will ever be able to fix it. So either that is relayed correctly so you might have a slim chance of a remote fix, or you find a competent mechanic that can conduct tests and diagnose the car properly. It really shouldnt be rocket science for any decent mechanic.
Or just sell the car.
natural idle values:
CO = 0.13 - Pass
Fast idle test:
CO = 0.99 - fail
HC = 99 - pass
Lambda = 1.035 - fail
2nd fast idle:
CO = 0.89 - fail
HC = 90 - pass
Lambda = 1.035 - fail
On this point Stevie:
And there is no point taking the car to a garage and asking them to test emissions, but undertake no form of diagnostic work whatsoever.
I wanted a 2nd opinion - as I said - because I have had this problem before with another garage, their gas tester wasn't working and I was cleaning plugs and changing oil and filters only for him to ring me up and say they found a fault with it and to come back in for testing.
Edited by GrannieTwoEight on Thursday 29th November 22:48
Edited by GrannieTwoEight on Thursday 29th November 22:50
Crafty_ said:
what stevieturbo said.
Post a pic of the emissions sheet.
The only way "plugging it in" is going to help is if you find someone with tech2 and experience of the engine, they can read live data from the car and use their experience to tell you what the data means and hopefully diagnose something.
Have you put new plugs in it yet ? even cleaned and gapped the old ones ?
does it use any oil ?
Uses no oil and plugs are newPost a pic of the emissions sheet.
The only way "plugging it in" is going to help is if you find someone with tech2 and experience of the engine, they can read live data from the car and use their experience to tell you what the data means and hopefully diagnose something.
Have you put new plugs in it yet ? even cleaned and gapped the old ones ?
does it use any oil ?
stevieturbo said:
It really is a borderline fail ( from what sounded like a huge fail at the start of the thread )
Again, whether you have replaced the lambda sensor or not. It's operation needs tested properly.
The high lambda value, which in some respects does indicate lean...although contradicted by the CO reading, there could well be a small air leak in the exhaust.
Again, any half decent mechanic should see this on a gas analyser. o2 readings would be higher than expected if there is an air leak.
But as Ive been saying, all that is needed is some basic diagnostic work and tests to determine if things are working as they should, or if there may be a problem.
It doesn't need any super fancy diagnostic equipment, although an oscilloscope would be very helpful.
The values posted were from first test, The CO values were triple what they should have been on the 2nd fast idle, although since I done all the engine work it is down to about 0.4 so it's really borderline now.Again, whether you have replaced the lambda sensor or not. It's operation needs tested properly.
The high lambda value, which in some respects does indicate lean...although contradicted by the CO reading, there could well be a small air leak in the exhaust.
Again, any half decent mechanic should see this on a gas analyser. o2 readings would be higher than expected if there is an air leak.
But as Ive been saying, all that is needed is some basic diagnostic work and tests to determine if things are working as they should, or if there may be a problem.
It doesn't need any super fancy diagnostic equipment, although an oscilloscope would be very helpful.
I was reading that the lambda switch on/off should be measured, which as you mentioned, I would need a scope. It's not something I can put my hands on and will see if I can borrow one, or ask the local car electrician if he has one.
Apologies the reading below was incorrect when I posted above:
CO = 0.13 - Pass
Fast idle test:
CO = 0.72 - not 0.99
HC = 99 - pass
Lambda = 1.035 - fail
2nd fast idle:
CO = 0.89 - fail
HC = 90 - pass
Lambda = 1.035 - fail
Edited by GrannieTwoEight on Friday 30th November 15:25
Edited by GrannieTwoEight on Friday 30th November 15:26
MGJohn said:
Very informative thread and a good read.
There's still a loose end to be tied though.
How did the car finally fare with those MoT emissions tests ?
Ha, 6 odd years later and this car is still going strong would you believe. I just got pissed off and ended up taking it to a mate who said he would "pass it" the last 6 years, but then this year I've had a bit of a rethink, I did want to get to the bottom of what was causing this and had another look at it. Firstly I discovered a huge rip in the air intake pipe that goes to the carb, I should think that likely wouldn't make a difference to un-metered air getting into the engine as it does on likes of the 2.0 cavy which uses the motronic and air-flow sensor, but it seems to have made a difference to the running of the car. There's still a loose end to be tied though.
How did the car finally fare with those MoT emissions tests ?
I also changed the idle control stepper valve as the revs seemed to hunt up and down. This has more or less cured that. Then I realised that I'd never changed the rotor arm, possibly never been changed since new, and I might have changed the dizzy cap way back in 2008, so plummed and got a new bosch one of each. this has made the actual running of the car much better. Also have changed the 02 sensor for a genuine new one.
I also fixed the back box and clamp which was poor fitting and the box was rusty; i'd patched welded it before but it was swinging like the dogs danglies in the wind. I also noticed that some of the back boxes I had got over the years has a little drain at the back, some didn't, and they were all VX parts. I reckoned maybe the ones that had a drain were pre-cat and so if I fitted one with a drain it would maybe have upped the Lambda. Although in saying that my Omega has a drain hole that I put in my self on all 3 silencer boxes and it still passed with flying colours.
The car is going through a bit of a refurb at the moment so it will be going for MOT soon and we will find out what happens. I do have a good spare cat that I can utilise as a last ditch attempt if it fails again, the cat is quite old now and was aftermarket so it might now be goosed.
Edited by GrannieTwoEight on Wednesday 30th May 19:05
Sardonicus said:
Just out of curiosity was you using a universal as in using part of the old wiring and crimping to the new 02 sensor? or can you recall the brand previously fitted before this OE Bosch unit was fitted ? I have a feeling this one is about to unfold
Never heard of doing that with 02 sensor, I don't remember make of the old one, but new one is VX one, might be bosch make in reality, not sure.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff