Cav 1.8 Emissions Nightmare

[GrannieTwoEight]

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

[stevieturbo]

So nevermind changing parts...is the lambda sensor working properly ?

[GrannieTwoEight]

stevieturbo said:

So nevermind changing parts...is the lambda sensor working properly ?

It passed the lambda test

[stevieturbo]

GrannieTwoEight said:

It passed the lambda test

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.

[GrannieTwoEight]

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.

[stevieturbo]

GrannieTwoEight said:

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.

Emissions tests are not tests the lambda sensor is operating correctly. You need to test the sensor with a scope to see that it is responding correctly to what it sees in the exhaust.

But a different gas analyser would be worth doing.

[davepoth]

Hang on...you spent all that money and didn't change the plugs and air filter?

First rule of maintaining an old car on a budget - change the cheap things first!

[ian_uk1975]

davepoth said:

Hang on...you spent all that money and didn't change the plugs and air filter?

First rule of maintaining an old car on a budget - change the cheap things first!

2nd rule of maintaining an old car on a budget: only change things when they need changing. No point changing the plugs and air filter just for the sake of it if they're perfectly ok.

[davepoth]

ian_uk1975 said:

2nd rule of maintaining an old car on a budget: only change things when they need changing. No point changing the plugs and air filter just for the sake of it if they're perfectly ok.

However, since they've not been changed, an experienced mechanic has told the OP that these are often the problem with these cars, and they are service items that can be put back onto the shelf and kept to be used at the next service if they don't improve things, thereby effectively costing nothing, it seems a bit daft not to give it a try.

[packman10_4]

Be nice to know the make model and engine type ........

[ian_uk1975]

packman10_4 said:

Be nice to know the make model and engine type ........

Doesn't 'Cav 1.8' pretty much say it all??

[packman10_4]

Vauxhall cavalier 1.8 b series ?

[GrannieTwoEight]

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.

[stevieturbo]

2nd opinion ?

So what diagnosis did the first mechanic come to when he conducted tests ?

And exactly what were all the readings ?

[GrannieTwoEight]

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 on

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]

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

[GrannieTwoEight]

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.

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]

GrannieTwoEight said:

Still to go for the 2nd opinion later on

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?

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 ?

[GrannieTwoEight]

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.

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.

[Sardonicus]

You should be able to flash fault codes out of a Vauxhall from this era, dont hold your breath with it showing anything untoward though.