FSI failed on emissions

[dances-with-pies]

Having finally solved the FSI's reluctance to rev when warm (FSI slow to rev) with a new N80 valve, it was time to MOT it.
It had passed previously when running poorly so I wasn't expecting any issues with emissions.

Here is the result.

The garage suggested that the low lambda reading was most likely due to a failing lambda sensor so I ordered a Bosch one from EuroCarParts along with a can of Cataclean.
When I came to fit it I realised that I had replaced it the previous year only 116 miles earlier!
I fitted the new one anyway and emptied the can of Cataclean into the tank which was just over a quarter full of one year old Shell V-Power.
Warming the car up before before taking it for a re-test, I went on a fifteen mile thrash to give the Cataclean time to do its stuff.
The car was brilliant fun and plenty hot enough when I arrived.
It was hooked straight up and tested with the following result.

The results are pretty much the same.
The MOT tester was surprised and questioned the make of lambda sensor.
I confirmed that it was a Bosch sensor and that it replaced another Bosch sensor that was only 116 miles old.
The next suggestion was the air flow meter but that was replaced with a genuine dealer part less than a thousand miles previously.
He then asked if it had been remapped because he had seen similar issues on other VAG cars after a remap.
It is fitted with a ProBoost ECU but other A2OC members have passed emission tests so I don't think that's the issue.

What else could cause these readings?

 

[EdinA2]

It might be as simple as the fuel having gone off. It can take a surprisingly short time, especially in high ambient temperatures.

 

[simon martyn]

A clue might lurk in the statement "I year old Shell V power" Old petrol is never a good thing!

Best of luck,

Simon

 

[dances-with-pies]

Thanks both.

It's certainly the next thing to try.

 

[Phil FSI]

 

[dances-with-pies]

Good figures.

 

[Phil FSI]

Forgot to mention when I uploaded the image that that was with a new cat that had just been fitted as it had just failed on emissions also.

 

[dances-with-pies]

Forgot to mention when I uploaded the image that that was with a new cat that had just been fitted as it had just failed on emissions also.

Do you have the results before the new cat?

 

[dances-with-pies]

I drained the year old V-Power which was orange and added two gallons of fresh V-Power (yellow).
Just returned from having the emissions checked again.
The results were almost identical.

I have a stock FSI ECU which I'm hoping to try but I need the immobilizer removing.
Can any members remove the immobilizer coding?

 

[audifan]

I thought that both @timmus and @depronman offered a postal service where you send in your ECU and they code out the immobiliser. Please check with either to see if the service is currently available. Although think you are looking at a contaminated / failed cat personally now.


In the mean time you have run fuel system treatment through but have you driven the car hard in all gears to help clean out the build ups with another treatment now on fresh fuel?

 

[PlasticMac]

I drained the year old V-Power which was orange and added two gallons of fresh V-Power (yellow).
Just returned from having the emissions checked again.
The results were almost identical.

I have a stock FSI ECU which I'm hoping to try but I need the immobilizer removing.
Can any members remove the immobilizer coding?

View attachment 97681

Did you get it scanned since fitting the N80?
Mac.

 

[Andrew]

@dances-with-pies

Reading this you make no mention of a second can of cataclean (the first can lost when the old petrol was drained) or another spirited drive prior to the third test?????

I must comment your garage's emissions test results have a lot of numbers, intimidating, feel I'm drowning in them, my result printout is a lot simpler. My FSI had its yearly test last week and I include it as something to compare to.

Note. My FSI only did 1600 miles in the last MOT year and nearly all short journeys, the worst I know, I wonder if I need a car as I
get deeper into retirement.

Andy

 

[simon martyn]

Just a thought. I can't help thinking that just 2 gallons of "decent petrol" is not really enough. Have you still got a bit of the old stuff lurking in the system? Personally I'd fill with good petrol and then drive it "like you stole it" for a goodly period. Then try again, Another MOT station maybe?

PS That's assuming that your cambelt and water pump are up to date!

Good luck.

 

[PlasticMac]

When petrol is left unused, the volatile compounds vaporise, and are lost. What remains is low octane base, and compounds that are designed to be dissolved in the volatile fuel, but aren't. This will contaminate the whole system, including sensors and, importantly here, the catalytic converter. The car needs a good, extended and spirited drive, to allow the detergents in the fresh fuel (a tank full), to do their job, and for the catalytic converter to get really hot, and stay hot for a good while. Only then will the emmissions control functionality start to work.
Mac.

 

[dances-with-pies]

Did you get it scanned since fitting the N80?
Mac.

Yes and despite only idling it, it has no engine codes.

 

[dances-with-pies]

I completely drained the tank of old fuel by disconnecting the pipe from the fuel filter and activating the fuel pump using VCDS.
I then removed the fuel sender to check that the tank was completely empty.
10 litres of Shell V-Power was added to get me going and then another £15 on the way to the test.
I took the less direct route, drove in low gears at high revs and floored it at every opportunity.
I had covered 10.3 miles when I arrived at the garage.
I plugged in VCDS and there were no codes.
I left it idling for 15 minutes until they were ready to test it.

Since the emissions test, it has two codes.


17912 - Intake Air System
P1504 - 35-10 - Leak Detected - Intermittent
16891 - Idle Control System RPM
P0507 - 35-10 - Higher than Expected. - Intermittent

I don't know for sure but I suspect that the first code is when they removed the dipstick which they did several times.

I appreciate that 10 miles isn't a lot of miles but I expected at least a small improvement in emissions.
Also, there is a risk with driving it hard with no MOT and TAX.

 

[PlasticMac]

Looking at @dances-with-pies results, and @Andrew results, the big difference is the engine speed used for the Fast Idle test. @Andrew engine speed was not checked, but limits are 2,500 - 3,000 rpm, whereas @dances-with-pies engine speed was 3,860 - 4060rpm. I don't think 3,860, or 4960 rpm can be described as fast idle, Google confirms the MoT limits as 2,500 - 3000 rpm.
Looks to me that the MoT test was carried out incorrectly.
Mac.

Edit, this is the text copied from the MoT Inspection Manual:

To pass the basic emissions test, the readings must be within all the following limits:

• CO up to 0.2% at fast idle (2,500rpm to 3,000rpm)
• HC up to 200ppm at fast idle (2,500rpm to 3,000rpm)
• Lambda between 0.97 and 1.03 at fast idle (2,500rpm to 3,000rpm)
• CO up to 0.3% at idle (450rpm to 1,500rpm)

 

[PlasticMac]

Please ignore this, and refer to post #21

I'd also say it's questionable, maybe foolhardy, to hold an FSI at close to 4000 rpm, no load, for an extended period. That's the point of maximum torque for an FSI, certainly not idling.
Mac.

 

[PlasticMac]

Please ignore this, and refer to post #21
Might be worth showing the attached to your MoT tester.
Mac.

 

[Andrew]

The mystery of 3750 - 4550 rpm fast idle test surfaces. Look at page 25 in the Annex.

Andy