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Vauxhall Signum 2.2 2005 - MOT emission failure, high CO and HC Lamda 0.946 #

Posted by Adrian Wellard on January 28, 2010, 5:38 pm

Year of Manufacture *: 2004
Engine Code or CC *: Z22YH
( Optional ) Scanner Used: ACR4

This car has failed its MOT on a high CO 1.7 ,high hydrocarbon 280 and lamda at 0.946 at fast idle .Have replaced the fuel pressure regulator ,this made a huge differance but it still wont pass on CO -just over limits after a good run and nice and hot .Seems like a catalyst fault but not sure how to prove .No faults stored .Last attempt before it goes to Vauxhall main dealer.

Re: Vauxhall Signum 2.2 High CO

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 6:21 pm, in reply to "Vauxhall Signum 2.2 High CO"
Peter Mutlow

Hi Adrian,

I am assuming the Lambda sensor is switching nicely and no codes stored. One thing I learnt from UKAT over the 2 years I have been a member is pay particular attention to the Lambda reading. If it is slightly over 1.00 on the re-test then you most probably have a cat problem. Also, if it has been running too rich for too long, then that will kill it. Also, do not buy a cheap one because it may come back and bite you!

Regards

Pete M

Re: Vauxhall Signum 2.2 High CO

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 6:22 pm, in reply to "Vauxhall Signum 2.2 High CO"
Glyn Morgan

Hi Adrian,

What are the fuel trims, can you scope pre & post lambda sensors ?

Regards Glyn

Re: Vauxhall Signum 2.2 High CO

Posted by Matt Booth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3028' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 9:37 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Matthew Booth

As Pete said, if it's been running rich for a while it's probably ruined the cat.

Make sure the pre cat probe is switching nicely. Look at the post probe and see if it is fluctuating frequently or steady. Should stay roughly around 0.45v although stamping on the throttle or letting off will cause a sudden change. If it's fluctuating like the pre cat probe then the cat is gone. If it's fine but still high CO then the cat is gone.

Either way I think the cat is gone! lol

Re: Vauxhall Signum 2.2 High CO

Posted by Nigel Yardley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2837' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 10:09 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Nigel Yardley

This might sound like a silly question... but have you tried changing the oil and filter?

Most near fails (or is it near passes) usually respond well to this, especially if they've been running rich in the past.

Re: Vauxhall Signum 2.2 High CO

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 10:50 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Aiden Birley

hi

May be worth posting current 4 gas + lambda readings and as said details of current o2 sensor activity.

As said, don't condemn the CAT until lambda reading is OK

Cheers Aidan

Re: Vauxhall Signum 2.2 High CO

Posted by George Cameron <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5426' width='330' height='300' border=0 style='border:none;'> on January 28, 2010, 11:44 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
George Cameron

Not sure about this but is 1.7co not too high to be cat fault most cat problem I've seen are around 0.6 co.

Re: Vauxhall Signum 2.2 High CO

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 10:16 am, in reply to "Re: Vauxhall Signum 2.2 High CO"
Peter Mutlow

Following Geeorge Cameron's comments, I am of the understanding that a good Cat will gobble up about 1.5% CO.

Regards

Pete M

Re: Vauxhall Signum 2.2 High CO

Posted by Adrian Wellard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1930' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 10:34 am, in reply to "Re: Vauxhall Signum 2.2 High CO"
Adrian Wellard

Just thought I would post an update.Put the signum on the gas analyser again. If its left idling for 10 mins the CO will reach 0.4-0.7 ,HC will reach 240,slowly creeps up . Lamda sensors reading 1400-1600mv sensor1,600-700mv sensor2 at idle,according to the diagnostics. Raise speed to 3000 ,CO stays at 0.3-0.4 ,HC 00 ,return to idle both at 00 then creeps back up .Thanks for the input.

Re: Vauxhall Signum 2.2 High CO

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 11:42 am, in reply to "Re: Vauxhall Signum 2.2 High CO"
Peter Mutlow

Hi Adrian,

Your pre-cat Lambda reading is too high and not switching between 200 - 800mv every second (1htz). This needs to be dealt with before the cat is changed. The cause could be faulty Lambda sensor, or poor Lambda earth. I am assuming the rest of the engine management system is ok. Sometimes taking the sensor out and giving it a good clean might do it. If you have a poor earth (voltage above 0.25v) then tapping in a direct earth will do it.

Regards

Pete M

Re: Vauxhall Signum 2.2 High CO

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 1:08 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Mark Carter

Hi, do we know what type of sensor is fitted to this vehicle? and therefore testing the component using the right test procedure?

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Signum 2.2 High CO

Posted by Sean Mc Gettigan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5291' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 1:19 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Sean McGettigan

' If you have a poor earth (voltage above 0.25v) then tapping in a direct earth will do it. '

Ever came across a floating earth Pete?

Sean

Re: Vauxhall Signum 2.2 High CO

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 4:06 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Peter Mutlow

Hi Sean,

No idea what ramifications a "floating earth" will present, but I have plumbed into a "direct earth" before with complete success with the Lambda Sensor.

Regards

Pete M

Re: Vauxhall Signum 2.2 High CO

Posted by Barry Eger <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5591' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 4:17 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"

Hi all

I think you will find this has a five wire wide band oxygen sensor fitted.

Regards Barry

Lets do it to them... before they do it to us...

Re: Vauxhall Signum 2.2 High CO

Posted by Matt Booth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3028' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 7:57 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Matthew Booth

Yup those readings sound like you don't have a conventional probe fitted. You can't test it the way that has been previously mentioned.

Re: Vauxhall Signum 2.2 High CO

Posted by Adrian Wellard <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1930' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 8:59 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"
Adrian Wellard

Must admit I am getting a bit out of my depth wih this one .Its going to the Vauxhall main dealer soon .If they fix it I will post the information here straight away. Have run out of time to try oil change .Thanks for helping ,hope to report back soon !

Re: Vauxhall Signum 2.2 High CO

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on January 29, 2010, 11:32 pm, in reply to "Re: Vauxhall Signum 2.2 High CO"

It took time, but we got there in the end.
NOTE;
Please, please do not feed four wire (or more) O2 sensors with a direct earth (without studing a wiring schematic), you run the risk of generating more fault codes than you will ever clear.

Regards mark

Modern cars, Its all wizardry and witchcraft

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