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cheapapples *
Joined: 24 Aug 2004 Posts: 41 Location: In the sticks near Mkt Drayton Shropshire
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Posted: Mon Oct 24, 2005 20:11 Post subject: MOT Failure on High Emissions, Lamda Sensor? **SOLVED** |
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My 3.5 V6 (1994) has just failed the MOT on high emissions. The report showed the following:
CO2 should be max. 0.30.
Actual on test 1 - 2.81%
Actual on test 2 - 3.46%
Actual on test 3 - 2.74% (this test is at idle)
HC Level should be max. 200
Actual on test 1 - 115 ppm
Actual on test 2 - 138 ppm
Lamda should be 0.97 to 1.03
Actual on test 1 - 0.93
Actual on test 2 - 0.90
The MOT guy suspected the Lamda sensor to be faulty, which would figure. I just wanted to get some more opinions before I laid out the cash.
Also is there anyway of testing the Lamda?
If I do replace it, I have been quoted between £35 and £60 for a universal one depending on style of fitting and number of leads coming off it. Do these universal types do the job well enough?
Thanks for any feedback. |
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Posted: Mon Oct 24, 2005 20:11 Post subject: Google Ads keep the POCUK free to join! |
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offroaddriver Moderator
Age: 37 Zodiac: Joined: 08 Jan 2005 Posts: 1496 Location: The big smoke
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Posted: Mon Oct 24, 2005 21:14 Post subject: |
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hi,
we had a honda accord aerodeck which had a mot failure on the lamda sensor. we had a universal one fitted for just under £50 and it worked a treat. saved loads of cash instead of buying a proper honda jobby! |
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M.A.B **
Joined: 20 Mar 2003 Posts: 74 Location: North Wales
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Posted: Mon Oct 24, 2005 22:14 Post subject: |
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HI there
have you got a check engine light, if the Lambda Sensor is no good then this should of come on to tell you, you have a problem.
You can check them with a digital voltmeter to see if they are working or not have a look at this site
http://www.lambdasensor.com/main/mtesting.htm
if you do find you need a new one try this place the most expensive 4 wire one is £25.38 +£5.50 p&p(postage is a fixed price so if you need other bits while you are there the more you save)
http://www.buypartsby.co.uk/lambda_sensors.php
Mark |
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cheapapples *
Joined: 24 Aug 2004 Posts: 41 Location: In the sticks near Mkt Drayton Shropshire
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Posted: Tue Oct 25, 2005 9:33 Post subject: |
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Superb, thanks for your responses, I'll check it out today and let you know how I get on. |
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ahalton ******
Joined: 17 Jun 2003 Posts: 2268 Location: ..........
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Posted: Tue Oct 25, 2005 10:47 Post subject: ECU |
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You can check to see if the ECU is storing any faults by doing the diagnostic, the engine check light doesn't come on for all faults.
I can let you know how to do the diagnostic if you haven't got or don't understand the Haynes manual, its not very clear in there.
Andrew |
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cheapapples *
Joined: 24 Aug 2004 Posts: 41 Location: In the sticks near Mkt Drayton Shropshire
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Posted: Tue Oct 25, 2005 12:28 Post subject: |
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A few tips on the diagnostic would be great mate.
I have found a white connector down by the pedals and fuse box (see attachment) I am presuming this is the beaut I need. Presumably I need to short out a couple of the pins and use a multimeter. But I could do with being a bitmore accurate than that.
Cheers |
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ahalton ******
Joined: 17 Jun 2003 Posts: 2268 Location: ..........
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Posted: Tue Oct 25, 2005 13:15 Post subject: Fault |
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Thats the one, didn't look right at first so went outside and got wet, my plugs black for some reason.
Anyway.
Ensure ignition is switched OFF.
Bridge (short) pin1 out with earth. As you look at the picture you posted, pin 1 is bottom left, the left hand pin on the fat side of the plug.
Switch ignition ON (don't start the engine)
If there is a fault the Check engine light will flash. There are two types of flashes, long and short.
Count the number of long flashes and the number of short flashes.
The long flashes are TENS, so if it flashes twice that means 20, the short flashes are the units, so short flashes would be 5, give a total of 25.
Hope its clear.
If you have a fault code then let me know the number and I can give you the fault.
Andrew |
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cheapapples *
Joined: 24 Aug 2004 Posts: 41 Location: In the sticks near Mkt Drayton Shropshire
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Posted: Tue Oct 25, 2005 13:36 Post subject: |
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Great thanks.
Just checked it, and the check engine light just flashes on and off constantly.
Judging by the results in the haynes this is normal operation. If you know different let me know.
I have been in touch with the guy from www.lambdasensor.com and the tests I have run on the sensor show that the sensor is working and trying to get the ecu to compensate for a rich mixture (as the voltage reading from the sensor is high) and the results from the emissions test indicate that there is not enough oxygen.
Below is the reply I had from him:
"I doubt it is the lambda sensor.
Voltage is stuck high wavering between 0.940v and 0.947v:
this indicates the sensor is working as it is creating a voltage, At this value it is "telling" the ecu the mixture is rich and please weaken off. The chances are there is another fault and the ecu cannot weaken any more.
Lamda level was low at around 0.90:
Again this indicates that there is little oxygen in the exhaust = rich mixture. A cat needs heat and oxygen to reduce the CO. In this case you have the heat but not enough oxygen."
So it looks like I may have to get a tuner to come out and check things over.
Thanks for your help guys |
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tony *****
Age: 68 Zodiac: Joined: 25 Oct 2002 Posts: 692 Location: warrington cheshire
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Posted: Tue Oct 25, 2005 15:33 Post subject: |
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not that sure of petrol paj faults, but when i put my newly imported fto in for mot we had simular results and all the guy did was kept it revving at about 3,000rpm for 10 mins till the engine and exhaust were really hot and retested it no problem! we put it down to the fact the car had been stood for months and only been stop/started! its worth a try as its only cost a drop of petrol.
good luck
tony |
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JJ1 *
Joined: 18 Aug 2005 Posts: 11 Location: WAKEFIELD
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Posted: Tue Oct 25, 2005 20:51 Post subject: |
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i had a rav 4 fail its emissions with similar test results, had the lamda changed and it passed fine after ,i was chuffed cause the test guy said it was the cat |
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cheapapples *
Joined: 24 Aug 2004 Posts: 41 Location: In the sticks near Mkt Drayton Shropshire
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Posted: Sun Nov 06, 2005 11:44 Post subject: |
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Okay guys, thanks for all your comments, the problem has now been solved, with the very kind help of Ivor Green, a big thanks to him.
I believed it wasn't the Lamda sensor, as I had tested it as per the information I gave above, and the results seemed to be pointing at something else causing the mixture to be rich, and the ecu not being able to weaken it.
Ivor recomended that I flush the engine (oil flush), with a decent flush like Protec, also replace the sump plug washer and use a genuine oil filter, as the cheap ones don't have an oil presure relief valve fitted.
After flushing and refilling the oil, I ran ran her up to temperature and checked the Lambda again. This time the sensor was registering spot on, alternating from 0.2 to 0.8v, so I took her back in for the MOT and she passed no probs.
Ivor belives that it would have been something internal that could have been sticking, possibly even a piston ring, therefore causing poor and uneven compression leading to poor combustion temp and therefore excessive emissions.
Thanks again to everyone for their input, I have learnt a few things along the way. |
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