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Topic: Idle emissions varying up and down, failed MOT (Read 1509 times) |
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ambyuk
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Idle emissions varying up and down, failed MOT
« on: Jun 3rd, 2010, 11:18am » |
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I've got a 1995 Scorpio Cosworth 2.9 24V. Just put it through it's first MOT since I bought it and it's failed on emissions. Garage has no idea what could be wrong with it really so I said I'd post on here.
Firstly he did run it around so it was hot, and retested it, still failed. Then he put fuel additive in and it still failed again.
What's happening is the emissions are up at about .8 or .9 % (not sure of the exact units but well into the 'red zone') then every few seconds they're dropping back into the green zone but not staying there long enough to pass.  So the garage who did the MOT reckons it could be a sensor, he said he doesn't think it's the cat(s) because assumably it would be constantly high? BUT he told me to ring Ford for advice and they say if it was a sensor the check engine light would be on, which it isn't.
I really hope someone has some advice for me, if I can't get it to pass emissions I will have to scrap it and I desperately don't want to do that to my beauty.
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martin_rowe
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Re: Idle emissions varying up and down, failed MOT
« Reply #1 on: Jun 3rd, 2010, 11:40am » |
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you need to post the actual values off the emission test, this vehicle is prone to vacuum leaks (pipes under inlet manifold, egr system ect) you will also need some 'live' data from the ecu, fault codes, fuel trims ect.
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Rally Drivers Do It Sideways
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Mike H
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Renault Clio
 
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Re: Idle emissions varying up and down, failed MOT
« Reply #2 on: Jun 3rd, 2010, 3:35pm » |
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I reckons, must be fixable cos it's obviously trying but not quite making it. (?)
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Mike H
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scorpio_man
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Ford Kuga awd
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Re: Idle emissions varying up and down, failed MOT
« Reply #3 on: Jun 3rd, 2010, 4:55pm » |
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hi there
as said earlier, post all the figures from your failed emission test for us to have a look at.
also post your location to see if you've near another member who might be able to give your car a diagnostic scan.
btw, the scorpio doesn't have an engine management light, so it could be a faulty sensor.
hth
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #4 on: Jun 3rd, 2010, 8:01pm » |
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Thanks. Unfortunately I don't have the values etc. I did ask the garage (having read some old threads here before I went to pick it up) and they said they can't do that? It's just a tiny garage in a little village so maybe he doesn't have the right equipment, he said his just shows him pass or fail.
Mike I hope you're right, I guess the problem is, can I find out what is going on without it costing the earth? I've been quoted £70 for 1hr diagnostics at the Ford garage - but not a great deal of confidence in them if they didn't know there wasn't a check engine light! The guy at the MOT garage did say his gut said sensor so maybe that's what it is then.
I live in NE Aberdeenshire, will be surprised but happy if anyone is near me!
Thanks for your help, can't tell you how much I appreciate it, just desperate to solve this problem so I can get my beauty back on the road.
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scorpio_man
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Ford Kuga awd
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Re: Idle emissions varying up and down, failed MOT
« Reply #5 on: Jun 3rd, 2010, 8:23pm » |
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hi there
we have a few members up your way, so hang in there!!
give them a day or two to see your post.
hth
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Highlander
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Re: Idle emissions varying up and down, failed MOT
« Reply #6 on: Jun 3rd, 2010, 10:14pm » |
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on Jun 3rd, 2010, 8:01pm, ambyuk wrote:| I live in NE Aberdeenshire, will be surprised but happy if anyone is near me! |
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I get up to Aberdeen/Ellon/Peterhead now and again but dont know when i'll be up next, when does your mot run out?
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on Oct 17th, 2011, 12:35pm, Simmo wrote:I give up !  Too much for an old boy!  |
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #7 on: Jun 3rd, 2010, 10:25pm » |
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It's already run out, but it's taxed so I'm driving it only around the village (purely because the brakes are on the verge of needing replacing, but I don't want to pay for that until we can figure out the emissions problem). Prepared to take the risk of a 60 quid fine if I get pulled over, which is doubtful anyway.
The garage said I should try and get it fixed by 16th June as that's the latest date they can retest it for free.
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Highlander
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Re: Idle emissions varying up and down, failed MOT
« Reply #8 on: Jun 3rd, 2010, 10:38pm » |
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Spend your £60 fine money on the diagnostic! 
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #9 on: Jun 3rd, 2010, 10:41pm » |
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I'm just not convinced they'll find the problem. As I said they didn't even know that a Scorpio doesn't have a check engine light, I'd rather someone who knows the cars looked at it. Plus they kept saying they couldn't guarantee they'd find the problem in an hour they might need longer at another 70 quid. They're also the ones who said it was 99% likely the cats but the other garage said 99% sure it's NOT the cats (and it doesn't make sense to me that it would be the cats either, what do you think based on what I've said?).
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Highlander
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Re: Idle emissions varying up and down, failed MOT
« Reply #10 on: Jun 3rd, 2010, 11:00pm » |
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I think somethings funny at your garage, MOT stations MUST be able to see the results and give you a printout, they dont just get a yes or a no...
MOT Printouts and check sheets
The 1996 specification analysers will produce two printouts. One printout must be retained with the VT20/VT30 records and the other printout must be given to the vehicle presenter. In the case of 'manual' catalyst testing, the check sheet should be retained with the VT20/VT30 records. A duplicate of the check sheet need only be produced if the customer specifically requests it.
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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tlundkvi
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Ex. Scorpio 2.9 24V -95
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Re: Idle emissions varying up and down, failed MOT
« Reply #11 on: Jun 4th, 2010, 8:30am » |
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on Jun 3rd, 2010, 10:41pm, ambyuk wrote:| I'm just not convinced they'll find the problem. As I said they didn't even know that a Scorpio doesn't have a check engine light, I'd rather someone who knows the cars looked at it. Plus they kept saying they couldn't guarantee they'd find the problem in an hour they might need longer at another 70 quid. They're also the ones who said it was 99% likely the cats but the other garage said 99% sure it's NOT the cats (and it doesn't make sense to me that it would be the cats either, what do you think based on what I've said?). |
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Some believe cats last the car lifetime, because often they do. Those who don't, have seen them fail and remember the irritating fault finding etc. In addition to OBD scanning, I would have them do the cat test first, i.e. check for switching rear oxygen sensors (if they still work that is). If the emission test shows a good lambda around 1.00 and you still get bad emissions, it is yet another pointing finger to the cats and not sensors or injection system, because the lambda is independent of the cat working.
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #12 on: Jun 4th, 2010, 8:35am » |
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He did say that lamda was fine. So if the cats need replacing why would the level go up and down like it does? Wouldn't it just be permanently high?
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tlundkvi
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Re: Idle emissions varying up and down, failed MOT
« Reply #13 on: Jun 4th, 2010, 11:58am » |
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on Jun 4th, 2010, 8:35am, ambyuk wrote:| He did say that lamda was fine. So if the cats need replacing why would the level go up and down like it does? Wouldn't it just be permanently high? |
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I'm not sure of which level you refer to? I refered to the voltage output of the lambda sensors, the front ones should switch all the time between 0.1-0.9V in very short intervals and the rears should produce a stable level of 0.4-0.5V if the cat does it's job. If the rears are switching, it means the cat does not change the composition of exhaust gases enough to pass the emissions test. You can check this: http://www.fordscorpio.co.uk/obd2scan4.htm
Lambda being around 0.98 and 1.02 shows the fuel trim is in perfect order (not running too rich etc), it should be quite stable. A car running too rich can cause higher emission values and failed mots. Since the lambda values were fine, the car is probably not running rich and lambda sensors are probably OK. If emissions are still high (HC and CO) the most likely culprit are the cats.
An OBD test could reveal if one or both cats are bad. A 24V with fresh cats reaches HC < 10ppm and CO < 0.1%.
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #14 on: Jun 8th, 2010, 7:55pm » |
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Sorry, didn't get an email notifying me of this reply. Can a garage do an OBD test? I guess if the garage I took it to today could have they would've done it...
As far as I recall, he said the only level that was high was CO.
The problem is, I have a very limited amount of money with which to find out what the problem is and fix it, and I really can't afford to gamble too much on fixing things that *might* be the problem. *sigh*
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scorpio_man
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Ford Kuga awd
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Re: Idle emissions varying up and down, failed MOT
« Reply #15 on: Jun 8th, 2010, 9:04pm » |
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hi there
did you or the garage check all the vac pipes as posted earlier?
this will give you an idea of the information we're trying to get from you or the garage.
http://www.fordscorpio.co.uk/ho2smonitor.htm
hth
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tlundkvi
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Re: Idle emissions varying up and down, failed MOT
« Reply #16 on: Jun 8th, 2010, 9:11pm » |
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A garage should be able to do this, they may have such "pro" stand-alone readers though, seeing the live data is difficult if they don't hook it to a computer. But they will probably have a plotting multimeter to hook directly up to the sensors.
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #17 on: Jun 8th, 2010, 9:13pm » |
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If they did check that, they didn't tell me they did. They were recommended to me by a vauxhall mechanic and so I just handed it over to them for diagnostics. Most of this stuff is totally over my head, I'm sure you can tell I know nothing about cars.
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ambyuk
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Re: Idle emissions varying up and down, failed MOT
« Reply #18 on: Jun 9th, 2010, 1:31pm » |
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OK, my friend's dad has been a mechanic for 20+ years and is going to look at it tomorrow evening. Please can anyone who's reading this post a summary of what you think could possibly cause the problem with emissions reading VERY high then low intermittently. All we know is that the Bank 1 rear sensor is faulty according to the diagnostics test. I'll print out a summary of what people have said to give him some ideas.
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scorpio_man
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Ford Kuga awd
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Re: Idle emissions varying up and down, failed MOT
« Reply #19 on: Jun 9th, 2010, 2:19pm » |
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hi there
check vac pipes (especially at the t connectors).
check spark plugs.
check what the long term fuel trims are (you need to be able to read live data for this).
check front (pre cat) lambda outputs (can be done with a multi meter if obd2 scanner not available. be careful, though)
are the revs steady at idle?
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