Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Ralph M on 16 September 2010, 09:52:31
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Does anyone know where I can buy replacement Catalytic converters at a discount price, because the pre-cats on my Omega 3.2 MVX 02 Reg saloon, are producing fault codes P0420/P0430.
Thanks
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I suspect there's probably nothing wrong with the cats but a common problem on the 3.2 whereby the lambda sensors are playing up because VX put them in the wrong place. The only way to permanently cure the problem is to have them moved from behind the pre cats to behind the main cats. I eventually had mine done by Mark DTM and have never had the problem since. I'm sure one of the other tech guys will be along shortly to explain in a little more detail. :y
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No and dont replace them.
The pre-cats are not important and the main cats will be fine.
If your very worried about the codes then get the post cat lambda sensors moved to after the main cats.
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No and dont replace them.
The pre-cats are not important and the main cats will be fine.
If your very worried about the codes then get the post cat lambda sensors moved to after the main cats.
Wait, wait.. Vx put the cat-efficiency lambda sensors after the pre-CATs and before the main CAT? I guess someone was asleep at the wheel in design, that day!
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No and dont replace them.
The pre-cats are not important and the main cats will be fine.
If your very worried about the codes then get the post cat lambda sensors moved to after the main cats.
Wait, wait.. Vx put the cat-efficiency lambda sensors after the pre-CATs and before the main CAT? I guess someone was asleep at the wheel in design, that day!
Nope, they had to ensure that they met the stringent start up emmisions for type approval, this requires a small cat mega close to the exhaust which gets hot very quickly.
We dont have to meet this for MOT's and hence as it starts to fail (it has a VERY hard life) we can move them
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Nope, they had to ensure that they met the stringent start up emmisions for type approval, this requires a small cat mega close to the exhaust which gets hot very quickly.
Yep, I know all about preCATs (the MR2 has them - they tend to disintegrate and grenade the engine..) - but on the MR2 the 'cat efficiency' third lambda is after the main CAT, with the fuelling lambda sensors before any CATs, which seems much more sensible since - AFAIK - the requirement of OBDII is to monitor the efficiency of the main CAT or full CAT configuration, not the efficiency of the preCATs alone..
(Let's put it this way, the MR2 was designed to meet ULEV and only has three O2 sensors - two for fuelling before any CATs on bank 1 & bank 2, and one after the main CAT as sensor 2 bank 1.. Apart from J-spec imports, which don't need to meet OBDII specs - they only have the fuelling lambdas)
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Nope, they had to ensure that they met the stringent start up emmisions for type approval, this requires a small cat mega close to the exhaust which gets hot very quickly.
Yep, I know all about preCATs (the MR2 has them - they tend to disintegrate and grenade the engine..) - but on the MR2 the 'cat efficiency' third lambda is after the main CAT, with the fuelling lambda sensors before any CATs, which seems much more sensible since - AFAIK - the requirement of OBDII is to monitor the efficiency of the main CAT or full CAT configuration, not the efficiency of the preCATs alone..
(Let's put it this way, the MR2 was designed to meet ULEV and only has three O2 sensors - two for fuelling before any CATs on bank 1 & bank 2, and one after the main CAT as sensor 2 bank 1.. Apart from J-spec imports, which don't need to meet OBDII specs - they only have the fuelling lambdas)
Chalk and cheese, this is a different scenario, design, setup, heavier car the lot.
Gm had to ensure they passed the EU test, the only way they can guarantee this is to ensure the pre-cats are upto temp fast hence they ARE monitoring the rights ones.
There would be no point monitoring after the main cats as it would take MUCH longer for these to heat up and the sensors to respond.....result, type approval fail! :y :y
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hey - get a load of you lot ... "type approval", EU Emissions, OBD-II
now I am impressed
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Does anyone know where I can buy replacement Catalytic converters at a discount price, because the pre-cats on my Omega 3.2 MVX 02 Reg saloon, are producing fault codes P0420/P0430.
Thanks
This is common on 3.2. Trust us, there is no need to replace the cats, it WILL pass the mot, it will NOT cause any running issues with the car, cats are about 700 sobs each, cheeper don't last.
Follow the guide in maintenance re moving post cat lambda, which is a good guide, but in effect, all it does in real terms is put the light out on the dash, local mech can do that if he can weld for a couple of hours work, some on here will do it for less than that.
Seriously, no need to change the cats.
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Another solution is to buy a cheap(ish) analyzer/resetter .. and when the light comes on .. just reset it. As long as it does not come back "instantly" there is no problem. I get this problem about once a year ... the GS500 quickly identifies the problem.. I turn the light out .. its fine for another year .. :) GS500 about £80 ... less than Vx charge just to read the codes .. :) and probably less than a garage would charge to move the sensors.
HTH
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Thanks everyone for the replies. I have tried resetting the fault codes by disconnecting the battery, but they return after a period and that period is getting shorter - currently down to 24 hours. Could anyone suggest who might help me to get the pre cat sensors moved? I live in Wilmslow, near to Manchester Airport.
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Disconnecting the battery won't clear the codes with this ECU. They are held in non-volatile memory. You need to clear them with a code reader. Having said that, in the absence of a continuous problem the emissions light will turn off eventually.
Relocate the lambda sensors or ignore the light, IMHO.
Kevin
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Thanks everyone for the replies. I have tried resetting the fault codes by disconnecting the battery, but they return after a period and that period is getting shorter - currently down to 24 hours. Could anyone suggest who might help me to get the pre cat sensors moved? I live in Wilmslow, near to Manchester Airport.
Although there may be other on here that are able to do this job, the only one I know is Marks DTM and he's in Nottingham. Might be worth a PM to Darth Loo-Knee as he does a lot of work on members Omega's at reasonable prices. Trouble is it's not a 5 minute job. Both sections of the exhaust with the cats and sensors on have to be removed, the sensors removed and holes plugged. Then new holes have to be drilled (requires a fairly hefty bench drill) and new boss's welded in place. Took a good few hours to do mine.
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Ignoring the dash light is the cheapest and easiest solution, no doubt there ;D
Or dare I say it, remove the bulb....
Regular pedal tricks will spot any issues.
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Just to add to this debate, your old, original cats will be far better (quiet, refined, durable, longer lasting) than brand new pattern cats.
As MDTM has said, moving the 2nd sensor on each bank to behind the main cat cures the code.
Again, MDTM is quite correct as to why the sensors are where they are. Precats is probably a bad description, in fact GM call them 'Starting Cats'
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I may have access to a rotabroach that should make drilling of lambda holes in the future easier (not that I am volunteering to do them ;D)
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Anyone tried spark plug anti-foulers?
If not, I will be doing so shortly. Might be an easier alternative to installing additional lambda bosses if it works...
http://forums.evolutionm.net/evo-how-requests-questions-tips/114931-how-install-spark-plug-anti-foulers-remove-ses-cel-light.html
Kevin
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Anyone tried spark plug anti-foulers?
No, but I've seen the results of trying to drill them out to accept the O2 sensor with a blunt drill bit.. (blue, mangled, burnt mess) ;D Apparently they're tougher than they look.
(Then again I've never found a sharp drill bit in Mark's workshop, and he's not known for his patience when trying to drill things!)
Well known fix on other cars, though - on the MR2 you can, so I'm told, get away with no CAT at all if you space the third O2 sensor out with a couple of anti foulers. Not that I'd know. Nor try. Nor recommend such things.
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Hi All,
I have a 3.2 with the same problem so I have been reading this thread with interest.
I have my GS 500 lead permanently plugged into the test socket, and the analyser in the glove box ready to use when the EML comes on.
It's no problem clearing the light, but it does get annoying.
I would be interested to hear if anti fouling extensions work.
I am also surprised that some electronics minded whizz kid hasn't come up with an answer to our prayer. There must surely be some way to raise the threshold level that the light is triggered.
Roger
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Hi All,
I have a 3.2 with the same problem so I have been reading this thread with interest.
I have my GS 500 lead permanently plugged into the test socket, and the analyser in the glove box ready to use when the EML comes on.
It's no problem clearing the light, but it does get annoying.
I would be interested to hear if anti fouling extensions work.
I am also surprised that some electronics minded whizz kid hasn't come up with an answer to our prayer. There must surely be some way to raise the threshold level that the light is triggered.
Roger
I've been thinking about that too. They key is to delay the response of the post-cat sensor. This is what spacing it out from the gas flow achieves, of course. The delay between front and back Lambda sensors under deliberate lean / rich conditions is what the ECU uses to assess cat efficiency.
Whilst the "threshold" is in ECU firmware and not easily accessible, it should not be that hard to fool the ECU electrically, but a spacer will probably be the easiest option for most (if you can find a sharp drill!).
Kevin
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There are circuit diagrams available on the 'net - it's a fairly simple NE555 based thing..
http://www.mkiv.com/techarticles/oxygen_sensor_simulator/
Or.. here's one ready made with a GM connector:
http://www.afterthoughtsauto.com/o2sim.html
Kinda expensive to import £5s worth of parts from the US, though, even if it does have a nice moulded connector ;)
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There are circuit diagrams available on the 'net - it's a fairly simple NE555 based thing..
http://www.mkiv.com/techarticles/oxygen_sensor_simulator/
Or.. here's one ready made with a GM connector:
http://www.afterthoughtsauto.com/o2sim.html
Kinda expensive to import £5s worth of parts from the US, though, even if it does have a nice moulded connector ;)
I don't think that will fool anything other than a very basic ECU.
The system on the 3.2 will use the front lambda as a reference, send the mixture rich, for example, watch both sensors and time the delay between the two. Over a few test cycles it will pick up a pattern. The delay has to be within an allowable window so just connecting a free-running oscillator won't cut it. Delaying the signal might, however.
Kevin
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Hi,
All very interesting.
Can anyone tell me where we can get these spark plug anti fouling spacers from. Surely we don't have to get them from USA.
From the threads mentioned, it seems we will need 4
I used them on an old oil burning Rover 50 years ago (shows my age)
but never seen any for some years.
Roger