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B-Don

Corolla Ts Exhaust And Eml Problem

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I have a 51 reg Tsport with a couple of problems.

18 months ago the EML appeared on the dash indicating a faulty catalytic coverter (cat defeciency level below threshold). I had it gas tested and sure enough the cat didn't appear to be doing it's job as the emissions were out and would have failed an MOT. So I had a reputable garage make up a new aftermarket cat as I couldn't afford the £900+ genuine toyota one and had it gas tested again. This time the emissions were better but still a little high.

Around two weeks later the EML came back on and indicated the same previous fault - after having the fault cleared on the ECU, the engine light came back on again a few days later. I took it back to the exhaust garage and they said that the cat works fine and the fault must be something else like a lambda sensor, air mass or overfuelling problem?

So I took it to another garage who also diagnosed the same cat fault code and also a problem with two of the engine coils, which (I was told) could possibly explain why the car could be overfuelling? I had the coils changed to be on the safe side but the the cat fault code didn't clear.

Now i'm thinking of just going back to the exhaust place and demanding that they change it but first wanted to ask if anyone else has experienced similar problems?

Could the fault code be due to an air mass or lambda sensor problem and how would I go about finding which one?

Would appreciate any knowledge on this type of problem.

Thanks

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Can anyone help me out with this? Had the car at the exhaust garage today and the bloke said it has to be another problem. The aftermarket cat they put on is a "metallic cat" and "virtually indestructable" - does anybody know if this is true?

I know that overfuelling can destroy the cat so if that is the problem, how would i diagnose what it causing it?

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Can anyone help me out with this? Had the car at the exhaust garage today and the bloke said it has to be another problem. The aftermarket cat they put on is a "metallic cat" and "virtually indestructable" - does anybody know if this is true?

I know that overfuelling can destroy the cat so if that is the problem, how would i diagnose what it causing it?

you need to get it on a proper scanner with live data not just a code reader.something like a ethos or solus by snap on will do the job that way you can check the lambda sensors/maf sensors are working.

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when you get a fault cat efeciency level below threshold it does basically mean that the cat is not working as efficiently as it should sensors measure the burnt fuel before the cat then its measured after the cat and obviously the cat is not capable of coverting all the remaining gasses to an acceptable level possibly due to a poor quality cat .if engine was over fueling you would get a fault with a sensor and giving a fault of rich mixture ,as if you had an air leak it would show you a weak mixture.sometimes poor quality aftermarket cats do not have the required quantity of the precious metals to convert the gasses thats why they are cheaper some work ok some don,t i,d guess yours doesn,t

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I haven't tried cleaning the MAF, no... how would I do that? And how would that throw the cat reading out?

Is it only specific garages that run the Snap On data scanners? I've seen that the Solus Pro kit to buy is over £2k so I'd imagine not too many use them?

Also, could an ECU remap possibly help? Just thinking maybe if the air/fuel mixture settings have altered and that's why the 2nd lambda is reading high emissions and therefore, saying the cat doesn't work?

The garage said that (although aftermarket) it is a "bulletproof metallic cat" and they've "never had to send one back under warranty"?

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I haven't tried cleaning the MAF, no... how would I do that? And how would that throw the cat reading out?

Is it only specific garages that run the Snap On data scanners? I've seen that the Solus Pro kit to buy is over £2k so I'd imagine not too many use them?

Also, could an ECU remap possibly help? Just thinking maybe if the air/fuel mixture settings have altered and that's why the 2nd lambda is reading high emissions and therefore, saying the cat doesn't work?

The garage said that (although aftermarket) it is a "bulletproof metallic cat" and they've "never had to send one back under warranty"?

Its a dirty MAF thats thrown all my lights up on my dash before now, and is a known issue on corollas. Its worth doing anyway, as a dity MAF sensor can give bad fuel efficiency. Its a small square thing screwed down just after the airbox by two screws. Just unscrew it, and using a cotton bud gently clean the sensor in the black plastic extension.

I don't know much else about this problem, but just because the garage say its bulletproof and has never failed before doesn't mean that you can't have recieved a duff one.

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