03 Avensis With The Dreaded P0420

[matyb2k]

Hi everyone, I'm new here and I'm after a little help!

I have a 03 T3-X which I bought a few months back. After a few miles of driving the MIL came one with the P0420 (cat efficiency below threshold (bank1). I had a good Google and found lots of people with the same issue, but no resolutions.

Since the MIL came on it started to misfire when cold for a minute or so and a good puff of blue smoke comes out the rear.

I found the Toyota ebullient (EG-5010). That talks a bout a problematic ECU and cat. But it lists fame numbers affected and mine isn't one of them!

I changed the plugs today but it still misses.

I'm booking it in to a garage to get him to take a look and check the emissions, hopefully he will find the problem.

Anyone got any other ideas ideas?

[t-spiritpete]

Maybe the ignition coils/leads causing the misfire, if these are faulty then unburnt fuel with be going to the o2 sensors and cat, there is no point in trying to clear the mil light until the car is running on all 4 cylinders. Hopefully your garage will sort this easily for you, when it's done take the car for a nice long fast drive in the lower gears to clear any residue from the sensors and cat, then check the emissions.

Pete.

[matyb2k]

Thanks for the reply Pete! I hope he can sort it too.

Seen lots of stories re ECU issues and Cat issues all looking really expensive!

The Coils are around £75 each. Just need to find out which one is causing the issue.

Its booked in for Sat, I'll update the thread once i know a little more. :)

[Druid Boy]

Change the leads before the coil - unless the coil is definitely identified as the problem. Leads are cheaper.

[matyb2k]

There are no leads on the Mk2 there are coil packs which connect to the wiring loom

heres a bit of a poor pic

cheers for the suggestion though

[cooper12000]

Change the leads before the coil - unless the coil is definitely identified as the problem. Leads are cheaper.

whats the point of changing the leads first if it is the coil pack then ur going to end up having a half knackered lead that needs replacing. if ur realy not sure and they r realy expencive invest in a coil pack tester and at least eliminate them from the issue.

never see the point in doing the work twice

coop

[Druid Boy]

Oh I see. No idea how to test them so it looks like I'm no further use to you. They are going to be expensive to replace thats for sure.

Um, maybe your plugs can give you a clue. If one of them is more sooty than the others it might be that cylinder thats missing - but that doesnt necessarily mean the coil has failed - especially as it is an intermittent fault. Hopefully someone else can help you.

[matyb2k]

i found this http://www.life123.c...tion-coil.shtml ) but i dont know if would knacker the car doing it this way???

[cooper12000]

u can buy different testers from a few pounds to 4-500 but the most reliable way is with an ohm meter the way to do it is discribed in the link matyb2k posted.

im sure someone on here can provide u with the correct readings however even if they cant. test em all and a majour diff in readings and u found ya culprit.

just becareful u get the right pins it dont matter if ya do but if u put the ohm meter across the pos and ground it will energise the coil and if ya not careful give ya a belt if ya touching the electrode. it wont hurt just not pleasent.

another thing to look for is the condition of the plugs as someone said check the electrode but also check the white insulator for damage.

i have also seen coils tested by pulling them out one at a time and inserting a sparkplug into the end then grounding the electrode and observing the spark while someone turns over the engine.... this isnt realy recomended as u run the risk of getting a belt... if u wish o do it that way i recomend buying a cheap inline tester.

hope this helps

coop

[matyb2k]

Here's a pic of the plugs. A little carbon on them. But all in all they look ok i think

[cooper12000]

the one on the right is ur issue its whats known as totaly knackered no 1 dont look too clever either. that brown band around the porcilaine insulator shouldnt be there. while ur at it did u alter the electrode gap they look huge to me but then again i have no idea what they should be. I hope u know which one came from what cylinder

coop

[cooper12000]

sorry ment to say with a healthy engine there shouldnt be any deposit on the electrode of the plugs apart from a biscuit coloured deposit

[matyb2k]

Yeah i took them out in order :D . I did think #4 look weired.The brown band around it shouldn't be there.

I installed a new set of NGK plugs the gap was pre set on them to 11 (i think they were BKR5EYA-11), They looked quite big too.

Mat

[t-spiritpete]

Instead of messing about why not just disconnect one coil at a time see what effect it has on the engine, the one that doesn't make the engine miss worse is the coil that in knackered ...you don't need expensive test equipment!

Pete.

[matyb2k]

The prob I've got is it only misses for the first 1min or so after starting. After then it runs ok.

I can get a pattern part on eBay for £30. If the garage can't sort then ill get one of them.

[matyb2k]

Well an update, i managed to get hold of a couple of second hand coils from a breakers on sale or return! I swapped them out one by one over a few days. But the problem is still there!!!

And on the way home from a 130mile round trip the oil light came on!!! i nursed it to a local garage and dipped the oil and it was dry!!! It took 2.5 ltrs to top it up!.

So i'm still no better off, i was speaking to a friend of mine who recomended checking the walter levels as it could be the beginnings of a headgasket.

I did notice while doing the coils the level was lowish.

So i don't know what this is going to cost.