Black Sooty Plugs

[swazioak]

I own an Avensis 2000-2001 GLS 1.8 VVTi. This last week I changed the oil, oil filter, air filter and plugs. Today I did a trip of some 28 miles one way and on getting close to my destination I notice the 'engine' light came on. It was flashing. I parked up and left the car for a while, got back in and started my return trip. The engine light had gone out. Half way through the journey the light came back on, flashing, then turned solid. The handbook says take the car to your Toyota Dealer, which I did. They did not have enough time to check the car out thoroughly today but said the fault lay with the 3rd cylinder. Could be electrical or mechanical, or both. I agreed to return the car next week. BUT I took the plugs out to check the status and found plugs 2 and 3 very black with soot. Plugs 1 and 4 were like new (which they were), these were Bosch Super 4. I went off and purchased the NGK indium plugs, the ones that last for ages. Put those into the car and still it ran with a lumpy idle, similar to a tractor. BUT, the soot on the two middle plugs has me puzzled .... what can this mean ?

The dealer told me they thought the head would have to be removed as 'parts' may have been dropped down by mistake (the old plugs came out without any damage or parts falling off). Or possibly they would have to change the electrics of the car. Surely the diagnoses computers at Toyota would be able to define the issue without having to strip down the motor - whether the issue was injectors - management settings - a blockage somewhere in the system - faulty fuel or WHAT .... Otherwise, why do they have these diagnoses systems if they do not work - is someone trying to con me into believing there is a major engine failure ?

[Konrad C]

Hi Michael, Welcome to the club.

From what you have said, it sounds like the coil packs may be the problem. Probably misfire causing the spark plugs to get sooty. It could be something else. I could say, recheck the connections to the coil packs/spark plugs. The other problem is the O2 sensor, pre cat located in the exhaust manifold. That could be giving the wrong signal. Cylinders 1 and 4 share one sensor, whilst 2 and 3 share the other. This may go some way to explain why 2 and 3 spark plugs are sooty.

You need an OBD2 code reader to see what codes have been stored. Lucky code readers are not expensive if bought from eBay or similar.

The other members may advise which is the best reader. Search the forum and you should find the answer.

Konrad

PS get a second opinion from a trusted mechanic.

[Mike169]

Hi, very good diagnosis from Konrad by the way.

Is it possible to swop the 2 O2 sensors located in the exhaust manifold and see if the sooty spark problem changes to cylinders 1 & 4 and if so will determine that this sensor now reading cylinders 1 & 4 is at fault and just needs a new one fitted which sounds like the problem.

Depending how rich you are feeling just buy 2 new sensors and replace them both but i'd try just turning them a bit first to make sure they are not seized in otherwise you may need a new bit of exhaust they are screwed into.

Mike.

[swazioak]

Thanks for your answers. The local dealer advised that this was a real BIG issue. Made me laugh as I took a Yaris in to them 2 weeks to have new disc pads fitted to the front - as advised by the MOT agent who had just passed the car as 99% fit. The dealer then gave me a list of 11 points needed to bring the vehicle up to 'standard' before taking it for a MOT, which included securing a loose floor mat !!!! The service desk had a few red faces when I showed them the MOT pass certificate when I collected the vehicle later that day. It would seem that there are a number of VERY DISHONEST Toyota dealers out there. What a shame as Toyota are a very good brand - one I have been using since 1971 - but now getting rather worried about 'trustworthy' dealers. Think Toyota needs to look into this situation

[mcorban]

Its quite possible one of the could packs could be gone. Sometimes it I best to stick with oe plugs and torque correctly! This would flag a fault in the ecu though.

Also, the pre and post cat sensors are different. You could try disconnecting the Battery and leaving for twenty minutes to reset the ecu.

[Konrad C]

Thanks for your answers. The local dealer advised that this was a real BIG issue. Made me laugh as I took a Yaris in to them 2 weeks to have new disc pads fitted to the front - as advised by the MOT agent who had just passed the car as 99% fit. The dealer then gave me a list of 11 points needed to bring the vehicle up to 'standard' before taking it for a MOT, which included securing a loose floor mat !!!! The service desk had a few red faces when I showed them the MOT pass certificate when I collected the vehicle later that day. It would seem that there are a number of VERY DISHONEST Toyota dealers out there. What a shame as Toyota are a very good brand - one I have been using since 1971 - but now getting rather worried about 'trustworthy' dealers. Think Toyota needs to look into this situation

Michael. Your post says it all. The dealers are saying something is wrong with your car, or it a big problem that need expensive work, when you have evidence that says otherwise - like the MOT certificate. That is why I said to see a recommended independent mechanic, for a second opinion. I am not a mechanic, but have done lots of things on cars, and made sure I understand how cars work and how to fix them. This and other forums are very useful.

Going back to your original fault, I still think that one of your pre-cat sensors are causing the two inner cylinders to run rich. Hence the sooty plugs.

Now if you cannot find a mechanic or friend with a OBD2 code reader, or you could get the following:

http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2054897.m570.l1311.R1.TR3.TRC1.A0.H0.XOBD2+fault+code+&_nkw=obd2+fault+code+reader&_sacat=0

http://www.amazon.co.uk/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=obd2%20code%20reader&sprefix=obd2+cod%2Caps

Your ECU has stored fault codes and these code readers can extract them, saving you a lot of money and time. A very useful tool to have.

Konrad

[swazioak]

Hi Konrad, I have had that done, the checking of the exhaust sensors and no luck there. Got a compression check carried out and that revealed nothing. A full diagnostics was done on the car and nothing electronic came back as a fault. After kicking the wall a number of times I have taken the car in and they took the head off to check what was going on 'under the metal'. They state - I have yet to see this - that one valve (exhaust) on cylinder 3 was cracked, showed a hairline crack under examination with slight burn marks in the area. Remain slightly puzzled as I can well remember that a crack in a valve, a valve seat, or a bent valve stem would show up on a compression test. I know, I have done enough of those in the past. Guess it could be that the modern 'replacement part' technician does not actually understand how a compression test is carried out anymore.

So, I have had to give the go ahead for replacement valves. I was rather bemused by a then phone call that suggested I had the rings changed at the same time, to which I replied 'oh yes of course, and what about the big ends - also checking the bore and going 1 size up on the rings'. The lad thought I had bought his story 'oh yes, a very good idea' he remarked - to which I added ' get the firkin thing fixed before the weekend, no big ends, no new piston rings - do what you are paid to do. If I have to go down that route I would buy a factory replacement engine laddie, not mess about with a load of spares'. It will cost sum and a bit, but, with the work comes a warranty that I will hold them to ......

[mcorban]

A leak down test would reveal all, it would show if your valve is shot.
New valves, means new gasket and perhaps a skim. I wonder how your guides are, is the car burning oil?
Like you said a replacement would be cheaper for all that work

[Konrad C]

Michael. When you said you checked the exhaust sensors, how did you check them. With a diagnostic scanner? Remember you said that the EML light illuminated. So long as the EFI fuse has not been pulled or the Battery not disconnected, code will be stored. You need the diagnostic code to find out why.

Did you take the car to a different mechanic/garage. It sounds like you went back to the same original garage! I hope I am wrong.

You have done a compression test, and so long as it is done properly the result should be valid. The garage would know this if you have told them, so an engine strip down is not necessary. The bores cannot be honed as they are lined with a special material.

Mikes post about the valve guides is valid too.

The whole point of your sooty plugs is a possible fueling/ignition/ECU/emission problem. You did buy a OBD2 scanner?

A garage/tuner with a state of the art diagnostic and emission equipment, will see how the engine is performing. So long as they have your cars parameters, they should be able to find out what is really going on. It does not need to be a Toyota dealership either!

I always start at the cheapest fix/test and work from there. This garage went for something which in my opinion was something expensive. They should have taken photos (very unlikely).

Lets hope the engine swap works since you are committed now.

Good luck and when you get the car back give us an update (rant).

Best regards,

Konrad

[Mocambique]

Hi Konrad, sorry it has taken so ;long to come back to you. The bill for the engine head overhaul was roughly £1600. I refused to pay as the original fault, management light on, was still there when they had completed the job. They wanted a further £254 odd to repair that. I asked for the original job sheet and then showed them what the fault was, management light of engine showing on the dash display and it was still on. They had to admit they had not carried out repairs as requested by the customer, that, were we to go to court over the bill they would loose the case.

That means my Toyota now has a fully reconditioned cylinder head at the Dealers expense.

And, by the way, Toyota did get involved with this problem and they agreed I had contacted them - after your message - to ask their advice as to what the problem was - they stated 99.9% the exhaust sensors. The Dealer could not back out of the corner and I got my car back. It does go well now, and, no lights flashing up on the display panel. My computer locked me out of 'Toyota Club' and it took me a while to work out where the fault was.

Have a good Christmas.

[Konrad C]

Hi Michael.

Very pleased your car is fixed now. I cannot believe that a so called experienced garage can be so wrong, on so many counts! As I said before, I am a DIY mechanic who understands cars, and you are experienced. These 'cowboys' basically tried to rip you off. I could go further and say they need naming and shaming. Imaging how they deal with someone who has no clue!

You gave instructions and they did something you did not ask, which cost them in the end. Let's hope they put the engine back together properly.

Going back to the original fault, the EML signalled a fault and the spark plugs sooting up showed rich mixture. The O2 sensors assist with the mixture and a faulty sensor caused your car the running issues. Diagnostics would have helped, and you can do this yourself.

Rant over and a happy ending.

Have a happy Xmas.

Konrad

[B3rtie]

Hi there, just got reading this post with interest but not sure exactly what the eventual diagnosis was in detail, please can you explain what work was done to solve after the cylinder head rebuild?

So pleased for you that it is fixed and I hate garages which throw parts at cars expecting the problem to go away, it just demonstrates poor problem solving abilities.

[Konrad C]

Hi Robert,

The fault was the sensors all along. Michael had ask the garage to do a diagnostic as the EML was on. The dealership/garage did not carry out his instruction and decided it was the cylinder head. The EML still remained on as Michael stated in his post, and after contacting Toyota themselves, the diagnostic was done and the sensors were faulty.

Then came my rant.

I think the customer should be listened to and not dismissed, because the dealership/garage don't know how informed that customer is. This is when trading standards could come into play. In this case, the dealership/garage made an expensive error. If I owned the franchise, that money would be coming out of a few pay packets for the loss. Also a bit of training comes to mind.

I have learnt to start from the cheapest and most obvious related clues and work my way via elimination.

Anyway alls well ends well.

Happy New Year

Konrad