Engine turns over but doesn’t start on a Toyota Yaris 1.3 Auto 2002 VVTi

[YarisVVTi2002]

I forgot to mention that I had recently cleaned the throttle, inlet manifold, and IAC valve. I still can't find an EGR valve, is there one on a 2002 1.3 petrol Yaris? If there is one I would be really grateful if someone could post a picture with its location on it. 

I took the plugs and coils out and left them on a radiator overnight and tried to start it with warm dry plugs - it still didn't start. 

I've connected a heavy duty car Battery and tried to start it with that. Thinking that the cranking speed may be too low as the cold would make the oil more viscous and reduce the Battery current. The cranking speed was still about 200 rpm and still no start. 

[YarisVVTi2002]

Any more ideas anyone? The Yaris is still the same; not starting. 

[Gerg]

I would like to say that your patience with this car is bordering on the heroic.  Respect is due here!

I'm no expert, but the pattern of your fault finding seems really comprehensive and logical to me.

Further to another poster or two; when reading a car owners manual years ago, I remember it saying that if the car didn't start within a few attempts then you should call a garage as you risk damaging the catalyst.  Clearly, this would be from the un-burnt fuel burning on the cat and overheating it.  I have also seen warnings that cylinder misfires could do the same.  I don't know if an overheated cat can block up on account of it, it's ceramic after all, but yours must have taken a real hammering.  I shall try to find out more about this. (I am mindful of your removing the oxygen sensor to get around this possibility).

When I last had to clean fouled spark plugs, usually on two-stroke motorcycles, I normally found that, for me, putting a blow torch on them briefly was the best method of restoring them to full working order.  I had it in my mind that a mild heat over time didn't work so well, although it should have done.  I know that sparking outside of the cylinder is much easier for the spark plug than during actual use inside the combustion chamber. So given the difficulty of this fault, may be worth bearing that in mind that the plugs are 'guilty until proven innocent' (as I read in one technical manual, years ago).

The VVT-i mechanism is driven by oil pressure, I can understand that.  Does anyone know what drives the cam to return to the 'start' setting?  I expect a spring mechanism, and not an oil circuit, but do these ever gum up?  Would the VVT-i work erratically if you had low engine oil pressure? A gunked-up oil pick-up strainer perhaps?  This is hardly likely given the mileage, but as you've tried everything else (twice), I just thought I'd lob it in, given the weird compression readings.

HTH.

[Gerg]

An update to the above post:-  Whilst I have seen forum posters (bathtub tom, madasafish) mentioning clogged catalytic converters, I thought I'd contact an aftermarket manufacturer of cats (in Flintshire) to see if they can throw any more light on this. They confirm that overheating the catalyst (i.e. putting unburnt fuel on to it ) can indeed cause it to overheat, which could cause a blockage.  I suspect you already knew that.  Unfortunately, I couldn't get him to elaborate much on the topic.

[Gerg]

Shortly afterwards, I managed to chat to a technical specialist in an OEM catalyst manufacturer, he agreed with the above, (especially a misfire at higher speeds causing overheating) and said that also, if the catalyst support matting (packing) had failed, the cat could break up and clog itself through vibration etc.  He said that it is possible to examine the cat with an endoscope through the oygen sensor hole, but that even then, the damage could be farther into the honeycomb, so not always visible.

So just as bathtub tom and Madasafish had posted earlier, really!  (Not that I disbelieved you, gents!).

[YarisVVTi2002]

Hi Gerg

Many thanks for taking the time to go over the history of this problem and for your kind words.

It does seem logical to suspect the catalytic converter given its history of producing an OBD error.

As you noted I had taken out the first O2 sensor on the catalytic converter to improve exhaust venting but it didn’t make it start. On my posting on the 18^th Nov 2017 (first one) I had disconnected the catalytic converter inlet pipe completely from the exhaust manifold downpipe. Exhaust gases can now escape without going through the catalytic converter but the Yaris still didn’t start

During the last summer, the car started and was running OK, whereas before then and now it doesn’t work, this intermittent behaviour indicates something changes

Perhaps something is wrong with the engine which has been producing unburnt fuel which then caused overheating of the catalytic converter and damage to it? There is some evidence of engine overheating under the rocker cover.

I am confident that the fuel and ignition systems are working, does that leave timing as the most likely cause of the non-starting problem now?

Is the catalytic converter problem a consequence but not a cause of the non-starting problem?

[Toyota yarış aydın]

Hi. Have you find out what's causing the problem as my Toyota yaris 2003 doing exactly doing same problems, thanks