Current Model Misfire & Stall Is Down To My Wifes Driving

[DougJ]

Current model 1.3 TR vvt-i auto, has been randomly generating a misfire and eventually stalling when stationary, say at roundabout or lights, for most of its 12 month, 10,000 miles life. No apparent problem when running otherwise, until engine speed drops, such as when in traffic queue then it can be bad enough to affect control of the vehicle until it stalls. Restarting the engine clears fault, until the next time. Dealer & Toyota GB both at a loss to locate the problem despite repeated visits to dealer so they can download the engine management data and pass to TGB. Dealer originally assured us that we must be wrong as an auto could not and would not stall, so is now eating humble pie but still not solving the problem. Changed pistons & rings and decoked - (a known issue on such a new engine?) new flow sensor and throttle body all to no avail. Wits end is fast approaching!

Bizarrely both the loan cars, same model autos too, have exhibited the same issue.

Dealer is now saying no-one else in whole of Toyota Europe has experienced what my wife has found on the only three Yaris autos she has driven! They are beginning to suggest that it is my wifes driving that is causing the problem. That won't be good press for Toyota GB. I am sure the Daily Mail would love a 'Toyotas don't work properly when driven by 57 yr old grannies on journeys between 2 and 130 miles' kind of story.

Before anyone suggests it, its not the fault of the electronic cigarette plugged into the 12v socket as we had the problem when I was driving sans electro !Removed!! As the dealer said, it wont be interference from Ipod or iPhone because EVERYONE has their iPhone with them in car.

If any one has any suggestions for resolution, similar experiences to share or just good headline, I would appreciate the response.

[Adam C]

Now that is weird! Would love to know how on Earth that could happen to so many automatics. Has it happened when a mechanic or service engineer has been in the car?

[DougJ]

Unfortunately no it has not. They have seen it running rough as we took the car to their dealership and hooked to the computer while it was running badly. I tried to do that again tonight but it stalled on the way and subsequent restart cleared the problem The computer did pull off the rough running and stall codes for dealer to send to TGB so we must wait and see, again. As the issue is random, unpredictable, the engineer could have to spend several days in car, driving around with my wife, before the issue ocurred. When the dealer has driven it in excess of 300 miles they were unable to replicate the issue.

[avensis57tr]

That is very strange is it the new CVT Yaris?

Only thing I wondered is do you left foot brake with it being automatic. If you do and then try to use the accelorator with your right foot whilst releasing the brake pedal with your left foot it may be confusing the engine management. As believe since the unintended acceleration debacle Toyota now have the system which cuts the throttle when brake pedal is applied. Might be completely wrong but just a thought. Its strange that its happened in three identical cars though does seem like some sort of software issue?

David

[Red Yaris 54]

Interesting observations.......Have you considered that it might be some poor quality fuel that you have uploaded?

[DougJ]

re #4 - it is MMT system which I understand is a basically a manual gearbox with and automated changer system. Unfortunately my wife is not a left foot braker and is unable to adopt 'heel & toe' brake and accelerator control! But it sounds to me like the connection between engine management and transmission is a possibility though the dealer had not considered this until I proposed it on Mondays visit.

re #5 - yes we initially considered the dodgy fuel option but given the period over which this has happened is more than 12 months and she buys fuel from Shell and BP garages plus the odd tesco refill, we can determine no pattern related to fuel.

Also the 'fault' is immediately cleared on powering down then restarting the car (we are just missing the Windows BSOD!) it seems unlikely to be fuel.

However I have asked the dealer to look at fuel supply side, maybe the cap/tank vent is sticking on occaisions making it hard to draw fuel at low revs, but I don't see how that would be reset on restart.

[FROSTYBALLS]

I thought the current 1.33 Yaris (2011 onwards) only came as a manual or a Multidrive-S CVT, and that the MMT was not carried forward from the second generation Yaris

[DougJ]

You are correct. Having now read the V5C it is shown as Yaris TR VVT-I CVT but when I spoke to dealer on Monday he definitely described it as MMT and as a manual box with a clutch and an automated change system. This is not my understanding of CVT system which is why I called it MMT above.

Apologies for the error.

[Lustral]

my Mk3 SR CVT did what you have described only once before. The RPM just dropped to under 600 and the car juddered like anything. But restarting the car the issue stopped and never happened again since.

Documented here :- http://www.toyotaownersclub.com/forum/index.php?/topic/18268-low-idle-juddering/

Might be worth checking the coil packs.

[avensis57tr]

A coil pack does sound like a possibility but would have thought it would misfire all the time not just at idle.

Could be to do with the emission controls on the engine which is getting an incorrect reading but only under certain conditions. Does it happen when engine is cold or warm? If you put the gearbox in neutral do the revs go back to normal which could sugest a sensor issue or brake switch?

Its a shame that there is no way to recreate it at will to demo it as thats the trouble if theres no code logged its difficult to get it diagnosed. When it does happen could you film the revs being very low on a phone?

It does sound like a few people have experienced it but Toyota not able to find the issue.

David

[icky221]

My 2013 Yaris 1.3 started doing this and the dealer took the engine to bits!!! This took place over three weeks despite only doing 4500 miles. I told them I didn't wa nt the car back after all this major surgery and came to an agreement to get a new Yaris. Now after 2000 miles this one as the same problem , been told they have now found the problem and to bring the car in to have the fuel pump recalibrated. Watch this space

[Awebb180]

Doug

Did this ever get sorted?

Alex

[DougJ]

If you are the Alex Webb I think you are, and still at Listers Cov, then you will know that the problem was not solved. my wife got worried about the situations she found herself, so eventually traded the car for a Yaris Hybrid and obviously has not had anything similar since.

it will be interesting if Bernard reports success following his fuel pump recalibration. Personally my view remains that it is management control or software issue as the problem corrects following a restart.