Engine Misfire

[markedgar]

hey all

i have a 998cc yaris 2000my

when on freeway at about 78mph cars misfire's jumps and engine gives out!!!

so take foot off pedal, wait a few seconds then its fine

only ever happens on freeway

any ideas?

[Red Yaris 54]

That would be the automatic speeding prevention device cutting in.

Make sure that the centre button on your radio volume control is pressed in and you will get at least 10 BHP more out of your car................but be carefull or you will pick up a ticket for speeding ;)

Welcome to TOC :)

[ssk2]

Red Yaris - really?!

I had no idea...

Where did you learn about that from? Also, would it still happen with aftermarket stereos?

[BLiTZ]

ROFL

[DaveSR]

ROFL

PMSL - quick somebody frame it

[BLiTZ]

ROFL

PMSL

i heard some kids have that button wired up to their nos bottles

[markedgar]

freeway??? eh.

ex us here ....... sorry motorway

[Red Yaris 54]

Red Yaris - really?!

I had no idea...

Where did you learn about that from? Also, would it still happen with aftermarket stereos?

Sorry to dissapoint you but I think it was only fitted on certain 1.0 litre models (predominently, but not exclusive to, those intended for the North American Market) so it may not be applicable to your 1.3

Not sure if "aftermarket" stereos have the device as the adapter cable needed to fit the "aftermarket" unit may not have enough connections to cope with the technology ;) :)

[ssk2]

I didn't think my Yaris had it, before anyone else falls out of their chairs laughing...

Interesting to know though, cheers!

[seveer unaek]

And to actually help the man....

Not a clue im afraid! You could try the basics... check the spark plugs for condition, check all the earth connections, clean the MAF sensor (attatched to airbox) run some engine flush and some petrol system flush through it, re-set the ECU (disconnect negative terminal on Battery for 10mins) then see how it goes.

[Red Yaris 54]

And to actually help the man....

To actually help him we would need to know quite a lot more information...............................How many miles has the car done?,....when was it last serviced?,...... When were the oil and water levels last checked?........Has he been buying some crappy petrol?......does it run ok after the initial slowing down?

Loads more serious and searching questions.......................but it is always difficult to diagnose faults from a distance and even more difficult if travelling at 78 mph on a motorway ;) :)

Hence my welcoming opening comments

[Bee]

998cc yaris [year] 2000...at about 78mph cars misfire...foot off pedal, wait a few seconds then its fine...only ever happens on freeway...

Markedgar, misfire at high speed means the electrical elements of the ignition system are faulty.

You need to check everything here: ensure clean, secured, and intact (no damage, frayed) wiring and wiring plugs on the ignition coils (coil-on-plug direct system), the engine earthing strap, and conditions of the spark plugs. It is best to read up sections "2 Ignition system - testing" and "3 Ignition coils- removal, testing and refitting" on page 5B.2 of the Haynes' "Service and Repair Manual".

You may want to change the spark plugs first. If there is still no change, measure the resistance of the primary (0.4 - 0.6 ohms) and the secondary windings (10.5 - 16.5 kilo-ohms) of each ignition coil. As it says in the manual, confirm the findings with a Toyota dealer before renewing the coil(s), as departure from the ideal is not uncommon (only no or infinite resistance is definitely wrong here). Also take note of the warning stated before Section 2, "...Extreme care must be taken when working on the system with the ignition switched on..."

Lastly, don't forget a dirty air filter can also compromise air-fuel mixture ignition at speed.

--

Bee.