2002 Corolla t sport *misfire*

[Curtis k]

Hi there I have a 2002 Corolla t sport 1.8 vvti 

on initial start up the car idles and drives fine, but when up to temperature and you switch it off and back on it runs with a misfire and brings up code p0301, I have checked sparks and coil packs and all seem to be fine, any idea what else it could be? 

[flash22]

Swap the coil packs around and see if the misfire moves, any oil down the plug wells ?, it could be an injector failing under load/heat

[oldcodger]

Agree with @flash22, try moving the coil packs around and see if it come up with p0302/3 or 4.

If you have checked the plugs, for the price always worth replacing them to be sure, plus assume that means there was not any oil around them as the rocker cover oil seals can leak.

Try removing the engines top plastic cover so the electricl leads are exposed and run the engine in the dark both when its ok and misfiring, if any of the HT leads are  'leaking' you may see the HT voltage arcing around.

[Curtis k]

Thanks guys, the sparks did have what looked like a little bit of dry oil around them, I have ordered new sparks and will definitely check them in the dark when not misfiring and when it does and I’ll keep you up to date 

[Curtis k]

*Update*
 

new sparks retest and all sparking as should, ran the car until up to temperature left running and timed after 20 mins started to misfire 

still have no clue what could be causing this 

[oldcodger]

Have you done what @ flash22 suggested and swapped the coil packs ?

You need to disconnect coil pack 1 , which is usually on the timing chain side, and swap it with one of the others.  say cylinder 2

Clear the existing p0301 codes, assume you have a code reader to do that with ? 

Do your 20min test run and see what error code it gives,  if its now p0302 then that shows it must the the coil pack.

If not, expect you could do a similar thing with the injectors but not something we have ever done so cannot say how easy or practical that is, though clearly  a lot of care is needed with the fuel, more a job for a garage ?  as the injector O rings etc might need replacing ?

[flash22]

As above, same method with the injectors move the suspected faulty one to a different position and see if the misfire moves

 

[Curtis k]

Hi guys after long time I found it one injector wasn’t working brought a replacement set and now no more misfire thank you