Engine misfire

[keithandjade]

Hi folks.  I have a problem with my daughters yaris.  It is not firing on No.1 cylinder.  I've changed the plugs and the coil pack, but no difference.  Does anyone have any ideas please?

 

Regards

 

Keith

[Madasafish]

Failed coil pack..  (on top of plug)

 

(You can buy s'hand on eBay..)

starting to appear a lot with age..

[keithandjade]

Thank you for the reply.  I bought a new coil pack, but it made no difference.

 

Regards

 

Keith

[Madasafish]

Then the cable to the coil pack must be faulty. You can check with a multimeter by comparing  resistances. with a working plug.

[keithandjade]

Thanks very much.  I'll try this weekend when I have light to work by.  Do you know of anywhere that I can look at the procedure, so I can see what to do?

 

Regards

 

Keith

[Madasafish]

err. No.

 

You need to disconnect the coil pack from the sparkplug  Leave plugs in engine.

Action for one indidual wire

 

Attach one end of multimeter to  end  of the cable which attaches to  coil pack and the other to earth. Measure the resistance. 

Do the same for a working plug. (Ignition switched off all the time)

 

Compare the two readings. If there is a circuit fault the resistance of the failing cylinder will be much higher..or infinite.. (broken wire).

Repeat for all 4? 3? wires to each coil pack.

Replace wire if broken.

 

http://www.sq-engineering.com/tech-articles/coilpack-info-guide  explains wiring.. you will have to test each wire individually  

[keithandjade]

Great, thanks very much.  I'll try this weekend, and post the results.  thanks again.

 

Regards

 

Keith