Diagnosing ignition problems...

[quiksilv]

Recently discovered my 4AGE twincam will crank but not start.

Have got it down to ignition problems of some sort (lack of spark).

I have replaced the ignition coil but still no spark.

What would be the next step to check... could be resistor pack but its unlikely I would of thought. Fuses seem to be ok but will check them again to make sure.

Any relays in the ignition sequence that could be the problem ?

Cheers.

[BeRad]

spark plugs , leads , or it could be something else effecting the spark,.... checked all the fuses? is the ignitor built into the coil packs on the 4a? if not maybe thats shagged, the ignitor needs to be earthed well (just incase youve moved it) in alot of cases the mount is the earth...have you checked the ignitor to coil lead has a good connection or is not damaged.


pull the plugs out soak them in petrol for a bit get a wire brush and give them a good scrub another quick dip to get the loose carbon off and connect one onto the spark plug lead and earth it out on the cam cover and get someone to crank the engine or if your talented you can do both watch where you hold the lead or youll get a nice wake up.


how have you determined theres no spark?

crank it for a bit before you pull the plugs out, if there not wet from fuel, fuel is the problem.

[quiksilv]

Thanks for the help but I think its more electrical related.

Pulling the lead from the ignition coil to the dizzy out and putting it up against the block while turning it over produces no spark/voltage.

There is also no voltage going to the ignition coil when cranking the engine.

[BeRad]

http://opc.mr2oc.com/online_parts_ca...CorollaFWD.pdf

page 5.


have a read through that it should point you in the right direction if it is electrical

if theres not power going to any of that, have a look at the main ecu relay, or test if the ecu is powering up anything.