2003 Corolla p0302

Hello
Looking for flow charts on checking computer driver for cylinder 2 ignition coil. I have a p0302. Brand new coil and spark plug. Still same misfire. Looking into computer driver before checking for burnt valves

Before you go digging into the coil driver, have you confirmed that the misfire is on the #2 cylinder? Does the misfire happen at all times, or under load? Engine cold, hot?

Probably the easiest way to confirm wiring integrity to the coil, including the computer driver, is to check for spark out of the coil boot. Remove the coil from the plug tube but leave it connected. Have an incandescent test light connected to a ground, and keep the tip inside the coil boot while someone else starts the engine. Here's a video demonstrating the idea:



Verify that there is spark, and how far you can make it jump out of the boot by pulling the test light away. If good spark is being produced, it'll produce a sharp 'crack' and a blue color. While you're there, drag the tip of the test light up and down the coil itself to check for high voltage leakage. I know the coil is new - do it anyway. Compare to another coil if you have doubts.

If strong spark exists, there is no wiring or driver issue. Your misfire lies elsewhere. If it does not exist, then we can go into checking power/ground/control at the coil. I dunno that I've ever seen a failed coil driver on a Toyota before. :silly: A restricted injector or a leaking intake gasket would be far more likely on this engine.

Do as advised by Tyler. A P0302 doesn't necessarily mean you got an ignition misfire.

Per OBD definition the computer is allowed to look of either of the two, ignition and injection. If there was no fault with the injector circuit (which is to set a P0202 for the #2 cylinder in a given case) the pcm would flag a P0302, although very well a clogged injector can be the cause of the misfire.

Desccribe the conditions when the misfire occurs.

Regarding testing the coil driver - basically an oscilloscope pattern should show if it is switching correctly, I think it's normally a 5v trigger and it should have a slope to it - also check for good earth and positive feed - make sure there isn't too much voltage drop when it switches.

I swapped injectors already and performed a cylinder drop test by unplugging the injectors and I know that's not the problem. At this point I'm looking at either timing or computer. There's a tapping noise that's present around cylinder 2. Cylinder is contributing but not even 50% according to my testing.

Yeah I don't own a scope

Are you able to perform a clear flood crank? If so, does the cranking sound even? If not, that would mean you're having a compression problem.

It sounds like you have a mechanical failure, not a bad coil driver.
It may be time to pull the valve cover and have a look at your valve lash clearances. That tapping could be a good indicator of the issue.

But, if you want to quickly check injector pulse so you can cross it off your list, you could make a homemade noid light using a 194 style automotive bulb. Steal it from your tag light, then put it back when you are done.

Just unwind the leads away from the glass base, and plug it into the disconnected two-pin injector connector.
You can watch the flash and see if it is being fired, you can even compare one to another and make sure its flashing for the same length of time.

Rev Scott wrote: But, if you want to quickly check injector pulse so you can cross it off your list, you could make a homemade noid light using a 194 style automotive bulb. Steal it from your tag light, then put it back when you are done.

Just unwind the leads away from the glass base, and plug it into the disconnected two-pin injector connector.

Lol, I've employed that tactic

Rev Scott wrote: But, if you want to quickly check injector pulse so you can cross it off your list, you could make a homemade noid light using a 194 style automotive bulb. Steal it from your tag light, then put it back when you are done.

Just unwind the leads away from the glass base, and plug it into the disconnected two-pin injector connector.
You can watch the flash and see if it is being fired, you can even compare one to another and make sure its flashing for the same length of time.

Now that's some resourceful thinking right there.

Thanks everyone for your input. I'm pretty sure it's mechanical and customer will have to decide whether to fix an old beater or live with it