Hey! I’ve got a real head-scratcher here. My 2003 Daihatsu YRV (1.3L K3-VE engine, very similar to the Toyota) was running like a top until I changed the valve cover gasket.
Now, it’s shaking at idle, blowing black smoke, and smelling like raw gas. I'm getting codes P0300 and P0314.
Here is what I’ve already checked:
- Spark: All coils and plugs show a strong spark.
- Wiring: Did a continuity test from the ECU to the coils and injectors—everything is perfect.
- Injectors: Resistance is within spec and they are getting power.
- Vacuum: Visually checked all hoses, everything seems connected.
Since it happened exactly after the gasket swap, did I mess up a ground wire or maybe a sensor that’s common to these Toyota-based engines? I'm DIYing this and could really use your expertise. Thanks!
I also pulled the spark plugs as you suggested. They aren't wet with fuel
Did you run the engine a bit before checking them?
Anyway, if they're all sooty then it's likely a systemic problem as you say. But many things can make it run rich. You need to gather more data.... Anything the scanner can give you that helps narrow it down. Fuel trims, MAF rates, ECT, fuel pressure etc.
Changing the valve cover you may have knocked a sensor loose, nicked a wire etc. (MAF, MAP, ECT etc). Could be a problem in the exhaust (leak, bad O2 sensor etc.). You could have sprung a vacuum leak.
Vacuum: Visually checked all hoses, everything seems connected.
visual check isn't good enough. Do a smoke test.
More misfire troubleshooting is in our FAQ on the front page.
I can't find a service manual (I think it's a JDM car isn't it?), but that would help greatly.
you could use a diagnostic scanner to find out which cylinders are misfiring the most. That could help narrow down the problem for you. You might even be able to tell just by pulling spark plugs out to see which are wet.
@imperator Thanks for the reply! I already used a scanner, but this specific car doesn't support individual cylinder misfire codes—it only gives me the general P0300 and that P0314 (single cylinder, unspecified).
I also pulled the spark plugs as you suggested. They aren't wet with fuel, but every single one of them is covered in heavy black soot/carbon. It looks like it's running way too rich on all cylinders.