99custom

My 02 es300 just threw these codes. I could hear a slight knock from the engine (went away after a few seconds), and I could smell gas. Before this happened the car was running great, was getting combined 27.8mpg since I changed the valve covers, denso iridium plugs, pcv valve about 5k miles ago. I know this is very hard to diagnose over the net. I'm just curious if anyone else has had these same codes. I need to take off the upper intake manifold just to check things out since #1&5 cylinders are in the back. Can I reuse my intake manifold gasket? I just replaced it 5k miles ago. Any help appreciated.......

FromFL

You're supposed to not reuse the intake gasket. However, when I replaced the plugs in my '04, the old intake gasket as was nice and pliable as the new one.

99custom

Thanks for the tip, I just picked up a new plenum gasket. I'm putting in 3 new coils, pcv valve, plugs and fuel injectors while i have it torn down. Anything else I should replace at the same time. Thanks for any help....
car has a little over 150k on it...

99custom

I'm just waiting for some parts to show up. I reset the codes yesterday and then took it out for a drive this morning. The CEL hasn't came back on, I can feel a slight miss on a cold start but it smooths out when I get driving. My idle is perfect, and my gas mileage is really good when driving 60mph+, I was pulling close to 30mpg. I also stopped and put some Chevron premium gas in, and added some fuel cleaner. I'm thinking vacuum leak now, what do you guys think.

Mrv8q

IME, a P030X code is either a coil pack or an injector. The 6 times I have had a P030X code, it has always been a coil pack. Make sure you are getting 12V at your injector wiring, just stumbled upon a YouTube video explaining the measurements... stupid Covid-19!

99custom

You want to post that video you watched, that'd be great.... Thanks

99custom

So I'm still waiting on the plenum gasket but the CEL hasn't came back on since I added some seafoam and fresh gas. I also cleaned the maf, and secured one somewhat loose vacuum line. I've done about 8 cold starts,maybe 30 minutes at idle looking for vacuum leaks, and put on about 50 miles now since I rest the CEL. The car seems to be acting normal again, I'm a little confused why this is. I did do a vacuum check with a spray water bottle, I haven't noticed anything except that one line. I'll keep this thread updated.