SquidTech

Car is a 2004 Automatic Base TL, ~140k miles. 105k service done.

Engine started fine early this morning, drove approximately 20 miles round trip. On the way home at a stop light, the engine began to bog down and had a rough idle. Taking off at the light, it hesitated but then eventually picked up. Luckily I was only down the street from home and made it back. As soon as I pulled into the driveway and put it in Park, the engine cuts off. Tried to crank it over, it cranks strong, but doesn't start. All electronics seem to work and no dimming that I can tell. I let the car sit for ~15 minutes and try again, same results: strong crank, but no start.

Here's where it gets a little weird: We have drive-by-wire, but just for giggles as I turn the ignition and crank, press and hold the accelerator pedal, the engine cranks over and runs. Idle dips a bit occasionally and definitely seems like a misfire while it is running. If I put it in any gear, the idle gets real low and even cuts the engine off sometimes, but not always.

-no CEL
-battery is fully charged
-fuel pump primes/buzzes when key is turned to ON
-rough idle after cranking over
-still feel misfire if i hold higher RPM's in Park

Any ideas as to what this could be? The fact that it cranks over with the accelerator pedal is throwing me off because we have a drive-by-wire system, and once it cranks over it barely holds idle and misfires throughout the rev-range.

typesdad

sounds a bit like a borderline O2 sensor...

SquidTech

Are our O2 sensors known to fail without throwing a CEL?

typesdad

Not that I know of... but it did happen once on my older Honda. I think it could happen when the O2 is just borderline, not dead enough to throw a code. Was the engine cut off preceded by rough idling when you park?

SquidTech

Rough and low idle while waiting at the stop light, nearly shutting the engine off. If, and when I can get the engine to turn over now, same rough and low idle.

typesdad

O2, dirty throttle body are the easy ones on top of my head. Hope it's not valve issues, which did happen to my old Integra years ago, exhibiting some of the same symptoms.

thoiboi

Bad gas or dirty throttle body

SquidTech

Regularly fill with 93 octane, and 90% of the time at the same station too. I threw in a fuel cleaner/stabilizer to see if it changed anything, but it did nothing to help.

What's the best way to clean the throttle body without needing to do the factory re-learn?

SquidTech

Pulled the coils, oil in every cylinder. Valve cover gasket and tube seals were done maybe a year ago and they've already failed.

I'm expecting to replace all 6 coils and spark plugs at this point and hoping that this solves the issue.