I think I’ve exhausted the usual suspects.
The car has about 150k miles, and I’ve had it about a year. It had a “new engine” put in a few years ago. The check engine light has been on since before the the engine was replaced. It was never subject to an emissions inspection and was “just a light.” I live in a state that requires the emissions inspection, and it failed. Since I’ve had it, it has gone from just over 30 mpg to about 29 mpg. After some repairs, the mpg’s have gone up (see below).
The first thing replaced was the catalytic converter. It was pretty clogged. This got rid of 2 error codes (I’ve forgotten which), leaving only P1349.
Next, I cleaned the VVT filter when I changed the oil and oil filter. The VVT filter was quite dirty. I also replaced the air filter and PCV valve for good measure (though I’ve since put the old PCV valve back. See below.).
Next, I replaced the VVT controller/solenoid thing. About 5 mile into the test drive, it had a momentary sputter at a stop sign, but then seemed to run better than ever for the next 70 miles. No check engine light, but one P1349 code stored in freeze frame. (It takes 2 occurrences to trigger the light. This happened after next engine start.)
Next, I flushed the oil. It came out fairly dirty. (Soon after I checked the VVT filter again to be sure it hadn’t reclogged. It was clean.)
I had noticed a continuous whistling hum (like a vacuum cleaner) since changing the PCV. I cleaned the old one (which looked slightly different) and put it back. The noise went away. Instead of P1349 coming up within a mile, it now takes 5-10 miles.
One stored P1349 code per car ride. Just a start and idle won’t set it off. It requires putting the engine under load. It takes 5-10 miles normal driving to produce the code. I can trigger the code in the driveway by holding the brake, putting the car in gear, and accelerating, then leaving off the gas quickly. A few times will trigger it. Flooring it then quickly releasing produces a sputter for a second. I managed to stall it once.
There’s a little bit of (lifter?) ticking noticeable when the car idles. It’s been there since I got the car.
Since repairs, mileage has increased. Only one fill-up since the new VVT solenoid, but it’s tentatively at least at 33-34 mpg.
Could it run this well with the timing chain a tooth off? Is it likely that the VVT sprocket thing is gummed up and not returning the timing back to normal fast enough or completely? Is there something to try that doesn’t require removing the valve cover and all that?