2007 Toyota Camry Rough idle, no engine codes

My 2007 Toyota Camry has a 2.4l engine 4 cylinders and it’s at about 197,000 miles. I’ve been going crazy trying to figure out while the engine is vibrating horribly when at a red light and it’s a lot worse with the ac on. I’ve changed motor mounts, checked evap purge valve, cleaned maf sensor, cleaned throttle body, bought an aftermarket pcv valve from advanced auto parts, I even bought a smoke machine from Amazon and smoke tested the evap system and found a easy leak after the maf senso rand sealed it but that didn’t do much. I’m not sure if it matters since it’s before the maf sensor but the little inlet plastic thing that’s attached to the front of the car has a hole in it but I don’t think it would do much, I’ve also noticed the gas cap is pushing out pressure in park. Someone please help I’m out of ideas

A bad crankshaft position sensor can cause the engine to run rough while sitting at a stop.

Tester

What are you using to check engine codes? Not all code readers are created equal and better ones will read things called “pending codes.” Those are just where the computer has seen X number of problematic readings but not enough to set a “hard” code yet. More than once I’ve had issues where I’m waiting or the computer the finally “catch on” and just give me the darned code. (And if you’ve been disconnecting the battery sometimes to do things like clean the MAF or TB and whatnot, then it will probably keep resetting that “clock”).

How old are your spark plugs? And I think those are coil on plug (?) - are those original? Not suggesting to keep doing things on a guess (as it seems you’ve been), but if the plugs are old there’s no reason not to replace those.

Do you have a scantool of any sort that can provide live data? If so, hook it up and record fuel trims to see what those look like.

And just fix the “little inlet plastic thing” - yes, it shouldn’t matter for this if it’s before the MAF, but just fix it.

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For the code reader I’m just using one from Amazon the Ancel AD310. It’s nothing too special but it does read live data, I’ll let you know on those fuel trims tomorrow. As for the spark plugs they’re not too old, they were changed just a few months ago. As for the ignition coils I couldn’t tell you I have no clue. Is there a specific way to test those coils?

Where did you buy new motor mounts? Dealer? You get what you pay for.

Yes from the dealer and had a shop install them

Did this start after replacing the spark plugs??

No when I changed the spark plugs it had no change on the idle

OK thanks.

Did you have or see oil on the bottom of the ignition coil boots??

Not sure, I’m at work right now but I’ll take off the coils later and let you know.

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If a rough idle occurs it is usually caused by misfires which would set a code. Maybe crank position sensor is a problem that often won’t set a code.

Seems like that might mean a mechanical problem to an electrical one. My thought is maybe the balance shafts somehow got out of time with the engine.

Does it get out of time with the engine with time? And if that were the problem is there a way to double check?

Check Engine Light

A failing or failed crankshaft position sensor may cause the check engine light on your dashboard to come on. A diagnostic scan tool will show a code between P0335 and P0338. The check engine light doesn’t always come on, though, so you could be experiencing any of the above symptoms for some time before you see the warning light.

Tester

Yeah sure all of the above but with that kind of mileage you could have valve or ring problems. A compression test would be in order. Oil change intervals?

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Yes, but the engine needs to come apart.

Crank sensors are cheap. Makes sense to just change it and hope it cures the problem.

That sort of shaking at idle is often caused by misfires. That’s the first thing to test for. Posting the fuel trims, both short and long-term at warm-engine idle, would be a good place to start the diagnosis.

With the car stopped at a red light at operating temperature in drive, the short fuel trim is around 1.6 and 2.3 while the long fuel trim is -1.6 and not moving

I presume the units are %. If so, that’s pretty near perfect. At least you know the fuel trims aren’t the clue to your puzzle.

hmmmm … what’s next? Could be a problematic ignition system. Is there a way to get a timing light on the hv wire from the coil to each spark plug? Or does the coil sit right on top of the plug?

The coils sit just right on top of the plug

hmmm … I own an older Corolla, but have never experienced that symptom so far , knock on wood … lol … I guess if I had that symptom my first step would be a visual inspection of the fuel and ignition system, and if nothing found (which I think you’ve already verified), I’d probably do a compression test. If all else fails , as a backup you can start replacing parts on a guess. The crank position sensor seems a good first guess. I’m not keen on the guessing technique though, b/c it is easy to run out of money before running out of ideas what to replace. If I had a question about the crank position sensor function, I’d measure its output signal w/an o’scope. I’d also probably try a dose of fuel injector cleaner, easy enough to do.

Make sure the grounds are all good, esp the ground connection fro the cylinder head to the chassis. On my Corolla there’s a connector in that line to make access easier during repairs , and it is easy to forget to reconnect.