rough idle mecury tracer wagon

[nickelfritz9]

in idle in park it idles a little funny shakes the exhaust and cab a little like a misfire but im firing on all four. i borrowed my buddy’s scan tool that does live data and the fuel trim 1 was reading 0.0 to 1.6 to .8 to 0.0 witch i think is normal but trim 2 was staying around -4.1 almost steady moving to -3.9 then back does that mean i have a small vacuum leak or something i really don’t understand fuel trim 02 sensors were reading right upstream back and fourth and rear steady

Topic

[ChrisR1987]

Rough idle could be a number of things. Your Trim 2 fuel readings means the system is having to lean which tells me the engine is running rich (someone please tell me if I got this reversed) Some of the things I often check for on a rough idle if Im not seeing a CEL is low coolent levels sometimes a dirty intake or a leaking intake could cause problems like that too. Motor mounts might be a possibility too but I think if your motor mounts are bad then youd have a constant vibration

[college man]

Try searching for vacuum leaks.

[ChrisR1987]

I knew I was forgetting something thx college man

[college man]

[quote=”ChrisR1987″ post=67616]I knew I was forgetting something thx college man[/quote]

🙂

[Bill]

Fuel trims look reasonable to me. Well within parameters. You could still have a small vacuum leak somewhere. You might also do a compression test to rule out a low cylinder. Also check for weak or sagged out engine mounts that could be causing you to feel like a rough idle.

[Author]

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