Very rough vibration at idle. Engine does not miss and but stays steady at 800 rpm - but engine vibration is shaking entire car. Runs well at speed, pulls strong - no misfires or bogging under load. Oil looks good. Fuel pressure is good at 35-38 psi at idle. Used multiple bottles of fuel system cleaner to date. Cleaned MAF. Recently replaced downstream O2 sensor, plugs, wires, coil pack. Replaced crank position sensor 6 months ago. Replaced all motor mounts 12 months ago. Not sure what to do next: check compression, replace injectors, replace fuel pressure regulator, replace MAF, check for vacuum leak (how)? I don't want to throw money at random parts.
Car starts right up, pulls strong. Getting ~24 mpg (which is lower than it should be).
My car has 123000 miles.
My car has a manual transmission.
Hi - I suspect your rough idling is an air leak (loose hose or crack in the air intake), or dirty idle air control valve. A leaking exhaust gas recirculation (EGR) valve would also cause rough idling. I recommend a rough engine idle inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.
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