My car has a rough idle so I cleaned the IAC and it now idles smoother but still not perfectly. I noticed that it is rougher when I select a gear (R, D, 1, 2, 3). If I select "P" or "N" then the idle is smoother but still a bit rough.
Everything is smooth when driving, it is just when idling that I notice this. The tranny was serviced a few month ago... what do you think could be the problem? The car is an ED Falcon.
Probably engine tune, try a set of good quality spark plugs and leads, good quality engine oil, Premium fuel, new fuel and air filter.
Check for vacuum leaks, make sure the breather hose and PCV valve are in good condition, retention manifold bolts, check ignition timing.
When engine is in good running order give the torque convertor a stall test; use a good quality tacho, foot on brake, hand brake on, trans in drive, floor the accelerator pedal and watch what RPM the tacho hits, from memory the stall should be 2000 - 2200 RPM.
Do not stall test for longer than 10 seconds, as stalling puts imense load on everything, including the cooling system of engine and trans. After stalling allow engine to idle for several minutes to cool trans oil.
Would any of that make it idle worse when in gear? The problem makes me think it might be the tranny but I have no idea what it could be specifically.
Thanks for the info, some of it is a bit over my head though... I'll try what I can.
The only time a trans can cause rough idle is if the torque convertor is faulty.
Most times, rough idle is caused by an out of tune engine. When selecting D or R the engine load is increased, there is resistance put on the engine spinning, so the idle (spin) is dropped. If there is an engine problem (out of tune) low revs will be rough.
Try this; when in gear, foot on brake, hand brake on, apply the accelerator slightly so as to pick up the RPM (revs) to about 850 - 1000RPM, does the engine smooth out?
Try this; when in gear, foot on brake, hand brake on, apply the accelerator slightly so as to pick up the RPM (revs) to about 850 - 1000RPM, does the engine smooth out?
It smoothes out at about 1000RPM. What does this mean?
Hmm, improved a little after the carby cleaner but still rough. I'll take it to a mechanic because I don't know how to check for vacuum leaks or ignition timing...
I was thinking torque converter too, because my xf has the same problem, so I need new torque converter :-(
sometimes you can hear a leak, if you have a good ear, I could hear a leak that was coming from my EGR valve, that was causing all greifs, really bad engine idle, I fixed that and it was fine....but because I am stupid and put big strains on my transmission, spooling it up etc. I have damaged the torque converter....
I was thinking torque converter too, because my xf has the same problem, so I need new torque converter :-(
sometimes you can hear a leak, if you have a good ear, I could hear a leak that was coming from my EGR valve, that was causing all greifs, really bad engine idle, I fixed that and it was fine....but because I am stupid and put big strains on my transmission, spooling it up etc. I have damaged the torque converter....
Don't call yourself stupid. Call it learning from experience.
Everyone does something stupid, doesn't mean were stupid as long as you learn from it & remember.
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