Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
[FIXED] 02 Acura TL type S rough idle, -15% ft at idle, random miss
Car is idling rough and has a misfire pop up for cylinders 4, 5 or 6 occasionally and will idle very rough. Stft is around -10% while Ltft is around -5%. Just did valve cover gaskets, spark plugs and all intake gaskets and issue remains. Tried a cylinder drop test and all coils made rpm change. Map reading is around .85v which is a little low.
Car has 230k miles, leakdown test performed and all cylinders holding around 18-20% leakage.
Cleaned egr valve it wasn’t that bad. Cleaned passages in manifold as well. Coolant temp was around 200f and in closed loop. Oxygen sensors were working but seems like cat is going out.
A valve adjustment fixed it. Most of the valves were in spec but I noticed on cylinder six intake valves were way tighter than spec. Map voltage is above .9v at idle now as well.
If you have any leakage you have a problem... valves not sealing or engine not at tdc compression when doing leakage test. If it is at tdc compression then which end do you hear airflow (through throttle body or exhaust pipe)?
