I've read about 1 bazillion posts on rough idle but haven't been able to resolve mine. It started about a month ago and has gotten progressively worse.
Symptoms: Idles smooth at 700-1000rpm while in park, a/c off. Turn on the a/c, idle drops slightly (that's normal) then gets erratic. It never goes high, just random hard drops, a couple times a second, almost to stall. Turn a/c off, goes back smooth. Now put it in Reverse or Drive, same erratic idle. Park or neutral, smooth. Drive + a/c is worse that either by itself. No CELs. Alternator is charging properly. When driving, it sputters off idle but gets completely smooth by 2000rpm. The symptoms aren't there on cold start; they start showing up after running a few minutes.
What I've done: Removed and cleaned EGR valve, IAC, and throttle body with carb spray. Carbon was fairly light for 150k miles and the EGR moved pretty freely when I took it off, so didn't think cleaning would make much difference, and it didn't at all. Cleaned MAF with MAF cleaner. It was pretty clean too, and no change. With engine at smooth idle I sprayed carb spray at every hose and connection I could find, nothing blipped. I cleaned the engine ground strap and battery terminals; they were clean to start with. Replaced gas cap. Replaced coils, plugs, wires. Replaced air intake 2 years go. Threatened to drive it off bridge or into tree. Let it idle both with and without PCV valve plugged in, no change. Idled with EGR both connected and not, no change. Idled with IAC connected and not. It wouldn't idle on it's own with IAC disconnected, but could hold it at idle by the gas pedal and still got the same symptoms. Threatened to drive into a bridge. Nothing has helped.
Somebody, anybody, ideas?
Thanks!
Symptoms: Idles smooth at 700-1000rpm while in park, a/c off. Turn on the a/c, idle drops slightly (that's normal) then gets erratic. It never goes high, just random hard drops, a couple times a second, almost to stall. Turn a/c off, goes back smooth. Now put it in Reverse or Drive, same erratic idle. Park or neutral, smooth. Drive + a/c is worse that either by itself. No CELs. Alternator is charging properly. When driving, it sputters off idle but gets completely smooth by 2000rpm. The symptoms aren't there on cold start; they start showing up after running a few minutes.
What I've done: Removed and cleaned EGR valve, IAC, and throttle body with carb spray. Carbon was fairly light for 150k miles and the EGR moved pretty freely when I took it off, so didn't think cleaning would make much difference, and it didn't at all. Cleaned MAF with MAF cleaner. It was pretty clean too, and no change. With engine at smooth idle I sprayed carb spray at every hose and connection I could find, nothing blipped. I cleaned the engine ground strap and battery terminals; they were clean to start with. Replaced gas cap. Replaced coils, plugs, wires. Replaced air intake 2 years go. Threatened to drive it off bridge or into tree. Let it idle both with and without PCV valve plugged in, no change. Idled with EGR both connected and not, no change. Idled with IAC connected and not. It wouldn't idle on it's own with IAC disconnected, but could hold it at idle by the gas pedal and still got the same symptoms. Threatened to drive into a bridge. Nothing has helped.
Somebody, anybody, ideas?
Thanks!
Warm idle, no a/c, in Park, 21 inHg. Put it in gear or turn on a/c, 16. Add the other one (a/c or put in gear), 14. Is that right? Should it maintain 21 with a/c in gear? Also, the drops knock it down another 5 for just an instant.