HT4100 4.1, 4.5, 4.9 Discussion, 86 Seville, 4.1, low idle in drive in Cadillac Engine Technical Discussion; 86 seville, 4.1, 48,000 miles. After the car is warmed up I seem to have a low idle in drive ...
86 seville, 4.1, 48,000 miles. After the car is warmed up I seem to have a low idle in drive or reverse when car is not moving, ie stop lights. It idles between 525-600rpm. I have replaced the plugs, wires, cap, rotor, fuel filter, air filter, pcv with delco parts. The motor sounds fine, no noises or anything like that. I have also taken off the air cleaner assembly and cleaned the TB with cleaner. One thing I noticed was that the metal tube that connects from the exhaust manifold to under the air cleaner assembly is not fully attached at the exhaust manifold. The only trouble code is B336. The car always starts, never dies or stalls, just low idle. Any ideas? thanks
Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
Re: 86 Seville, 4.1, low idle in drive
Doesn't seem low to me. My 84 Eldo idles at 600 to 625 warm. My 91 Allante idles at 650 to 700 warm. The hot air stove to the air cleaner has no effect except regarding gas mileage. If that hose (metal hose)is off, the door in the air cleaner inlet wont open which restricts air intake thus lowering fuel economy. You can verify ISC (idle speed control) motor operation by watching it extend and retract as the A/C compressor cycles on and off. If it extends a 1/2 second before the compressor cycles on, then retracts just as the compressor goes off, its working as designed. Unless you are familiar with adjusting TPS and ISC and minimum idle, leave it alone. Its within 50 RPM of spec.
Your idle speed is fine. Normal idle is 530-550 rpms in drive. The car has an idle speed controller that will bump up the idle if a load is placed on it. Otherwise, it putts along slowly in order to conserve gas.