Very Rough Idle and sometimes cuts off while idling
Relaced fuel filter, cap, rotor, spark plugs, and plug wires. 3.0 engine...Car runs good while travelling down the road but idles very rough and will sometimes cut off now. Can smell gas sometimes but can't find any leaks. No check engine light comes on.
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1. Error Code 24. Intake Air Temperature Sensor.
Solution: Check the following:
- IAT Connector and wiring.
- Intake Air Temperature Sensor.
- Engine Coolant Temperature Sensor.
- ECM. 2. Rough Idling when the engine is hot. The following are the reasons due to which the engine can perform bad when it is hot.
- Fuel pump control circuit.
- Fuel pump pressure.
- Fuel injectors.
- Non Return Valve clogged, located on the lower side of car chassis above the fuel tank.
- Engine compression, valve clearance, spark plugs.
could be a boggle of things but lets start with basics first the gas tank debries in tank and filter clogged which when it cuts out the suction is lost and debries fall back to bottom of tank again dirty fuel sifon out and filter check for debries bad thermo sensor it can cut off if stuck in position loose wire from change in your plugs rotor cap might have hit a wire by accident air filter clogged
generator failing throttle body needs cleaning
now the more rough end the crank or cam sensors speed sensor bad ground now the 1991's were known for a burn out ground melting of the shielding around ground wires next to exhaust and hot areas of car this had been remedied by simple longer wire replacement and or new shielding added to wire
Nephew had similar problem on different vehicle - had spark to plugs, limited gas, everthing else checked. I did one thing first - check for two fuel filters - one in the tank was only screens and one in the line itself. Found a little in line filter just outside of engine compartment under car next to frame that looked like it had never been changed - partially clogged - replaced it.Almost ran but would not keep running. I had rotor and cap pulled - found that the screw holding rotor in place was loose. The rotor edge next to plug wire leads was chopped up and the cap's plug wire leads were heavily oxidized. Replaced them and got it running but a little rough. Pulled the spark plugs and found gaps from 25 - 100 ---replaced the plugs with correct gapping and it ran really well.
When using gas treatment, it's a good idea to pull the spark plugs after 500 miles. Most engine / gas cleaners are effective but the impurities burn off on the plugs and they can become fouled. Another place to look is the distributor cap and rotor. A tiny crack in the cap is all it takes for an engine to run rough. Lastly, inspect the spark plug wires very closely. Look for any bare spots and ensure that they are tight both at the spark plug and at the distributor cap.
Oxygen sensor only report the condition of the engine the rough running condition can range from a worn sparkplug wires to worn sparkplugs to valve problems to injector problems. with the cadillac deville a tune up should be the first attempt to smooth the rough idle with the inspection of the cap and rotor cap and rotor do have a tendancy to arc internally and create misfire so does sparkplug wire that can leak spark voltage to ground and create misfire. the spark plug wire especially if they are brittle and hard can create issues