Hesitation again and again...
sephroth777
09-22-2004, 09:28 AM
1997 Oldsmobile Aurora 91,000
Currently my vehicle is hesitating. At idle there is a slight knock/shutter every few seconds sometimes not even noticeable. When accelerating you can feel the lack of power but the engine runs smooth however when the vehicle gets into fourth gear and low 1500 rpms the hesitation is much more pronounced. At higher rpms and highway speeds the engine is smooth however still with the lack of power. I have changed all the plugs/wires/coils/control module with AC/Delco OEM parts. Plus have installed a new PVC valve and fuel filter. After I did the above the car ran fine for a few weeks then the same problem occurred again. I had AutoZone run the codes which came back O2 sensor high voltage and cylinder 7 misfire. I changed the # 7 spark plug again with AC/Delco platinum for another $6. Car ran fine for a few days then the same problem. Same cylinder # 7 misfire although I pulled the plug out it looks fine however there is oil on the threads and on the tip of the plug. Is this normal? So before I change my third # 7 plug what else could be my problem? I would hate to have to bring in the car to the dealer since I have not had to yet except for the recall. Any advise would be greatly appreciated! Thanks in advanced.
Currently my vehicle is hesitating. At idle there is a slight knock/shutter every few seconds sometimes not even noticeable. When accelerating you can feel the lack of power but the engine runs smooth however when the vehicle gets into fourth gear and low 1500 rpms the hesitation is much more pronounced. At higher rpms and highway speeds the engine is smooth however still with the lack of power. I have changed all the plugs/wires/coils/control module with AC/Delco OEM parts. Plus have installed a new PVC valve and fuel filter. After I did the above the car ran fine for a few weeks then the same problem occurred again. I had AutoZone run the codes which came back O2 sensor high voltage and cylinder 7 misfire. I changed the # 7 spark plug again with AC/Delco platinum for another $6. Car ran fine for a few days then the same problem. Same cylinder # 7 misfire although I pulled the plug out it looks fine however there is oil on the threads and on the tip of the plug. Is this normal? So before I change my third # 7 plug what else could be my problem? I would hate to have to bring in the car to the dealer since I have not had to yet except for the recall. Any advise would be greatly appreciated! Thanks in advanced.
IronAuroraV8
09-22-2004, 02:07 PM
it could be number of things that cause hesitation esspecially in mid rpm's - it is very hard to diagnose a problem without actually looking at the car.
Make sure your MAF sensor is working , also check your Engine coolant temp sensor - when this sensor goes bad - the ECU will take longer to go into closed loop of operation. make sure your fuel filter its not clogged, The misfire in cyclinder # 7 could be caused by faulty injector , The fouled spark plug could be caused by bad gasket under valve cover if the tip is covered with oil, if the electrode of spark plug is fauled with oil - it could be sign of leaky piston rings.
replacing the # 7 spark plug its not going to take care of the problem - rather look what causes the plug to go bad
If you hear knocshutter maybe your knock sensor stopped working and now your ECU is running is "safe" igintion retarded mode - thus you feel lack of power. Knock sensors go bad without giving you the check engine light.
It can go on and on .... try the basic stuff first.
good luck.
IronKrakus
Make sure your MAF sensor is working , also check your Engine coolant temp sensor - when this sensor goes bad - the ECU will take longer to go into closed loop of operation. make sure your fuel filter its not clogged, The misfire in cyclinder # 7 could be caused by faulty injector , The fouled spark plug could be caused by bad gasket under valve cover if the tip is covered with oil, if the electrode of spark plug is fauled with oil - it could be sign of leaky piston rings.
replacing the # 7 spark plug its not going to take care of the problem - rather look what causes the plug to go bad
If you hear knocshutter maybe your knock sensor stopped working and now your ECU is running is "safe" igintion retarded mode - thus you feel lack of power. Knock sensors go bad without giving you the check engine light.
It can go on and on .... try the basic stuff first.
good luck.
IronKrakus
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