96 sunfire very rough idle

Help,
My girlfriends 96 sunfire has been idling very rough. The shop can't figure it out. we repalced the spark plug boots, and the housing of the coil pack. it gets a misfire code and a rich fuel mixture code. Any Ideas?

broken injector(s), rough idle as in not firing a cylinder? does it level off at higher rpm's?

Clean the bore for spark plug for the cylinder that is misfiring. Since the plug grounds on the block it may have grease or something in there causing a bad ground. just make sure you don'tuse something tha could drop particles into the cylinder!

It does level off at higher rpm. It's not just one cylinder that misfires. it alternates. Though more on one then the others. At one point it shut down at about 60MPH, But caught itself and kept going.

by spark plug boots you also mean wires? since it alternates, its before the plugs and wires. weak spark maybe? a test i did which i dont necessarily say is safe, but it shouldnt harm anything, is take the plug wire off a terminal, start the car, make sure it sparks every time. it should to one of the close cover bolts. if it sparks every now and again, its internal electric, if its solid, go to the next plug. do to all 4, if any of them spark less than half the time (which i suspect) then its in that area. i am knowledged in basic auto mechanics, so i dont know the specifics of this car, so if its intermitent, make sure all cables (power in/out and ground primarily) are good and connected. make sure the battery and alternator are good so you are supplying the current to the car, then itll have to be between where the power goes into the ignition module/distributor cap(depends on model) and before the wires. there arent many pieces in there to replace. hope this helps.

by spark plug boots you also mean wires? since it alternates, its before the plugs and wires. weak spark maybe? a test i did which i dont necessarily say is safe, but it shouldnt harm anything, is take the plug wire off a terminal, start the car, make sure it sparks every time. it should to one of the close cover bolts. if it sparks every now and again, its internal electric, if its solid, go to the next plug. do to all 4, if any of them spark less than half the time (which i suspect) then its in that area. i am knowledged in basic auto mechanics, so i dont know the specifics of this car, so if its intermitent, make sure all cables (power in/out and ground primarily) are good and connected. make sure the battery and alternator are good so you are supplying the current to the car, then itll have to be between where the power goes into the ignition module/distributor cap(depends on model) and before the wires. there arent many pieces in there to replace. hope this helps.


2.4 doesn't have plug wires, has 3" boots that it on the plug and join direct to the IDI (integrated Direct Ignition) plate that contains the entire ignition system so it's not possible to do what you have advised!

Okay, I've tried new plugs, boots, coil pack housing, crank sensor. still doesn't help. I did find out from the previous owner that she had a guy change the water pump and when she got it back it idled rough. This is timing chain driven. could the crank and cam be out of time? HELP!!!!

Okay, I've tried new plugs, boots, coil pack housing, crank sensor. still doesn't help. I did find out from the previous owner that she had a guy change the water pump and when she got it back it idled rough. This is timing chain driven. could the crank and cam be out of time? HELP!!!!


Possibly but the valves would proabaly foul the cylinders, it may be that the person that replaced it used the old timing chain which should always be replaced when you change the water pump! The guides, and tensioner too. it may be that! But could also be a spark plug not grounding in the block properly as per my first post. even new plugs may not make a good enough connection if there is oxidation (white powdery stuff- aluminium oxide) or grease/oil that is preventing it grounding properly!

Thanks everyone for your suggestions. It ended up the exhaust cam was one tooth off. Once that was fixed the car runs great!!!!

Thanks everyone for your suggestions. It ended up the exhaust cam was one tooth off. Once that was fixed the car runs great!!!!

sweet!