Car has 209,000 miles and the engine runs great all other times. It’s the GM corporate L61 2.2L engine used in millions of Cavaliers, Cobalts, Malibus, Grand Ams, Sunfires and is a DOHC timing chain motor.
If it hasn’t been started in a day or more, when I do start it, sometimes it will miss badly for the first 20-30 seconds, after which it will gradually smooth out and miss goes away. The thing is, it doesn’t happen ALL the time after sitting. It may start up just fine as well.
When it does happen, it barely runs as it only seems to have 2 cylinders working. Scan tool shows many misfires on #1 and #4 but zero on 2 & 3. Codes are P0300 for the misfires and P0341, Cam position sensor performance. This engine doesn’t have a cam sensor, but gets the data from the ignition module.
Work done so far includes new AC Delco iridum plugs, Spectra Premium coil pack, oil change with 5W30 and AC Delco filter, Purolator air and fuel filters.
I have two thoughts so far.
1) Ignition module on the way out since that’s where it gets the cam signal.
2) Timing chain and/or tensionor worn and causing a timing issue by oil draining out while sitting until next start. When it is started after a day or two, it takes 20-30 seconds for the oil to fill the tensioner and take up the slack in the chain. Is the tensioner oil fed on this engine? And why a miss only on 1 and 4?
Any other things to consider? I could do a fuel injector flow test to see if they are even or leaking down into the cylinder.
If it hasn’t been started in a day or more, when I do start it, sometimes it will miss badly for the first 20-30 seconds, after which it will gradually smooth out and miss goes away. The thing is, it doesn’t happen ALL the time after sitting. It may start up just fine as well.
When it does happen, it barely runs as it only seems to have 2 cylinders working. Scan tool shows many misfires on #1 and #4 but zero on 2 & 3. Codes are P0300 for the misfires and P0341, Cam position sensor performance. This engine doesn’t have a cam sensor, but gets the data from the ignition module.
Work done so far includes new AC Delco iridum plugs, Spectra Premium coil pack, oil change with 5W30 and AC Delco filter, Purolator air and fuel filters.
I have two thoughts so far.
1) Ignition module on the way out since that’s where it gets the cam signal.
2) Timing chain and/or tensionor worn and causing a timing issue by oil draining out while sitting until next start. When it is started after a day or two, it takes 20-30 seconds for the oil to fill the tensioner and take up the slack in the chain. Is the tensioner oil fed on this engine? And why a miss only on 1 and 4?
Any other things to consider? I could do a fuel injector flow test to see if they are even or leaking down into the cylinder.