Mechanics

WHAT WOULD CAUSE MISFIRE OF #2 AND #3 CYLINDERS?

1999 Saturn SL2 • 190,000 miles

The car abruptly began to misfire, on the highway, with loss of power and vibration. It was turned off for refuelling, turned back on, and continued to misfire. After a five minute drive, it cleared itself for 5 minutes, was shut off, but resumed the same symptoms upon restarting. Codes P0300, P1599 and P1555 (previously registered, have not replaced EVO) registered. Followed advice to disconect plug wires, with engine running. Disconnection of #2 and #3 resulted in no change. Replaced O2 sensor for Bank 1 Jan 2011.
Avatar
1999sl2
January 28, 2012.




Keep me posted on how it goes.

Saturntech9
Jan 31, 2012.
I bought a new ignition module, installed it and that did the trick, but not the idle is high and erratic. I removed and cleaned the spark plugs and removed and wiped off the O2 sensor on the header, figuring that the plugs and sensor might have gotten fouled with unburned fuel. No joy. Is there another valve/sensor that would have been fouled by the unburned fuel, or do you have other thoughts?

Tiny
1999sl2
Feb 18, 2012.
What codes do you have now?How high is the car idling?How many rpms?What kind of spark plug do you have in the engine?Not platnuim ones I hope?

Saturntech9
Feb 18, 2012.
No check engine light, yet. 2000, but up to 3000, sporadically. Stock Saturn dealer ones (?)
AD

Tiny
1999sl2
Feb 18, 2012.
With that high of a idle I would check for vacuum leaks first.

Saturntech9
Feb 18, 2012.

AD