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

1999 Saturn SL2

Tiny

1999sl2

January, 28, 2012 AT 12:24 PM

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.

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15 Answers

Tiny

1999sl2

January, 28, 2012 AT 12:55 PM

And the exhaust smells as if it has a lot of unburned fuel. Maybe the downstream O2 sensor has died, so the ECU is cutting spark to cylinders 2 and 3?

Tiny

saturntech9

January, 28, 2012 AT 2:14 PM

No a o2 sensor would not cut out two cylinders bad or not check for spark on number 2 and 3 cylinders. Let me know if you have spark on those two and we will go from there. If you have spark then we need to check compression. Only three things really tie those two cylinders together spark same compression stroke and fuel injectors firing. My money is on spark first then compresson issue.

Tiny

1999sl2

January, 29, 2012 AT 4:20 PM

I checked spark with the 3rd from left plug against the header. No spark. Are the coils the next thing to check? Is there an easy way to swap them?

Tiny

1999sl2

January, 29, 2012 AT 4:28 PM

Voltage on the battery when running is over 14.2, also.

Tiny

saturntech9

January, 29, 2012 AT 5:14 PM

You can swap the coils from left right to right you jut have to take the four bolts out see if the no. Spark follows the coil. Let me know what you find.

Tiny

1999sl2

January, 30, 2012 AT 5:53 PM

I swapped the coils, left to right, marking the original left, and the misfire still occurs on #2 and #3 cylinders, confirmed by disconnecting spark and injector wires. Still smells like gas. As you face it, the left coil feeds cylinders 1 and 4. The ignition control module didn't have anything visibly wrong with it.

Tiny

saturntech9

January, 30, 2012 AT 5:57 PM

Are you getting spark from the number 2 and 3 cylinders?If not then you have a bad ignition module. Let me know what you find.

Tiny

1999sl2

January, 30, 2012 AT 6:04 PM

Yesterday, I pulled the #3 spark wire and grounded it against the header: no visible spark, with the engine cranking.

Tiny

saturntech9

January, 31, 2012 AT 4:50 AM

If you have spark on the number 1 and 4 cylinders and not on the number 2 and 3 cylinders and its not the coil then the only other thing left is a bad ignition module.

Tiny

1999sl2

January, 31, 2012 AT 6:29 AM

Thank you!

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