What would cause misfire of #2 and #3 cylinders?

Tiny
1999SL2
  • 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.

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Saturday, January 28th, 2012 AT 12:24 PM

15 Replies

Tiny
1999SL2
  • MEMBER

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?

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Saturday, January 28th, 2012 AT 12:55 PM
Tiny
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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.

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Saturday, January 28th, 2012 AT 2:14 PM
Tiny
1999SL2
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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?

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Sunday, January 29th, 2012 AT 4:20 PM
Tiny
1999SL2
  • MEMBER

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

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Sunday, January 29th, 2012 AT 4:28 PM
Tiny
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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.

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Sunday, January 29th, 2012 AT 5:14 PM
Tiny
1999SL2
  • MEMBER

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.

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Monday, January 30th, 2012 AT 5:53 PM
Tiny
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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.

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Monday, January 30th, 2012 AT 5:57 PM
Tiny
1999SL2
  • MEMBER

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

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Monday, January 30th, 2012 AT 6:04 PM
Tiny
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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.

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Tuesday, January 31st, 2012 AT 4:50 AM
Tiny
1999SL2
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Thank you!

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Tuesday, January 31st, 2012 AT 6:29 AM
Tiny
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Keep me posted on how it goes.

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Tuesday, January 31st, 2012 AT 6:40 AM
Tiny
1999SL2
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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?

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Saturday, February 18th, 2012 AT 11:10 AM
Tiny
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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?

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Saturday, February 18th, 2012 AT 4:23 PM
Tiny
1999SL2
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No check engine light, yet. 2000, but up to 3000, sporadically. Stock Saturn dealer ones (?)

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Saturday, February 18th, 2012 AT 4:39 PM
Tiny
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With that high of a idle I would check for vacuum leaks first.

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Saturday, February 18th, 2012 AT 10:14 PM

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