996 3.4L Misfire replaced plugs replaced coil P0303 Just reinstalled engine
04-16-2015, 05:23 PM
#1
Track Day
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996 3.4L Misfire replaced plugs replaced coil P0303 Just reinstalled engine
Hello All,
I am new to 996 ownership. I recently bought a 996 with the infamous cracked head problem. Got the head rewelded after reading tons of Dharn's posts about his issue he had with his. While I had the engine out I replaced as much as I could. (I will spare you gents with the complete listing of all that was replaced).
Just got everything back into the car and started driving around and started to get a misfire on Bank 1, Cylinder 3. This after about 400 miles on the car
It through a check engine light and I pulled the code for P0303, as well as P1539 (VarioCam Soleniod Bank 2).
So the misfire has been contained to Bank 1 Cylinder 3.
I recently put in 6 new Beru 14 FGR-6 KQU Spark plugs when I had the engine out. As soon as this misfire started happening I just replaced all the coil packs because the car was still on the OEM Set, all the Part Numbers on the coils were 996 602 107 00
I had recently replaced 2 coil packs before due to me thinking I had 2 bad coil packs on Cylinders 1 and 2. Those ended up not being bad so I used one of my old coil packs on Cylinder 3 and that worked for a day or so then crapped out.
So then I just replaced all of the coils to the 997 revised coil packs so the entire ignition system has a grand total of 300 miles on it.
The car runs beautifully but at higher RPM's under heavy load specifically after a brisk shift I will get a misfire momentarily then it will go away, only in 2nd sometimes but usually in 3rd Gear.
Its been mind boggling to say the least.
I went through and tone tested the grounds in the coil pack harness to the engine case and that shows fine.
I am at a loss, I would greatly appreciate any help you guys could offer, I read through probably 90 other misfire threads at this point before making this thread.
I am new to 996 ownership. I recently bought a 996 with the infamous cracked head problem. Got the head rewelded after reading tons of Dharn's posts about his issue he had with his. While I had the engine out I replaced as much as I could. (I will spare you gents with the complete listing of all that was replaced).
Just got everything back into the car and started driving around and started to get a misfire on Bank 1, Cylinder 3. This after about 400 miles on the car
It through a check engine light and I pulled the code for P0303, as well as P1539 (VarioCam Soleniod Bank 2).
So the misfire has been contained to Bank 1 Cylinder 3.
I recently put in 6 new Beru 14 FGR-6 KQU Spark plugs when I had the engine out. As soon as this misfire started happening I just replaced all the coil packs because the car was still on the OEM Set, all the Part Numbers on the coils were 996 602 107 00
I had recently replaced 2 coil packs before due to me thinking I had 2 bad coil packs on Cylinders 1 and 2. Those ended up not being bad so I used one of my old coil packs on Cylinder 3 and that worked for a day or so then crapped out.
So then I just replaced all of the coils to the 997 revised coil packs so the entire ignition system has a grand total of 300 miles on it.
The car runs beautifully but at higher RPM's under heavy load specifically after a brisk shift I will get a misfire momentarily then it will go away, only in 2nd sometimes but usually in 3rd Gear.
Its been mind boggling to say the least.
I went through and tone tested the grounds in the coil pack harness to the engine case and that shows fine.
I am at a loss, I would greatly appreciate any help you guys could offer, I read through probably 90 other misfire threads at this point before making this thread.
04-16-2015, 07:16 PM
#2
You can swap the coils and spark plugs between cyl 2 and 3 and see. If that still gives you P0303, you may want a compression and leak down test at least on all cylinders in bank 1 so you can compare the numbers. Then fuel injector #3 is next.
04-21-2015, 12:37 PM
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Track Day
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Gents,
I found the problem. It was not plugged cats (although that was my next step). It seems that in my efforts to diagnose a different misfire I had earlier I had used a multimeter incorrectly on the Coil Pack Plugs.
Therefore the connector from the engine harness to the actual coil pack on coil 3 the pins were shoved apart far more than usual.
I used essentially a dentist pick for cleaning teeth (actually it was a tool I used for replacing key cylinders on E39 BMWs). Pushed the pins back together and solved the problem.
Thank you for your help.
I found the problem. It was not plugged cats (although that was my next step). It seems that in my efforts to diagnose a different misfire I had earlier I had used a multimeter incorrectly on the Coil Pack Plugs.
Therefore the connector from the engine harness to the actual coil pack on coil 3 the pins were shoved apart far more than usual.
I used essentially a dentist pick for cleaning teeth (actually it was a tool I used for replacing key cylinders on E39 BMWs). Pushed the pins back together and solved the problem.
Thank you for your help.
