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Discussion Starter #1
While accelerating on an entrance ramp, I felt the car shudder and then start misfiring. The engine vibration would only settle out at/above 3000 rpm. When I got home, I read the codes and found P0301 (cylinder #1 misfire) and P1182 (Long Term Fuel Trim Additive Max Value Air / Fuel Too Rich). What is surprising is that I replaced the spark plugs (NGK) and Ingition cassette less than 12 month ago and the car was running well until this highway incident. In scanning the threads, I'm trying to determine the best way to troubleshoot the failure. Potential causes of these codes would be oxygen sensor, vacuum lines, premature failure of a plug/ignition cassette, or possible the throttle body? The TB is original and I thought I smelled an electrical burn, but I didn't get a TB code. Any suggestions on the best way to troubleshoot and rule out the potential causes? Thanks...

Vehicle: 2004 9-5 Aero w/ 145k miles
 

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Discussion Starter #3
It was not a Genuine Saab part. The DTC was sourced from FCPEuro in CT. They supply good aftermarket components and it was listed as "OEM". Is there a way to test the DTC? FCPEuro has a lifetime parts warranty, so they will replace it for free if that is the bad component. Let me know whether there's a test method. Thanks,,,
 

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Discussion Starter #5
Update on the misfire situation... I purchased a new DIC and found no change to the misfire on Cylinder #1. After running the engine, I removed plug #1 and found it wet and it smelled of gasoline. After checking the gap and cleaning up the plug, I reversed the plugs in cylinders #1 & #2 and found the same condition. The plug that was originally in cylinder #2 and now installed in cylinder #1 was found wet with unburned fuel. The plug originally installed in cylinder #1 fired perfectly in cylinder #2. Therefore, based on this testing, I've ruled out a bad DIC and a bad plug, but I don't know where to go from here. What would cause cylinder #1 to not fire? The signal to the DIC? I've considered other potential causes, but they would have impacted multiple cylinders, not only cylinder #1. Any suggestions on the next step?
 

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Have you had a compression test done on the engine? if one cylinder is still not firing properly you're looking at either fuel injector or bad compression. I'd test compression first as it's the easiest to test.
 

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Discussion Starter #7
Thanks for the suggestion. I will invest in a compression tester and see what I find. Much appreciated...
 

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Keep your head up. But also be mindful in the future if you buy /any/ car, if you only do one test on it, make it a compression test.
 

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Discussion Starter #9
Good suggestion on the compression check (although unfortunate news....). I found the compression to be 0 on Cyl. #1, 180 on Cyl. #2, 170 on Cyl. #3, and 170 on Cyl. #4. Based on this info, the issue would be either with the valves leaking/not sealing properly or a failure of the piston rings, correct? Is the next step to take the head off an inspect the valves? Are there any other less invasive steps to determine with it's a top end or bottom end problem before removing the head? Thanks....
 

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Discussion Starter #10
I just added some oil to the cylinder and did a wet compression test and had the same result- 0 psi. I'm thinking of getting a boroscope to look inside the cylinder for signs of damage and if no findings, then seriously consider pulling the head to inspect the valves. Any other suggestions before going in that deep?
 

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Discussion Starter #11
The cylinder head is off and we found one valve with a chunk missing that caused the misfire and 0 compression. The head is being reworked at a local machine and I'm waiting to hear whether any of the other valves are suspect. The bad valve was one of the exhaust valves on cylinder #1. FYI...

IMG_0106.JPG
 

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OUCH. Sorry to see you finding that as the issue. Now the question becomes, what actually caused that to happen in the first place?
 

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Discussion Starter #13
My mechanic says that he's seen similar failures on other Saabs and attributes it to the valve metallurgy. If you google Saab valve failure images, you will find other examples. The engine is in a 2004 Aero wagon with 145k miles. After this fix, I hope to get another 145k from the engine... (wishful thinking....)
 
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