Fiat 500 Multiair Burned Exhaust Valve

Ronald Technical Support Specialist Trail, British Columbia Posted   Latest   Edited  
Question
Drivetrain
2012 Fiat 500 Sport 1.4L (EAB) 6-spd
P0304 - Cylinder 4 Misfire Detected
P0340 - Camshaft Position Sensor "A" Circuit Bank 1 or Single Sensor
Burned Exhaust Valve

This is same vehicle that I posted using pressure transducer to diagnose. I have taken the cylinder head off now. In the process I physically checked valve timing which was out 15 or so degrees and the timing belt was very slack. One of the number 4 cylinder exhaust valves is no longer seating and is burnt. We need to fix this vehicle up now. I did a bit of research and burnt exhaust valves are common in these vehicles. Are there any Fiat experts who can suggest best way to repair this vehicle and try to prevent future exhaust valve problems? This vehicle has only 60 000 miles. 

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Douglas Engineer
Webster, New York
Douglas Default
 

Ron I had been following this case since the startup and was interested in the outcome. It appears that the timing issue was the root cause of the burnt valve correct? If so it would seem to me you need to figure out why the timing belt become so slack to jump a tooth. Let me know if my logic is correct for this car and the issue. Maybe I have oversimplified it and/or missed something along the…

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Ronald Technical Support Specialist
Trail, British Columbia
Ronald Default
 

I don't know if timing was the cause of the burnt valve. This vehicle was purchased used recently. If you google the forums for these vehicles burning exhaust valves is common. I don't know if loose timing belts or incorrect valve timing would be the cause. The number of loose and missing bolts etc indicates someone was into this vehicle before me.

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Douglas Engineer
Webster, New York
Douglas Default
 

Ron I did a little research and stumbled into the burnt exhaust issue as well. Here is one excerpt I found: "It seems that indeed, the heads on the U.S. spec 1.4L Multi-air engines are significantly different than the European design. This includes the combustion chambers and even the way the valve train works. Most of the original Euro-spec 1.4L engines don't have the Multi-air hydraulic valve…

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Ronald Technical Support Specialist
Trail, British Columbia
Ronald Resolution
 

Finally got this Fiat back together. We put a new cylinder head on it and a new timing belt and tensioner. I thought I should get some good cam/crank and running compression waveforms. Thanks for all the insight.

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