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Discussion Starter · #1 · (Edited)
My wife’s 2003 Murano has been misfiring during cold starts. After driving it a bit the car would fire on all cylinders. I pulled the codes and got a code for cylinder 2 misfiring. I swapped cyl. 2 and 4 coils and sprayed both coil connections and injector connection with contact cleaner. Car then ran fine without misfiring anymore.

On another note, the car has been using a bit of coolant. I couldn’t determine where the leak is. There are no obvious signs of a blown head gasket such as pressure in the circuit, coolant in the oil or white smoke. I haven’t been able to determine the cause of that coolant consumption or leak so far.

I am now away from home for a week and my wife called me to tell me the misfiring at cold start is back. Misfire stops after a while, but engine light came on.

Not being home, I cannot pull the codes. While doing a web search, I read that misfiring at cold start up could be due to coolant making its way in a cylinder. Once home, I will pull the plug on cyl 2 and see its condition. I will also take the compression and compare with cyl. 4 and 6. But having not otherwise noted any symptoms of a blown head gasket, I am wondering if some coolant can make its way in the intake manifold once the car is stopped and then be ingested by cyl 2 at start up? Did any one ever experienced a similar issue? I’m trying to get as prepared as possible (and avoid pulling a head if I don't have to) as I will only have a few days home to sort it out before going back on mission for work. So, any help with diagnosing the issue and where to look will be very appreciated.

Thanks!
 

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How many miles do you have on your Murano?
 

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Discussion Starter · #3 · (Edited)
The car itself has 150,000 miles, but the engine was professionally rebuilt by a trusted local machine shop when the car had 117,000 miles. Engine has been working like a champ since rebuild, and still is when firing on all cylinders.
 

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The car itself has 150,000 miles, but the engine was professionally rebuilt by a trusted local machine shop when the car had 117,000 miles. Engine has been working like a champ since rebuild, and still is when firing on all cylinders.
What was the reason it was rebuilt @ 117k miles?
 

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The coolant consumption may or may not be related to the misfire--check the trouble codes and see if it's the same or a different cylinder. If the misfire moved then probably not a blown head gasket.

If you think the cooling system has a slow leak somewhere, you should pressure test the cooling system to confirm the leak and where it is. If system pressure drops during the test and you still can't find any evidence of an external leak, there are kits you can buy to test the coolant for the presence of hydrocarbons that would confirm a head gasket leak. If you happen to have a refrigerant leak tester, you can try using that too (sniff the radiator neck and coolant reservoir).

BTW, why was the engine rebuilt at 117k miles? Very unusual.
 

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Discussion Starter · #6 ·
My wife bought that car at 52,000 miles, and we realized it was burning oil. We kept adding oil until it got really bad. I took the compressions and cyl 4 was very low (to the point idle wasn't smooth). We were told it could be some particles from the catalytic converter that were sucked back into the cylinder. It sounds weird but apparently it happened on some Nissans. Machine shop found a collapsed piston N. 4 and rebuilt the engine. It has been working very well, very smooth since then, without burning any oil.

I also believe the car was in reality more than 52,000 miles when we bought it, judging by the mileage at which I had to replace some items which should have lasted longer (notably suspension items).

I will pull the codes and do all the diagnosis steps once I'm home. Just trying to find out if there is a known issue with coolant finding its way into cylinders, via some faulty seals in the throttle body or intake manifold for ex.

Thanks for the help!
 
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