Rep: 1
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I bought a used 06 Altima 2.5L and it had a check engine light on. The diagnostic read (P0300) a random misfire with no specific details. I’ve checked the coil packs and replaced the anomaly, I’ve replaced the cam and crank sensors also. I even put gasoline directly into the intake to rule out fuel issues. Still won’t start. I need help!!??
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Rep: 145
3
Engines running need 3 things. Air, fuel and spark. To some extent the fuel needs to be the right quantity (a little too much - like the suggestion of spraying starter fluid) is OK to run. As for spark, it needs to come at the right time (hence crank and cam position sensors).
Air is pretty simple and almost never lacking. Fuel, make sure the computer is work (scan tool reports no problems) and you have pressure on the rails. Most/Many fuel systems have a shrader valve to test fuel pressure. Fitting like a tire air fill - poke it with a small screw driver and gasoline should squirt out.
As for spark. Assuming the computer is good, there are various tools that can detect spark.
One last thing. If the car fires up for a few second, then dies. Consider the possibility of a clogged catalytic converter. A missfire (your earlier problem) could have sent raw fuel to the converter which processed it (burned it) and overheated - internally melting, forming a clog. Since you fixed the spark issue (hopefully), just replace the converter.
If the car fires for 1 second and dies (instantly). Look for a sensor malfunction. Cars with MAF sensors. Essentially the computer detects no air-flow and puts in the appropriate amount of fuel (which is zero -for zero air). Some cars you can unplug the sensor and the computer will estimate the amount of fuel needed - it just wont run as smooth or efficient and throw a check-engine light error.
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Okay so I checked to spark and I Do have one... and after trying the starter fluid trick I’m beginning to think the timing chain has maybe gotten off track somewhere... could this be a possibility?? I mean, if there’s spark and fuel, what else could it be that’s preventing it from firing up?? And it has never fired up and died on me. The starter just keeps trying hard and never catching.
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@flexnyo "I’ve checked the coil packs and replaced the anomaly" let us know how you checked the coil packs and what anomaly you replaced. You also want to let us know if it ever started after you "replaced the cam and crank sensors also." Any engine needs three things to work: Fuel, Air, and Spark. Seems like you are missing one of those. Since you already tried starter fluid etc. it sounds to me like you do not have a spark (or proper spark due to timing issues etc. You need to check for that first.
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Wow. Okay I checked the disconnected coil packs with a ohm reader to compare the resistance of current. They all were the same resistance except for one. Which I assumed was the issue so I got a new one. Still had trouble starting. But eventually i tried and tried and it fired up but once I shut it off again I haven’t been able to start it since then. I then replaced the cam and crank sensors and that didn’t work. Haven’t had any luck getting it going after that. I’m going to check the spark this afternoon and I’ll return for updates later on this evening.
Okay so I checked to spark and I Do have one... and after trying the starter fluid trick I’m beginning to think the timing chain has maybe gotten off track somewhere... could this be a possibility?? I mean, if there’s spark and fuel, what else could it be that’s preventing it from firing up??
It's a possibility amongst many others. I think we need to start from the beginning with your P0300 fault since that was were the trouble started. Right now it appears we are all chasing our own tail.
I suggest you go down the list and check things out for the P0300
Faulty spark plug (s)
Faulty ignition coil (s)
Clogged or faulty fuel injector (s)
Intake air leak
Fuel injectors harness is open or shorted
Fuel Injectors circuit poor electrical connection
Ignition coils harness is open or shorted
Ignition coils circuit poor electrical connection
Insufficient cylinders compression
Incorrect fuel pressure
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8 commentaires
@flexnyo just to clarify, it does not start at all? You did check to make sure that you do have a spark?
par oldturkey03
It will crank but won’t start. The first time it happened I had to keep on and keep on starting it and it eventually turned over but I haven’t had any luck since then. Plus I don’t wanna ruin my starter so I haven’t been giving it !&&*
par Joshua
I haven’t actually checked to make sure that I have a spark but I did pull the plugs and serviced them. They don’t seem to be in terrible shape?? How do you check this??
par Joshua
try to check the starter
par Amr Ateef
I tried spraying starter fluid in it today. No luck.
Tomorrow I’ll check the spark...
I was told to take the coil pack off the cylinder and leave the harness on it. Then take a screwdriver and ground it to the block and bring the end of the tool close to the end of the boot and see if there’s a spark. Is that the same as what you explained??
par Joshua
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