Hello I have a 06 Nissan Altima 2.5, and it has a slow cranking problem but it does it randomly, I have changed the starter, spark plugs, ignition coils, fuel pump, camshaft and crankshaft sensor and it still is acting up, sometimes it cranks fine and other times I have to crank it twice, can you help???
My car has 148000 miles.
My car has an automatic transmission.
If I were working on a car with a slow cranking problem, the first thing I’d do is check the battery
Just how old is it?
Does it test good?
Are the connections clean and tight?
All this advice is based on the assumption that your description of the problem is accurate. For example, do you literally mean the engine cranks slowly? Slower than normal?
Or do you mean it cranks over several times, at normal speed, before it actually starts?
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cranking means when you turn the key to “start” & hear that rrr rrr sound right before the engine starts and runs. If that’s sounding like it is turning the engine slower than normal on your Altima, then it might take several attempts to get the engine to start. On both of my vehicles, there’s no prolonged “rrr rrr rrr rrr”. I barely hear the first “r” before they pop and start running. Less than 1/2 second of cranking is all that is necessary to start the engine on most cars if they are operating correctly.
Changing the spark plugs and coils is a reasonable thing to do for an engine that doesn’t quickly start up, but changing the fuel pump and the two sensors isn’t something you’d normally do unless you had a reason. So why did you change those? Cranks ok but doesn’t quickly start up could be caused by a lot of things, including poor engine compression. If you think you’ve pretty much covered the routine maintenance items, check the compression next probably.
If the only problem is slow cranking, then none of those parts you changed besides the starter would have any effect. Slow cranking as posted by @db4690 above is usually caused by the battery or the battery connections. After that, less likely, the starter itself. A very unusual cause for slow cranking would be some kind of major engine or flywheel problem. cranking problems are best diagnosed by starting with a couple of voltage tests at the starter motor during attempted cranking.
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