Cranks, won't start

jcjimz • 15 November 2019

I have a 2005 Nissan Altima 2.5s. I have just replaced the computer with a used one and it was running better than it ever did before. The other day I went to the store and when I came out the car would crank all day but not start. like it was getting no fire. I've changed the camshaft sensor, checked the fuel pump and made sure it was working, it still won't start. It is getting spark but it is a very weak spark. I'll pull a spark plug wire, put a spark plug in it, ground the plug with a jumper cable and crank the car. I have to cup my hand around the spark plug and get it in the shade to see the spark. It is there but very weak. Any suggestions?


Since the problem has started AFTER you changed the computer, the first culprit might be poor programming. Have you tried, completely restarting the computer to see if the problem can be solved.

There is obviously a spark but not enough, which can also lead to problems in the circuit. Do you have a scanner to test the issue at home?

Also, this is an old car, so old you had to change the computer, your car might be developing other problems, especially in its circuits.

Are the batteries okay? How long ago did you change those?

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  • Restarting the computer?? I've shut down and re-started the car several times, had it shut down for several days. When I put the computer in I took it to Nissan and had them flash it. The car ran better than it ever dide with that new computer for several weeks before this happened.

    I have an OBD2 scanner on order. I have a cheap one but it can't read the ECM. I don't have a scanner for the circuits. Wouldn't know where to start if I did. The battery is fine and only about a year old. It holds a charge very well when I charge it with my sons truck.

    I still have the old computer which works fine. I replaced it because it is throwing a bogus code and I had to get it inspected. A mechanic that I trust told me it was the computer. When they change the cfdomputer they program the computer to the key, correct? They don't do any programming to the key do they? If my key is still the same I was going to put in my old computer and test that. Will the key still work with it?

    Thank you very much for your help. I need to get this car running, it's the only one I have, I just moved to a new area and am on foot.

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