QuestionI have a '94 Nissan Altima with about 80k miles on it. Last weekend I drove it approximately 300 miles, stopping along the way twice for gas (it still has over half a tank). When I left the event I was at, it started fine but died as soon as I gave it gas - it acts like it's running out of gas. It started again and drove about half a block before dieing again. I hauled it back to my house and here is what I've checked so far.
The fuel pump is fine, the fuel pressure coming into the rail measures 35 psi at idle, 42 at turnover (in specs), and the fuel pressure regulator is also working within specs. I thought it may be the cam position/distributor but replaced that with no change. Mass air flow, throttle position sensor, low and high rpm switches all test good, EGR appears to be good, no code error on the ECM, intake manifold vaccum meaures at idle at about 20 inches, have ignition fire which appears to be ok, the plugs all fire and fuel is getting to plugs. The injectors are also firing (no measurement but firing) and the timing looks good.
It has fire when cranking but doesn't really attempt to start until you release the key.
It will start and runs better if I open the air intake at the air filter but still doesn't run so that you could drive it. When you close the air intake it tends to stall.
It Idles smooth and you can slowly raise and lower rpm but if you try to give the engine gas as if you were accelerating, it dies.
When it dies it acts like it just ran out of gas so I went there first but now I don't know if this is a fuel, sensor/computer, or exhaust problem anymore; however, I've gone over every sensor I can think of and as far as I can tell the fuel system is fine so now I'm checking the exhaust system (just thought of this tonight).
Tomorrow I'm going to pull the O2 sensor to releave any back pressure and see if it will start/run that way.
Any advice or ideas you could give would be greatly appreciated.
Thank You,
Chris
AnswerChris,
Check to see that you have voltage to the coils when you have it in the start mode. You might have a relay that is going out. When you said is tries to start once the key is released is the first clue. Then in start mode you throw all twelve volts to the coils but when they are in the run mode they get something like nine volts. So, check to see that the ignition circuit is working properly. I would get a volt ohm meter and check what is going on at the coils in both start and run mode. You might have a bad ignition switch, chaffed wire or if there is an aftermarket alarm someone might have messed up a connection. Check under the dash to see what someone has been up to if there is an aftermarket alarm. I do not think the problem has anything to do with your oxygen sensor. And, if your fuel pressure checks out and the injectors are clicking I cannot see the pump or hall effect pickup being bad. I would go with the primary ignition circuit first and see that all the wires and the ignition switch are good.
