1990 300zx : Please Help car will not run. My headache for over a year now.

[kool-aid54]

The car was in an accident. I fixed it up. Now won't run, starts up and immediately dies within a second. I unplugged the MAF and it starts and runs perfectly. Got new MAF and plugged it in and still won't run. Unplug new MAF and it runs fine. With the MAF plugged in and spraying gas into the intake the car would run until it burned off the gas and would then die. So for some reason the injectors won't run in non-limp mode. So its either the MAF harness or the computer. There is absolutely no check engine light. How do I check the MAF harness or make sure the car has the right computer in it. The car is a 90 2+2 coupe. I bought it from a guy who owns a 91 turbo Z. I called him the other day and he said his won't start either. I asked if he switched anything and he said no. Do you think he switched computers. But, please how do I check the harness with a multi-tester. PLease help this is the 3rd or 4th post I've made about this on here in the last year.

[Silvia007]

Well, I would make sure the mafs is getting power, then clip the signal wire with enough length to extend the signal wire all the way to the ecu just to make sure. What this is sounding like is it's either a bad mafs, the wrong mafs, bad signal wire, or no power to mafs. The reason being is that once the mafs is hooked up, it thinks so little air is comming in, it basically shuts off the fuel. So chances are, it may not be getting power. Check with a voltmeter to see if the mafs is getting power, if it is, I would suspect a bad signal wire, perhaps. It's definately the mafs though by how your post went.

[Ni2s4s0aSnX]

Sounds like an ECU problem to me. YOu have tried to mess with your ECU at all have you?

[NISTECH]

Get a noid light and plug it into one of your injectors. See if they are pulsing when the maf is plugged in. post back.

[kool-aid54]

NISTECH, the only way to get the car to run with the maf plugged in was to spray starter fluid into the intake. The light pulsed on the noid light but not as bright as when I ran the car with the maf unplugged. Silvia007, I ran a wire from the ECU wire number 27white in the manual. That one goes directly from the ECU to the maf. Wire number 59 white goes to the maf and it also goes to the cam sensor and the ECCS relay, which I just replaced today to make sure. I unplugged the Maf and checked the plug for power. Wire 59 white had power and wire 27 would not display power. When I jumped 59 to 27 the car shut off just like plugging in the maf. When I jumped from the ECU to the maf I had no power on that wire which was 27. For some reason I think ECU is not supplying power to that wire.

Here is a link to the 300zx online manual with the ECu wiring diagram I'm talking about http://www.300zx-twinturbo.com/cgi-bin/manual.cgi

and when I switched the ecu into diagnostic I got 2 slow flashes and 4 fast. and the maf was unplugged, I'm not sure what the code is?
Modified by kool-aid54 at 10:44 PM 11/5/2005

[NISTECH]

Dude you need to stop jumping wires. #27 is the signal wire FROM the maf to ECM. The power that goes down that wire is regulated by the MAF. Its amperage will not be substantial enough to take out the ECM due to the maf essentially being the load in the circuit. By jumping power to terminal 27 directly you have eliminated the amperage regulator in the circuit. This can fry the circuit inside the ecm. Not good! If you are extreamly lucky you didnt do that. The fact your injector pulse on the noid lite was dim when trying to start the car suggest that you might have a weak power or ground to the injector. The power is direct from a relay. The ground is a pulsed ground by the ECM. Start by hooking everything back up the way its suppose to be and redo the injector test both ways you did and make sure the car can still run after zapping the ECM. If it will it still doesnt mean you didnt fry the ECM. If you get the same lite results you did before you did that, you want to then test the power side of one of the injectors while the maf and injector are plugged in[probe the injectors power wire with a t-pin or small paperclip from the back of the connector]. You will be trying to see if you have battery voltage available there. See what your available battery voltage is during the testing condition [cranking the car] before you test the injector, it wont be 12 volts while cranking but it must be more the 10v.

[kool-aid54]

thanks NISTECHm, try to get to it in the next few days. My kids keep me pretty busy.