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View Full Version : 1990 300zx na has a cel and a code 45, need diag help please


08-13-2010, 12:57 PM
Im new here, i dont know much about nissans, im a ford tech so im having a little trouble with this obd1 nissan. well im working on a 1990 nissan 300zx na. It sat for three years and the customer wanted me to go thru it and get it running. so i did. replaced the master cyl, did some break work, changed all fluids and it fired up and runs great. well on the way to smog the check engine lite came on. i figured out how to get the code i think. even tho it said there should be an led blinking on the ecm i was not able to see that, but the check engine lite was blinking, so i figured i could pull the code from there. i got a 4 in the tens place and a 5 in the 1s place. so a 45. the def. for that code is a leaking injector. well i pulled plugs and only one looked slightly rich. and the car runs fine so im weary about it being a leaky injector. i ohmed the injectors out and they are all in spec. one is 9.8 ohms a little under but it is not the corresponding cyl with the rich plug so i dont know. now im pulling the intake to get to the fuel rail and see if any injector leaks. what a pain in the ass, not liking this z anymore haha. but i found a good tech write up on here on how to do it so that is making it easier. well my question is is there anything that can make this code come up except an injector. how does the computer know the injector is leaking, fuel pressure? or the o2 sensors? And being that it runs fine do you think it really is an injector? any info on this would be great. i searched and couldnt really find what i was looking for. thanks
--David

08-13-2010, 03:29 PM
so i got the manifold off just a few mins ago. i hooked up the fuel rail and let pressure go to it and i have no injector leaks. but the orings to the intake where the injectors sit are destroyed. to my knowledge bad orings there might cause a lean condition. so im confused why im getting a code 45 injector leak. i mean it might be leaking a little fuel to atmosphere, but more than anything i think its probably a vacuum leak. i think if i knew what the computer looked for to see an injector leak would for sure help me diagnose this thing correctly. any info would be great. thanks