Was running fine... now won't start?

[slimmyslim1420]

I have a 92 2+2 na 5 speed. The car was running fine with no problems at all. I also have a 91 tt with a few problems. So my issue started when I took the ptu off my na and put on my tt to do some work on it. After I was done I put the ptu back on the na started it and it ran fine. The next morning I went to leave for work the car started then suddenly died and I haven't got it started since. It turns over just won't start. I suspected ptu so did a few tests on it (which it works fine on my tt also) and it seems to check out. Checked and cleaned all the connections for it. Even tried a different harness with it. Also checked my ignition relay it checked out. I haven't checked all the injectors yet but did pull a plug and it was wet. On my to do list is check out cas check individual coils and plugs for spark and injectors. Oh and I did pull codes got ignition circuit and detonation sensor. Pretty sure the det sensor was already bad and unrelated but not 100% sure as this is the first time I needed to pull codes. So I guess my question is is there anything other than the ptu and ignition relay that could go out pretty much instantly and cause enough cylinders not to fire to not be able to start it?

[evildky]

ignition circuit code generally means a bad ptu, how did you check it? you test for the 6 individual inputs? and the 6 square wave outputs?

[slimmyslim1420]

Well I checked for contiuity as per the online manual. I also checked voltage on each pin a way someone on here said you could on the other topic I started called ptu test. But with either on my other z the car still started and ran. But I actually have gotten it started since but didn't do anything to fix it. Had already cleaned it up and everything. Put the ptu back on was gonna do individual spark test but tried to start it and it fired right up. It's been running since. So I dunno what happened with it

[300zxnismo]

I Was working on my 300zx 1990 today. I knew it wasnt performing well, so me and my grandfather went out and found that it was a bad O ring on one of the injectors. So after installing a new o ring and placing the injector back, we tryed to start it. To make a long story short, we think its the PTU. can any body tell me how I can test the PTU to see if it in working order? The car is getting fuel through the fuel rail so we think its an ignition problem.

[300zxnismo]

I Was working on my 300zx 1990 today. I knew it wasnt performing well, so me and my grandfather went out and found that it was a bad O ring on one of the injectors. So after installing a new o ring and placing the injector back, we tryed to start it. To make a long story short, we think its the PTU. can any body tell me how I can test the PTU to see if it in working order? The car is getting fuel through the fuel rail so we think its an ignition problem.

[slimmyslim1420]

Well there are a few ways to test the PTU. There are a couple in the online manual. There is also a post I made on here recently that someone replied with a way to test it. You can search for PTU test. But I would start by checking spark at each cylinder. Remove the COP with plug attatched get it on a ground and turn the car over. If they all have visible spark then the PTU is probably fine and your issue is some where else. But also since you just had an injector out I would check all the fuel lines and make sure they are hooked up right.

[300zxnismo]

Well I put a test light on the coil packs and it said it was receiving power. I then took out the sparkplug to test for spark but I saw none. When I put a test light on one of te harnessess of the ptu, it had power. I tested the other side of the ptu to see if power was coming out and nothing happened. Is power supposed to come out of the other side of the ptu? I know that power is going in.

[slimmyslim1420]

Yea it should have some power coming out of the side that goes to the plugs. But from what I understand its kinda hard to measure. But that's what that other topic talks about. Search ptu test. Also make sure all your connections are clean they tend to corrode and that can make it act up as well