| Hi all, I've been trying to chase down two issues which may be related with my Z and am looking for advice. As backstory, I recently got the car and have been working on it to make sure it is 100% before I start pushing it, driving it hard etc. In the few times I've pushed the car it pulls like a demon with no hesitation. I didn't want to go over 5000rpm lol. The PO said he got the injectors that are currently on the car off eBay as "remanufactured" injectors. They are a darker yellow color with no discernible manufacturer markings. I'm thinking they are likely fakes from what I've read here. The two issues are:
1. The Z idles well at right around 700rpm but will chug a bit sometimes and misfires every 1-2 seconds. Sometimes it sounds almost like there is a small backfire in the exhaust. This all seems to be worse when the Z is warm.
2. The Z starts instantly when cold and I mean instantly. But when hot, it struggles to start. It will crank and crank sounding like it is firing but won't quite start. Giving it ~50% throttle when hot starting will generally get it to start up. Also, if you wait 10-15 it will start right up. My testing/parts cannon work thus far has included:
1. I compression tested the Z and all cylinders were within the range 150-160.
2. I installed all new NGK PFR6B-11B spark plugs
3. Verified timing belt was installed correctly and installed full 120K timing kit while I was there.
4. Checked CHTS is working via Nissan Datascan
5. Checked TPS voltage and TPS closed switch is working
6. Pulled CAS and used it to test each coil pack seeing that there was spark. Also while the CAS was pulled I pulled the fuel rail and set it up so I could spin the CAS and watch each injector fire fuel into a plastic bin I setup.
7. I smoke tested the plenum and found it had a small crack due to over tightening the balance tube so I replaced it with a good used plenum.
8. Ohm tested the injectors and all were right around 12.5 or so.
9. Tested resistance of the PTU per the manual, all tests passed. With all that, does any one have any ideas about what might be going on here? I am thinking the issue may be injectors, I am skeptical of them because I'm not sure they are legit. Although they all passed the ohm test, and I watched them spit fuel maybe one/a few are not performing properly when the engine is running at speed. My thought is to get some JECS 850cc injectors from Z1, a new EPROM to match, injector seals and fuel rail to plenum seals but I just wanted to see if anyone had any experience with an issue like this before I lay out the cash. Thanks!
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15:22:57 10/25/22
