Hello!
Long time stalker, first time talker. I hope this is thorough, and let me know if there is something missing.
1978 280z
Basically, my car is acting lean. Front firing from the afm... I'll tell you how I got here, what i've done, and any seemingly relevant questions I can’t seem to get an answer on.
Been chipping away at getting this car running well for a bit, passed smog (CA) last year. Car was running pretty good minus a rich issue. I was modifying the car back to stock (previous owner put larger injectors/a number of things). We are friends, so I was aware of these changes. Savvy Porsche guy leaned me out to pass smog car ran great all year.
I threw in a "fuel cleaning" supplement. One day in traffic here in LA the fuel pump got real loud (intermittently would get loud from time to time) shut down on me. Waited 20 minutes then it started up, barely made it home. Seemed to only happen when the car was hot. When the weather was great (72F) the car ran great (besides the rich issue). Hot days, the noise would return and then it would get sluggish, and the RPMs would get high. I thought it was fuel clogging since the cleaner was probably the culprit.
I started with checking/changing Fuel pump, filter filter, and in the process unplugged the fuel rail to make sure the injectors were all spraying (new connectors and they were clicking with the screw driver test). I thought maybe the fuel dampener was clogged…did some research on here, and I had some extra fuel line, so I deleted it.
Thermostat wasn’t really getting to the middle, and it made sense that the car was reacting a bit too much with the weather to me, cheap part. Swapped it. Started working a bit better.
Did a starting fluid round on the hoses, nothing was really reacting to a leak, but there were some small cracks in a few things, just started replacing them. Intake boot, and PCV hose
The air regulator was reacting properly, took it off to check the lil bean out, I thought maybe it was getting stuck open and sucking the pump off too much.
Popped off the vacuum of the FPR (which wasn’t leaking before), now it was leaking! Thought my fuel dampening choice was haunting me… I changed the FPR with one I had on a fuel rail from a part swap (maybe the culprit?)
The car started running lean under load, but man that idle has never purred that consistent.
While I was poking around, I made sure timing was at 10 degrees, replaced the coil (old one with no external resistor was 3.6ohm) with a 1.5ohm, and replaced spark plugs.
I thought, well since it was running rich, this shop that helped me pass smog probably leaned it out on the AFM. Did my research and marked my spots. I was able to see the old glob on the black sprocket (must have been 12-13 teeth leaner) Tweaked it back to the glob, and it really doesn’t make a difference.
All along I’m going back n forth the FSM and here just checking around. Did the AFM test at the ECU, all the testing reads fine! Except the continuity on 6-8, 7-8, 8-9. Poked around and Zed head seemed to confirm its probably the AFM gone bad….
TOOK THE AFM OUT. Did the bench test, it passed everything. Cleaned contacts and connector put it back in. Still failing those continuity tests.
Questions.
Can’t seem to get a solid answer from a Z car.. Can the FPR make the car run lean ? When I unplug the vacuum line nothing changes. Figured it was a weak link since it was used.
AFM continuity test, does that mean my wires to my ECU are funky?
ECU itself is funky?
Feels good to say this all out loud. Thanks for your time and any advice you have.