I've been getting a 1977 280z up and running after ~20 years sitting. I've replaced all fuel lines, pump, tested for vacuum leaks, etc. I feel like ive tried to tune this thing with the AFM, TPS, and idle screw. If finally have it idling around 800-900 rpms and good power up to ~3000 - 3200 rpms then it feels like it loses engery and sounds like an airy fart. sorry but i dont know how to explain the feeling/sound. it doesnt sound like its about to die b/c its at higher RPM but it feels like it loses all get it up and go. it tried to increase RPM but does very slowly. this is very apparent on 1st and 2nd gear. When i shift into 3rd and 4th i am going fast enough im dont want to floor it. What should i be adjusting?

***side note*** when not in gear I can rev the engine 4-5000+ RPMs and it revs beautifully without hesistations. only when under load.

Is it popping out the tailpipe? If so you should read this. I've got one on my '77.

https://atlanticz.ca/zclub/techtips/tempsensorpot/index.html

Edited 9 hours ago9 hr by siteunseen

It might be the front, AFM? It'll spit and sputter and buck under load. A lot of folks have done this tweak. I did mine when there was a Radio Shack in every mall. Cost me $5 and it runs like a top.

Thank you for that info, ill see what i can get done. i would like to see if this would be a main cause and a fix verse a bandage. In the long run im doing to be redoing most of this with more modern technology so it might be a moot point.

searching for a potentiometer is not so easy now adays. i miss radio shack.

Are you sure your exhaust can breathe properly? Possibly the exhaust system could be a variable.

Does it have Cats?

to be honest i havent even looked at the exhaust. Im assuming it does have cats. I did have a 10K potensiometer laying around and tested this hack from siteunseen and it did work when setting the ohms to ~1000. Car reved to 4500-5000 before shifting without any hesitations. im not planning on driving aggressive at all. but just trying to get the car running well.

Cats can stop up and restrict the exhaust