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Help with Air Flow Meter Issue?

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Hello! I have a 1977 280Z stock 5-speed manual transmition. The original AFM seemed like it was having some issues. The engine was running rich (you could smell it and I was getting horrible gas mileage), at idle the engine did not run steady/consistent (it revved up and down sort of like ooooOOOOooooOOOOoooo ... if that makes any sense ... and the tach would move with it below 1000 RPMs to slightly about 1000 RPMs), and, lastly, sometimes when going slow in third gear the car would hit a point where it would jerk until you either sped up or slowed down even further.

 

I had a spare (used) AFM and swapped it out today. The first thing I noticed is the car idled smoothly/evenly right about about 1000 RPMs. This is the best this car's sounded since I've had it. So, I took it for a ride. That's when I ran across a different problem. The car seemed to do great when driving in the city (no jerking when running slowly in 3rd gear), but I ran into a problem when I went on the highway. The entrance ramp I was using is slightly steep (uphill) and the car chugged (moved sluggishly). I could barely get 'er over 35 MPH and so I could not get up to highway speed. Once on the highway I was able to get her going, albeit slowly. Once up to speed, she had a lot more pep.

 

I am assuming that she is now running a tad lean? But I am no mechanic. Not by a long shot. Obviously the new AFM made a difference, solving a few issues and introducing a new one. So, where do I go from here? What should I check? And how do I tweak this?

 

Any help would be appreciated. Thanks. tango_face_grin.png

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I have not. I am not a mechanic, so can you point me in the right direction to check for vacuum leaks? I am pretty sure I can check the fuel pressure by hooking a gauge into the nipple (don't know the proper term here) on the fuel rail. Is that correct?

 

When I first got the car, it was stalling a lot. I took it to a mechanic I trusted. He ended up replacing all the fuel lines and vacuum lines. The rubber part that connects the AFM to the rest is also brand new and everything is tight. So, I don't think there are any leaks. The car also has a new fuel pump and filters.

 

In any case, why would there be such a big difference between the two air flow meters?

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