1977 280z slow to return to idle, any thoughts?

Hi,

I thought I knew a fair amount about EFI in the 1975 on Zs but this one has me stumped. 1977 280z, runs well, in time, valves set right, head replaced recently with a 1975 rebuilt head.

Car idles fine but the idle screw has little effect, gently tightened the car idles at 800RPM, half a turn open gives 1000 RPM.

On the road the engine does not return to idle quickly enough, this means that for had acceleration you cant go up to the next gear for a few seconds. The engine dawdles back to 1000RPM and sometimes stays at

2500RPM for ten seconds or so before beginning its slow decent to idle speed.

Any thoughts?

Best,

Phil Sharkey

Reply to
Phil Sharkey
Loading thread data ...

I know what/where it is, but what does it do and how does one test it?

Thanks,

Phil

Reply to
Phil Sharkey

Found the answer myself, just posting it in case anyone is interested:

The dashpot is the "spinning top" shaped item mounted just inboard of the idle screw on the throttle body.

There should be a clearance of 1.9mm (0.0748 in) between it and the throttle lever, which corresponds to 2000 rpm under no load.

I need to check that the dashpot rod end closely touches the throttle lever when the dashpot rod is fully extended (or when no backpressure is present at the diaphram). If necessary, I should loosen the nut and turn the dashpot assembly until correct adjustment is made.

I also received the suggestion that I check the Boost Controlled Deceleration Device.

Any other thoughts, suggestions, clarifications, advice, warnings, etc.?

Thanks,

Phil Sharkey

Reply to
Phil Sharkey

Reply to
NissTech

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.