Spring Screw by TPS

[ramsesosirus]

Good news

Got my car to stop spewing black smoke; I cleaned all electrical connectors and adjusted the idle screw and the spring loaded screw on top of the intake, the one right above the TPS; What is the name of this screw? Manual doesn't seem to list it, and I'm sure it's not the idle or fast idle since it does not contact the throttle itself;

[Nissanman]

Assuming it is the 280Z you are referring to, the idle control screw is the one on top of the chamber.

It acts on an air passage not the actual butterfly valve.

[sblake01]

adjusted the idle screw and the spring loaded screw on top of the intake

The 'spring loaded screw' is the idle speed screw. What else did you adjust? The screw on the air flow meter? That's the bypass port. Adjustments to that should only be made with the use of some type of exhaust analyzer. Without one, you'll get it close but you won't get it right. Sounds like you need to read the manual a little more carefully. The fact that the car runs better with that 'seat of the pants' adjustment means either the adjustment is compensating for some other problem or the screw has been 'messed with' in the past and you adjusted it back to somewhere close to where it should be. Do you have emissions tests in Nebraska? Edited October 24, 2008 by sblake01

[ramsesosirus]

first of all no emissions in Nebraska. I don't think the 76 could ever pass, no cat converter! (never was);

Ok if that is the idle screw, what is the smaller screw by the actual throttle linkage? Is this the fast idle screw?

We moved both screws to get it running better;

Oh I had also cleaned almost all of the electrical connections (CTS, bullets, fuse links, etc...) with some spray the previous day. They were pretty green. I think that probabaly had more of an effect than anything, since we'd adjusted those screws before and could never rev it without a HUGE plume of black smoke, now there is pretty much NO smoke! Voltage guage also reads higher now. (like 14 but when I test at battery I only get about 12.9)

I read the book pretty good and know better than to adjust sensors unless you ARE SURE about it.

I guess we'll see if the smoke stays away...

Thanks:cool:

[sblake01]

Which smaller screw? The only screws I see on the throttle linkage are the ones that hold it together. My 78 may be a little different than your 76, but it has a dashpot that basically is a damper to keep the throttle from closing abruptly when you release the accelerator. It contacts the linkage at the throttle chamber where the rod from the linkage connects. I actually think that your cleaning of the connections had the most effect on correcting you car's problems. As far as the voltage guage, I've never seen a stock one that was accurate. Trust your voltmeter. My guage reads just under 16 (when the car is running) but the voltmeter says about 14.2-14.4 at that point. When not running, the guage says about 13 but the voltemeter says 12.4-12.5.

[Nissanman]

Here is a pic. that might help: -