I have a 1981 280zx non turbo that is idling at 1500 RPMs no matter what the temp is outside. It is also getting 8 MPG right now. This just started two weeks ago. I replace the cap and rotor, fuel filter and fuel pump relay a week ago due to an unrelated issue.
Is there anyway to test the thermo timing switch before replacing it. If I unplug it the problem consists and I tried using a jump wire between the two wires but no change.
Does anyone else have any Ideas. Funds are super tight right now and I dont want to buy any uneeded parts.
Thanks
Steve

 

Welcome to ZDriver!

Sensor test specs can be found in the FSM: www.xenons130.com/reference

Have you also checked for vacuum leaks? And the sensor connections have a tendency to corrode... make sure they are all tight and clean.

 

My Car Used To Do That And Couldn't Pass Smog Cus It Was Running Way Too Rich I Was Getting Like 10 MPG And Gas Over here Is 4.55 A Gal . So All i Did Was Adjust My Air Sensor New Injectors I Got from Ebay I Got Them For $150 all 6 And Also Changed My FPR Because Mine Was Leaking Though The Diaphragm. And Now My rps Are Normal And I Am getting Way better Gas Mileage All For less than 200. So YOu Should Proly Check Those Things

 

Stupid question.... What does FPR stand for? Fuel Pressure regulator? I have checked for vacuum leaks none found. Has anyone heard of a thermo timing sensor causing these symptoms? What about the cold start valve?

 

Indeed FPR = Fuel Pressure Regulator.

The CHTS (cylinder head temp sensor) is a possible culprit. The thermotime switch in the thermostat housing controls the cold start valve. If you think the cold start valve is stuck open, pinch off the fuel line to it and see if that makes a diff. You can also pull it and check for carbon build up.

 

Ill check those, thanks. I was just now able to download the FSM in your link. It wasnt working until about an hour ago. I dont know why but I really appreciate you posting it Nismo. Sorry about the fpr comment I had fuel pump relay stuck in my head for some stupid reason.

 

No problemo broski... we are here to help.

You've got questions, we've got answers. .... where have I heard that before?

 

Radio Shack! lol
http://www.google.com/search?q=You%2...ient=firefox-a

 

I pinched the cold start valve fuel line and I can feel fuel running threw it but there is no change in RPM when it is pinched at idle. thermo time is also ok.

 

I pinched the cold start valve fuel line and I can feel pulsing running threw it but there is no change in RPM when it is pinched at idle. I still felt the pulse and no RPM change with the sensor unpluged. Thermo time ohm load also tested ok. Pinching the intake on air regulator and did nothing to RPM.
CHTS tested within range per FSM. 105F water tested at 1.3 ohms. On another forum they mentioned the CHTS measures temp per coolant temp. Not sure if thats true. I lost no coolant when I pulled the sensor and it was dry.
Throttle valve swich tested between 000.2-000.5 with throttle closed and no load then throttle was open.
Running fuel pressure is 32psi
41 psi at 0 inHg Should be 36-37psi
37 psi at 5 inHg Should be 33-35psi
36 psi at 10 inHg Should be 31-32psi
33 psi at 15 inHg Should be 29-30psi
30 psi at 20 inHg Should be 26-28psi
If I put 25 inHg while running the car idels at 900 Rpm
Could 4 psi cause this problem? I seem to doubt it and Auto zone wants $70 for it. Not that I would buy it there. I read a spec that it should be 36psi vacuum while running. How can I test this? Any other ideas?
Thanks
Steve

 

Vacuum Gage At Autozone are Like 13 Bucks

 

Sorry I should have been more specific. Those are the readings of the pressure regulator.

 

have You Tried Pulling The Vaccum Line Of FPR And Checking If Theres Gas There??? If There Is Then The Diaphram On FPR Could be Bad