I think I have narrowed my "pulsating" idle problem down to the air flow meter or the throttle position sensor. I can manually hold the afm door almost shut and the car will idle normally. Does anyone know how to test the tps?
OK, I tested my TPS and it checked out in specs on 3 out of 4 tests. SO I went to my local salvage yard and "barrowed" a complete throttle body from them. Tested it and it tested the same. So I put it on my car, Idle is smooth, but very high. Starts out at 2500 and ends up at about 3000. My temp guage doesn't read (my theory is that it not reading is not telling the ecu to slow the engine down) but I can't imagine it reving the engine that high. I unplugged the O2 sensor and what I believe to be the cold start sensor. No codes...
Only way I can get teh idle to go low is to manualy close the AFM door.
The temp sender for the gauge on the dash is not what the EFI computer sees for coolant temperature. The EFI coolant temp sensor is one of the two on top of the thermostat neck (the other one is a cold start timer switch). If you have an '85 I would short the check connector and drive it around like that and see if it give you any codes. The things to look out for idle switch in TPS is FUBAR (usually what gives out and causes an erractic idle), ISC valve is stuck or the stepper motor is giving out, EFI coolant temp sensor is shot. Even if the coolant sensor is out the idle should never go that high. I would put my money on the ISC valve being stuck open. By holding the AFM door shut you are basically doing the function of what the ISC valve should do (restrict or control air going around the throttle plate at idle). If it is the ISC you might get by with cleaning it up.HTH