1987 Toyota Supra Idle
 

My Supra 5spd 3.0 non-turbo idles from 1000rpm to 2000rpm, back and forth. Doesn't matter if in neutral(no gear) or what temperature the engine is. Could this be the air flow meter, idle air control valve, or throttle sensor? Cleaned around all the spark plugs and replaced with bosch platinum quad tip. The idle air control valve had alot of carbon so I cleaned that also. Checked for vaccuum leaks, could not find any. Vehicle runs ok on highway, but when in idle it just goes up and down from 1500 to 2000rpm. This might be important, I broke the BVCV that is attached to thermostat housing, would that cause me my problems. Also, I just replaced the power steering pump amd am wondering how important is vaccuum hose connection? Last thing-the fuel gauge sometimes reads empty even though its full. All the other gauges working.

i believe that if it were you air flow meter, which i assume is a mass air flow sensor as i know it, your car wouldnt run at all. someone please correct me if im wrong though as im still in the process of learning things.

as for the other two, throttle position sensor would be my guess. you should probably wait for someone more knowledgable to reply too but im using your post to see how correct i am.

thanks for listening to my 2 cents.

The 7MGE uses an Air Flow Meter, which has a little spring loaded door inside that opens more as the amount of intake air increases.

First thing, get 2 bottles of Techron injector cleaner (or Lucas)and put it into a full tank of gas and drive it till that tank is gone. A partially clogged injector(s) can lean the mixture, which may be more noticably at idle. If the computer senses a lean condition, it will richen up the mixture, then maybe to rich in other cylinders, then back and forth, which can give the problem you have.

Generally (of course anything is possible) the TPS won't cause your problem. At idle, the switch is supposed to be closed. So it is possible that the TPS is the problem. If the switch is 'open' the computer will not function properly, thus ...

The TPS could be out of adjustment, too.

Try these first. TSRM will tell you how to check the TPS and adjust it.

me too
 

yeah my 86 idles crazy and I also broke my sensor on the therm housing. I have changed the valve cover gasket,replaced the isc, fuel pump, filter, ecu, vaccuum checked this bitch,spark plugs, wires, cap and rotor, brake master cylinder and changed the oil/filter and ran lucas injector cleaner and still idles wildly. Its really pissing me off. so if anyone can help some brothers out that would be awesome