WillWykeham
New Member
My idle is intermittently low and rough, around 500 rpms and sometimes lower, but is always steady. The car idles fine, at about 1200-1300 rpms right when I start it up, and only develops the problem once fully warm. No codes. The strange thing is that about 30% of the time the car idles fine at around 800 rpms. So far I have:
-replaced spark plugs
-removed the throttle assembly and cleaned thorougly
-removed and cleaned the idle air control valve
-checked for air leaks with carb cleaner
-checked the engine's vacuum
-checked fuses
-replaced air filter
-bled air from cooling system
-checked the voltage on the electrical connectors for the air intake and engine coolant sensors
-checked the resistance on the the air intake and engine coolant sensors
I read 200-300 ohms on the engine coolant sensor once the car had been warmed up to the point where the radiator fan came on. Haynes tells me this means my coolant temperature is between 230 and 250 F, which seems high. The temperature gauge in the dashboard does not indicate an overly hot engine, with the needle just below the half-way point.
Does this mean I have a bad coolant sensor?
Things I am also planning to do:
-check the O2 sensor
-check the throttle body and MAP sensors
-do a vacuum test
-check pcv valve
-replace IACV if nothing above works
-replace ECU if nothing above works
A few more notes: when I initially cleaned the throttle and IACV, the car revved very high, but then after driving around for a few minutes it normalized. The problem returned. I reset the ECU a few days ago and there was no change, but then after driving about 150 miles on the highway the car started to surge at idle, going up to a steady 3000 rpms. I pulled up on the gas pedal and the idle fell, and when I returned home I loosed the throttle cable to allow for more deflection at the point where it attaches to the throttle body.
-replaced spark plugs
-removed the throttle assembly and cleaned thorougly
-removed and cleaned the idle air control valve
-checked for air leaks with carb cleaner
-checked the engine's vacuum
-checked fuses
-replaced air filter
-bled air from cooling system
-checked the voltage on the electrical connectors for the air intake and engine coolant sensors
-checked the resistance on the the air intake and engine coolant sensors
I read 200-300 ohms on the engine coolant sensor once the car had been warmed up to the point where the radiator fan came on. Haynes tells me this means my coolant temperature is between 230 and 250 F, which seems high. The temperature gauge in the dashboard does not indicate an overly hot engine, with the needle just below the half-way point.
Does this mean I have a bad coolant sensor?
Things I am also planning to do:
-check the O2 sensor
-check the throttle body and MAP sensors
-do a vacuum test
-check pcv valve
-replace IACV if nothing above works
-replace ECU if nothing above works
A few more notes: when I initially cleaned the throttle and IACV, the car revved very high, but then after driving around for a few minutes it normalized. The problem returned. I reset the ECU a few days ago and there was no change, but then after driving about 150 miles on the highway the car started to surge at idle, going up to a steady 3000 rpms. I pulled up on the gas pedal and the idle fell, and when I returned home I loosed the throttle cable to allow for more deflection at the point where it attaches to the throttle body.
