My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles = cold fine, and runs fine warmed up. When warm and I put it in neutral = (AT) the idle oscillates between 1800 and 2200 with about 1/2 second = cycle time.
MAS was the first guess -- so I put a rebuilt mass airflow sensor assy = in and same problem. Checked all the connections and vacuum - all OK. =20
Also took the throttle assy apart and cleaned all - helped the running = but still oscillating. Cleaned Idle air motor, checked voltages and = resistance for all sensors and also voltages coming from the computer, = and all OK.
About out of ideas -- anyone have some thoughts on how to start = troubleshooting this?
cold fine, and runs fine warmed up. When warm and I put it in neutral = (AT) the idle oscillates between 1800 and 2200 with about 1/2 second = cycle time.
assy in and same problem. Checked all the connections and vacuum - all = OK. =20
running but still oscillating. Cleaned Idle air motor, checked = voltages and resistance for all sensors and also voltages coming from = the computer, and all OK.
troubleshooting this?
Thanks Jamie. Checked it out today and was OK. Also getting good signal = from computer to sensor.
fine, and runs fine warmed up. When warm and I put it in neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 second cycle time.
same problem. Checked all the connections and vacuum - all OK.
still oscillating. Cleaned Idle air motor, checked voltages and resistance for all sensors and also voltages coming from the computer, and all OK.
troubleshooting this?
computer to sensor.
Some one made a suggestion of a vacuum leak.. If you remove the load from the engine, it cold have problems at idle.
You may want to check your EGR valve if you have a vacuum type servo on it.
I wonder if you have problems with your air ducts? In some vehicles, the defrost for your windshield behaves differently if you are sitting in part verses rolling down the road. Is it possible your vacuum servos for your air duct system has a leak? I know in my new jeep it changes behavior if I am sitting there in park verses drive. I think it is to keep the air from blowing on your face? When you have the engine loaded, you most likely wont feel this. You may even have a vacuum switch on your shifter or from the ECM.
idles cold fine, and runs fine warmed up. When warm and I put it in = neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 = second cycle time.
assy in and same problem. Checked all the connections and vacuum - all = OK. =20
running but still oscillating. Cleaned Idle air motor, checked = voltages and resistance for all sensors and also voltages coming from = the computer, and all OK.
cold fine, and runs fine warmed up. When warm and I put it in neutral (AT= ) the idle oscillates between 1800 and 2200 with about 1/2 second cycle tim= e.
sy in and same problem. Checked all the connections and vacuum - all OK. = =20
ng but still oscillating. Cleaned Idle air motor, checked voltages and re= sistance for all sensors and also voltages coming from the computer, and al= l OK.
bleshooting this?
nal from computer to sensor.
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Couldn't it be the gearbox comparator sending wrong/wild signals to the com= puter? it's kind of strange that moving it from parking to neutral would ca= use this change, the gearbox entry shouldn't add such strain on the engine = as to cause this...
in message news:lQvyr.54484$ snipped-for-privacy@newsfe05.iad...
idles cold fine, and runs fine warmed up. When warm and I put it in = neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 = second cycle time.
assy in and same problem. Checked all the connections and vacuum - all = OK. =20
running but still oscillating. Cleaned Idle air motor, checked = voltages and resistance for all sensors and also voltages coming from = the computer, and all OK.
troubleshooting this?
signal from computer to sensor.
servo=20
vehicles,=20
sitting=20
servos=20
changes=20
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Couldn't it be the gearbox comparator sending wrong/wild signals to the = computer? it's kind of strange that moving it from parking to neutral = would cause this change, the gearbox entry shouldn't add such strain on = the engine as to cause this...
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Howdy Lars. =20
A lot of time and work were between posts. It turned out all the = sensors were fine. Went over it one by one, checking sensor signals, = ECU signals and connections. =20
Troubles were..... 2 burnt capacitors in the ECU (not a big deal - = just followed my nose. LOL!!) Turns out that that brand of cap were = later discarded by Mitsubishi. =20
Wrapped some worn insulation on a cable that was shorting the O2 sensor = signal intermittently. Bad connections all over - throttle position = sensor connector was loose.
At that point I got the car running fine, except when the engine was up = to temp, it oscillated when in not in gear. In gear it was fine. I = suspected a temp sensor at first, but it was simpler than that. = Evidently when I cleaned the idle speed stepper motor, it was not reset = properly and the ECU could not move it far enough during idle. This = procedure did the trick....
It shows how to isolate the idle stepper from ECU, reset it and then set = the idle. Much easier to follow and better illustrations than most = shop manuals....
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Hopefully this will be my last fix-it posting on this car for awhile!
Thanks to everyone who posted and pointed me in the right direction!!
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