High idle when cold, low when warm
06-20-2012, 04:13 PM
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High idle when cold, low when warm
Long time listener, first time caller.
I've checked out pretty much every idle thread I could find but none matched up. 1990 4runner, 220k on the chassis but 60k on the motor. I've had it for 2.5 years and it ran like a watch. Start up at 1100-1200 RPM, after a minute drop to 800 RPM and ran all day. I live in Cali so the weather/temp usually is not a factor. About a week ago, I started the car in the morning and it went up to 1500, then 1600, and up and up and up until it was sitting at 2000-2100. After a few minutes all at 2k+, I started driving and as soon as I hit the gas it choked up like crazy and lost all power. Rolling power on slow doesn't affect it, but giving it some gas sharply almost cuts out the engine. Concerned, but late for work I went on and as soon as the engine was warm all was normal. Driving home, it started fine, idled fine, and ran fine.
Next day starting was the same problem, climbing idle, but I made some stops before work and noticed that when the engine was warmed up at normal temp, the idle was crazy low, like 350-400. I haven't had much time to work on it yet, but gearing up to tackle it this weekend. I've heard vacuum leak, or coolant temperature sensor on the block. Any thoughts on where to start? I have a FSM I've been checking out, but never had the split diagnosis where it runs high when cold and low when warm.
Symptoms:
Cold start (but in like 60 deg F weather) = 2000-2100 RPM idle for several minutes
Hit the gas and the engine almost stalls out completely
Roll on the gas and it's fine
When engine is warm = 350-400 RPM idle
Just noticed today that the temp reading on the engine has been jumping around a bit above normal at idle. Hopefully this is just because the low idle speed is not pulling enough air through, but is this related?
Thanks in advance for any advice.
Cheers.
I've checked out pretty much every idle thread I could find but none matched up. 1990 4runner, 220k on the chassis but 60k on the motor. I've had it for 2.5 years and it ran like a watch. Start up at 1100-1200 RPM, after a minute drop to 800 RPM and ran all day. I live in Cali so the weather/temp usually is not a factor. About a week ago, I started the car in the morning and it went up to 1500, then 1600, and up and up and up until it was sitting at 2000-2100. After a few minutes all at 2k+, I started driving and as soon as I hit the gas it choked up like crazy and lost all power. Rolling power on slow doesn't affect it, but giving it some gas sharply almost cuts out the engine. Concerned, but late for work I went on and as soon as the engine was warm all was normal. Driving home, it started fine, idled fine, and ran fine.
Next day starting was the same problem, climbing idle, but I made some stops before work and noticed that when the engine was warmed up at normal temp, the idle was crazy low, like 350-400. I haven't had much time to work on it yet, but gearing up to tackle it this weekend. I've heard vacuum leak, or coolant temperature sensor on the block. Any thoughts on where to start? I have a FSM I've been checking out, but never had the split diagnosis where it runs high when cold and low when warm.
Symptoms:
Cold start (but in like 60 deg F weather) = 2000-2100 RPM idle for several minutes
Hit the gas and the engine almost stalls out completely
Roll on the gas and it's fine
When engine is warm = 350-400 RPM idle
Just noticed today that the temp reading on the engine has been jumping around a bit above normal at idle. Hopefully this is just because the low idle speed is not pulling enough air through, but is this related?
Thanks in advance for any advice.
Cheers.
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