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1995 chevy truck intermitent high idle and solution...
Hi, I'm really puzzled, about four years ago my truck started to idle @ 1100 rpms. (not the normal 750) So, I ran to the autoparts store to buy and replace the iac valve which apparently solved the problem. About six months after a got the same issue and another iac valve, after few months another one. then,the problem came back later. this time I just cleaned the valve and the truck ran just fine. The problem continued but I learned by accident that disconnecting the battery something was ''reset'' bringing the engine to normal operation.
The good thing is that I don't buy valves any more but I have to have my wrench ready behind the seat to disconnect the battery when needed.
I ran the scanner to get the stored codes, it happened to be the coolant sensor. it was replaced but the idle deal continues.
my truck is 1995 chevy 1500 vortec v6
any ideas or suggestions would be greatly appreciated.
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Hi Joseph, When starting the vehicle from cold in cold weather, the RPM can be as high as 1300 and in temperate climates about 1100 RPM. The RPM will drop to normal as the coolant is warmed. Normal idle speed is between 750 for Auto and 650 to 700 for manual transmission. Regards John
Sounds like a dirty air filter is putting the mass airflow sensor out of range. The throttle position sensor is subject to physical wear, the age of your truck warrants replacing it. The coolant temp sensor controls the Idle Air Solenoid which determines idle speed ( cold, high idle, 1200 rpms open loop mode for the ECU) and (hot, low idle, 800 rpms, closed loop mode for the ECU) If the truck does not have a Mass airflow sensor, check the Manifold absolute pressure sensor (MAP). Perform an OBDII scan for stored fault history to avoid buying parts you don't need. Do the cheapest fixes first. Go ahead and change the fuel filter also. There is a lot of water in todays fuels
Why wasn't the Throttle Position Sensor replaced? The first suspect should probably have been the IAC (but you would have gotten a code), the next logical step would have been checking for something mechanical like the throttle body being gummed up and needing cleaning, but I would replace the TPS before I'd EVER think the PCM would need replacing...I'd hate to see that bill. I have a 2001 Aurora with a 4.0 and I have replaced the IAC (got one at a salvage yard, out of a Caddy, same one)-it did fix mine, but the next culprit would have been the TPS in any case, PCM's rarely go bad.
my 99 Burb acted that way. i tuned it up and still had the miss. turned out to be a coil. a year later it did the same thing and that was a bad injector.
Hi,
You need to get your engine coolant thermistor checked and tested.
This is what tells the ECM when the engine temperature is at normal working temperature and turns the idle down.
But when the idle won't come down from cold to warm this is usually the main fault.
Hope this helps.
Thanks
Jason
Vacuum leak or fast idle sensor inside throttle body. Also check to make sure throttle cable and cruise control cable is not out of place on the cable roller/pulley on top of intake manifold.
Sounds like you have a problem with the crank sensor.They can have an intermitant fault.like an open curcuit Try changing the sensor.good luck hope that was helpfull.
hi, i would say the automatic choke spring broke, this is what controls the cars idle at cold and hot engine tempatures. if it's broke it is no longer able to automaticly regulate the rpm's the for making it idle at hi rpm. hope this could help you.
truck idles high
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