Almost Stalls After Starting
08-23-2004, 11:00 PM
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Almost Stalls After Starting
I have a 93 Bonneville SE with 118,500 miles on it. It still runs great, but I have a concern with the way it starts. Immediately after starting, it seems like it wants to stall... the RPM'* drop all of the way down to 500 and then it goes back up to around 1,500 RPM'* (where it idles). When it drops down to 500 RPM'*, it gets real rough and sounds like it is stalling. The colder it is outside, the more pronounced it is. If the car has been driven recently before restarting, it barely does this at all. The whole start - drop to 500 - and back up to normal idle only takes about a couple of seconds. It only seems like it is going to stall for maybe 1-2 seconds, but it is rough enough that you can feel it and hear it. If it is really warm outside, the semi-stall is not as pronounced. I have been lucky and it has not actually been stalling, but I am concerned as to what it will do in the upcoming winter when it is actually cold outside. Does anyone have any ideas? I appreciate anything you can think of. Thanks
Jim
Jim
08-24-2004, 08:45 AM
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I have experienced this with the TPI engines on the F-Bodies. The common fix is a coolent temp sensor. Sensor is giving the PCM the wrong temp so it does not know to kick the idle and mixture up.
A good check is to disconnect the plug to it and start it when its cold. The default reading should go to -40 (or something close) and tell the PCM to start like its cold.
Jay
A good check is to disconnect the plug to it and start it when its cold. The default reading should go to -40 (or something close) and tell the PCM to start like its cold.
Jay
08-24-2004, 10:36 AM
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Originally Posted by karfreek
I have experienced this with the TPI engines on the F-Bodies. The common fix is a coolent temp sensor. Sensor is giving the PCM the wrong temp so it does not know to kick the idle and mixture up.
A good check is to disconnect the plug to it and start it when its cold. The default reading should go to -40 (or something close) and tell the PCM to start like its cold.
Jay
A good check is to disconnect the plug to it and start it when its cold. The default reading should go to -40 (or something close) and tell the PCM to start like its cold.
Jay
08-24-2004, 10:50 AM
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It would if it was cold. It uses the temp sensor to adjust the idle and mixture when the car is cold. A car starting cold, (Ex; sat overnight) needs a high idle and rich fuel mixture to run for the first few minutes until it starts to warm. Kinda like starting a lawn mower or snow blower. Basicly, if the the sensor is telling the car that it is warm, when it isnt iIts like trying to start a carbed car without the choke set, it may start, but not run right until warm.
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
08-24-2004, 10:58 AM
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Originally Posted by karfreek
It would if it was cold. It uses the temp sensor to adjust the idle and mixture when the car is cold. A car starting cold, (Ex; sat overnight) needs a high idle and rich fuel mixture to run for the first few minutes until it starts to warm. Kinda like starting a lawn mower or snow blower. Basicly, if the the sensor is telling the car that it is warm, when it isnt iIts like trying to start a carbed car without the choke set, it may start, but not run right until warm.
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
thanks a lot jay
08-24-2004, 11:01 AM
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Originally Posted by Kennginn
Originally Posted by karfreek
It would if it was cold. It uses the temp sensor to adjust the idle and mixture when the car is cold. A car starting cold, (Ex; sat overnight) needs a high idle and rich fuel mixture to run for the first few minutes until it starts to warm. Kinda like starting a lawn mower or snow blower. Basicly, if the the sensor is telling the car that it is warm, when it isnt iIts like trying to start a carbed car without the choke set, it may start, but not run right until warm.
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
thanks a lot jay
Jay
08-24-2004, 11:08 AM
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Originally Posted by karfreek
Originally Posted by Kennginn
Originally Posted by karfreek
It would if it was cold. It uses the temp sensor to adjust the idle and mixture when the car is cold. A car starting cold, (Ex; sat overnight) needs a high idle and rich fuel mixture to run for the first few minutes until it starts to warm. Kinda like starting a lawn mower or snow blower. Basicly, if the the sensor is telling the car that it is warm, when it isnt iIts like trying to start a carbed car without the choke set, it may start, but not run right until warm.
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
Bad coolent sensors can also cause driveability and performance problems. They only cost $8 @ NAPA, so it is not a ton of $$$ lost if it isnt the problem.
When my Trans Am had a bad coolent temp sensor, it would start, then drop the RPM, to 600, then surge back to 1,200, then down to 600, then back. Also it would bog down until it was warm when trying to accelerate. Now that it is fixed it starts and goes to 1,200 until warm and then cuts to 500-600.
There is a VERY GOOD article in the newest GMHTP, (silver Z28 on the cover) it covers the GM Coolent temp sensor and the roll it plays in the GM engine management system.
Jay
thanks a lot jay
Jay
