RPM's Plummet when stopping
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Joined: May 2002
Posts: 31
RPM's Plummet when stopping
When i am cruising along at around 40 miles an hour coming to to a stoplight, and i let off the gas and start applying my brakes, my rpm's go from around 2000 rpms and plummet suddenly down to 500 rpms, and when i stop it feels like it is ready to stall. I have read through the search an d have found 2 possible problems. Ignition coil and IACV. Anyone know which of the two is more likely for it to be? and i have a haynes guide, so i can test both of them, but i dont really understand it that well for what i should do(IM DUMB). Any help would be great. I would really like to get my idle problems solved.
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Re: RPM's Plummet when stopping
The condition you describe makes it very unlikely that an ignition coil is at fault.
A faulty IACV (idle valve) *could* be the problem, but instead I think it's likely either a uncalibrated throttle sensor (TPS) or a throttle body that needs to be cleaned. Why? If the voltage from the TPS is high enough, the ECU will think you are on the gas when you're not. The ECU will then keep the IACV idle air position valve closed. If the throttle really is closed all the way (you're off the gas completely) but the V is too high, the engine will try to die because it's starved for air. The ECU then reacts and opens the IACV idle valve and the engine idles normally. The fix for this is to first clean out the throttle body. Do a search here to find a write-up. The next thing to do when that is complete is to check the voltage from the TPS when the throttle is completely closed. I believe the allowable range is 0.35 to 0.65 V. If it's over 0.65, that is the problem. The TPS should be calibrated to ~0.55-0.60 for best performance. Calibration is done by loosening the two screws that mount the sensor to the throttle body and rotating the sensor slightly until the voltage is where you want it, then tightening it down. A service manual will provide full instructions.
A faulty IACV (idle valve) *could* be the problem, but instead I think it's likely either a uncalibrated throttle sensor (TPS) or a throttle body that needs to be cleaned. Why? If the voltage from the TPS is high enough, the ECU will think you are on the gas when you're not. The ECU will then keep the IACV idle air position valve closed. If the throttle really is closed all the way (you're off the gas completely) but the V is too high, the engine will try to die because it's starved for air. The ECU then reacts and opens the IACV idle valve and the engine idles normally. The fix for this is to first clean out the throttle body. Do a search here to find a write-up. The next thing to do when that is complete is to check the voltage from the TPS when the throttle is completely closed. I believe the allowable range is 0.35 to 0.65 V. If it's over 0.65, that is the problem. The TPS should be calibrated to ~0.55-0.60 for best performance. Calibration is done by loosening the two screws that mount the sensor to the throttle body and rotating the sensor slightly until the voltage is where you want it, then tightening it down. A service manual will provide full instructions.
Originally posted by ignentchoker
When i am cruising along at around 40 miles an hour coming to to a stoplight, and i let off the gas and start applying my brakes, my rpm's go from around 2000 rpms and plummet suddenly down to 500 rpms, and when i stop it feels like it is ready to stall. I have read through the search an d have found 2 possible problems. Ignition coil and IACV. Anyone know which of the two is more likely for it to be? and i have a haynes guide, so i can test both of them, but i dont really understand it that well for what i should do(IM DUMB). Any help would be great. I would really like to get my idle problems solved.
When i am cruising along at around 40 miles an hour coming to to a stoplight, and i let off the gas and start applying my brakes, my rpm's go from around 2000 rpms and plummet suddenly down to 500 rpms, and when i stop it feels like it is ready to stall. I have read through the search an d have found 2 possible problems. Ignition coil and IACV. Anyone know which of the two is more likely for it to be? and i have a haynes guide, so i can test both of them, but i dont really understand it that well for what i should do(IM DUMB). Any help would be great. I would really like to get my idle problems solved.
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Has your check engine light lit up at all lately? If not, I would still check it for the codes. To check your ECU for codes, Click here.
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Joined: May 2002
Posts: 31
Already tried that
Originally posted by Ramius83
Has your check engine light lit up at all lately? If not, I would still check it for the codes. To check your ECU for codes, Click here.
Has your check engine light lit up at all lately? If not, I would still check it for the codes. To check your ECU for codes, Click here.
Re: Already tried that
find out what the idle rpm is set at. The ecu will try to return it to normal but your rpms will dip if it is set too low.
Warm the car to normal operating temperature, turn off the car, disconnect the tps, restart the car and rev it to 3000 a few times before letting the rpms settle to idle. Adjust the rpm with the throttle plate screw if it is off a lot or with the IAC idle adjustment screw if it is off a little. Turn off the car and reconnect the TPS. See if the car's rpms dips now.
My 5 speed manual was doing something similar to yours. Found out the idle was way too low. No problems after resetting the idle.
Warm the car to normal operating temperature, turn off the car, disconnect the tps, restart the car and rev it to 3000 a few times before letting the rpms settle to idle. Adjust the rpm with the throttle plate screw if it is off a lot or with the IAC idle adjustment screw if it is off a little. Turn off the car and reconnect the TPS. See if the car's rpms dips now.
My 5 speed manual was doing something similar to yours. Found out the idle was way too low. No problems after resetting the idle.
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Member
Joined: May 2002
Posts: 31
Re: Re: Already tried that
Originally posted by Mishmosh
find out what the idle rpm is set at. The ecu will try to return it to normal but your rpms will dip if it is set too low.
Warm the car to normal operating temperature, turn off the car, disconnect the tps, restart the car and rev it to 3000 a few times before letting the rpms settle to idle. Adjust the rpm with the throttle plate screw if it is off a lot or with the IAC idle adjustment screw if it is off a little. Turn off the car and reconnect the TPS. See if the car's rpms dips now.
My 5 speed manual was doing something similar to yours. Found out the idle was way too low. No problems after resetting the idle.
find out what the idle rpm is set at. The ecu will try to return it to normal but your rpms will dip if it is set too low.
Warm the car to normal operating temperature, turn off the car, disconnect the tps, restart the car and rev it to 3000 a few times before letting the rpms settle to idle. Adjust the rpm with the throttle plate screw if it is off a lot or with the IAC idle adjustment screw if it is off a little. Turn off the car and reconnect the TPS. See if the car's rpms dips now.
My 5 speed manual was doing something similar to yours. Found out the idle was way too low. No problems after resetting the idle.
Re: Re: RPM's Plummet when stopping
Originally posted by Keven97SE
The condition you describe makes it very unlikely that an ignition coil is at fault.
A faulty IACV (idle valve) *could* be the problem, but instead I think it's likely either a uncalibrated throttle sensor (TPS) or a throttle body that needs to be cleaned. Why? If the voltage from the TPS is high enough, the ECU will think you are on the gas when you're not. The ECU will then keep the IACV idle air position valve closed. If the throttle really is closed all the way (you're off the gas completely) but the V is too high, the engine will try to die because it's starved for air. The ECU then reacts and opens the IACV idle valve and the engine idles normally. The fix for this is to first clean out the throttle body. Do a search here to find a write-up. The next thing to do when that is complete is to check the voltage from the TPS when the throttle is completely closed. I believe the allowable range is 0.35 to 0.65 V. If it's over 0.65, that is the problem. The TPS should be calibrated to ~0.55-0.60 for best performance. Calibration is done by loosening the two screws that mount the sensor to the throttle body and rotating the sensor slightly until the voltage is where you want it, then tightening it down. A service manual will provide full instructions.
The condition you describe makes it very unlikely that an ignition coil is at fault.
A faulty IACV (idle valve) *could* be the problem, but instead I think it's likely either a uncalibrated throttle sensor (TPS) or a throttle body that needs to be cleaned. Why? If the voltage from the TPS is high enough, the ECU will think you are on the gas when you're not. The ECU will then keep the IACV idle air position valve closed. If the throttle really is closed all the way (you're off the gas completely) but the V is too high, the engine will try to die because it's starved for air. The ECU then reacts and opens the IACV idle valve and the engine idles normally. The fix for this is to first clean out the throttle body. Do a search here to find a write-up. The next thing to do when that is complete is to check the voltage from the TPS when the throttle is completely closed. I believe the allowable range is 0.35 to 0.65 V. If it's over 0.65, that is the problem. The TPS should be calibrated to ~0.55-0.60 for best performance. Calibration is done by loosening the two screws that mount the sensor to the throttle body and rotating the sensor slightly until the voltage is where you want it, then tightening it down. A service manual will provide full instructions.
Senior Member
Joined: Nov 2000
Posts: 308
Originally posted by SprintMax
clean your throttle body..
clean your throttle body..
no soup for you.. i said it was his problem 
Originally posted by ny96max
same problem here and its NOT my throttle body!!
just cleaned it yesturday.
sorry Sprint
.... now wheres my $20
BTW: how much would a TPS sensor and a new IACV run me?
Ant
same problem here and its NOT my throttle body!!
just cleaned it yesturday.
sorry Sprint
.... now wheres my $20 BTW: how much would a TPS sensor and a new IACV run me?
Ant
Senior Member
Joined: Jul 2001
Posts: 7,530
Originally posted by ny96max
same problem here and its NOT my throttle body!!
just cleaned it yesturday.
sorry Sprint.... now wheres my $20
BTW: how much would a TPS sensor and a new IACV run me?
Ant
same problem here and its NOT my throttle body!!
just cleaned it yesturday.
sorry Sprint
.... now wheres my $20 BTW: how much would a TPS sensor and a new IACV run me?
Ant
SuDZ
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