Stalling At Idle Help !!!!!
Thread Starter
Instructor
Joined: Mar 2006
Posts: 131
Likes: 0
From: San Bernardino California
Stalling At Idle Help !!!!!
So all of a sudden ... last week .. my 91 decides not to idle .. and stumble and shuts off ....
If you get it above 1400 rmps or so .. no problems .....
everytime i start it .. i have to feather the gas to keep it one .. and if it does stay on it sounds like it is dying ...
checked fuel pressure... 40 psi .. and slowly bleeds off with car off .. injectors are new ... used the paper clip method and got a 22 code... tps right .. what should i do .. neeed to get this thing back on the road..
If you get it above 1400 rmps or so .. no problems .....
everytime i start it .. i have to feather the gas to keep it one .. and if it does stay on it sounds like it is dying ...
checked fuel pressure... 40 psi .. and slowly bleeds off with car off .. injectors are new ... used the paper clip method and got a 22 code... tps right .. what should i do .. neeed to get this thing back on the road..
Burning Brakes
Joined: Jun 2002
Posts: 1,001
Likes: 1
From: sd
Do you have the FSM from www.helminc.com? If so you can follow the trouble shooting chart to see what to check next. Just because you have a code 22 doesn't necessarily mean that you have to replace the TPS. It could be other things like the wiring or a bad ground. I just went through this on Saturday with my TPS and after going through my trouble shooting charts in my FSM I just replaced the TPS as all else checked out fine. If it is the TPS you will have to have a multi-meter to get the TPS set correctly at .54 volts although I don't own a 91 so it could be different. Good luck!
Thread Starter
Instructor
Joined: Mar 2006
Posts: 131
Likes: 0
From: San Bernardino California
I have the meter .. thanks for the help .... I dont have the book ... so without it could you someone give me a brief lesson on how to test it .. and how do i know if its just bad .. or out of adjustment .. any info is appriecated
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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The throttle position sensor is a potentiometer, connected to the throttle shaft on the throttle body.
The TPS electrical circuit consists of a 5V supply line which is grey and a ground path line which is black, both provided by the ECM. A third wire is used as a signal line to the ECM.
By monitoring the voltage on the signal line, the ECM calculates throttle position. As the throttle valve angle is changed (accelerator pedal moved), the signal voltage of the TPS also changes. At closed throttle position, the signal of the TPS is low -1.25 volts. As the throttle valve opens, the signal voltage increases so that, at wide open throttle it should be approx. 5 volts.
The ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TPS can cause intermittent bursts of fuel from the injector and an unstable idle, because the ECM thinks the throttle is moving. A problem in any of these TPS circuits, will set either a code 21 or 22. Once a trouble code is set, the ECM will use an artificial default value for the TPS, and some vehicle performance will return.
The TPS is not adjustable. The ECM uses the reading at closed throttle for the zero reading, so no adjustment is necessary.
A Code 22 will set if(signal voltage low):
Engine is running.
TPS voltage is below .2 volts (200 mv).
A Scan Tool or Lab Scope is required to perform these tests. Hope this info. helps! Good luck.
The TPS electrical circuit consists of a 5V supply line which is grey and a ground path line which is black, both provided by the ECM. A third wire is used as a signal line to the ECM.
By monitoring the voltage on the signal line, the ECM calculates throttle position. As the throttle valve angle is changed (accelerator pedal moved), the signal voltage of the TPS also changes. At closed throttle position, the signal of the TPS is low -1.25 volts. As the throttle valve opens, the signal voltage increases so that, at wide open throttle it should be approx. 5 volts.
The ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TPS can cause intermittent bursts of fuel from the injector and an unstable idle, because the ECM thinks the throttle is moving. A problem in any of these TPS circuits, will set either a code 21 or 22. Once a trouble code is set, the ECM will use an artificial default value for the TPS, and some vehicle performance will return.
The TPS is not adjustable. The ECM uses the reading at closed throttle for the zero reading, so no adjustment is necessary.
A Code 22 will set if(signal voltage low):
Engine is running.
TPS voltage is below .2 volts (200 mv).
A Scan Tool or Lab Scope is required to perform these tests. Hope this info. helps! Good luck.
