91 RS TBI Auto Throwing Codes 21 & 32?
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Junior Member
Joined: Aug 2012
Posts: 7
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From: Discovery Harbour
Car: 1991 Camaro RS
Engine: 305 TBI
Transmission: 700R4
91 RS TBI Auto Throwing Codes 21 & 32?
I think 21 has something to do with the TPS and 32 is the EGR. Is a replacement of both parts in order? IS there a way to diagnose my issues? How do I fix this? Any help would be appreciated!
New 3rd Gen owner by the way
10 days young! I prefer my 91 RS to my 95 Z28
New 3rd Gen owner by the way
10 days young! I prefer my 91 RS to my 95 Z28 
Junior Member
Joined: Jun 2010
Posts: 12
Likes: 0
From: Omaha, NE
Car: 1991 RS
Engine: The 305
Transmission: Upgraded 700r4
Axle/Gears: 3.42 Limited Slip
Re: 91 RS TBI Auto Throwing Codes 21 & 32?
Code 21 is due to your TPS voltage being out of limits.
"Out of whack" as in...TPS voltage was above 2.5 volts for 3 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more, or TPS was above 4.8 volts at anytime. (http://www.troublecodes.net/GM/90-91_50F.shtm).
IF it's a persistent Check Engine Light (CEL,SES, etc)..I'd replace the sensor as they are relatively cheap and would rule out the sensor as being the issue.
For Code 32...it is EGR related. I've seen them thrown for stuck diaphragms in the EGR unit itself, clogged passages in the manifold, and vacuum issues at the electrical sensor -- which controls the vacuum coming for the tbi unit to the top of the EGR.
Best course of action would be to check for proper EGR diaphragm operation (make sure the diaphragm moves up and down freely), check the vacuum line coming from the top of the egr unit to the solenoid, make sure the solenoid is connected properly, check for cracks and vacuum leaks up to the vacuum port on the tbi.
I had the solenoid crack at one of the vacuum routing outlets and had to buy a replacement... You can find a junkyard part but I found it new at the Autozone area hub for about 60 bucks.
There's also a Technical Article about code 32 (https://www.thirdgen.org/egrdiagnose)
"Out of whack" as in...TPS voltage was above 2.5 volts for 3 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more, or TPS was above 4.8 volts at anytime. (http://www.troublecodes.net/GM/90-91_50F.shtm).
IF it's a persistent Check Engine Light (CEL,SES, etc)..I'd replace the sensor as they are relatively cheap and would rule out the sensor as being the issue.
For Code 32...it is EGR related. I've seen them thrown for stuck diaphragms in the EGR unit itself, clogged passages in the manifold, and vacuum issues at the electrical sensor -- which controls the vacuum coming for the tbi unit to the top of the EGR.
Best course of action would be to check for proper EGR diaphragm operation (make sure the diaphragm moves up and down freely), check the vacuum line coming from the top of the egr unit to the solenoid, make sure the solenoid is connected properly, check for cracks and vacuum leaks up to the vacuum port on the tbi.
I had the solenoid crack at one of the vacuum routing outlets and had to buy a replacement... You can find a junkyard part but I found it new at the Autozone area hub for about 60 bucks.
There's also a Technical Article about code 32 (https://www.thirdgen.org/egrdiagnose)
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 7
Likes: 0
From: Discovery Harbour
Car: 1991 Camaro RS
Engine: 305 TBI
Transmission: 700R4
Re: 91 RS TBI Auto Throwing Codes 21 & 32?
Code 21 is due to your TPS voltage being out of limits.
"Out of whack" as in...TPS voltage was above 2.5 volts for 3 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more, or TPS was above 4.8 volts at anytime. (http://www.troublecodes.net/GM/90-91_50F.shtm).
IF it's a persistent Check Engine Light (CEL,SES, etc)..I'd replace the sensor as they are relatively cheap and would rule out the sensor as being the issue.
For Code 32...it is EGR related. I've seen them thrown for stuck diaphragms in the EGR unit itself, clogged passages in the manifold, and vacuum issues at the electrical sensor -- which controls the vacuum coming for the tbi unit to the top of the EGR.
Best course of action would be to check for proper EGR diaphragm operation (make sure the diaphragm moves up and down freely), check the vacuum line coming from the top of the egr unit to the solenoid, make sure the solenoid is connected properly, check for cracks and vacuum leaks up to the vacuum port on the tbi.
I had the solenoid crack at one of the vacuum routing outlets and had to buy a replacement... You can find a junkyard part but I found it new at the Autozone area hub for about 60 bucks.
There's also a Technical Article about code 32 (https://www.thirdgen.org/egrdiagnose)
"Out of whack" as in...TPS voltage was above 2.5 volts for 3 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more, or TPS was above 4.8 volts at anytime. (http://www.troublecodes.net/GM/90-91_50F.shtm).
IF it's a persistent Check Engine Light (CEL,SES, etc)..I'd replace the sensor as they are relatively cheap and would rule out the sensor as being the issue.
For Code 32...it is EGR related. I've seen them thrown for stuck diaphragms in the EGR unit itself, clogged passages in the manifold, and vacuum issues at the electrical sensor -- which controls the vacuum coming for the tbi unit to the top of the EGR.
Best course of action would be to check for proper EGR diaphragm operation (make sure the diaphragm moves up and down freely), check the vacuum line coming from the top of the egr unit to the solenoid, make sure the solenoid is connected properly, check for cracks and vacuum leaks up to the vacuum port on the tbi.
I had the solenoid crack at one of the vacuum routing outlets and had to buy a replacement... You can find a junkyard part but I found it new at the Autozone area hub for about 60 bucks.
There's also a Technical Article about code 32 (https://www.thirdgen.org/egrdiagnose)
Ill inspect my EGR system. Had a similar issue with my 86 Vette
Thanks!
Junior Member
Joined: Jun 2010
Posts: 12
Likes: 0
From: Omaha, NE
Car: 1991 RS
Engine: The 305
Transmission: Upgraded 700r4
Axle/Gears: 3.42 Limited Slip
Re: 91 RS TBI Auto Throwing Codes 21 & 32?
When I had a TPS issue ( I had code 22 aka. Voltage too low) I just went over to autozone and bought a replacement. It was not adjustable but I have heard that you can buy those. Just make sure all the connections match. Buying an OEM replacement has not caused any issues and the TPS doesn't give me any problems now.
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