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Problems with TPS? or what?

Ezmunie

Well-known member
Joined
Feb 10, 2006
Messages
233
Location
Sherman,Texas
Corvette
1986 Black Convertible
Beautiful day today, so I take the vette back to work from lunch, and, on the way home it is running great and when I accelerate, it falls flat on it's face and acts like it is not getting fuel or something. I had to pump the accelerator to get it home. The check engine light came on and when I got home I checked the codes and got 22 (TPS circuit-signal voltage low) and 33 (Mass Air Flow). I went to check the TPS voltage per the Haynes manual with the jumper wires and could never get a voltage reading. Does that mean the TPS is done? Will the car even run if there is no voltage to the TPS? I started it up again and it idled and ran, but the check engine light came on again after I had disconnected the battery and re-connected. I had this problem a few months ago and replaced the MAF relay and the burn-off relay, located behind the battery and it seemed to cure the problem. Is it the relays again, or is it the TPS that is faulty, or what? Help?
 
Joined
Jan 15, 2004
Messages
2,240
Location
Northern Indiana
Corvette
1987 Z52 Black Convertible
One way to check the MAF is to just unplug it and see if the car runs worse, not the same, or if it is bad it might actually run better. I can't locate my service manual for mine but make sure you are connecting to the bottom two wires I think to test the voltage with just the key on. I used two paper clips to shove into the sensors and just connected a volt meter to those. I almost forgot also remember to check it at WOT too with just the key on to see if you get any voltage, if you arent getting anything you can try to adjust it.
 

Ezmunie

Well-known member
Joined
Feb 10, 2006
Messages
233
Location
Sherman,Texas
Corvette
1986 Black Convertible
One way to check the MAF is to just unplug it and see if the car runs worse, not the same, or if it is bad it might actually run better. I can't locate my service manual for mine but make sure you are connecting to the bottom two wires I think to test the voltage with just the key on. I used two paper clips to shove into the sensors and just connected a volt meter to those. I almost forgot also remember to check it at WOT too with just the key on to see if you get any voltage, if you arent getting anything you can try to adjust it.​
Thanks for the reply, I will unplug the MAF and see what difference that makes.
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
TPS

From what you said it sounds like a fuel problem. On a carburetor when you put more throttle down the accelerator pump squirts a little extra gas into the venturi of the carb. This allow the engine to rev higher thus causing more air flow through the carb and that pulls more fuel from the jets to keep the engine accelerating. That is an over simplification of the process to make an engine run and accelerate. With a car with computer controlled fuel injection something has to tell the computer when to release more fuel for the injectors. The TPS does this by taking the place of the old mechanical carburetor functions. As the throttle position changes the TPS sends a signal to the computer and it responds by either increasing or decreasing the amount of fuel injected into the cylinder.
 

Ezmunie

Well-known member
Joined
Feb 10, 2006
Messages
233
Location
Sherman,Texas
Corvette
1986 Black Convertible
From what you said it sounds like a fuel problem. On a carburetor when you put more throttle down the accelerator pump squirts a little extra gas into the venturi of the carb. This allow the engine to rev higher thus causing more air flow through the carb and that pulls more fuel from the jets to keep the engine accelerating. That is an over simplification of the process to make an engine run and accelerate. With a car with computer controlled fuel injection something has to tell the computer when to release more fuel for the injectors. The TPS does this by taking the place of the old mechanical carburetor functions. As the throttle position changes the TPS sends a signal to the computer and it responds by either increasing or decreasing the amount of fuel injected into the cylinder.

Thank, John, I will proceed looking in that direction and see what I come up with.
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
More advice

If it turns out to be the TPS do not get temped with the cheaper replacements at places like Advance Auto Etc. I replaced my TPS with a cheapo and 8 months later it led me into thinking I needed an ECM which I bought. My car still would not start and finally I checked the TPS even though I new it was new and could not be bad. I went with the good old GM part for the car not only did it start it runs better now than it has for some time. I have been convinced that as far as anything electrical I will use OEM parts. A friend of mine(Who retired from Olds emissons lab) explained it this way to me. GM designed the sensors for the emission etc with a very close tolerance and held their suppliers to those tolerance's. After market parts are often designed to function but in reality they are allowed to be at the high end of the tolerance range whereas GM held their suppliers to a much tighter range.
 

Robertwav1

Well-known member
Joined
Jan 7, 2003
Messages
826
Location
Ocala, Florida
Corvette
1993 Blue
Beautiful day today, so I take the vette back to work from lunch, and, on the way home it is running great and when I accelerate, it falls flat on it's face and acts like it is not getting fuel or something. I had to pump the accelerator to get it home. The check engine light came on and when I got home I checked the codes and got 22 (TPS circuit-signal voltage low) and 33 (Mass Air Flow). I went to check the TPS voltage per the Haynes manual with the jumper wires and could never get a voltage reading. Does that mean the TPS is done? Will the car even run if there is no voltage to the TPS? I started it up again and it idled and ran, but the check engine light came on again after I had disconnected the battery and re-connected. I had this problem a few months ago and replaced the MAF relay and the burn-off relay, located behind the battery and it seemed to cure the problem. Is it the relays again, or is it the TPS that is faulty, or what? Help?

Fuel filter changed lately? Don't mean to sound basic here.
Erratic error codes can be caused by insufficient fuel. The computer will try and make all kind of adjustments until it just can cope anymore with not enough fuel....just my .02
 

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