hey guys my car is acting funny it will sit and idle fine but every so often it will fluctuate surging from 500-1000 rpm sounding like its going to stall but it never does. usually when this is hapening it has poor throttle response off idle. I think its the tps sensor but i am not sure i was wondering what you guys think.

 

There's a simple way to find out. Hook up a volt meter to it and find out what it is sending.

The TPS simply a potentiometer that receives a 5V reference signal from the ECM and sends back a voltage value ranging from .52 to 5V depending on how much the throttle blades are open.

I doubt it's the TPS. Unless it somehow has an intermittent connection on the inside.

Do you have access to a scanner? When it starts surging, you'd be able to monitor what the ECM is seeing.

 

well ill check that out thanks for the info. but if its not the tps than what could it be? I had a similar problem in my last camaro and i changed the tps and the problem seemed to go away for a long time and it came back before i sold it. It seems to be weird that it is intermitent though.

 

I believe the TPS should be at a minimum of .52V (or there-abouts) at the closed-blade position. You should get close to 5V at WOT.

When the volt meter is hooked up, what you should do is slowly open and close the throttle blades a number of times and see if the voltage steadily increases (when opening) and decreases (when closing). Like I said, the TPS voltage output is directly proportional to the angle of the blades. So see that the voltage does not spike, or drop, or get stuck at a particular value, etc.

 

Look at your IAC.. it could be clogged with tons of good stuff to jam it to where the idle is that erratic that it could use a good cleaning. DONT spray it with carb cleaner.. there is a special thing you need to spray that wont interfere with the electronics.

 

ya i think i found the problem, i heard a exaust leak last night it turns out the oxygen sensor seemed to have fallen out which is realy weird, but i dont understand how it could have fallen out. the service engine soon light is on and wont go out. but it is idleing ok right now but we will see when i put the new sensor in.

 

the new sensor did not fix the problem i am back were i started now. any ideas?

 

.. check you IAC.

 

I'm experiencing a similar problem with my 92. It seems to me that if the problem only starts when you start to open the throttle blades that it would be unlikely that the iac is the problem. I guess my poor *** is gonna have to go buy a volt/ohm meter, can anyone suggest a decent one with a resonable price?

 

Does anyone recall a posting a long time ago that said that if you increased the voltage reading that the TPS gives from .52 to about .67, you could gain some horsepower?

 

i found out yesterday that when its idling bad if i unpluge the TPS the idle smooths out and it runs perfect. Also if i advance the TPS by hand when its idling ruff then it also smooths out. I did not check the TPS voltage yet i was wondering how exactly you go about cheking it?

 

the IAC is ok