Hi everyone , Looking for some ideas in tracking down a stumble in rpm .i have an 1988 iroc TPI 5.0 .I noticed that if i hold the throttle at 1500 rpm the revs hold for a sec or two then drop down , then i have to apply more pedal to get it up again . plugs good, wires good cap and rotor good. tb all clean , sometimes i get code 32 MAF . Could i test the TPS while the car is running to see if i get a drop in voltage while motor is stumbling ? i dont think this could hurt ? I work in the industrial electrical field and have seen resistors similar to this set up get a dead spot , Also would the ECM see this and set off a TPS code ? Thanks

 

Yes you can test it while running, but I think it would be more important to do it while the engine is at operating temp. Sometimes it hard to see a dead spot on a volt meter becuase it happens so breifly. If you are in the electrical business however, no doubt you have a meter that has a graphing feature.

 

use a hair drier to make it hot.

 

Find an old school analog meter and hook that up in place of a digital one.

Slowly work the throttle and observe the needle. Any "flat spot" will show up as a dip in the needle reading.

 

And when you discover it has a dead spot, buy a AC-Delco #213-905 for $60 and set it to .54 volts and be done with it. Auto Zone/Cardone/off brand are junk. Good luck!

 

THANKS ,for the replys ,will let you know how it turns out.