Strange Rpm's

[rangerred]

What would cause a warm engine to "pulse" at 3K rpms ?

It starts at normal idle, then, when I bring the revs up to 3K, and hold it there, the engine revs go up and down, as if I were tapping the petal.
It's not trying to stall, just a rapid increase and decrease in RPM.

The kicker is, the tach doesn't indicate the revs going up and down.
It sits on 3000 until I let off the throttle, at which point it returns to normal idle ! ???

 

[TomJenks]

What would cause a warm engine to "pulse" at 3K rpms ?

It starts at normal idle, then, when I bring the revs up to 3K, and hold it there, the engine revs go up and down, as if I were tapping the petal.
It's not trying to stall, just a rapid increase and decrease in RPM.

The kicker is, the tach doesn't indicate the revs going up and down.
It sits on 3000 until I let off the throttle, at which point it returns to normal idle ! ???

It sounds like you have it in park or neutral while doing this. If thats the case I'm sure it has a rev limiter to prevent damage to the engine. Most vehicles cut the injector pulses to stop putting fuel into the cylinder.

 

[rangerred]

Strange RPM's

As a matter of fact, this does happen only when in neutral or park.

Thanks.

 

[gw33gp]

You should also have a red line rev limiter when in gear that will react the same way but at a much higher rpm. You should also have a speed limiter that kicks in a little over 90 mph. All designed to protect the engine, vehicle and you.

 

[BlackBII]

A rev limiter kicking in at 3000rpm??

Your not holding the pedal to the floor are you?

 

[rangerred]

Didn't know about the speed/rev restricter. That explains why I can't get it much beyond 92 mph. Somewhat disappointing !

Thanks for the help.