Engine stutters off idle

[chuckfryer]

Engine has begun missing and stuttering just off idle. Idles fine and runs strong and smooth with more throttle. This developed and got worse over about a month. In the beginning it only happened during the first several minutes of driving. Now it's constant.

Engine parameters bounce around crazily while it's stuttering: LV8, integrator, block learn, MAP and RPM.

I must have a bad sensor. Any ideas? Thanks.

 

[dank GN]

coil pack or ICM or bad MAF

 

[Sleeper-6]

Unplug your cam sensor while the engine is running and go for a ride. If it goes away you've found your problem.
My old motor just would not run right with the cam sensor adjusted exactly to spec. I don't remember what direction I moved it in now, but I only had to move it a few degrees and my problem went away.

I don't know what this works, because everything I read says cam sensor timing has no effect on how the engine runs (as long as it's not 180* out of sync ), but it worked for me.

 

[dank GN]

Cam sensor just tells the ECM where #6 cylinder is after the motor is on the sensor can be unplugged because the ECM already knows where 6 is

 

[TurboBuRick]

Cam sensor just tells the ECM where #6 cylinder is after the motor is on the sensor can be unplugged because the ECM already knows where 6 is

Unplugging the cam sensor will put the system in limp mode. The injectors will batch fire. You can clearly here them change rhythm.

Unplugging the cam sensor is a good test.

 

[Sleeper-6]

I should have said, "I don't know why this works". The engine should run about the same as long as the cam sensor is close enough to get it started. but it made a profound difference in drive-ability in my car. So it's worth a shot

Un-plugging it is a quick test that will either point to or take the cam sensor out of the equation.

 

[chuckfryer]

Good suggestions, thanks. So I've tested and the following are good: cam position sensor, throttle position sensor, idle air control valve, mass airflow sensor and manifold absolute pressure sensor.

A friend (who builds his own engines and burns his own chips) thinks it might be a failing crankshaft position sensor. I'm not wise enough to know how this could cause the problem, but I'm wise enough to listen to experts. I'm changing the crank sensor as soon as the motor cools down.

If that's not it, then I'll swap in a good ignition control module.

Thanks for your help. I'll post the solution when I find it.