Hey Peter,

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My thought there was that since idle is controlled by the throttle body, and idle quality is poor, my throttle body may be bad electrically or even mechanically. I've heard you can damage them by holding them open while cleaning.

But seeing the 76% pid made me question the pcm.

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No, its a speed density engine. I really didn't think a vacuum leak would be problematic here.

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Vacuum is steady and normal, until the surge of course, but any change in airflow whether it be a misfire or a change in idle speed, will move the gauge needle. Which tells me what i already know. I may have to check static/running compression check as a last resort. I just feel like thats a shotgun approach to diagnostics.

One thing i did notice is that LTFT seems to continue to follow STFT. Seems like LTFT never settles in, but they are no abnormally high, and return to 0 at wot.

Bank 1 o2 signal seems to switch much faster and more erratically than than bank 2, however bank 1 is a new sensor.

I may have to just scope them all and do the compression checks like you suggested. Im just fixated on the throttle pid being too low.

Thanks for the response Peter

Kevin Mowdy
Technician
USMC-Exercise Support Division
Yucca Valley, California, USA