Idle Surge Lack Of Power And/Or Stall At Idle - Inspect Ground G107

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may describe an intermittent idle surge, rough idle, lack of power on acceleration, stall at idle, and/or stall when coming to a stop. The engine will restart fine it stalls and the engine will run fine off idle. They may comment that this occur with a cold or hot engine. Upon inspection, it is unlikely that any DTCs will be stored. If a DTC is stored, it will most likely be a P0300 due to some random misfires that may occur during the concern.

If the SI diagnosis does not isolate a cause for this concern, inspect G107 on the transmission bellhousing (shown below) to see if it is loose or corroded. This ground is for the MAF sensor, ECM, TCM, and P/N Switch. Even if this ground cable feels tight, place a wrench on the nut to see if the nut is tight. If okay, perform a voltage drop test by attaching a DVOM from G107 to the negative battery post with the engine running. Typical voltage drop for this ground is normally around 50 mV. If a concern is found, disassemble and clean the ground, reassemble the ground, and re-evaluate the concern.

1. Transmission Case
2. C100
3. G107
4. Engine Harness

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.