86.5 Starting Issue, turns over cold start only

When I wake up early morning and go to warm up the car, it turns over fine and the idle stabilizes fine like there is nothing wrong. For the rest of the day, i have to pump the gas and stabilize the idle myself. The only other case is when the car is warm and i turn it off and immediately start it again in which case it starts like nothing is wrong.

I've replaced the ISV and that wasn't the problem, so I figure at this point it is a crank position sensor issue, a vacuum issue, or a fuel pressure regulator or dampener. Anyone have any ideas? Cheers

There are several items that could be causing such a problem. Two that immediately come to mind are:

1. Temperature Sensor or connections to the sensor: your 928 has what is called a TempII sensor, it is two sensors in one housing, one sensor provides water temperature readings (via resistance) to the LH fuel injection module, the other to the EZF spark module. If the sensor isn't providing the correct resistance the engine will not run correctly. Corroded connections will result in improper resistance, so inspect and clean them. The sensor is located in the front of the engine near the upper radiator hose. With the age of our 928s, replacing it is a good option regardless of condition.

2. Mass Airflow Sensor. Most Porsche 928s MAFs are out of calibration after more than two decades of use. After each run cycle, the hot wire glows red to burn off contaminants. The wire thins with age and resistance changes. I provide free MAF calibration reporting to 928 OC members via my Electronik Repair business ( email info@electronikrepair.com).