Late 99 7.3, 207k miles. Last night dropped down to about 28*, it's currently almost 3pm and 65 degrees outside. I just started my truck up for the first time today, let the glow plugs warm up for about 25 seconds and turned the key over.

It romped and bucked for about 5 seconds. Why would it do this when it's so warm?

When I plug it in and start it on real cold mornings it doesn't romp.

The 2003 7.3 I used to have would start at 15*, not plugged in, and never once romped on me.

I use Rotella 15w40 but am considering switching to 5w40 synthetic for the winter, but I am concerned the truck will start leaking more than it already does using the synthetic.

 

Try unplugging the ICP sensor next time and see if it starts normally. I'd say disagreement between ICP and IPR. Start with the ICP, then IPR, finally move on to the HPOP if all else fails.

 

Where are those sensors?

 

Sensor locations

 

Sound like couple bad injectors.

How it drive in overdrive at 40-45 mph when engine is COLD?

Mine did that all times for 1 month before I got 2 injectors replace after that romp went away but come back on because I still had 1 bad injector. It only happened at 35oF It ROMP for 1-2 sec then away.

5w40 will help but it mask your real problem.