Hey y'all I was told to make at least 5 posts so here's another that's been on my mind. I will start my truck up, cold morning or warm afternoon, and it will surge for about 15 minutes. The tach well jump about 30-40 rpms up and then come back to idle at 600. It goes away after she warms up. No codes are thrown I've scanned it a few times. I have asked local diesel mechanics and they say it's normal, but I really don't trust a guy that doesn't know what a uvch is so figured I'd ask you guys.

1996 xlt 2wd 7.3
90,000 miles

 

That's a good hunch...

Automatic or manual transmission? If an automatic, try starting it in neutral, see if it makes a difference.

What device are you using to scan it? Are you at least getting a P1111 (code for "all systems go")?

 

Its an automatic my bad. Yea the scanner I used is my buddies he has the same truck as I do. It does show p1111 code the last time we scanned it. I'll try it up in neutral this morning. What would make it different? I'm just trying to gain more knowledge about it.

 

Mine does exactly the same thing. Although I wouldn't call it a power surge as much as a fluctuation in idle rpm.

 

There's a switch on the tranny, Trans Range Sensor (TRS), aka Neutral Safety Switch (NSS). Along with contacts for starting the engine only in Neutral and Park, and turning on the reverse lights, it also sends a signal to the PCM as to what gear you're in. Sometimes when the PCM doesn't "know" you're in Park or Neutral when you start up, the idle will romp. So if it helps to shift to Neutral, either the switch is out of adjustment (not picking up Park correctly), or that part of the sensor/switch is just worn out.

 

I've thought about the trs being the problem. Should that throw any codes? Also how frequently does that happen?

 

Yes! Exactly what I was trying to say!

 

Also forgot to mention it will occasionally do this in drive at a stop light after I begin to warm her up