I just went through a head gasket rebuild. I have a thread about that. Runs good. Anyhow in the morning when I first start the truck my check engine light comes on. If I drive down the road. Say a mile and turn off. Then immediately back on. It’s gone for the day. Drive around town. Hauls butt. Well for a 3.0. I enjoy. Next day same thing ? Any ideas ? I replaced the EGR last year when it had a code. Then of course the rebuild. Will the code still be present if I do the jumpers and check or since it’s off now I won’t see it. It’s getting some stereo stuff done so I don’t have it with me right now.

 

First thing to do is clear the codes. Do you know how to do that? You don't want to read codes from a previous problem, and chase troubles you no longer have.

Once you're sure any and all previous codes are cleared out, get it to pop the CEL light again, if it will. THEN put in the jumper to read out the current code. Even without the CEL coming on currently, once it does, the code it's warning you of is stored in the ECU. That's why you want to be sure you've cleared out all the old codes, and are only reading out the most recent. As I said, you don't want to go down the rabbit hole of codes that are no longer valid.

Once you've had the CEL pop up at least once after you've cleared the old codes, you can read out the latest code(s). See what the FSM says it (they) mean, and troubleshoot from there. The FSM has a pretty good set of troubleshooting flow charts, that give you at least a good starting point of where to look for a particular code's problem(s).

Does this help?
Pat☺

 

I had no idea it would store the code. I believe he cleared the code when I took it back for the a check engine light that stayed on. But I will clear again.

if it does continue to act this way ... and it ends up being a code 71 I’m deleting this sucker. I was just wondering if this particular problem has ever come about. My search of the forum doesn’t show much with a cel that was just going on at the start of the day.

 

Some codes can store, others don't. The easiest way to delete stored codes (usually a good idea at the start of diagnosis) is to remove the EFI (MFI) fuse for about 30 seconds. (You can just pull the battery connection, but you'll lose all the radio pre-sets if you care.) Then drive until you get the cel, and check for codes at your leisure.

Asking around for "a cel that was just going on at the start of the day," without even checking for the code, is just chasing your tail. Get the code first; then you'll have some idea what your truck is trying to tell you.

"deleting this sucker" in response to any code is a sure sign of the BFH school of automotive tuning. Most of the time just fixing the problem is easier than amputation. Figure out the source of your cel before jumping to conclusions.

 

Well I reset the light. While under there I checked the vacuum lines and found based on a diagram that it’s possible one was crossed. So I corrected that. Hopefully that’s the end. But while under there I did find this “T” line that I don’t see in online diagrams. Anyone know what this is going to or what it does ?

Thank you all for the help.

 

The vacuum lines connected to the "gas filter" (the 3-port gadget mounted on the plenum) drive the PAIR, FPR, AC idle-up, ADD, and Cruise. You only have two ports used, so I'm guessing you don't have 4wd or Cruise. The orange-white check valve goes to PAIR, so the tee most likely goes to FPR and AC idle-up. You can trace them; that's not much more I can tell from your photo.

 

Here

is a better photo of its entire route. I don’t have cruise that’s for sure. Thanks for the info I just didn’t see this on any diagram.