Just a quick update; I haven't had the chance to do anything as of yet, but I did get the TCC solenoid ordered and it's on its way. The "slipping" into lockup is a very random thing. I'd say about 80% of the time, it goes into lockup just like any other gear, and holds just fine. The other 20%, it is very lazy about going into lockup and seems to not lockup completely. When It locks up as it should, my revs are right around 2100 at 70 (even this still doesn't seem right, but my speedo seems to be off a little, according to the school zone radar). When it "slips" into lockup, my revs are about 2300 at 70. If I keep very light pressure on the brakes (just enough to get the lights to come on and keep it out of lockup) my revs are 25-2600 at 70, and fluctuate slightly depending on road grade, which to me, seems normal. When I get the TCC solenoid installed, I will update further. I am hoping to get the solenoid before the next fill up to get a full tanks worth of readings, but if not, I will update with Captain's "no warmup" mileage.

 

Here is the link to a video I took today on the ride home from work. Filled up this morning and averaged 13.6 on the last tank, which is a good 2MPG better than the tank before that. Don't mind the horrible focus. I think the camera focused on the dash instead of the cluster. As the video shows, it takes a good 2-3 seconds to fully lock up, but once locked, it stays locked and the revs are just a hair below 2100 now. It seems to be very inconsistent how it locks up and how much it locks up. Ran DTCs and there are no pending or stored codes in the PCM, and all parameters are open, as it just passed inspection earlier in the week. Changed the plugs before the inspection, as my local GMC dealer decided to use Bosch instead of Delco. I used the Delco Rapidfire Platinums, as the double Platinums seem to be out of stock EVERYWHERE!!! they were $5 each instead of $6.50. Waiting to see how this goes and hopefully everything added with the TCC PWM solenoid makes this thing run like it should. Thanks for the input guys. Much appreciated!

 

20%+ increase in fuel mileage.... not bad! It's definitely sliding into lockup, should be much quicker. When is the solenoid supposed to arrive?

 

Yea I definitely can't complain about the increase. Slowly getting there! The solenoid is here, it's rainy and not so nice out today, so I will be crawling under the truck, hopefully, tomorrow.

 

Here is a video of a standing start highway run. About halfway through, I tap the brakes to get the converter unlocked. Thanks Captain. I definitely noticed a difference in the way it locks up.

 

Yup, slides a bit at highway speeds. Slow accel the lockup is more noticeable.
BTW, nice road! Reminds me of ours around here in Michigan:

 

So this is what my plugs looked like after about 1400 miles. They don't seem bad, but they don't seem too good for being as new as they are. I asked for the ebst plugs at the dealer, and this is what I got.... I have never understood these multi-ground plugs in a regular 4 stroke. I have Delco Rapid Plats in there now. I will pull them again in about the same time frame to see how they look.

 

I was never much on marketing gimmicks. AC Delco 41-993 gapped at .060 work the best in these things.

 

Yea same here. There can only be one spark at a time, so unless you are keeping the same plugs for 200K, these serve no purpose. How would you even gap these properly? The ceramic insulator is in the way of traditional gapping......

 

those look like stupid plugs.