I got the Superchips 3865 on Friday and from my earlier thread, I used it for 400 miles in TOWING mode towing about 7k lbs obviously with TOW/HAUL switched on, I got to my destination and unhooked the trailer and set the Superchips to PERFORMANCE mode. (ive been using 93 octane the whole time btw) It went great and everything was fine. I hooked the trailer on this morning EMPTY so about 2k lbs, switched back to TOW mode and drove 400 miles today and got to my shop and dropped the trailer off and drove home (10miles) leaving the Superchips still in TOW mode. I got home ate and went out for a quick 10 mile errand and this is where im getting the THUMP all of a sudden, it happens at low rpm's about 2k and its right when it goes into 5th gear, did it each time, I immediately switch TOW/HAUL mode so it doesnt go into 5th, got to the store and switch the truck back to PERFORMANCE mode since I was still in TOW mode hoping it would go away. It didnt, it did the same thump in Performance, I then pull into a gas station and switch it back to STOCK mode and the THUMP went away, I drove it in STOCK mode home and drove around for about 10 miles to see if the THUMP would happen again but it didnt. What happened? The Superchips was fine all weekend, why am I getting this THUMP all of a sudden, its obviously NOT my truck since it doesnt do that in STOCK mode, which I got worried for a second too. Please help, still kind of worried actually.

 

Any ideas, need help on this asap

 

Never experienced it but the SC tunes do significantly increase transmission line pressure, it may be exposing an issue that's there that won't show up under normal pressures.

If you want a quick answer, I might suggest either creating a post on the Superchips forum or putting in a call to them...

 

i did, I did an update and it barely does it now, it kind of feels like it happens whenever MDS kicks in, might not be the trans

 

Doesn't hurt to change your trans fluid if you're close to your interval - made my truck shift noticeably quicker/firmer.

 

ill do that, whats the point of TOW mode when I have to use premium octance and spend more money, why not just run it stock? Same goes with the performance mode, my mpg got a little better but im also spending more at the pump

 

the point of tow mode and performance mode is exactly what it says... towing and performance. you can make more power with 93 octane if it's tuned right. put it on performance and then fill it up with 87 octane... see what happens. It's a truck, not a 4 cyl hatchback. if you care about mileage you shouldnt be driving a truck.

 

Youre missing the point, im pretty sure everyone cares about mpg unless youre driving a 10 sec cobra which i dont care about, but this is a highway truck for me and id like to get the possible mpg i can

 

I actually find that I get the best fuel economy with the performance tune and 93 octane gas (non ethanol or ethanol treated does even better). The MPG gains are enough to compensate for the difference between 89 and 93 octane (87 I'll NEVER put in a Hemi - although if the stock tune is de-tuned to an 87 specific tune it's safe).

I'm sure EVERY ONE OF US cares to some degree about fuel economy, but realize that it's a full size, heavy and in some cases 350+ HP truck, it's NEVER gonna be good...

 

your wheels/tires probably weigh close to 100 pounds each, your truck is lifted and its 4wd..... your going to suck gas. although, you may want to check to make sure your tuner has the right tire size programmed in it. if it's wrong it'll throw your speedo off and your mileage.