hello, i have a 2003 hummer h2 with a aem cold air intake and a magnaflow exhaust. truck runs tip top and i got all the maintenace done recelty like plugs tranny service filter etc etc
so in the city the truck is perfect like any time i am driving under 60 mph

however when i hit the highway it gets annoying. so the speed limit is ususally 80mph and i want to drive at that on cruise control but for the even slightest hill on the highway the transmission always downshifts to 3 and then revs up to 3000 and stays there and the truck gets so loud etc and its very annoying. it like very rarely will upshfit back to 4th. its just very hard to drive like at that speed. it just always wants to keep downshifting and it gets so loud and its just hard, it also drives the tranny temps up when it keeps having to shift.
i usually end up just keeping cruise off and driving by foot but it gets hard too drivinf 6 hours etc on the highway

i understand if the hills are big and stuff but like idk i would just rather have it chilll in 4th gear most of the time and only drop when it actually needs to..

i assume this is a problem because the engine is a little underpowered? i dont want to supercharge or spend that much but was thinking if mayve those handheld tuners would help? i dont care for gas mileage that much like i would rather have it easier to drive when i drive on the highway.

would those handheld tuners help or do anything or do they barely add any power? would tthis solve my highway problem or does everyone have this

 

Don't think they will do much for your issue as explained

our trucks are square blocks and have a substantial amount of drag at those speeds, the only thing will be HP or RPM's to get it to act the way your wanting

Neal

 

Based on recommendations from this forum, I went ahead w/ the Diablo (Diab-Lew) ECU and TCU tune on my '08. My power has improved, my mileage has gotten better and my transmission shifts better than ever. I did this tune almost a year ago and it continues to improve on my H2. I had a couple of '06's that I didn't tune and anything over 75 mph was really uncomfortable. We just finished a 1,000 mile road trip and the truck had no problem doing 90 mph when needed - the big surprise was averaging over 14 mpg over high mountain passes w/ all of our gear. It was an iterative process working w/ Lew to get the new tune installed, but it worked out great and was well worth it. I would recommend contacting him to see if he can improve the drivability of your H2. Best of luck!

 

Excellent and glad to hear that skiracer. Was likely me that suggested Lew. Makes a world of difference in driveability!

 

I have the same issue!!!

it “finally” got annoying enough and I have started researching tuning. I used to drive around town most of the time; but, life has changed and now i drive on the highway a substantial amount more.

As far as your situation.....mine matches 100%
i even have an external trans cooler and the temps creep up. I have just stopped using cruise control altogether. Mine is a 2005.

however, before resolving that.....I need to clear some Tc/abs codes and deal with my squishy brake pedal.

 

ok thats good then, i was gonna be annoyed if i was the only one experiencing this but one thing i noticed is that when i ran a few tanks of 94 octane it actually was a bit more driveable on the highway. idk if this is paranoia or something because i think ive heard that the lq4 cant take the full benefits of higher octane but i literally felt a difference on the same highway with similar road conditions

 

I had a Diablo with a custom Lew's tune and loved it, it made a world of difference in how the truck drove, shift points, throttle feel and the like but on the hwy other than HP/Torque, RPM's or gearing there really isn't much you can do.

Probably the easiest thing to do is to drop the tire size and see how that works for what you want, for me personally going with a smaller tire hurts the look of the H2

Gearing in my opinion is the best option but can get pricey depending on who installs them

Neal