PCM tuning

[H3nightrod]

Hello everyone.

I have a 08 H3 alpha on 35s and has a little over 120k. She runs great in town but my worries are on country roads with steep climbs. I want to make sure I am not stressing out my drive train too much while towing on such roads. My last two road trips she was running way to hot. I have recently added a Efan and new thermostat to help but still seems to be running too hot. The only other option I see is aluminum radiator for the spring.
For now I am considering sending out my pcm to pcm of nc.
Has anyone done this mod to the H3 Alpha with 35s? What were the biggest improvements? Did anyone see temp drops with a tune? I'm not looking to have a sports car feel just want to make sure everything is in line. This mod is very common with the I5, just want to know if the same results go for the V8.

Thanks in advance for any feedback.
Josh

 

[High Five H2]

an efan won't help with cooling. they move less air than the mechanical fan.

If you're having trouble cooling, it's probably the radiator. A new one would probably solve your problem and make your system more efficient, but I you might check to make sure you don't have mud on your radiator or bad coolant or something like that if you don't want to spend $500 on that CSF radiator.

 

[650Hawk]

Not sure if the Hummer is known for it, but on some vehicles, a faulty fan clutch will have a huge effect on running temps.

 

[rsc]

Fan clutch may be going out, it should almost always "roar" for the first mile or so in the morning. The 35's cause more heat out of the transmission that the radiator has to shed. The PCM tune helps the trans. run cooler by keeping shifts quick and firm with less slippage.

 

[Happy Hummer]

It's a hummer on 35's towing hills and slopes... seems just about right. Thermostat won help.
Efan nope. Separate trans cooler possibly to highly likely.
New radiator may be.

My thoughts your tires are heating things up pretty done good.

 

[H3nightrod]

I was considering going back to stock tires. It's cheaper than re-gearing the axles for 35s

 

[Ghostbuster]

I was considering going back to stock tires. It's cheaper than re-gearing the axles for 35s

At least go 33s the adventure models came with 33s. Not sure if your's is an adventure but I hope it is.

I'm thinking about getting some 295-75-16 Toyo Open Country AT II tires. They are a little bit bigger than the stock 285s but not as bad on the truck as 35s

 

[ReconH3]

Get rid of the efan and make your hood vent functional. The additional transmission cooler also helps.


"Ex Umbris Venimus"

 

[Brien W]

Get rid of the efan and make your hood vent functional. The additional transmission cooler also helps.


"Ex Umbris Venimus"

I have a 09 alpha T I removed the old hood vent installed a functional one, added an external oil cooler to avoid the radiator trying to keep everything cool. I'm running 37" military tire and wheels. Also built my trany to very heavy duty. haven't had any over heating issues.

 

[amrg]

What kit did u use to build up your tranny?

 

[rascole]

x2 on the fan clutch. When I replaced my fan clutch a few weeks ago I could spin it by hand with very little resistance. a new one should be very hard to turn. So even at low RPM's the fan was barely moving.

 

[Babyjohn460]

I'm likely going to have the same issue next spring when bigger tires are ordered. Anyone have any suggestions or recommendations on an external tranny cooler?


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