Hi all,
I have just become a H2 owner, 2003 with 41000 miles. Great thrill to drive so far and thoroughly enjoying the experience, however a few things need attention which is difficult as I am in the UK and not many garages here have experience with Hummers;
Here goes;
Speedo needle is playing up, sometimes gives up and starts again next journey, perhaps speedo sensor on gearbox end?

The engine management light is on and during a 6 hour drive back after collecting the car, about 2 hours into the journey I felt a loss of power and the engine light flashed instead of staying permanently on. I pulled in and restarted the engine and haven't had the problem since.

I have a whipple supercharger fitted but with the engine light on I am keeping very light on the gas just in case, I have no idea if the supercharger is related to the engine light being on and Im unsure on how the performance would be because this is my first hummer. Hoping someone can recommend a diagnostics kit I could purchase or a garage in the uk who could help? The journey home sitting st 60 to 70 mph achieved around 14 to 17 mpg which I was happy with do hoping that sounds like everything is running normally. Having read that the transmission is under greater strain with a supercharger am I better off removing this for the long term? Original manifold Needed I believe? Any help is much appreciated!! Thanks

 

Welcome to Hummer World! It's a great place to be once you get your issues sorted. The speedo tends to be stepper motor issues, the little ones inside the dash pod that runs the speedo, clock, and the mini gauges. Replacement kits can be had fairly inexpensively on ebay: QTY-6 HUMMER H2 03-06 STEPPER MOTOR SPEEDOMETER GAUGE KIT INSTRUMENT CLUSTER | eBay
The dash pod comes out readily, not difficult at all.

The CEL needs to be diagnosed to find out what specific codes are being set by the various computers. Sometimes the CEL is telling you something is bad but other times it is saying that it is not receiving correct information from one of the using systems. It can be confusing. So I would definitely make it a priority to find a garage or shop that can check out the codes for you.

I would not worry about the supercharger as yet. I would not try to outpace a DB9 or similar but just normal driving should not be an issue. The prior owner may have upgraded the transmission and torque converter if they spent the money for the Whipple. It would be nice to know the history of our H2s but most of us do not get that lucky when we buy used.

Wish I could recommend a garage in the UK but have not spent enough time there to have heard of any. It is a large enough country also that I could mention a shop in Cardiff but you are located in Liverpool so that would be no help!

There's a bloke on here, Ocean Brave, whom I believe is somewhere near London, and there may be others located in the UK with better ideas about support. Try a pm to Ocean Brave and see if he can help.

I hope you can do something with this info going forward. The Hummer is just a fun ride, you will enjoy it immensely once you get it sorted. Cheers.

 

If the engine light is flashing that means the engine is misfiring. Seeing its super charged you do need to run premium fuel, 91 octane minimum.

 

Thanks flyday for the info, great help...
I will aim to get the diagnostic code asap to see what I'm up against! I'll also order the cluster repair kit you mentioned. Thanks again

Humtech, our fuel in uk is generally 95 octane as standard and we can pay more for what is 'super unleaded' and has 98 Octane. Am I ok to use just the standard 95 octane do you think?

 

Also without service history should I think about doing the transmission oil change? If anyone can advise the oil grades for both engine and transmission I'd be grateful.

 

5w30 full Synthetic in the motor. The transmission originally came with Dexron III ATF but that has been superseded to Dexron VI. If the CEL (check engine light) is flashing there is a chance you are damaging the catalytic converters, due to large amount of unburned fuel going through them.

Congrats on the H2 You will love it.

 

At 95 octane your fine. You do need to get to the root cause of misfires though

 

Yes, it's a worry, I need to do that first for peace of mind, luckily it's only happened once where it started flashing and lost power, but just having the engine light on staring at me is bugging me!
I just want to confirm the engine oil Calif Phil, you mention fully synthetic but a company I tried to buy the oil from yesterday said I should be putting just a 5 30 mineral oil and not synthetic? Do you know the reasons normally causing the unburnt fuel to get to the cats?

 

While mineral oil if fine, Synthetic is a better choice. Especially with a supercharger. Most common cause for the unburnt fuel will be a misfire caused by spark plugs, plug wires, coil, injector, plugged cat. or a mechanical issue. I would start with the tune -up first.