Thanks much to all 3 of ya!

 

Tech 2 is incredible for transmission issues also- it easily pays for itself. The only thing I have found thats funky with it, on the clone you MUST get an adapter that keeps 12v continuous - I believe this one works


When you do crankshaft relearn with the clone - when it goes to vehicle on/off/on, the Tech 2 reboots.... This cord resolves that by keeping constant power to the Tech 2, the genuine Tech 2 had a proprietary power supply that kept the tech2 powered in the vehicle on/off/on....
Here is a more detailed explanation -

 

Great info Chrmer3, appreciate it.
Yep there is always enough going on with these Hummers that it won't be wasted money WHEN I learn what I'm looking at, which I will. I'm decent mechanic and have rebuilt motors over the years truck and outboards. I repair everything I can around farm and house here if I can source the parts and some info on whatever it is.
Today I had NAPA scan it looking for more info on the P0300 and they got a throttle sensor code was well. 2 weeks ago AutoZone it was a O2 and ECT sensors which I replaced both but P0300 came right back. I haven't plugged my ZR11 in yet to see if it gives me the throttle sensor code as well before I go down that hole. For some reason it seems to only want to give the main P0300 and not the what I will call the secondary codes which are the ones I need. I need to just get the Tech2 ordered before I replace any more parts. I'm looking for source on specs I should see for the different sensors and items like STFT/LTFT at idle etc so when I'm looking at live data I know if one is out spec or not. I know last week I had a LTFT @99% on bank 1 and the others where all low and/ or believe even maybe a negative value. I'm gonna take picture when I do plug ZR11 in so I have record to compare.

Anyway, thanks again and anyone feel free to chime in since this is common but could be 10 different things tripping it on.

 

There are a number of issues that will trip the P0300 code,
have you changed any part of the rotating assembly, ie cooling fan, torque converter, u-joints etc......
Have you replaced the crank of cam sensor?
Do you feel a miss-fire?
How's the power of the engine?

Neal

 

Do you have a laptop that you can put the nano software on?
The nano is around $125 with software on Amazon
With Tech2Win (nano) you have all the functionality that the tech2 hand held offers

Not sure how much you want to spend,

Neal

 

Let me say 1st-I appreciate your all's help and promptness. Sometimes I'm slow getting back with a lot going on but don't mistake my slowness for not being grateful for your input.
These questions Neal asks and everyone else's who try to help going forward need to know all the history which could give clues to someone that has been in the hunt before. I've read I believe all your previous threads over the past years and truck forums for this and am using that info to help me as well. Hence the crank relearn and why I had the shop in the beginning of this adventure do an Induction intake cleaning. Plus since it sits a lot I run a cocktail of Stabil marine and Seafoam in all my stuff, have for many years because they all sit a lot. When I started this recent trying to get her alive I gave her a slug of cleaner with low fuel and then got a fresh 3/4 tank in her when I went to AutoZone. Normally it stays low and I add 5gal from jug when needed to keep from running out.

So Power sucks now and feel the mis-fire, MPG now 6ish was 12-13. That only became the case recently. I have attached the history in a pdf and what I have done in last 2 months since I started working on her. I understand this is a lot and long winded so if someone passes on reading it , no worries.

 

Neal,
Yes I have 64bit Win10 Home edition I'm on. I keep a big old Toshiba running XP going as it has OMC Diagnostic software for one of my boat motors. I got another I have to dig out and check on if it has Win7 still on it and if it is usable or not, been several years. Hopefully this one running WIN10 Home will work but it is 64bit. Thought I saw something required a 32bit. I like the $125 price on Nano and that it potentially could be used on something more recent than our Hummers. The TECH2 would solely be for the Hummer so that's a few hundred more for a dedicated but possibly more solid/ user friendly(?) tool. I'm trying to find someone in the area who has used either of these so I could see interface and functionality of at least one of them.

 

Has anyone changed out the fuel injectors yet? They are relatively inexpensive and not hard to change. For not much money and time - you can pull the intake, freshen gaskets, do the injectors, clean the MAF & replace the harness on the knock sensors (if you do the knock sensors also (rusted to hell) make sure you use ORIGINAL AC Delcos from dealer or NAPAs version). Also while open, change the valve cover gaskets...

Dont really consider this throwing parts at it, with the heat & age they are most likely worn and this may resolve the issues..... its about a 4 hour task start to finish. You could probably do yourself under $300 +/- in parts (remanufactured injectors are fairly cheap for a set)

 

No not yet. Trying to follow the scanner leads and only replace what I have to right now. I got a couple guys in the performance outboard community that I use to clean and flow test my injectors that I will do first. Even though it has the 142k miles it has been treated well and stored indoors, fuel treated etc. Soon as I finish pre-winter detail and wax on wife's suv I will be back on the H2 and pull MAF and Throttle body for clean and inspect and retest to see if I am replacing throttle position sensor as yesterdays scan called for.

Ideally I want to change out intake, cam and possibly heads which all this would dictate possibly injectors and definitely a tune, so knock sensors and gaskets etc would be covered then. But I may have to do injectors and knock sensors just to get it running correctly. Few years ago I would of already tore into it , but as we are all seeing the money get tight I need to be frugal and keep it to absolute needs.

 

are you sure you just don't have the classic clogged cats or exhaust.
on mine the engine felt a bit bogged down. i tried chasing it down with new sparkplugs then cleaned the throttle body, checked intake for leaks sometimes would get miss fire codes. thought my coil packs where duff. but the rusty crusty Basterds where fine. then i thought it was injectors or fuel pump / pressure but those checked fine. then i would get a blinking CEL light at 4000 rpm's doing 60 mph when i would mash the pedal.
clogged cats....... i cleared the obstructions now all is dandy.