If yes what diagnostic tools are required?

 

None that I'm aware of.

 

Plug and play. They does not.

 

it would only need programming if you change the size of the injector for anything other then the stock size.

 

Thanks for the reply.
I order GM OEM injectors , so hummer H3 doesnt need reprogramming injectors if OEM.

That's what I found in some forums, some old cars dont need it
Common rail Injector coding | techtalk.ie

 

correct.
stock OEM is direct swap no programming required. Usually GDI engines might need programming which these are not.

 

I had a bad batch of gas I guess and was running on fumes, started badly misfiring = barely drivable.
Siphoned gas tank and put premium gas seems to have fixed it for a 10 miles test.
If not I replace injectors.

Thank you
I will keep you posted.

Ps: can a faulty valve give intermittent problem?

 

what valve?

 

If a Valve seat problem can it be intermittent or is it permanent?

 

it can depend how loose it is.