99 blazer 4.3 p0300

[autojoe]

i plan on looking at missfire counters on scan tool and doing a injector balance test.....i know that these poppet noozles open at 40 psi...if they are sticking is there any way to fix.....i know gm uses high detergent top end cleaner and removes lines to tank because can damage pump to clean or atemp to clean......does this procedure work?if it does not work should i convert from csfi assembly to mpi assembly?autozone has one made by dorman i think.....325 dollars.truck has high miles.any input would be appreciated.

[Tech II]

Yes, you would need the special injector cleaner setup to clean the injectors......it attaches right at the fuel rail.....cost prohibitive to get this setup....it can be sent to a GM garage for this......if it fixes the problem, money well spent....if it doesn't, then you wasted your money....and now you need an injector(these injectors can be replaced individually).....of course, you replace one, and then another can go on you down the road.....or you can be lucky, and that is the only bad one.......really depends on how long you plan to keep the vehicle....

So for your year vehicle, I think MPFI is a simple switch, and doesn't need any reprogramming of the PCM/VCM.....

Maybe GMTech1 can jump in on this.....

[autojoe]

hooked up scan tool and got p0300 and also p0131 02 b1s1.....closed loop 02 was stuck at 43mv......no current missfire counts......history missfire counts were like 28000 for cylinders 1/3/5......at idle stft was 138 on bank 1 and got better under acceleration down to 130.....ltft was 128.runs rough.plug wires came in contact with manifold and replaced all plug wires/cap and rotor.p0171 lean bank 1 in history.friends truck.....i was going to introduce propane into engine and see if i could drive 02 bank 1 rich but he replaced bank 2 sensor 1 02 and is going to replace bank 1 02 because truck has 130000 miles on it....i told him maybe 02 bank 1 was bad or contaminated with carbon.my question is would a bad 02 sensor bank 1 cause a missfire on cylinders 1/3/5 all 3 cylinders on bank 1?i was thinking if 02 bank 1 was lean it would increase injector on time for both banks.....i am thinking a vacuum leak relating to bank 1.....what do you guys think?02 needs replaced anyway due to high miles.

[autojoe]

any ideas?