ok engine gurus need some help

It is so obvious what is wrong...











it is a gm product.

have you ever checked your fuel pressure? also check pressure leakdown. i will take a stab at the missing, black smoke issue. i had a 9with the vortech 4.3 do this to me. what solved my problem was replacing the pickup coil in the distributor. i have seen these do this with a leaking intake gasket too. as far as the overheat problem, do you lose ANY coolant? the4.3 and 5.0 and 5.7 engines are notorious for the head gasket blowing between cylinders, causing overheating and washing the cylinders down a little. what did the plugs you took out look like? do you have a pic of them? later, brian

mine started having the same problem. its a 91 jimmy with the 4.3 i tried resetting the computer after i changed a bunch of stuff on it, but somehow all the gauges started to read backwards and upside down... like when i go faster, my tach reads less rpms, when i crank it the battery meter goes to 0, and the more gas i put in it... the less it says i have on the gauge? its all electric digital gauges... and the worst part is it stopped overheating, but now i cant trust my gauges. anyone have a clue about that?

when i took the first set of plugs out, they were fideous, they had not been changed in so long thatthe electrodes were all but gone, but this didnt start till after i chnaged the plugs and wires cap and rotor,can i ground the obd out with apaper vlip cause i cant find my code key that i used to have, cause that is how i would get codes for my s-10

you really need to get the codes from the ecm, check the wiring to the diag. con. if thats all good you may have a bad ecm. If you can find a buddy with the same engine try the air flow sensor. If the egr valve has been replaced 2 times there is something causing excess carbon to build up on it. pull a vacum on the egr if it hold vacum the remove it and clean the carbon from it so the plunger seals. my $$$$ is on the afs.

correct me if im wrong, but i dont think these trucks have mass air flow sensors, at least the tbi motors dont, i dont think the cpi ones do either.

mine didnt have one...

dude did you take my advise and just fix what broken? it should run better if you do

its also funny cause my blazer is also without a thermostat and the heatercore has been bypassed too haha. wierd.