Timing/vaccuum issue?

[93Chevy_1500]

Hi I havent been on in awhile, Ive got a 93 chevy with a 350, the mods done to the motor currently are an edelbrock 3702 cam and intake. I believe im having a timing or vacuum issue could possibly be fuel. If i try and put the timing at zero (computer should correct it 10 degrees when plugging in est wire) the truck runs but will blow black smoke out of the exhaust and have absolutley no power. The only way i can get power from it is if i out the timing mark straight up and down (vertical with the motor) but doing this the motor will have planty of power but the idle will be low (around 500rpms) and sometimes stall out and skip after several minutes of idling but going down the road run great but have an occasional back fire through the tbi. The only codes im throwing is a timing code, My brakes are also becoming spongy could my motor be taking to much vacuum or not enough vacuum? if i unplug the hose that runs from my map sensor to my tbi the idle will pick up to around 700 rpms and seem like it will have power if i were to take it down the road. Could it be a map sensor? Im truly stumped and i just need to figure it out. Thanks for your help.

 

[98_k1500]

I don't see that cam being an issue, I would lean more towards MAP being bad. Be sure to check the hose on it too, can be cracked or not connected to manifold vacuum.

 

[TylerZ281500]

never had a sensor do all that personally, id say recheck your timing if its 180 out itll run but itll run like , also check for vacuum leaks use propane it works better than brake cleaner or carb cleaner or starting fluid and what not, that cam isnt large at all your LSA is right where it needs to be and the lit isnt all that much so id put that out of your mind.

what timing code is it pulling? the one for ESC? did you pull the motor out entirely when you did the head/cam swap? check for broken grounds as well.

 

[cjman250]

map sensor is cheap to replace, sound like that could be a problem if you unplug it and the idle picks up

 

[93Chevy_1500]

Im gonna pick up a map sensor today on my way to work, I just replaced the vacuum lines going to the MAP and the EGR, I also unplugged the hose going from my master cylinder to the metal tube that comes out of my intake and the idle picked up like its supposed to and i pressed the brake with it unplugged and had a nice firm pedal. Plugged it back in motor lugged again and i had a spongy brake pedal. Could my master cylinder be on its way out drawing to much vacuum from my motor? If i Put my finger over the hose as if it were plugged into the master it lugged.

 

[93Chevy_1500]

But i dont think that explains why i cant set my timing the right way. Doing it the way im supposed to the truck blows smoke like a diesel at idle.

 

[cjman250]

if it lugged with your finger over the hose unplugged then i wouldnt think that it would be the MC

 

[98_k1500]

no, it is a bad map or something flooding it if it will run without the hose hooked to the booster. It should run perfectly with the hose unhooked and your finger over the end of it. This confirms that your issue is from it over-fueling. Did the truck run with the setup that is on it or is this a fresh engine?

 

[93Chevy_1500]

the 350 has been in it since 2012 i've now developed the back firing issue, its always had sort of a rough idle anyway but never where it skips and picks up idle etc, My timing mark isnt in the right spot its been that way since 2012 when i did the cam and intake swap it was the only spot i could get it to run and get good power at the same time.

 

[93Chevy_1500]

the truck used to be a v6, i tried the map sensor off of that motor on sunday and it didnt make any difference.