after putting anothervortec 4.3engine(same as o.e.m)in my 2000 chevy blazer, i am now getting a trouble code of random/multiple misfires.Prior to the new engine starting it had to be cranked ALOT and quite a bit of starting fluid was used. Im thinking the plugs could have been fouled. But besides this code nothing else appears. I really have no idea what it can be. in low idle the engine shakes. but when it revs up it seems to do ok.

ANY SUGGESTIONS??

 

Man, that is the absolute worst trouble code to get. It could be just about anything fuel related, spark related, timing, air intake, exhaust, just about anything. Plus you swapped engines means everyone of those systems has been touched.

Is that the only code you get?
Could you go into more detail about the engine swap?
I am hoping to get some clues, so make it the long story.

 

well as i said before, after the engine was put in it had to be cranked alot before it started... the timing was set prior to it being installed and i'm skeptical about that being the problem. the wires are new. and i just put new plugs in today. After removing the old ones the 3 plugs on the driver's side all had carbon deposits and apparently were running rich, in contrast to the other sides three where they seemed to run a little rich and were free of carbon. In the last few times with the old engine it was spitting out blck smoke from the exhaust along with what seemed to be oil. Some of that residue remained on my floor and is now hard. i am thinking that it can maybe that the o2 sensors have been somewhat damaged by this???? As of now that is the only dtc that i am getting. And yeah man i get ou this is a problem in a BROAD field.

 

Hard to start like that might be exhaust related. Like the cat is plugged from the previous engine. Pop off the cross over pipe after the exhaust manifolds. It will eliminate a plugged cat problem. I wouldn't drive it taht way.

Verify your not 180 degrees off in your timing. You got the #1 piston set to TDC on the compression stroke and not the exhaust stroke.

Does it fire right up when you spray ether in the intake? If so, fuel related. You did prime the fuel system before you tried to start it the first time, right? Turn the key to run a few dozen times, excess fuel will go back to teh tank. Did you crimp a fuel line during the install?

Verify all the wires are connected. Look for the wires on the back side of the distriburator,the oil pressure sending unit (back of block next to distrib), and you did tighten up all the wires that bolt to the headon the dirvers side, like the ground strap off the firewall?

Do you have a crank position sensor, if so make sure it hooked up as well. It tells the ICM when to give spark.

Check those things out. We are going to have to go back through all your basic system settings, wires, timing, connections to rule them out.