Chevrolet Repair: 94 blazer w/vortec engine, vortec engine, egr valve

Question
Mark,
I have a 94 Blazer w/vortec engine "W". I have started getting a service engine soon light with rough idle, sometimes stalling while in drive and while stopped. The idle goes low then normal constantly. I changed the oil, no help it needed anyways. Then went to the plugs,cap,wires,and rotor and now it's running like I am misfiring. I have a Haynes and the firing order says 165432 clockwise, sitting in vehicle left bank is 135 and right is 246, is this correct. Prior to tune up truck ran good  except the idle problem, now runs aweful while in drive as well. If I have messed the firing order up what would the original problem be. I see all kinds of things from egr to cpi. Thanks in advance. Vinny

Answer
Hi Vinny, Cylinder order is drivers side...1,3,5 and 2,4,6, on the passenger side. Double check the wiring order to make sure that it is correct. The problems that could cause your running rough and stalling are both the ERG valve getting carbon in the pintal and the CPI unit. They make a EGR valve gasket with a screen in it to stop the carbon from getting into the valve. I would install one of these!! The CPI unit will drain gas into the number 2 and 4 cylinders, if you remove these 2 spark plugs and they are wet with gas you know that the CPI is bad.


Hope this helps you

Have a  Great Day
Mark