hey,
I just changed the plugs on my 2000 gmc jimmy the other day. I was planning on just doing the plugs and not the wires, but ended up doing the wires too when I accidentally ripped one of the wires. The car has 160k on it. I put in Bosch platinum 2+. I usually always stick with delco iridiums, but I told myself when I got this car that I was going to put as little money into it as possible because I'm graduating college next year. After the spark plug job I started up the engine and it was backfiring, blowing out white-ish smoke, and I think I even heard a lifter tick, but I'm not sure. I checked the passenger side of the engine today to make sure I didn't cross wires. It's all as it should be. The drivers' side has a bunch of crap in the way and it's raining so I might not be able to get to it today. I DID see that the closest plug wasn't snapped on though, and once I put that back on it stopped the lifter tick noise.

It's still throwing a PO300 (multiple cylinder misfire) code. I was warned at advanced auto parts about using Bosch plugs in an American engine but I didn't listen because the plugs were buy-1-get-1-free, making them $15 compared to the $48 for iridiums.

Do you think the PO300 code is from crossed wires on the drivers' side or from the bosch plugs? I noticed today that the distributor is labeled 5-1-3 on the driver side. I know I have the 3 going to the cylinder closest to the firewall. 5 and 1 I'm not sure offhand without looking at the engine. which cylinders are 5-1-3 supposed to be connected to?

 

u know i got some of those same plugs too and my blazer is running like poo. maybe it is them plugs? looking at the front of ur motor on the right side it is 1 3 5 and on the distributor right side starting up front its 3 1 5. also 5 should be closest to firewall

 

with gm motors Delcos work the best, i have a slight miss at idle in my silverado because i put in autolights but its not enough to throw a code and im to cheep to buy delcos. as for crossed wires no it would give you specific cylinder misfires. the P0300 is random missfire. could have cracked a vacuum line when replacing plugs?

 

cheap wires are bad wires.....but I buy them anyways I did a tune up on my truck this winter and it did the same exact thing (plugs, wires, distributor cap, rotor, column) What happened with mine was the wires on the driver side were arching and creating the P0300 code aka cross fire. Check to see if wires are even remotely close to touching and seperate them to see if that solves your problems.