Upper tanker
TYF Newbie
- Joined
- Dec 4, 2015
- Posts
- 27
- Reaction score
- 5
Hey all. So, I have 3xxx misfires on cylinder 2 and cylinder 4 in the history when I had the shop scan the obd2 for a small misfire that I can feel. I can only feel it when I'm in gear, at idle, with my foot on the brake. It's a very small stutter, and also when it's in neutral/park and you tap the throttle, the rpms stutter when they increase, and you can see it on the tach.
The block is the stock 97 vortec block that came with the truck. Full roller valvetrain, with comp hardened pushrods and full roller rockers. 020" pistons, longtube headers, MPFI conversion, full msd ignition. Blackbear tuned.
When I did the first start up on this engine, I was getting a terrible backfire out of cylinders 2 and 4 that was popping pretty loud, which ended up being the brand new MSD cap that we put on. Swapped it out for the stock one that we pulled off and it ran great. So, I got a replacement MSD cap and installed it and it was good (I thought.)
I pulled both plugs, and they looked great. Porcelain looked new still, no abnormal colors on the electrode. The gap was also correct.
My question is, does this seem like a valve adjust issue? The shop also checked all of the spark plug wires and all of them measured right around the same as one another (35000kv rings a bell? Not sure). Anyways, even though the wires measure all the same, does that definitely rule out a shorted cap? I'm thinking I'm going to swap out the msd with a delco unit, just because the MSD cap left a bad taste in my mouth. However, I'd hate to pull the valve cover just to find out that the valves are adjusted fine. I hate wasting time.
Anybody have any thoughts/input?
The block is the stock 97 vortec block that came with the truck. Full roller valvetrain, with comp hardened pushrods and full roller rockers. 020" pistons, longtube headers, MPFI conversion, full msd ignition. Blackbear tuned.
When I did the first start up on this engine, I was getting a terrible backfire out of cylinders 2 and 4 that was popping pretty loud, which ended up being the brand new MSD cap that we put on. Swapped it out for the stock one that we pulled off and it ran great. So, I got a replacement MSD cap and installed it and it was good (I thought.)
I pulled both plugs, and they looked great. Porcelain looked new still, no abnormal colors on the electrode. The gap was also correct.
My question is, does this seem like a valve adjust issue? The shop also checked all of the spark plug wires and all of them measured right around the same as one another (35000kv rings a bell? Not sure). Anyways, even though the wires measure all the same, does that definitely rule out a shorted cap? I'm thinking I'm going to swap out the msd with a delco unit, just because the MSD cap left a bad taste in my mouth. However, I'd hate to pull the valve cover just to find out that the valves are adjusted fine. I hate wasting time.
Anybody have any thoughts/input?