YeahIt'sReal

Just got motor in. Got 530 mi on it and 200 of them are with it tuned. Car was running real rich to start off with. By the way it's a 383 stroker with a big cam and stock heads if that makes a difference in this. M6 car. Alright when i'm cruising down the road in 3rd or 4th (gears it's worst in) if i'm at any rpm below around 4,000-4500rpm then it wants to miss. It doesn't miss at idle or when i hold at steady rpm. Just under full throttle in gear. If i ease into the throttle and slowly go to the floor as i almost get to the floor it starts missing. So am i looking at possible fouled out plugs from before tune running rich, or too much gas? I'm about confused. I thought plugs at first but then i figure it would do it all the time. Well i'm gonna go pull them out and take a look. If anyone has any other suggestions on what i should look for please help. Thank you.

derek_silvy

My guess it a tuning issue, but before you go that route.... pull the plugs one @ a time, and turn the lights out. Have some1 crank the motor and see if you are getting good spark to all of them.

Also, what octane are you using?
Good luck!

YeahIt'sReal

using Premium 93 octane. Also service vehicle light is on but my local GM experts said that it was only one code he could find and that was my EGR that i removed. No service engine light just service vehicle. came on during dyno GM guy said because of the rear wheels spinning real fast and the front not. Anyways i'm gonna pull plugs soon. Hopefully it's that simple.

blkbeaZ28

iTrader: (4)

Definately start with the plugs. I had the same problem when I did my motor swap a while back and it was a fouled plug. When I replaced with new plugs the car was still missing. I was confused then. I thought it needed to be tuned. While I was at MTI getting a retune they asked if I had changed out plugs. Confident that I had taken care of that and they were not the problem. Jayson took out plug 7 and saw I had cracked it while installing it. This was a while back.

A few days ago my car started missing last night I swapped plugs out this time being careful.. anyways car runs fine.

Check the plugs, wires, and then O2 sensors

Gilbert

1970judge

iTrader: (12)

my guess is the stock heads have stock valve train?..its never wise to upgrade to a nasty cam with stock valve train equipment..thats my guess

YeahIt'sReal

naw. only thing stock in vlave train is rockers and those will be gone soon when i do the heads. Thanks for the input everyone. None of my plugs looked bad but i did replace all of them. The only thing was is that all the gaps were set at roughly .30-.35 I set all around .46 this time. Other than that and my first oil change i'll see how it does.