anthony251

I have a 2003 silverado 1500 5.3l the motor has a 228-230 comp cam and hooker long tube headers (o2's are in) the trams is built with shift kit and 3200 stall. The problem I'm having is I get a po300 code and its misfiring on all cylinders at idle but when u give it a little gas (off idle) all misfires go to zero . Also getting a map sensor code as well. Truck runs good except will die on hot starts every now and then also likes to surge here and there but will idle fine while at a stop light & has good mid to top power just not so much down low and I believe it has the stock gears in the rear end oh also running a new set of oem ac Delco plugs . Any help would be great thanks

nonnieselman

iTrader: (10)

yea tune should have been done with the cam.. thats were your misfires are coming from

anthony251

Thank you for responding ! Also what about the other code I'm getting for the map sensor? A tune will fix this as well rite? Also wanted to say I was sold the wrong plugs ( ac delco platinum #6) and got a lean code on bank 1 & 2 so I took them back and got the oem Delco plugs that came in the truck from the factory and I don't think the lean code came back, could the plugs I was sold cause a lean code? Thanks

nonnieselman

iTrader: (10)

ill have to look up which plugs you used the first time but i dont think so.. prolly cause of the cam?

Do you know exactly which "P" codes your getting? there are a bunch of them, so narrowing it down helps alot.

anthony251

yea it was the cam, at idle the computer shows miffire on all 8 cylinders, if u pick up the rmp all cylinders show 0 misfire so I def need a tune, but I have no idea what the po code was I just know it was saying lean bank 1 and bank 2 I think it was po171 and po174.