hey guys just got the truck dyno tuned. im having a badddd misfire up top when im in boost and its graduale got worse. the truck will just fall on its face and pop and basically rev but go no were..

my mods are a 5.3 67k miles. isky triple 12 cam, kb racing 72mm FMI kit. stage 3 4l60e from performabuilt. 3200 stall. 3.73 gears. im running meth, and only 9lbs of boost.

to start out the truck did throw a p0300 code.. my tuner said it was down low from the TQ so u just to that code off. we bought a brand new MAF sensor when we were on the dyno. now all of a sudden it is throwing a p0101 code: MAF range and voltage etc.. im running NGK TR6 plugs.. was gapped at .035. so i changed the plugs cuz i thought i was gettting spark blow out, put new TR6s in and gapped too .28 no luck!!! i also have msd wires, volts are good on them i checked em. also i know im going to get realitivly bad gas milege. but im getting HORRIABLE gas milage. i burned nearly a 1/4 tank yesterday cruising not in boost, and i only went 25-30 miles...

any input would be greatly appreciated!! i need to figure this out!

 

switch to ngk BR7EF plugs gapped to .028 and get rid of the maf and go speed density. It sounds like the maf is maxed out with your setup

 

luckily i got some 7s yesterday i will try that foresure.. but on the dyno with the new maf he didnt tell me it was maxed.. it never threw this code until i went back up there and was street tuning it with him. cud it be a tuner error? it use to always cut out in boost above 5k but never did it immediatly fall on its face and just basically rev until i drove it home. approx 100miles.

also forgot to mention, i have five-0-motorsports 60lb injectors, and a aeromotive 340 steath intank pump with a casper hotwire kit.. it is returnless style. i also have no problems with Fuel pressure. its about 63 all the time.

 

Check coil packs... And what was your tuner saying? Ignore a misfire code?

 

how do you check your coil packs?
and basically.. he said he tuned numerous corvettes that had this code after a verter install, and said the verter was causing it down low.
but when the truck is realitivly cold it shakes at idle like its got solid motor mounts.. lol

 

What is the wide band saying when it is missing up top? Also how much timing and what fuel?

 

afr reads 11.2 11.3 somtimes it will go as low as 10.3 10.6 up top.. he told me its only at 13 degress of timing and im running 93 octane

 

Possibly valve float? What springs do you have? I'm having the same problem with my truck falling on its face at 5k, minus the missing though. I ended up going with dual springs for the added security from dropping a valve and also attempt to fix the problem. Mine ended up being a fuel problem.

 

i guess its possible.. i have PATC single behive springs from TSP. but i doubt it tho, cuz im only pushing 460 to the wheels on 9lbs..

 

Usually with valve float and boost it doesn't start missing, it just stops making power. That's if it doesn't tear your valvetrain up first. You can check coil packs by measuring coil resistance. Sometimes though, certain coil packs just aren't up to the task. I have seen this problem many times, and it is popping up more often now with more and more people getting the "LS boost bug". I might have to do a writeup on checking coils...