...this would be the time id need it!...i just finished the install of the lq4, 6.0l w/ a MS4 cam at 112 lsa into stock exhaust manifolds, with a nelson tune....okay to me it sounds loud like all the exhaust manifold bolts werent tightened enough...it idles fine at 600 rpms and revs up from idle strong and fine in neutral but when i was driving home from my local craft shop... when i gently got on the gas it felt like power wanted to come on but it began sputtering above 3000 rpms...the power feels like it wants to be there but it just isnt....im going to tighten the exhaust manifold bolts, change spark plugs and go thru injector and coil wires making sure everything is secure but other than that i dont know what to do...

 

cam might not be installed correctly

 

How could it not be though? When installed...with zero marks lined up if things are one tooth in either direction off it shows a noticable difference in the allignment. I made sure it was alligned correctly!

 

Tune problem possibly.

 

I do plan to cover that base by calling Allen Nelson on monday for any clues...
I am actually throwing a code, P0121 but if that has anything to do with my problem i just dont know.

 

then you are good

 

could the Custom Tune really be the problem?... or could it be the stock exhaust manifolds either not flowing well enough or not being bolted on tight enough?

 

how tight are they??

 

well, tight enough not to see daylight through them but in my opinion not tight enough where they'r 3 bolted from the manifolds to the y pipe...

 

oooo those bolts i thought you were talking about where they bolted to the head itself...... o bro if it was leaking right their then their wouldn't be a question about it..... you would definitely know 100% if it was leaking bad enough to cause performance issues