Very Long Story but very informative.

Well basically my buddy has a 97 Lt1 camaro with a 383 a 236/238 L.E cam and L.E3 heads and intake. 7.150" pushrods, 1.6 promags, comp cams lifters all new stuff. 58mm ASM throttle body not monoblade, 4k stall and stage 4 built trans and a 3.73 12 bolt. This is a brand new balanced engine that has been decked, milled, honed and all the goodies. 42# injectors and yes it was base tuned TRYING to get a actual dynotune, but this is what happened now. While all the other parts are used but were on a perfect working car from before. Like the opti and all other parts just swapped over to this engine and ran it. It runs like a beast and sounds awesome with the help of LPP headers with a LM2 exhaust and cutouts. But we had taken it to the dyno 2x and it falls on its face from the start of 4500 rpms all the way up top. The dyno shop says it could be a opti, bad wires,plugs etc......Well we check the plugs they are all fine and the wires are not arching or crossed, the coil is a msd and the ICM worked before and has a spacer mod could it be culprit (idk). The next day we swapped the opti for a complete gm unit with cap and rotor with loctite BECAUSE when taking off the old unit guess what the rotor fell off due to the screws backing out...hahaha So with the new one now and loctite on the screws for the rotor and figured that this had to be the culprit on why the dyno was a bad day. Well back on the dyno again and guess what the exact same problem as before with the new opti, what can be wrong now? We had double checked the pushrod length and re set the valve lash, the opti cant be bad but you never know, correct? Fuel pressure is well above 45 and all the grounds are good. Can the ICM be bad? Need help this is bullshit its a new setup and the car needs to get out already, way to much money is involved in this and would like to get out this month. Any help would be greatly appreciated.
thanks, TOM

 

what # injectors r u having, and did u get a tune ??

 

added to post, sorry

 

A few things come to mind, just throwing them out there...
-valvefloat
-incorrect valve lash adjustment of the rockers
-bad coil
-fuel pressure dropping at WOT under load

 

Could be the fuel pump failing under load like SS.slp.ls1 said. Stock worn pump just might not be able to supply the new set up with enough fuel above 4500. The same pump on a stock motor could be fine and show no signs of failing.

 

Yep I agree, fuel pump could be weak starving the motor above 4500rpm.

 

Well everything I would have said, was already stated above. So I must say I concur with the above posts.

 

Same thought here as that is what happened with mine. The thing is though, once it was determined something was up, the dyno operator taped a fuel pressure gauge to the winshield on the next pull to confirm this. Was that done with yours?

 

sorry for the late posts but yes it does have a brand new fuel pump which is a 255 in tank pump. The valve springs were also checked for coil bind and they are okay. Fuel pressure was never checked at w.o.t but that is next on the list. The coil was perfect and has less than 5k miles on it and is a msd!

 

well even though its a new pump it could be bad....how did you check coil bind??

 

well we had tested the new pump and it has steady pressure across the board at 45+ which is good, so what else can it be. How would I test the icm or coil, can I even test it?

 

not for inconsistencies, you could test as a complete failure but not a miss...

 

Spark plug gap to wide, and having spark blown out?????

just a thought.