Wide Open Throttle miss?

[grumpyvette]

Questionn Wide Open Throttle
Hello all, I have my super ram installed, and my third trans. build lol and finally have my car back, it starts fine and runs fine on a normal take off, If I gun the car full throttle I hear a popping sound almost like a misfire at wide open throttle, I guess at High RPM's ,the car has been sitting for the last six months and I just filled up the tank with fresh gas, not sure what the problem is but if im driving it with a normal throttle its fine but if I gas it I get the pop at high rpms right before shifts, not sure what is causing this. 383 Stroker- Forged Scat Crank,Probe Forged Pistons-LT4 HotCam-Accell Super Ram Lower and Upper intake-Holley 52mm Throttle Body-MSD ignition-Headmen Ceramic coated Headers-30lb red tip injectors-PCM Forless Chip-1.6 Roller Rockers,Yukon 373 gears, and Hours of Head Scratching



IIf your sure the timing is correct and your TPS sensor is set correctly, and you have at least 39 psi of fuel pressure and your injectors all test near nearly the same in the range of 12 -16ohms (they should all test within 2 ohms) your going to find if run it hard for a couple minutes than shut it off without letting it idle, pull all the plugs and post very clear pictures of each labeled as to cylinder number , you can tell a great deal from clear plug pictures, if your running the stock injectors chances are excellent your exceeding the expected pulse duration limits and its leaning out at higher rpms under load.
even those 30 lb injectors may not be keeping up with demand, it depends on the pulse duration the CPU allows,
this is one area in trouble shooting where having pulled trouble codes after experiencing the problem, being able to correctly read spark plugs and having a scanner and posiably a fuel air ratio meter, and IR temp gun can all will come in handy

http://www.injector.com/injectorselection.php

http://www.witchhunter.com/injectorcalc1.php4

viewtopic.php?f=55&t=606

 

[grumpyvette]

87vette81big ADDED THIS GOOD INFO

"Injector flow rate, ECM tune, TPS setting all important.

You may have an ignition misfire also.

A fuel fowled spark plug that won't clean fully.

Spark plug projected nose porcelain tip contaminated with conductive deposits that are near impossible to remove due to old gasoline ran through the engine running & driving.

Spark plug gaps that are too wide & cause a misfire only at WOT when combustion chamber PSI pressures are at the highest peak.
Snuffs the bright hot blue ignition spark out from jumping across the "J" gap as normal.

You may have dropped a spark plug accidently on the garage concrete floor.
May appear to be OK, but a crack in the outside porcelain spark plug body may be present.
When dropped, a hairline crack is developed between the porcelian & steel shell- hex body.
Best to check carefully here, any doubt, replace spark plug.

Carbon tracking or hairline crack in the distributor cap.

Center carbon brush in the distributor ignition cap burnt, worn out, or missing.

Defective ignition wires.

Spark plug wire boot is loose on spark plug.

A spark plug is loose in the cylinder head,
prevents proper heat transfer from combustion chamber to spark plug, through steel body of spark plug, to cylinder head, & through water jacket casted in head.
Spark plug severly overheats on WOT operation.
Pre ignition occurs & could lead to detonation also.
Pocketing piston ring upper lands on piston top & center dome top of piston.
Melting small amounts of aluminum away gradual,
& beating the crankshaft main & rod bearings to death & rest of shortblock.

I find loose spark plugs all the time turning wrenches for a living.
Many people don't get them tight or even close.
Turn them loose with my fingers & threads in head not stripped out.


As Grumpy said, incorrect base ignition timing set with distributor.

Very worthwhile reading Grumpy's links always.
very valuable tips & know how inside of each reading he provides.

BR "