During the dyno runs on the newly rebuilt engine tonite, the number 2 cylinder temperature decreases rapidly after holding the throttle at higher than idle for a few seconds. This happens after holding the throttle at mid - high RPMS for several seconds under light - moderate loads. It appears to be a function of time as opposed to the RPM that it is held at.

Once you bring the throttle back to idle, the engine and EGT in the cylinder stabilize and the engine idles perfectly.

It appeared to effect the #2,4,6 and 8 bank of cylinders once, but most notibly on the #2.

The engine is a Procharged, Fuel Injected 454.

All vitals seem fine and the EGT's are at 1250 - 1300 range.

All mechanical items have been checked - Lifters, valve adjustment etc... Fuel injectors have been flowed and new screens installed.

What if anything would cause #2 or that whole bank of cylinders to do this without effecting the 1,3,5 and 7? Like I stated it may not be the whole bank, just #2.

Engine is on the dyno waiting for troubleshooting tomorrow AM.

Thanks,

Kirk

Possibly a broken spring in the #2 injector-pintle is floating open as injector pulse widens causing an overrich condition.

Kirk, I'd be looking for water. Call me.

Rod

??

Connected scan tool today....no codes.

All parameters appear to be normal - MAP, ECT, Operating Temp, Oil Pressure ETC...

Swapped Injector from #2 to #1 cylinder, no change. The #2 cylinder seems to go cold once throttle is held at any RPM for several seconds. Cylinder 4,6 and 8 start to drop EGT soon after.

Wouldn't I see a code on the scan tool? No Knock Sensor problem either!!!

Someone has to have seen this happen. Engine Idles perfect and runs up great!!

Have you tried swapping the EGT sensors to make sure they are OK ?

Kirk, what are you running for fuel pressure, idle and WOT? If you are running more fuel pressure and larger injectors with a pretty much stock calibration its getting too much fuel. Are you using an A/F ratio sensor? EGT's are indicators, but not the real answer to tuning and proper fuel/spark curve mapping. I know you don't want to do it, but look at what you just spent. I'm pretty sure you don't want to do it again. Call me on my cell.

Rod

Swapped EGTs no change.

Rod,

I started at 40 PSI at idle which regulated up to 65+ at 4500 RPM.
Lowered it to 35 PSI at Idle and now its 58-60 at 4500 RPM. Wouldn't too much fuel affect more than #2 cylinder? If we leave it a high RPM then #4, 6 & 8 start dropping, but it is real noticable on #2.

Pulled a couple of partial runs up to 4500 RPM - as soon as we noticed the EGT decreasing, reduced throttle to 2000 RPM, cylinder came back and were able to run it up again.

Idles fine and until the cylinder drops out, all seems perfect!?

Again no fault codes on the scan tool.

ttt

Something's cooling it down in a hurry if the EGT's drop that fast. Its either dumping fuel or water into the cylinders.

Have you pulled any spark plugs????? If not I'd start there. Be careful running it, cuz if its fuel it will wash out the cylinders and fry the rings. If its water it could hydroloc and bend a rod.