I recently installed (600 miles ago) a Banks Six Gun kit and Speedloader on my LLY. Up until just a few days ago, everything was fine. Within the last couple of days, the truck has developed a surge under load. I've been driving in level five for the majoity of the time, but the surge is apparent in other levels as well. It seems to be the most noticeable when I'm pulling a grade at a steady 50mph or so, then, when I put my foot in it to accelerate... say close to half throttle, the truck will accelerate but it starts surging. The egt is around 950 - 1,000 and boost is around 15psi. Once it gets over 65mph (load decreases on engine) the surge slowly goes away. Every now and then I will even feel it on flat ground under hard acceleration. I've tried changing the six gun selector to different power levels while it's surging, but it seems to make no noticeable difference. Any thoughts on where to go from here?

How many miles on your fuel filter?

8,600 miles on truck and 8,600 miles on fuel filter.

Pop a restriction gauge on it or change it and see. I may be wrong, and it may be the Banks, but my guess is that you are restricted which is quite common on the LLY even with stock programming. Lift pumps have shown to take care of this in most situations.

Thanks for the advice, I'll replace the filter tomorrow and try it again. When you say it may be the Banks, do you mean it might be a defective box, or is this typical behavior for an LLY that a lift pump will cure?

Most likely the fuel filter. Forget that I mentioned the box until you determine that the filter does not cure the problem.

Consider addding lift pump supply as a priority to reduce/avoid further issues.

I admit I don't know anything but can certainly guess when it comes to this topic, so, I'll ask a question...when a transmission "slips" can that seem like "surging" under load? ...or would that result in a limp. Haven't had either that I'm aware of and am just building my seat-of-the-pants data base.

Well, I replaced the fuel filter today, and no improvement... it still surges. I then disconnected the Banks box to see if it would make a difference. I went back to the same grade I had pulled just twenty minutes earlier and the truck ran worst than with the box connected. Halfway up the grade, I put my foot in just like before and it actually started cutting out, really bad. Before I disconnected the box it would surge, but now it's acually cutting out... really, really bad. I lifted on the throttle and babied it to the top of the grade. When I reached the light at the top of the hill it was missing at idle. Prior to starting up the grade, it was not missing. When I threw a u-turn at the light to head back home, it was missing and chugging. It felt like it had dropped a cylinder. One cylinder seemed to be rattling really loudly. I babied it all the way home, and by the time I got home, the check engine light was on. It's still missing on one hole. Any thoughts as to whats going on? Could it be a bad injector? I completely removed the Banks hardware so I can drop it off at the dealer tomorrow. Will it damage the truck (engine/cylinder) to drive it to the dealer, or should it towed?

Mine did the same thing My PDA told me it was #1093 somethin about fuel rail pressure.Took it to the dealer they said it was a bad sensor. Still dont know if they fixed the sensor or just cleared the code!

Check for codes. The missing could be the injector connectors.

Dropped the truck off at the dealer this morning. I'll let you know what they find in a few days... hopefully soooner.

I get my truck back tomorrow. The dealer says the F.I.C.M. was causing the misfire/dead hole. Not sure what FICM stands for. The service rep could not recall what the F and I stand for, but did know that the C and M stood for control module. Anyone know what this part is or what it does?

Fuel injection control module, think its on the left side of the engine.