Competition Defueling Problem While Sled Pulling??????

[JStrosnider]

Ok guys and techs here's something to scratch your head about. . My friend has an 01 Dually with a H. O. 24V 6 speed. Here are the mods.

1. TST Powermax Comp box.

2. Lightning 2 Injectors from Scheid 150HP.

3. 95 GPH Fass Fump

4. Brand New VP 44 pump from Industrial Injection

5. 4" exhaust directly off charger to twin 4" stacks.

6. A Bigger charger (I'm not exactly sure what size but it's almost equivalent to a 64 super by Industrial Inj) but I do know it's definately way bigger than stock. .





Now here's what's going on. . Driving (WFO at about 3000RPM's) down the street this truck runs with no flaws and produces about 30psi boost max. Smokes like a freight train, fuel pressure stays right at 15 psi and the the truck doesn't hesitate, spit, sputter or nothing at all. It runs flawlessly!!!

However we are having a problem when he is hooked to the sled. Going down the track the truck smokes pretty heavily although normal (nice even steady cloud from both stacks) and then all of the sudden the engine just quits fueling (such as like he has hit the speed limiter). The smoke stops engine idles down slightly and then all at once resumes it's Wide Open Throttle. Depending on where he is on the track determines how many times this happens during a single pull. So far it has consistently done this 3 times per pass. To us it seems like the engine is defueling itself and then fueling again. . Oh and during each pass he is taching approximately 3000 RPM's and is carrying a steady 30 psi boost and the fuel pressure stays right at 15 psi.



TST states that it has an anti-defueling device built into the comp box and therefore should not be creating this problem. The box is currently on it's way back to TST for inspection. . Does anyone have any suggestions or has anyone ran into this problem before?? Please help me if you can!!!!

 

[BHaner]

He doesn't have an EGT defuel on the TST does he? That's the only simple thing I can think of.



It seems to be load related. Do you have any video of the pull? Could it be tire spin causing the RPM's to spike and defuel due to high RPM? That would explain the good fuel at the start, and at the finish when there is traction again.



If not tire spin, maybe he is pulling in too slow of a gear. This would cause load at the start and at the end... But he would be at redline at half track.

 

[JStrosnider]

I'm not sure if the TST has an EGT defuel on it but that may be something we need to look into. But if I remember correctly he said it's only getting to about 1000-1100 degrees. . Yes we do have video of the pulls but I have no idea how to set them up on here for all to view. If I knew how, I would. I honestly don't believe that it is tire spin, the truck is really hooking well on the track and is getting excellent bite. The gear he is pulling in is High Range 2nd. He has attempted 3rd but doesn't have the needed horsepower for it. The same goes with Low 5th. Also he is taching 3000 RPM's all the way down the track maybe even a little more.

 

[Rebel Ram]

I dont know if these are related but before i got my smarty I couldn't hardly get any rubber without the same thing as you discribe. I knew something was up because I had great power otherwise. Without the smarty the trucks ECM shuts off fuel for torque controle limiting wheel spin. I dont know how it works but after the smarty I can posi for days and no defuel. Borrow one and try it.

 

[Bob Wagner]

The smarty remove torque management Oo.



let the good times roll :-laf

 

[JStrosnider]

I found out today that TST has the defuel set at 3200 RPM on the Comp Box. They said they are going to check the box for problems and then clear out the 3200 RPM Defuel and program it to 4500 RPM. . We should have that box back by Friday so hopefully this weekend we will know more of what's going on. . If this doesn't cure it then I'll look into the smarty box. . thanks

 

[MCharlebois]

how can you borrow a smarty when it locks into a vin number??

 

[Bob Wagner]

the smarty unlocks when the first truck is returned to stock

 

[tshort]

Is that EGT pre or post turbo, I would think with those mods that truck should peg an EGT gauge with or without a sled. I would think a defueling issue also. Just my 2 cents.

 

[Todd T]

There is also a speed limiter (Torque Management) built into the truck. Have you snipped the Vehicle Speed Sensor (VSS) input to the PCM yet?

 

[JStrosnider]

OK everyone. We got the TST back installed it back onto the truck and also made a boost leak repair. We found about an inch and a half of intake gasket missing. But with everything back onto the truck we pulled on Satruday night and everything is great. No more Defuel problems and the truck really hooked to the track and was good enough to take first with a pull of 306 ft!!! TST removed the the 3200 defueling program out of the box and installed a 4500 defuel program back into it. So far the truck is running better than ever. However after fixing the boost leak we now have lost half of the amount of smoke we were putting however we putting down a ton of more power. Thanks for everyone's input and hopefully this will work for anyone else that runs into this problem...

 

[JStrosnider]

Is that EGT pre or post turbo, I would think with those mods that truck should peg an EGT gauge with or without a sled. I would think a defueling issue also. Just my 2 cents.

The Pryometer Probe is the manifold. Honestly after fixing the boost leak the truck ran cooler. Making more boost and more power because we were able to flow more air... The Truck is currently border line on being to hot for a daily driver. I have similar mods on my truck (same hp inj. but different fueling box and turbo) and over the weekend I pulled our 20 ft horse trailer loaded with through the Mountains of West Virginia and my truck with my box turned all the way down my EGT's were at 1100 degrees pulling the mountains. When the box was turned all the way up it would run hotter than 1300 degrees ( I would get it close but not over) and took it a few seconds to get there. . However I only turned my box up just to see what it would do... It blew lots of smoke and yes it did get hot but it did take it several seconds to get their. But it is kinda cool because now when I'm pulling our horse trailer I forget it's back their because the truck pulls it like it's not even their. OH here's one for thought!!! I also got 12 MPG with the fully loaded trailer through the mountains. Is their fair fuel mileage coming from a truck pushing around 500 HP at the Rear Wheels... .