Hi guys, been awhile since I've visited. finally got my cummins swap completed, been driving it everyday to work and so far I had no trouble. I took a gas 360out, and put the cummins in my 2500 ram. The question I have is it seems real sluggish at times. It seems to me that it doesn't build boost quick enough.This motor is bone stock with 80,000 mi on it and I do not have boost or egt guages yet. I really notice the loss between third & fourth gear, especially if i'm starting out at the bottom of a long hill. I'm not loosing boost it just doesn't seem to recover as quick as I think it should. The motor originally came with an auto tranny behind it, I put a nv-4500 behind it. I heard somewhere that their are two different springs for the fuel pump, one for auto and one for standard, has anybody heard of this. Just somemore info it's a 95-12v p-7100 pump nv-4500 3.54 rears. At highway speeds it's great, it runs like a top, the problem is running around town. Hope somebody can help clear this up.

 

make sure that the hose that bolts to the top of the AFC housing on the Pump is either connected to the intake of the head or to the compressor housing of the turbo. this adds fuel as boost builds. if the pump doesn't see any boost it won't add near enough fuel for the truck to go.

 

look at the black hose that goes from the back of the pump on this motor to the turbo compressor housing. that is the one i am talking about.

 

It has a tee on the back of the AFC , one goes to the intake, the other goes to the waste gate. To my knowledge the waste gate has never been tampered with, and it does move in and out freely when I move it by hand.

 

you can move the wastegate rod that is sticking out of the piece the hose connects to by hand? if so then that is your problem. you need a new wastegate actuator. it should be preloaded with a good bit of force to keep it from opening from the exhaust drive pressure pre-maturely.

 

Hope you read this ben, the truck does build boost, could this still be the problem? Just didn't want you to think it wasn't building anything.If so I will get a new one,if I can get just the waste gate. If not I will upgrade the turbo. Thanks alot man!

 

look into an adjustable boost elbow it screws into your compressor housing its about 20 bucks and takes about 5 minutes to install.

and the reason for the loss between third and fourth gear is normal. thats the worst part of the nv4500 trans is it has a horrible gap between 3rd and 4th

 

if the wastegate is not closing properly it will prematurely open and cause you to not build any boost or build it REAL slow. for testing purposes, take the wastegate actuator rod and pull it toward the actuator itself as tight as you can and use some bailing wire or a turnbuckle to hold the wastegate flapper closed and see if this makes a big difference. i have NEVER seen a turbo that had a working wastegate that you could easily move by hand.

here is a picture of how the turnbuckle can be installed. i do not recommend running this for long, but it should help you test to make sure the wastegate flapper is working properly.

 

i just re-read your post for the 4th time. it is kind of normal to lose boost under a load at a low RPM. you can adjust the star wheel in the AFC housing to allow fuel to come on a little harder down low to see if this might help it spool a little quicker.

have you done any fuel plate work on this truck? is it bone stock? if so then get gauges and start modding the crap out of the truck. once you get gauges there is alot of free stuff that you can do to get more HP out of the motor.

but for the time being get an 8MM allen wrench and remove the plug on the AFC housing. use a flat head screw driver and reach in the hole and rotate the star wheel toward the head, this in turn will make the wheel move towards the front of the motor. this will allow the fueling to fuel faster down low. doing just this IMO won't require you to have gauges, but it should help some.

and then put the plug back in there. buy you some gauges and then go to town, we can get you set up with all the great tech info we have on here on how to turn your truck up.

 

Thanks for all the help,yes the motor is bone stock. I plan to put a little fuel to this motor, but being that this was orriginally a gas truck I want to make sure everything is working properly, and put a few miles on it first. Other than this minor detail, everything is working great. Their may be nothing wrong at all, but it's hard to tell when you have nothing to compare to. Like I said it runs great, it's just a bit sluggish at certain spots. Where do you think I should start first, the wastegate or the starwheel? I would think the wastegate, and if it doesn't do much, try the starwheel or grind my plate down. After I get some guages in.

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Not to sound like I have no idea, but what exactly does this wastegate do. Maybe I have a big misconceptsion(spelling?) about it. I'm most familiar with big cam cummins motors where there is no wastgate. I was under the assumption it was to prevent to much boost.? Anyway I tryed wiring it back, didn't see a difference. I moved the star wheel 1 complete turn and did notice a little difference coming up the hill,but noticed a bigger difference on level ground as the splice between 3 & 4 gear was alot smoother. More like it should be. I want to try this one turn at a time. If I dial this to where I think it works best, will this have to be changed if I decide to turn it up a bit. I have know problem grinding the fuel plate, but don't know if a #100 plate will be to much. I don't want to hot rod the truck, but do pull a big camper. ( I did put a suoth bend clutch in it already) Let me know what you guys think.