First time posting on this site, i have to say this site is amazing always have found stuff that has helped me. Well im hoping someone could explain whats houng on with my truck. First and foremost the truck is a 1999 2wd 5 speed 3500 2nd gen cummins and it has a cold air intake and a intake horn, edge ez, 50hp injectors, new H. O vp44. The truck has 307k miles and runs amazing and has no issues. But when im driving on the highway at a steady speed around 80mph the sound in the engine bay will change every 15-20 seconds it is most deffinetly the sound of combustion changing and or the injection timing changing. The truck will have the typical knocky 24v clatter that sounds kind of like a machine gun but every 15-20 seconds that knocky sound will totally disappear and the engine sounds so smooth at this point, after about 5 second, sometimes a little longer it goes back to the klattery machine gun sound for another 15-20 seconds and then back to the smooth sound. It is most deffinetly the sound of combustion and not like valves or anything like that im 100% sure of that. Its like the ignition timing is changing and changes the engine sound. Exhaust note doesnt change its all under hood noise . Has anyone ever seen this or have a clue at how and why it does this? I wish i had a way to view the timing commands in real time and see if their is a correlation in timing changing and the sound changing. It would be nice to find a way to make it have that smooth quiet tone all the time while on the high way it would deffinetly keep some decibels off  

 I believe the ratio for the 2 cycle oil to fuel is 1oz oil per gallon of fuel. That's what I've been doing for a couple years now.

 Also, did the map sensor connections clean up good? You stated that it had green corrosion in the plug. You may want to replace the plug or sensor to be sure of a good connection.

 The w-t mode shouldn't take more than a couple hours under the hood and we'll worth the effort. Read the w-t ground mod simplified article by @Mopar1973Man, it gives you the meat and potatoes of the process. 

It seemed to clean up fine i sprayed starting fluid in the connection(all i had, no contact cleaner) and i took a pick and scratched the pins a little it didnt look horrible to begin with just deffinetly had signs of corrosion from the green dielectric shmoo. And deffinetly guna do the w-t mod when i get a chance, woulda tackled it today but its been pouring all day, i skimped through the link and it doesnt seem to difficult i think i could gdt it done in less than a couple hours. Is there any real world problems on manual trucks that you guys have hear this mod fixing? Also wire tap tuners, have you heard of anyone taking their stock vp cover and drilling and tapping a hole for a long sharpened set screw for the wire puncture like how bd diesel sells a cover and blue chip?

BD Stealth Plate is what your looking for. I've got one on Beast.

Oh i know bd sells them just looks wicked simple for me to just drill and tap a hole in the same location on my stock cover and throw a sharpened set screw in. Is that all the screw does is poke a hole in the wire?

 

NO. It pierces the plastic case and lightly touching the circuit board tracer internally. There are no wires inside the case just a circuit board.

 

 

Ahh i see, so how do people do a wire tap without the cover? And ill probabily get the cover then instead of messing around with it 

Tap the wire. Problem like me up north the salt would rot the splice and your in for a VP44 replacement. Best to use the plate being it is a weather proof connection.

Yea im guna get a plate, also im in the middle of doing the w-t wire mod as we speak not fully understanding, so the big wire on the back bottom of the alternator that now goes to the positive terminal on the passanger side right? And the other wire that necks down to like 4 wires that gets cut at the 4 wires and grounded to the timing cover right? And that it right? 

I see i use the wire that i cut off of the 4 wire that go into it and use that to ground the batttery to the case aswell but what do i do with the wire that comes out of the fuse pannel and goes to the alternator i know it gets cut and connected to passanger side posative terminal but what about the fuse and **** thats in the fuse pannel 

 The large wire on the bottom of the alternator is the charge lead, that should go to your 150a breaker or fuse then to the passenger side battery.

 The wire from the fuse panel to the alternator is tour field lead. That goes back into the loom going across the front of the engine. No cutting for that one 

All good ended up figuring it out was a little confusing  on some things but everythings all nice and soldered. Truck still seems to be hunting timing on the highway, i have my edge unplugged its quieter with it unplugged. Guna try to sell the edge on market place and put it towards the adrenaline. I have a quadzilla xzillaraider model DXZ01s and im trying to find a male and female pig taile for the map sensor as someone cut them off the harness any idea where i can find these plugs the male ones are easy to fine but thr female i cant seem to find. There a metri pack 150.2 i belive

Well i figured out that a gm oil pressure plug extension has what i need, both plug ends same style plugs but here's my dilemma now the xzillarator harness i have had the plugs cut off. Well im trying to figure out how to wire the new plugs on the harness only has 2 wires coming out of the loom for the 2 plugs 

@daav544, before we go putting another tuner on her how about we try to sort the problem first. Since you did the ground mod have you checked for a/c noise? There is an article explaining how to do so.

 You said you have 50hp injectors so she should run fine with no tuner. I run 100hp sticks on stock tune no problem.

 Do you have a scanner? One that will give you live data? If so, you could try driving down the road at a steady speed to recreate the issue and take note of engine load, if your on flat ground, climbing a grade and so on.  If you hit a small hill obviously the engine load will change. If this is happening on flat ground for no reason then we need to figure out why timing is changing when not needed.

 You also stated that it has a new H.O. vp44 pump. Who installed the pump? There could be something there. Maybe wrong key when installed? Someone with more vp44 install experience can chime in on that part. 

 Just thinking it through trying to help.

I have a obd link MX+ its a bluetooth scanner (100$) and i belive it reads engine load it does live data in graph form and stuff i used it to watch my o2 sensors on my old 4.3 silverado that was acting up would throw a blinking check engine light when on the highway moderatly accelerating in 3rd or 4th gear long pulls never did figure it out weirdest thing was throwing random missfire codes i think it was a sticking valve from what i had read but thats neither here nor there sold that for the cummins but ill have to get the scanner from my pops. And i wanted to atleast get the tuner wired so i could put it up for sale as well

 

 And the quadzilla zillaraider you have there, honestly that's the first I've heard of one. Not saying they're good or bad, I've only heard of the quad adrenaline and the xzt. @dieselautopower may be able to help with that when needed.

Its an older one fuel tap does 30hp 70hp and 120hp the instructions are for the xzillarator standard(the one i have) and the xzt but it is an older discontinued one. Any who with watching engine load at a steady speed what do you think ill see? And there wasnt much things i could watch on the scanner compared to my silverado. Not as much **** in these engines to watch im guessing but i belive engine load was one thing i could watch

 Mainly watching for engine load change for no reason. On flat ground, cruise set the engine load shouldn't change a whole lot. If it is then something may be causing the timing to fluctuate for no reason. Engine load is what would cause the computer to change timing.  

Oh and a friend of mine who had the truck before me installed the pump im sure he installed it with the key that is in it. But i talked with power driven diesel when i was on a different form on facebook this guy had a cam gear one tooth off and people were saying spin the engine over again it will line up. Which obviously you know will never line up cus they are same sized gears any who people were bashing me saying there a hunting gear and will eventually line up i asked pdd and they said same sized gears which i knew but the guys truck was running fine and they asked if it was running fine and i said it was and they said that the vp could compensate for that. Dont know if thats true or not so in that sense i wouldnt think if the key was wrong it would be an issue considering if a cam gear was off 1 tooth and there saying the vp could compensate but who am i.

And i never did check the a/c noise as well illl have to do that. I did it to a tee though soldering everything all nice and stuff

 I won't claim to know alot when it comes to a vp44 install, I have yet to do one myself. I do know that if you don't use the key the new pump comes with it can mess with things. I don't know if the pump will compensate for something being "off".

Yea i wouldnt think that either but straight from power driven diesels mouths and considering this guys truck was 1 tooth off and running just fine idk. But ill ask my buddy tomorrow if he used the new key im sure he did. Now what would be the difference in a new key and old key arnt they just a regular key for a keyway? Or do they have some degree to them like an advance key for some old motorcycles ive seen

 The keys are selected when the pump is being tested and calibrated. They are a specific size to obtain the proper timing for that particular pump.