Today I went up to the mountains and noticed something.... Whenever my EGTs were below 350* and I stepped on the throttle (NOT in gear) it really struggled to rev up. It would buck and pop and blow white smoke, then when it got to around 2,000 rpm it would smooth out and rev up higher just fine. I tried it multiple times because there were no cars around, and had the same result every time. 

 

Now why would it do this?? Could altitude be a factor? Could outside ambient temps cause it? Could high timing at low rpms cause it? I've heard of pre-ignition on diesels with high timing but I'm not sure if that's what it was.

I will say the smarty was on #1 which is supposed to have higher timing than the rest, but I didn't bring it with me to see if setting it back to stock would change anything. 

 

Let's hear what you think!

It's a VP thing, Step up to a CR and leave your worries behind.   

Could altitude be a factor?

 

Shouldn't. MAP sensor should adjust to elevation and sense atmospheric pressure changes. Unless your MAP sensor has failed within limits which will not throw a code.

 

Could outside ambient temps cause it?

 

Possible. Colder the IAT temperature the more advanced the timing. Warmer the IAT the less timing.

My theory... chamber and head gets cold on the long descent down the mountains, and doesn't get warm enough to fully combust.

I see cooler than coolant temp coming down hwy14 from walden and it will chuckle a little when I first get back into it.

Shouldn't. MAP sensor should adjust to elevation and sense atmospheric pressure changes. Unless your MAP sensor has failed within limits which will not throw a code.

 

 

Possible. Colder the IAT temperature the more advanced the timing. Warmer the IAT the less timing.

MPG fooler was on.... so IAT's said 143*

Remember my thread about the MAP sensor sticking on higher than zero? Well it was doing that again today. It would bounce between 2 and 4 psi while idling. Would that cause enough timing advance combined with the smarty? Also, ever heard one of these engines when a wiretap programmer is trying to fuel and the ecm is trying to idle?? It isn't pretty.

 

CSM you should try popping it out of gear and snapping the throttle a little bit... see if you have the same symptoms.

 

CR and College budget do not mix!!

For what I see you have invested into that rig in the last couple years you could have had a really nice 3rd gen with extras by now.

I'm in the same boat, Bill. But I'm in too deep and can't find decent 3rd gens.

I kick myself for not buying one.

For what I see you have invested into that rig in the last couple years you could have had a really nice 3rd gen with extras by now.

I think I'm right at 15k including the truck, and I'm at 500hp. To do that in a 3rd gen you need over 20k including the price of the truck....

Plus, my VP can put out more fuel than a stock cp3, my injectors are 1/4 the price of a third gen, nv4500 parts and pieces are cheap, and Second gens LOOK BETTER 

Early 3rd gens are about that price right now and a Smarty is about 5oo bucks and you have 500hp. I have a totally stock 05 with a smarty jr and am over 400hp already. :gun:I think the 3rd gens are equally as good looking as the seconds but the cabs are way tighter with 4 doors rather than quad cab and the frame and drivetrain is way stronger to boot.

Next go around flip back to normal IAT.

Early 3rd gens are about that price right now and a Smarty is about 5oo bucks and you have 500hp. I have a totally stock 05 with a smarty jr and am over 400hp already. :gun:I think the 3rd gens are equally as good looking as the seconds but the cabs are way tighter with 4 doors rather than quad cab and the frame and drivetrain is way stronger to boot.

Maybe where you are?? 03-04s around here still top 18K. Maybe a smarty set to kill could top 500, but at that point you're stressing the injector solenoids, EGTs are sky high, Drive pressure is crazy high, and a new clutch is needed. If I was shooting for 8-900hp I would absolutely go with a 3rd gen! But being in college, if I break parts on my 2nd gen they are relatively cheap. I will step into a 3rd gen when I'm out of college.... probably and 06 or 07 5.9 and I'll go crazy on that one. Until then I'm going to enjoy tinkering with this one!

 

Thank you for the tip Mike, I'll do that next time.

This is something that I have wondered about because it was a big problem back with the 855 cummins with the pressure pump back in the 70s and 80s when I was a owner/operator and we were told that on any down hill run to put your foot onto it about every 30 sec. as to not to run the pump dry. I have not had any long down hill runs to check mine but I have wondered about this with our trucks.  For this reason I have not taken the route through Denver on my yearly trip from Wi. to NV. because there is a down hill run that is so steep that I don't touch the accelerator for about 65 miles with my trailer behind me.

No. The overflow valve will continue to flow fuel as long as supplied fuel pressure is above 14 PSI.

This is something that I have wondered about because it was a big problem back with the 855 cummins with the pressure pump back in the 70s and 80s when I was a owner/operator and we were told that on any down hill run to put your foot onto it about every 30 sec. as to not to run the pump dry. I have not had any long down hill runs to check mine but I have wondered about this with our trucks.  For this reason I have not taken the route through Denver on my yearly trip from Wi. to NV. because there is a down hill run that is so steep that I don't touch the accelerator for about 65 miles with my trailer behind me.

Mike is right! You aren't going to hurt anything on these trucks. The EGTs will drop and you'll experience some engine temp drop, but it won't hurt a thing. My injectors, programming, IAT fooler ect are probably the reason mine was acting funny.

Like Pepsi71Ocean taught me a while back its possible to fool sensors and create problems too. Like him he was paranoid of hot shutdowns on the VP44 so he used a fan to cool the VP44 all the time. What would happen is the truck will start up and run backwards. So it's possible with the Smarty and IAT fooler or both is causing your issues. Like I said try dropping the IAT and then try it again without the Smarty.

How often does your map read not 0 psi at idle? 

 

sounds like it is time for a new sensor to me. 

How often does your map read not 0 psi at idle? 

 

sounds like it is time for a new sensor to me. 

Well the last two times I have driven it the reading has gotten off over time, BUT both times the truck was started at high altitude and driven down to a much lower altitude.

I think I'm right at 15k including the truck, and I'm at 500hp. To do that in a 3rd gen you need over 20k including the price of the truck....

Plus, my VP can put out more fuel than a stock cp3, my injectors are 1/4 the price of a third gen, nv4500 parts and pieces are cheap, and Second gens LOOK BETTER

2nd gens don't rot as fast ether. I see more 3rd gens in worst body shape.

i miss the sound of my 2nd gen. Yes the 3rd gens is quieter, but that older cummins sound is music to my ears. price wise, i had more into my 2nd then i do my 3rd.

sorry i have nothing useful to add to the post.

I think there are lots of people who like the look of a second gen better. They are sure holding their value around the big city Portland, Oregon anyway. I see them for 18-22 k for nice ones.