amount of boost for RPM/load
 

i'd search but how?

i think I might have a boost leak..sure make a tester and check..I'm planning on doing this..but

many time when I'm towing my work trailer(4-5Klbs) up reasonable hill..if without the trailer..no issue..with..at about 60mph..pedal down to the point the auto will down shift..I'm only seeing 10psi boost( 1800ish RPM).
is this about right? if the tranny down shifts..rpms go up and boost will hit 20 easy.

any thought? or do I need to just forget the issue and its not a problem.
as far as I know the truck is stock with 245K miles..

just wondering

-dkenny

Check the lower drivers side boot...the sheetmetal of the fender can cut into it...

Is it blowing white smoke?

Are you experiencing a loss of power?

Thanks..
I'll check it out.

its hard to answer the loss of power question since I have not driven another dodge diesel..nothing to compare it to.

if its got a leak I'm guessing its a small one..

no white smoke. that I know of

-dkenny

Any release of boost would affect performance. If you can get someone to rev it up while you watch the boots you may find your problem.

do you see any boost while just reving the engine?
I don't...hum..

-dkenny

You have to stab it so the turbo can kick in, usually to around 2500 rpm...

I would pull the inlet hose and check your turbo for sideplay and oil residue...

I tried that today..in neutral at 2500 it might have been 1psi..
normal? low?

I'm thinking I need to make a tester and pressurize the system.
do I need to plug both ends or can i just remove the air intake to the turbo and pressurize there?

thanks
-dkenny

That is out of my area of knowledge, I'm hoping some other members while post.

I'd pull the inlet off the turbo and visually inspect, for starters...

DKenny, I am no expert on our trucks but I have an Edge Insight that gives me a gauge for my boost pressure (data comes from ECM) and the numbers you mention in your very first post seem about the same as what I am seeing. I am pretty sure that if you are losing much boost pressure you will start to see white smoke and high EGT's. Sadly the only way to measure EGT's is to get a pyrometer and drill/tap the exhaust maniflold. That being said, most of the people who do heavy towing or performance mods say that a pyrometer for EGT's is about the best insurance policy you can get for our trucks (oh wait, that is after you get a fuel pressure gauge between the LP and IP). If you are losing boost then your EGT's can go up in a real hurry towing up a hill.

I hope this helps a bit.

You have to plug both ends. Plugs can be made from wood or Home Depot items. A few psi is enough pressure. It should hold tight. soap solution can be used.

Boost may drop off around 1550 rpm, Above that with a load and steady tach it should be 20+. I have heard wastegate issues may also be the culpret.

thanks for the help so far..
now I just need to make some things and do some testing.

my pressurizing line to my waste gate acturator is plugged..
could the waste gate just stuck a little bit open?
a couple of years ago I tried to make so the waste gate would move easily
but never could..hum?? maybe I need to remove the bolts. almost afraid to because of the rust..

-dkenny

Sounds completely normal to me. Your truck is stock and stock boost for your '99 is between 18-20 psi. So really your truck is at the high side of average for stock. If you have a pryo to compare with then you'll know more if you have a leak because EGT's will be higher than normal for the load. To know what "normal" is will generally just take time to recognize what range the gauges run in for your truck.

Its hard to determine and explain what boost should be to someone because boost levels aren't straight forward. In neutral you can hammer the throttle and boost will only get up to about 2 psi max. Thats because boost is a byproduct of both heat and airflow (rpm). Heat with no air will create high EGT's..... aka boost leak. Air with no heat will cause low EGT's and no boost. Just like the example I gave in neutral. This is why boost levels increase as fueling increases but trying to increase boost without fueling is a waste of time. Also EGT's dont increase at the same level of the load applied because the boost is shoving all that hot air out of the cylinders. Its really a marriage of components which work in perfect harmony.

So with all that said, your truck is fine. :thumbsup:

the other day I was watching the egt..it'll hit 1000 easy..most time its around 900..never seen it over 1100 either..

but now I have another problem..unrelated..

the rear driveshaft u-joints broke..the front 2 of the 3 came apart..
so I was thinking new ujoints good to go..
but then I found the transfercase extension was cracked..2 of the 4 mounting bolts are broken..and the yoke of the rear driveshaft section is bent.. :(

anyone know if its hard to swap the inputshaft from one transfer case to another..I found a used one but don't know if its for an auto or manual.I need a manual..would it be easier to just swap the tail extension.mine one piece from the transfer case out.

-dkenny

I dont know but I advise you ask such separate questions in brand new threads otherwise you'll only get a limited response by only the ones already on this thread. One topic per thread is the best way to get answers.

Just curious here and I might be completely wrong but free reving a truck shouldn't really produce much boost I would think. I have heard people advise people to just rev it up to 2500 rpms and see what their boost is and in reality, it will probably be little to none because the engine has no load on it. I'm sure someone more knowledgable will chime in, but this is just the way I would think: If an engine is free reving, the pistons are moving much faster and consuming the "boost" to a point where it is not enough to register on the guage or is registering very little. Once a load is on the engine it slows down the piston speed which allows more time for boost to build up, which at that point it can be measured on a guage. If I'm wrong someone feel free to correct me.....