I finally got to tow my 4k pound camper this weekend with my truck that I have had less than a year. When I drive down a flat freeway empty (no camper/empty truck) at 65 MPG my boost is between 2 and 3, EGT around 480. Boost gradually goes up on mild grades and power and speeds are easily maintained with only slight increases in go pedal.

When towing a 4K pound camper and beginning to climb a slight grade (maybe around 3% grade?) at 60 to 65 MPH at 1900 RPM to 2000 RPM in 6th gear I will see increasing boost up to around 8 or 9 PSI with smooth acceleration. However, the boost level will not be sustained at a certain point of climbing in the slight grade. At this point significant additional go pedal is required to maintain speed AND the boost just drops down to 3 or 4 PSI like clockwork. At this point power becomes diminished and EGTs jump very quickly from 750 to around 980. My thought is that the wastegate is bleeding my boost out prematurely. I duplicated this several times today and the boost PSI drop happens at the same point with respect to go pedal amount and climb point in a slightly increasing grade. I have no problem installing a Turbo Master adjustable waste gate unit if a failed factory waste gate is the problem. I just want to be sure before going there.

I checked the following: No soot or any apparent leakage around uppipes, no tears in boots and they are all snug. No codes.

Background: Overall city/hwy empty mixed mileage is around 19 hand calculated. Truck blows no smoke even under accelaration when towing up a mild grade when the boost level bleeds off (power drop is pronounced though). No noticeable oil consumption between 3,500 mile oil changes. Did a quick blowby check with engine warm...upside down oil cap will just sit on filler tube and not get ejected. Engine is stock with exception of Edge Evo run in mild tow tune and CCV mod. Same behavior noted in stock tune as well. Truck has 118K miles on it. Trying to figure out what else to look at before pointing my finger at the factory wastegate controller and replacing it.

 

Try hitting the grade around 2200 rpm's or a little higher and see what that does.

You don't mention the drag. How tall is your trailer above the truck roof line? I can tow an 8000# flat bed easier than a 4000# sail into a headwind.

 

Trailer is 10.5 feet high. It is an Orbit Ultralight and is 21' long.
When towing I did try slowing up a bit on the grade and down shifted out of overdrive to bring up the RPMs to between 2,200 and 2,300. Same result, boost drops to right at about 4 PSI at that point in climb. I can build boost up to a certain point but can't sustain it above 5 PSI when under a towing load. During beginning part of slight grade I can see only 9 PSI for a few seconds before it drops.

 

just to give you another ref. point...

i towed mine home (10# camper) on interstate yesterday and on the flat spots boost was steady 5 psi and EGT's maybe 850* come to a slight hill at 65-70mph in 6th gear and the boost would go up to about 12psi and EGT's to 1150*

i think i have some EGT issues since I'm stock but havent tracked them down yet.

Good luck with your issue

 

bump..i just want to follow this thread

 

Ok, thanks for that comparison. Your boost is the same as mine while in 6th on flats at 65 MPH. Your EGT is a bit higher than mine but you are pulling 10K rather than 4K in my case. Where are your RPMs at 65 MPH in 6th while at 12 psi on slight grade? Also, I take it that your 12psi is maintained the entire time while traveling up that slight hill and does not taper off during your climb, correct?

 

If you want to follow a thread and have nothing to say there is a subscription option at the top of the thread that you can use in the Tools menu.
Just FYI, not being rude

 

Try unplugging the wastegate via the red tube and see what happens. This will basically shut the wastegate off.

 

Yes, good suggestion. I actually disconnected the red tube yesterday to see if there is any change in boost levels while driving empty and not towing. I noticed after reading a few other threads that many run with it disconnected when the truck is stock or under a mild tow tune. I did not notice any change initially when getting on the go pedal while empty but my issue seems to be sustaining boost level when towing. I won't be pulling the camper for another couple weeks. However, I am leaving it unplugged and will tow with it that way to see if sustaining boost PSI changes. Do you know if most people typically see higher boost levels when not working the truck (loaded/towing) with the red tube disconnected?

 

Some do. Some see a couple extra pounds at max. I didn't notice any difference on mine so I just plugged it back in.

 

I can't believe a malfunctioning wastegate would dump that much boost.

No smoke makes me suspect an engine control/fueling problem rather than a turbo/boost problem. Do you have any way to check fuel pressure?
Have you tried disconnecting your ICP?

 

I reached back to the wastegate rod and opened and closed the valve. It definately is under a few pounds of tension and requires firm pressure to move it. Haven't tried disconnecting the ICP but I can do that and see if it changes the engine idling or if it has oil in the sensor. Haven't had any codes come up though. I don't have a fuel pressure gauge but if that becomes the next item to check I can buy a gauge and order the bowl port from DieselOrings. I originally thought that maybe the wastegate return spring had possibly become very weak over time and is letting off boost way too early. However, I got on the go pedal the other day when empty (3/4 throttle or so) on a slight grade and got to 11 PSI quickly in a couple seconds. Went from 55 to 70 MPH like a rocket with no smoke (with unplugged red hose). If early opening of wastegate was a problem I don't think I would get that performance? Unless there is something very different about towing a 4k load up a grade that changes the symptom of a weak wastegate return spring. As it turns out, I will be towing about 100 miles today and will see if boost changes at all under load with red hose disconnected.

 

Broken record here.
Have you done the fuel pickup yet?
Loss of fuel pressure will do what you describe.
Also adjust your wastegate rod so that it doesn't open before 12 psi.
On that long hill from 145th to Northgate southbound I maintain 12 psi empty.
Towing the trailer boost holds 19 stock tune.
4.88 axle makes the engine spin pretty good so that helps.
Call me if you have some questions.

 

I would say RPM's are around 2200-2400 at 65mph....and the boost does not drop off till i either let off the pedal or start to crest the hill.

 

If you opened the wastegate by hand you are either very strong or the return spring is weak.It's fairly tough to move with the turbo on the bench