Questionable boost and egt's while towing

[CookJ]

Just returned from a 700 mile round trip in the hill country towing about 6K (Jayco bumper-pull). Prior to this trip, I've recently had the transmission rebuilt, boost hoses replaced and fuel filter changed; I also run fuel cleaner/additive every other tank and service air filter regularly.



For some time now, I've believed the stock lift pump is about to go south, or, the rail relief valve has failed, as the truck just doesn't seem to have the grunt it used to. For that reason, and, as a start, I have a replacement pump I bought from Geno's in the garage I hope to install this weekend; if this should not improve anything, I'll check the rv and correct as needed. By the way, the truck has 152,000 on the odometer and prior to this vacation, I removed the VA entirely and set the EZ on the tow setting (40 hp). Also, pyro is pre-turbo.



While towing, I realized my boost and egt #s were somewhat higher than previous trips. In other words, boost was around 18-24psi and exhaust temps were in the range of 975-1050F. I also fealt the truck drove sluggish, or, lacked power. On prior trips (or rather, before the transmission burned up), boost was around 10-16psi and exhaust temps around 900-950F, depending on road conditions.



My question is, would less than adequate fuel supply (i. e. weak lift pump, bad rv, etc. ) be cause for these elevated #s and poor performance, or, could there be some issue with the ecm or other that is "de-fueling" the engine? Any information would be appreciated. TIA

 

[BHolm]

Any kind of defuelling would be more apt to drop egts and boost numbers. More fuel=higher egts, more boost generally cools egts.



Is it possible you were just running it harder, a headwind perhaps? Those numbers don't look too bad depending on your speed.

 

[CookJ]

Any kind of defuelling would be more apt to drop egts and boost numbers. More fuel=higher egts, more boost generally cools egts.



Is it possible you were just running it harder, a headwind perhaps? Those numbers don't look too bad depending on your speed.

With regards to your statement on defueling, that's been my understanding too. I was just curious if the higher boost was causing the ecm to defuel, or, maybe there is something going on with the Edge box. I've never had the box checked out, nor have I ran on anything but level 1; this would include removing the VA completely before I tow anything.



I don't believe headwinds played a role here and I run the truck the same every trip (basically, I drive by my exhaust temps). It just so happens the last few trips I've made, I notice the truck isn't as responsive and I have to keep my right foot in it more to accomplish the same driving habits. I'm going to replace the stock lift pump anyway as I believe I have been more fortunate than most running it this long. I'm still curious why the boost/egt's are elevated. Any other ideas? thanks

 

[AH64ID]

What does the VA 3. 2 do?

 

[DerekW]

With regards to your statement on defueling, that's been my understanding too. I was just curious if the higher boost was causing the ecm to defuel, or, maybe there is something going on with the Edge box. I've never had the box checked out, nor have I ran on anything but level 1; this would include removing the VA completely before I tow anything.



I don't believe headwinds played a role here and I run the truck the same every trip (basically, I drive by my exhaust temps). It just so happens the last few trips I've made, I notice the truck isn't as responsive and I have to keep my right foot in it more to accomplish the same driving habits. I'm going to replace the stock lift pump anyway as I believe I have been more fortunate than most running it this long. I'm still curious why the boost/egt's are elevated. Any other ideas? thanks

is it possible the brakes on the trailer are draggin hard? been there done that with a rental trailer I got an unimpressive 17 mpg towing the trailer EMPTY. my buddies trailer was rate 2 tons less and It didnt touch my normal hwy 26 mpg. I am asking this because either you werent clear or i wasnt paying attention to if you drive the truck without the camper and it being sluggish.



also wouldnt if the rail pressure was low the fuel not atomize and not combust when its supposed to and still be burning as it comes out of the cylinders hence high egt and high boost no power? I would try a rail pressure gauge and a guage on the fuel lines to see if this is your issue first.

 

[SierraRam]

You EZ will keep the ECM from sensing a overboost condition. Your numbers do not seem high to me. Is your truck smoking more than usual? If you injectors are not atomizing corectly you should hear some injector knock and smoke more.



SR

 

[CookJ]

What does the VA 3. 2 do?

Duration only.

 

[CookJ]

is it possible the brakes on the trailer are draggin hard? been there done that with a rental trailer I got an unimpressive 17 mpg towing the trailer EMPTY. my buddies trailer was rate 2 tons less and It didnt touch my normal hwy 26 mpg. I am asking this because either you werent clear or i wasnt paying attention to if you drive the truck without the camper and it being sluggish.



also wouldnt if the rail pressure was low the fuel not atomize and not combust when its supposed to and still be burning as it comes out of the cylinders hence high egt and high boost no power? I would try a rail pressure gauge and a guage on the fuel lines to see if this is your issue first.

Derek, that was kind of a thought of mine too (poor atomization due to lack of fueling) which is why I want to install the LP. However, because I'm still learning here, I didn't bring it up. As for the trailer brakes, I checked at each fuel stop and did not see/feel anything out of the norm. Even unhooked, the truck feels weak. When/if I have the funds, I plan to install a fuel supply gauge; just wish I already had. Thanks and keep the responses coming.

 

[CookJ]

You EZ will keep the ECM from sensing a overboost condition. Your numbers do not seem high to me. Is your truck smoking more than usual? If you injectors are not atomizing corectly you should hear some injector knock and smoke more.



SR

SR, the truck does not seem to be smoking anymore than previously, and, I don't hear any knocks from under the hood. I will say this though, immediately after the transmission overhaul (which I still need to take back to the shop) I had the EZ on 2 and the VA on mid setting (65hp), and after hammering on it, I noticed a whole lot of smoke initially but it would clear up as fast as it came on. My thought was I'm running out of fuel, or, I have a leaking rv. thanks

 

[CookJ]

Well, I installed the replacement lp this morning and do not feel I've improved on anything (30 minute job?, yea right!!). Guess I'll check the fca and rail valve sometime this weekend and inform all of my findings. thanks