I've got a 6.4 with 70,000 miles and towed with it tuned for the 1st time this past week. It did great but I noticed while towing that the EGT's were stable except when it down shifted and rev'd up. Then the EGT's would be all over the place. They would go from 0 to 7 or 8 hundred and the guage needle would be swinging over the entire range also from 0 to 700/800 degrees. Is this normal? I was running around 70 mph and the camper weighs in at about 12,500 lbs.

 

Does not sound normal to me. I do not tow heavy with mine with the tuning on. I always tow with it in the no power setting. Everyone has told me the trans will not hold up in the long run towing tuned. As far as your egts go, almost sounds like you have a loose connection or something causing the gauge to jump all over the place. You should see the egts go way down when the truck shifts to lower gear.

 

thanks, I'm going to talk with the guys that installed it today.

 

Maybe I don't understand what he means but the EGT will not go down when the truck down shifts. The truck down shifts and the RPMs go up, the turbo works harder and the EGT gets hotter, right? Or am I losing my mind. Anyway, 750 is not hot at all. The stock truck goes to 1250 or more during exhaust cleaning. My trailer weighs as much as most anybodys and I don't remember getting real hot during towing. I'm on my second tuner (edge and mini) but I don't remember being over 1100 or so with either.

But the answer to your question is what he said above, something seems wrong, maybe a bad EGT sensor. But if that's the case it would be erratic when not towing too. Take it out and kick down into passing mode a couple times and see what it does. If it's still jumping around the first thing I'd try is to remove and reload the tune and see if that does anything.

 

thanks to you also, Stanley, I'll take it out and let it rev up a few times on the interstate like you suggested and see what happens. I'm also going to get a bite of lunch and run it by the guys that installed it. I'm not too worried about it getting too hot but I am concerned about the temp not being somewhat steady rather than jumping around widely. Thanks again guys, I really like this forum!

 

Well it still does it w/o the trailer by just punching it on the interstate. I never noticed it because it gets up to speed so quickly w/o towing that I never noticed it doing it. I took it over to the guys who installed it and they believe it to be the pyro or in simpler terms the sending unit so they removed it and sent it off for a replacement part. Hopefully this will fix it, I'll know next week when the new part comes in and I get back over there for them to install it.

 

That's good if that's all it is. please come back and let us know so the next person who searches for the same problem will be able to find your solution.

 

Will do, should be a week or so..

 

When the truck down shifts and the rpms go up the engine will be moving more air through the motor then it does when it is being lugged in high gear. With the rpms up the engine is operating more in its optimal powerband and running more efficiently. The engine will also be making more boost which in turn helps to lower your egts. This really is seen more when you are pulling a heavy load more so then just riding around unload and towing some thing light. If the trailer is not heavy then there usually is never a need to downshift because the truck can pull the hill with no problem in high gear.

 

I've been towing stuff since around 1957, some of it pretty heavy. Even so, I'm ashamed to say that I am not absolutely sure what you are saying is incorrect, but I can say that I very much doubt it.

Tomorrow I am towing my 5er (17,000 lbs more or less) out of south florida. So, what you are saying is that if I am cruising along with EGTs of say 600 degrees, when I step on the go pedal to increase power and the truck downshifts, my EGTs will go down because the engine is in a better place on the power curve and is getting more air into the turbo? Is that what you are saying? Because if it is then one of us don't have an understanding of how a diesel engine works. More air does not reduce EGTs. I believe more air and more fuel being burned makes higher EGTs, and that's what happens in a down shift. The computer calls for more power, the tranny down shifts, the RPMs increase, the timing advances, the turbo spools up, the injectors send more fuel to the cylinders, the fires burn hotter producing more power and the exhaust temperture increases. It will stay elevated until the computer reduces the demand for power or the engine defuels.

Never the less, that's just my opinion and I am always willing to learn, so tomorrow I will experiment, take notes and report back.

 

You are correct. The call for more power =more fuel and more air. That means more EGT and more boost to help it all along.

Trans shift is a by product of the need for more speed.

 

I think you have misunderstood what I was trying to say. I know that when you stand on the throttle and the truck downshifts that egts are going up because you are burning more fuel. What I was simply trying to say is that when you are towing and driving at a constant speed if your egts are running high, try downshifting to a lower gear and it should drop the temps a little. I was not talking about when push the throttle and the truck downshifts due to the increase in engine load, of course that will increase egts.

 

OK, we agree on part of that. I tried to test today but the truck is so powerful (4.30 RA) that it would not down shift on it's own between Fort Myers and Tifton Ga. So, I took a couple opportunities to try and make it down shift. wasn't easy because I would put it to the floor and all it would do is go faster. Did not need the downshift. But I did pay better attention and at 2000 RPM I'm at 60 MPH, 12 lbs of boost and around 670 degrees EGT. It held pretty close to those numbers all the way. As I accellerate the boost increases and the EGTs go up. I could not find any situation when towing at a higher speed produced lower EGTs except on a down hill situation in which case the speed went up while the boost and EGTs went down. And there weren't many of those situations due to the terrain.

 

still waiting to get the pyro sensor back but i wanted to ask you, Stanley if you by chance went to Georgis Veterans State Park up close to Tifton? The wife and I stayed there the week before last and was very impressed with the park. If you haven't camped there I highly reccomend you give it a shot.

 

still waiting to get the pyro sensor back but i wanted to ask you, Stanley if you by chance went to Georgia Veterans State Park up close to Tifton? The wife and I stayed there the week before last and was very impressed with the park. If you haven't camped there I highly reccomend you give it a shot.