Dodge-Ford-GM

[MA2LA]

I'm with Power on this. . something isn't right ... . it can be a sensor that isn't quiet reading right or something in the trans isn't right but the truck should down shift... Power. . Have you tried lifting of the throttle then flooring it to see what it does. . Mine at times wount down shift but its the combination of the mods i have and a trans that is set up for the intant boost and low end power of twins and my stock turbo just dosent want to spool up like twins can

 

[Grizzly]

This is exactly why I buy manual transmission's. I never did and still don't trust electronics to think for me.

I completely agree with you on a stick shift!

 

[HBarlow]

Harvey, perhaps you missed the part where I said I drove a new truck off the lot towing my trailer up the exact same grade. Although the new truck didn't "need" to downshift, when I floored it, it WOULD downshift. My truck will not down shift even though it "needs" to to maintain speed...

I seriously doubt the PCM is programmed to lug the truck down to that low of an RPM, in fact a simple test would be for every one of you guys driving an automatic, go out and try it. Get your RPM around 18-1900 in top gear and floor it, let's see how many actually downshift. I'm betting they all will, just like the new one off the lot did. MY truck WONT. That's the problem... .

Actually I did have a hard time understanding what you were saying because it seemed you were mixing reports of what your truck did with perhaps another truck you borrowed but I wasn't able to distinguish which truck with which load did what.

Taking the engine speed down to 1700 rpm is not luggiing it. You expecting that based on what you know about V8 engines. I keep saying this: the Cummins ISB inline 6 cylinder diesels product peak torque at 1500 rpm to 2700 rpm. If the Cummins engine will hold rpm and pull at 1600 rpm or even 1500 rpm it is safely operating in its peak torque range.

I don't know if the automatic should shift down with pedal to the floor or not. I have never driven one that way. Perhaps it should but I don't allow mine to do that.

If I'm pulling a steep grade loaded and see that the engine is not going to be able to hold rpm, I back out of it, manually shift the automatic, then put my foot back in it. I've only driven an automatic transmission Ram a little over 300k miles so may have missed that feature.

 

[Powder Extreme]

Apparantly you missed that feature. I've only driven Cummins powered Dodges around a half million miles. Most of which were manuals. I've also only driven a few hundred thousand miles in Allison equipped GMs, certainly not enough time to understand how an automatic transmission should work.

Yes Harvey, an automatic transmission should downshift itself. Im sure mechanics will back me up on that. You go on driving your truck any way you like.
Cheers. =)

 

[RVTRKN]

You can choose to believe whatever you wish and operate your truck in any way you choose, that is no concern of mine.



But when you post is here on TDR newer members may read it and believe it and I consider bad information harmful.



Here is a copy of a message I sent to an engineer in Cummins, Inc. several years ago. For obvious reasons, I have redacted his name to protect his anonymity.



+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

(Addressee's Name Deleted),



Greetings. I Haven't communicated with you for some time. I hope all is well with you.



I know the question I want to ask is not something you are directly involved with and it may not even be fair to ask. I want to ask you first for an informal answer because I'm not sure the Cummins engine engineers will be willing to answer. If you can answer but direct me not to share the info with the TDR membership at all or if you permit me to share the info but direct me to protect the name of the source, I will honor my commitment to do exactly as you direct.



My question is this: What is the maximum exhaust gas temperature a Cummins ISB engine can safely tolerate for sustained operation at full power and full rated load measured with a typical aftermarket pyrometer with the probe installed in the center of the exhaust manifold?



The reason I ask is, as you know, the numbers are continuously batted around on the TDR forums. Some preach that 1300° is the maxiumum allowable temp for sustained operation because, they claim, aluminum pistons can begin melting at 1300°. Others think temps should be kept below that level. Still others claim that the Cummins engine can stand operating at higher temps without incurring damage or that temperatues measured in the exhaust manifold are not necessarily an accurate measure.



I have no facts but I suspect that all Gen II 24 valve HO engines with electronic injection pump and all Gen III HPCR engines will produce EGTs higher than 1300°at full power and maximum rated load.



My 2001 HO/6 speed, with Bosch "275 hp" injectors (I know that engine modifications are anathema to Cummins engineers but my truck is well out of warranty and my risk alone), is occasionally capable of pegging the 1600° pyrometer climbing a grade under full throttle when operating in high summer temperatures. I am frequently forced to back out of the throttle to avoid what I have been told are excessive EGT levels. I regret that I did not have a pyrometer installed before the injectors were installed to establish a baseline EGT but I suspect that all factory stock HO engines produce high EGTs. I'm not an engineer but I do know that in a diesel engine, more power requires more fuel and results in greater heat.



I have read several threads recently indicating that several owners who have installed pyrometers on their factory stock Gen III HPCR engines are reading EGTs in the 1400° to 1500° range at full power. This makes me think that EGTs in this range are a fact of life and to be expected and accepted.



Can you comment on this subject? Any information or advice you can share will be greatly appreciated and whatever level of confidentiality you direct will be maintained.



If you are unable or unwilling to comment I will understand and will still consider you a friend and a valuable asset to TDR members.

... ..... and here is his reply, again with his name redacted.



++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



Happy holidays! EGT's are always a touchy subject due to differences in measurement locations and differences in the devices used. It's difficult to say what a true upper limit is on EGT for the ISB engine because we don't test it above the "stock" settings. However, I can tell you what we have measured on the latest 2004. 5 and 2005 engine configurations.



MY04. 5/ 325 exhaust temps can be as high as:



Sea Level: 1375 Deg F pre turbo, 1125 Deg F after turbo.

Altitude: 1450 Deg F Pre turbo, 1200 Deg F After turbo.



The above are typical temperatures from development trips. The MY04. 5 product was developed to operate at these temperatures. I have no idea what would happen at temps above these, because they haven't been tested.



I don't mind you sharing these numbers as long as the source remains anonymous. We don't want someone thinking "Cummins approves this temp on my engine because . . . " . This really isn't a guideline or approval or anything, just some results from tests we've conducted on stock engines.



I hope this help answer you question. If you need anything else, let me know!



-(name redacted)



+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



This information is obviously several years old and I have not asked about the ISB6. 7 so can't provide exact information regarding the latest engines. I think it is reasonable to assume that current Cummins engines are at least as capable, durable, and using metallurgy as good as the MY04. 5 engines.

Sure, drive them the way you like, its a free world, bla bla bla bla. Do you own a pyro gage? Oh, and for the new members here, this is your introduction to "HBarlow".

 

[HBarlow]

Yep, that's me. The evil guy who occasionally posts facts from authoritive sources to dispute misinformation, rumors, or nonsense posted by some members.

Everyone can chose to drive their trucks any way they choose but they should not be burdened by misinformation that makes them think they can't safely operate their trucks at full throttle. Now they know there is a different point of view and can make their own choice.

 

[domehead]

Just take the truck to the dealer and see what he/she has to say about the issue you are having.

Second Harvey is correct about the information he posted.



Third any of us that has been around on this web site or others there are times when there is miss guide data.

 

[RVTRKN]

OK, I won't post any more about EGT, if you can explain why you own a Pyro gage. The funny thing is, I don't own a pyro gage and rely on the theory of more air equals cooler EGT and keep up my RPM's when climbing a grade. Unnamed sources don't make you the EGT God. The pyro gages are mainly for chipped engines that run well outside of CTD parameters, but then we all have a coolant temperature gage even though you probably would never need them. Wait a minute, climbing grades can over heat our engines anyway, despite the well designed engines Cummins have engineered.

 

[HBarlow]

Steve,

I have a set of three DiPricol gauges because I wanted them. I like them. They look nifty. I have them for the same reason you have a fuel tank gauge and a coolant temp gauge. They were installed on my '06 Ram dually. When I sold it I decided to keep and transfer them to my current truck. I like the green lights at night. They make me feel like I'm a real truck driver. They confuse dummies who don't understand what they are for or why I want them. Pick one or all. The choices are free.

The gauges tell me several things about my engine's performance such as when it is in regeneration mode. The gauges will also tell me if something is wrong for example unable to develop full boost. That happened once on my '01 on a return trip from NV pulling a trailer. Neither Cummins Amarillo or the dealer could diagnose the cause under warranty. Because I could understand and describe the symptoms to Bill Stockard and Joe Donnelly by telephone I was able to return to the dealer and tell the service manager and tech what to check to find the problem - the MAP sensor.

The gauges also tell me that under full throttle and full load, actually a bit more than Dodge's rated full combined weight load, I can climb any mountain grade of any length without fear of melting a piston or overheating the Aisin automatic.

The gauges allow me to recognize false information when posted on the TDR.

 

[RVTRKN]

fear of melting a piston .

H'mmmm

 

[HBarlow]

OK, I won't post any more about EGT, if you can explain why you own a Pyro gage.

You can continue to post anything you choose. Done.

The funny thing is, I don't own a pyro gage and rely on the theory of more air equals cooler EGT and keep up my RPM's when climbing a grade.

That's your choice.

Unnamed sources don't make you the EGT God.

That's true, but they do allow me to recognize truckstop rumors and misinformation when posted here and avoid falling victim to it.

The pyro gages are mainly for chipped engines that run well outside of CTD parameters, but then we all have a coolant temperature gage even though you probably would never need them.

I guess I didn't see that product warning in the Geno's catalog or website and I overlooked it on the product box. Is it okay if I continue to use them on my truck?

Wait a minute, climbing grades can over heat our engines anyway, despite the well designed engines Cummins have engineered.

I've pulled some mighty heavy loads, often exceeding manufacturer's rated gross combined weights in 49 of the 50 states including Death Valley and much of Canada and never overheated any of the three Dodge Rams I've owned, even when the previous two trucks had 325k miles and 230k miles respectively on their odometers. I've never seen a coolant temp beyond about 210 or 215*.

 

[RVTRKN]

Then why are they there?

 

[RonD]

Ford just announced a payload increase of several hundred pounds, plus 10 more HP, and a 65 pound increase of torque, just thought I would pass it along, I suspect Dodge still has a plan under wraps.

 

[Powder Extreme]

Wow Harvey, never seen over 215°? My truck hits 225° on a regular basis. I know, I know, its because I have a 3. 42 rear end! Lol

 

[67guzzler]

Wow Harvey, never seen over 215°? My truck hits 225° on a regular basis. I know, I know, its because I have a 3. 42 rear end! Lol

OMG! Too Funny. :-laf

 

[Grizzly]

Ford just announced a payload increase of several hundred pounds, plus 10 more HP, and a 65 pound increase of torque, just thought I would pass it along, I suspect Dodge still has a plan under wraps.

I'm not impressed, in fact, I really don't care what Furd does.



My CTD may have less HP and torque than brand X, but it gets the job done and it's reliable and it's paid for.

 

[Powder Extreme]

I know what you mean about trying to avoid high temps, but the engine fan doesn't even kick in till around 220° so Cummins evidently built this motor to run hotter.

 

[RVTRKN]

Powder, lets get back to your original conversation, if it doesn't down shift itself pulling grades then down shift it yourself, until you get your issue resolved. Despite what HBarlow says, your CTD is not running at the proper parameters and lugging it will cause high EGT. When a gas engine has a rich fuel mixture it will run cooler, and with a Diesel, not just brand X, it will over heat when to much fuel is introduced into the system. I'm not talking about the coolant, although it will eventually be effected, but the exhaust and all related componets. When you lug a Diesel that means your foot is pegging the pedal to the floor, causing it to run rich. It is the reason I keep my RPM's high during a grade pulling heavy, to introduce more air. Because of the increase in HP over the years with the CTD they also changed the valve structure (not sure of the correct term) to help with the increase in EGT due to burning more fuel. It is also the reason you need a pyro gage when you chip a Diesel, because it programs for more fuel as well as changing the timing.

 

[HBarlow]

I've been hearing the tale about downshifting to reduce exhaust gas temperature since I attended my first TDR rally in Kerrville, TX in summer of 2001 right after I bought my first CTD.

I accepted the information as gospel and as soon as I returned home I had a set of gauges installed because Joe Donnelly had installed Bosch RV275 hp injectors in my truck at the rally site.

I soon learned that the only way I could reduce egt while climbing a grade was to back out of the accelerator pedal. I tried downshifting to the next gear down with my manual six speed on many occasions. I found that as soon as I put my foot back in it sufficient to maintain speed on the grade, egt returned to the original level. I thought maybe it was because of the injectors.

Later, with my '06 Ram I installed a set of gauges but retained a completely OEM engine. Same experience. The only way to reduce egt on a grade was to back out of it and allow speed to drop off. Putting my foot back in it sufficiently to hold speed returned egt to the original level.

I have found the same thing to be true with my current C&C w/ISB6. 7.

I can only conclude that a certain amount of power is required to maintain speed on a grade with trailer behind and as long as the engine is within the engine's torque band changing gears simply doesn't reduce egt.

It should be noted that I have had egt and boost gauges on all three Rams I've owned. I'm not guessing what egt is, I'm reading it off the gauge.

 

[Powder Extreme]

Okay guys, I do know what I'm talking about, I have "been there, done that" The only reason I even brought this up in the first place is my transmission does not auto down shift as it should, PERIOD. The down shifting of my transmission is not due to 3. 42 gears in the rear end. RVTRKN, I appreciate your input and that you agree something is wrong with my truck. Rest assured when I am towing heavy such as last week when I was grossing 28,500lbs I do manually shift the transmission. However I can't control the silly *** way it downshifts while descending a hill. I think that goes right back to the fact my transmission isn't programmed correctly, has a bad sensor, whatever.

Harvey, I'm sorry, but you are wrong about EGT, yes, Wrong, this isn't opinion, this is fact. A truck will have a lower EGT at a higher RPM in a lower gear than it will at a Low RPM in a higher gear, with all other things remaining equal. PERIOD. This isn't opinion. I have driven well over a million miles towing heavy loads in 7 different Semi's and 10 different pickups, it has always been that way. Couple my experience with the same as RVTRKN on here and I would certainly say that is more than enough example to make it fact. I'm also sure Joe Donnelly, Piers from BD diesel, and any other big time diesel guy will agree with us. Lugging a diesel motor increases EGT, that's all there is to it.

My old pickup had more than enough power to pull a 6% grade hauling my 14k 5th wheel in 6th gear at 75mph. However my egt would quickly rise to 1400 degrees and I'm certain would have gone right on past that. If I would manually down shift it to 5th, the EGT would drop to around 1200. Knowing this I would always drop to 5th gear before I started climbing, and the EGT wouldn't go over 1200. Same rings true for the semi's I drove. Drop into a lower gear early, keep the RPM in the upper range, and the EGT stays lower. The biggest reason the EGT is lower is because of the amount of air the motor is moving through it. A whole lot more air is passing thru your exhaust cooling it down at 2600rpm than there is at 1800rpm, not to mention you are generally blowing a few more pounds of boost at the higher RPM.

These statements are not simply my opinion Harvey, I'm quite certain any diesel mechanic worth his salt will agree with me. As will any truck driver who's been there done that.

I purchased my truck with 3. 42 gears with the sole intention of turning the motor up like I always have. With the motor turned up there would be WAY more than enough power to spin the taller rear end. I would simply use 5th or even 4th gear when towing heavy. BUT when I wasn't loaded I would be able to enjoy the fuel mileage such a tall rear end would give me. However, I'm having other issues with the truck so I decided to replace it. Problem solved.

I don't mean to sound like an *** Harvey, but I'm pretty sure I have more experience towing than you do. Like I said, I have driven well over a million miles in all sorts of vehicles. I've never had a motor failure of any kind whatsoever with the exception of the crappy lift pump from the early 24v trucks. I was always able to feel when the lift pump was going bad so I was fortunate enough to never have injection pump problems.

So, can we please all shake hands, group hug, whatever and finally put this one to bed?
=)