High EGT diag help please

[EDKtrans]

I could use a little diagnostic help here. Just to check I'm maybe heading in the right direction...


My issue is high EGT's. At idle things are fine but once running EGT's are constantly quite a bit higher than I would consider normal. Cruising down the road, flat terrain, no load, and I can be at 1300 degrees. Not right. It's also gotten worse over a short time frame. The EGT's didn't just jump to where they are now. I noticed them climbing over time.



So first, the truck. It's a 2008 C&C, auto trans, with a bit over 400,000 miles on it. The truck is completely stock. No tuner, never had one. It starts and runs fine with no smoke. The DPF was replaced around the 380,000 mile area and the truck performs its active regens just fine. I've had an Edge Insight in the truck since new and can
monitor regens with it. The truck feels a little down on power but as I mentioned it runs fine. Due to this issue I haven't been driving the truck much but it doesn't seem to be growing oil, and the oil looks and smells normal.



So far I've removed and cleaned both MAF sensors with no change. I removed the EGR valve and intake horn both of which were pretty clean but I soaked and cleaned
them anyhow. I haven't pressurized the intake system to check for leaks but my boost pressure will hit the high 20psi area and I don't hear any whistling. A visual check doesn't find any issues. The air filter is fine but just to check I ran without it and no change.



I had the dealer check for codes and nothing was found.


Considering how well the truck starts and runs I'm not thinking I have an injector issue. However, they are original to the truck. Lotta miles for injectors, but it's not unheard of. I'm thinking maybe an exhaust obstruction but since the regens are running as normal I'm thinking the cat could be the issue. It's original to the truck. My understanding is that it's the one located in the down pipe correct? Can they clog as with a gasoline system? I'm thinking my next moves will be a more thorough leak check of the intake and then a cat
bypass pipe. What do you all think? Have I missed an obvious thing to check, do you think I'm on the right track?



Thanks for your time, help, and any insight!

 

[6V92TA]

have you ever heard it said maybe you shouldn't trust your gages. I'd get out and look under the hood and see if my turbo or exhaust manifold was glowing red

 

[Jim W]

O.K. I have a 2008 6.7L Cummins but not a C&C model, mine is a pick-up truck. So, the horse power and torque numbers will be slightly higher. I have as stock 350 HP at 3,000 RPM's and 650 lb.-ft. at 1,500 RPM's. Your numbers are 305HP/610lb.-ft. which are approximately 12% lower than the stock numbers on the pick-up truck. But this should not alter the EGT’s temperatures during regeneration since the operating temps needed to clean (burn off the soot) in the DPF would be the same. Fuel will still be injected during the 5th cycle of the fuel injectors which is used to burn off the soot.

This is all from my memory since I am no longer stock! These were readings from my EGT gauge and the probe is in my exhaust manifold. At idle my EGT's were above 450F never ever under 400F. Normal day to day driving (not towing) the EGT's were in the 750F to 900F range depending on speed and RPM's + gear I was in. When Regen would occurred and this could be every 250 to 300 miles the EGT's would climb to a max of 1450F but normally hovered around 1200F. I could hit the OHD and see the Fuel mileage drop off to a low of 6 to 7 MPG. When regeneration was over the MPG's would slow climb back to 11.5 MPG's or so.
I know that Harvey Barlow who had an early 2008 C&C model had similar readings as I had. Since we were the first ones to install gauges and document the install on the 6.7L forum.

Now please list your EGT’s at idle, normal day to day driving what gear and speed along with RPM’s. Than list when the temperatures rise to and how long are they at this temperature, duration. Also check your OHD and see what your MPG’s are and did they drop off?

With this information we might be able to answer your issue better!

 

[Missouri Mule]

Your cat could be plugged.
Is your truck regenerating (cooking the particles out of the dpf) if not that could be plugged.

 

[Bob4x4]

Your cat could be plugged.
Is your truck regenerating (cooking the particles out of the dpf) if not that could be plugged.

Both those issues should trip codes

 

[EDKtrans]

have you ever heard it said maybe you shouldn't trust your gages. I'd get out and look under the hood and see if my turbo or exhaust manifold was glowing red

I checked the gauge in boiling water and it's within a few degrees of being correct. Plus the pyrometer itself looks pretty much new.

O.K. I have a 2008 6.7L Cummins but not a C&C model, mine is a pick-up truck. So, the horse power and torque numbers will be slightly higher. I have as stock 350 HP at 3,000 RPM's and 650 lb.-ft. at 1,500 RPM's. Your numbers are 305HP/610lb.-ft. which are approximately 12% lower than the stock numbers on the pick-up truck. But this should not alter the EGT’s temperatures during regeneration since the operating temps needed to clean (burn off the soot) in the DPF would be the same. Fuel will still be injected during the 5th cycle of the fuel injectors which is used to burn off the soot.

This is all from my memory since I am no longer stock! These were readings from my EGT gauge and the probe is in my exhaust manifold. At idle my EGT's were above 450F never ever under 400F. Normal day to day driving (not towing) the EGT's were in the 750F to 900F range depending on speed and RPM's + gear I was in. When Regen would occurred and this could be every 250 to 300 miles the EGT's would climb to a max of 1450F but normally hovered around 1200F. I could hit the OHD and see the Fuel mileage drop off to a low of 6 to 7 MPG. When regeneration was over the MPG's would slow climb back to 11.5 MPG's or so.
I know that Harvey Barlow who had an early 2008 C&C model had similar readings as I had. Since we were the first ones to install gauges and document the install on the 6.7L forum.

Now please list your EGT’s at idle, normal day to day driving what gear and speed along with RPM’s. Than list when the temperatures rise to and how long are they at this temperature, duration. Also check your OHD and see what your MPG’s are and did they drop off?

With this information we might be able to answer your issue better!

OK, I cant get out and get all the detail your asking for right now but I can tell you my current idle EGT's are pretty much normal for this truck. Mine are lower than what you say you were seeing, sitting in the low 300 degree area. Again, this is normal for my truck. My normal temps seem to be lower than your normal temps overall. Normal driving with no load, around town type stuff I would be looking for temps in the 500 degree area. Hard acceleration with no trailer would stay below 1000 degrees. Now its pretty easy to hit 1300. I used to climb out of Denver on I70, with my flatbed on the back, heading west (long steep climb) and would be concerned if I had to spend much time over 1200. I used this truck for oil field hot shotting and with a normal load on my flatbed, gross trailer weight around 19,000 pounds, (the truck itself weighs 10,500) I would rarely even see 1300 degrees. Could be my easy on the truck driving style, could be a C&C thing, could be my Edge Insight gauge, I don't know but those are the temps I'm working against. Now I hit 900 driving down my residential street (no trailer) and cruising around town am hitting 1300 with no effort. I haven't driven the truck enough to notice any real fuel mileage difference but yeah, it seems worse. Regen would always cause the temps to climb but I know I'm not stuck in regen as I can monitor it on the Edge. I've had a couple regens recently and both completed in a normal amount of time with no issues. As for how long the temps hold high, they are constant with my driving situation. What I mean is, the problem doesn't go away, the temps are just high. Normal at idle, but as soon as I start driving they are always higher than they should be. I've been driving (and servicing) this truck watching the gauges for 400,000 miles now and am going to have to ask you to trust that what I'm seeing isn't at all normal. Something is making my temps much higher than normal for this truck.

Your cat could be plugged.
Is your truck regenerating (cooking the particles out of the dpf) if not that could be plugged.

As mentioned above, yes it's completing regens with no issues. Doing some further looking I see too that C&C's don't have a cat in the down pipe as on the pickups (I was going to delete the cat to see what that would do). My DPF was replaced recently and seems to be working.
I have ordered the AutoEnginuity OBD software and should have the kit on Thursday. Fridays plan is to figure it out and see what it can tell me. I'll be getting the Chrysler add on too so I should be able to get whatever info the truck will feed me. I'll be checking sensor voltages to see that they are in line. If anyone can suggest areas to be looking at past the MAF and MAP sensors let me know. I was a bit unhappy to see that the C&C's don't seem to have O2 sensors, I was hoping to take a look at my fuel mixture which I'd expect to be rich. Interesting that Dodge seems to only use the O2 sensors in the pickup as a way to monitor the cat's functionality and thus don't have them on the C&C. I should also be able to be sure my DPF isnt having issues but between the completing regens, and no CEL I'm guessing it's OK.

Thanks much for the help!

 

[Bob4x4]

The o2 sensors on the versions equipped with them have nothing to do with fuel mixture.They are only used for the egr system.You should be happy to not have them,they are just one more expense

 

[Missouri Mule]

Do you have boost gauge? Turbo mite be acting up( as I recall you have variable vane turbo.)
Boots to intercooler loose ?

 

[Bob4x4]

An actual boost leak will trip codes.A turbo that is way out of spec also trip codes.These trucks monitor just about everything.Its the small deviations that some times will bite you.Even the airflow control valve can sometimes slip by without setting a code if it is intermittent.

 

[Wiredawg]

It sounds like yours is doing what mine did right after reinstalling the DPF and EGR after 8 years off. I went so for as to purchase DPF cleaning fluid and applied it while running. I ran the truck down I-10 doin almost 80 for 60 miles. It corrected not long after, which all told was about a month. Don't know if I needed a regen in the DPF before removing it and letting it sit for 8 years, or if I needed to recalibrate back into the system, or what. Mine is heavy unloaded, around 12Klbs, so my normal flat running EGT is 800', but can easily push up to 1200' on easy grade. On steep grade loaded I see 1500 and occasionally, 1600. Not sure if running the crap out of it is the answer for you, but it was for me. Ron

 

[EDKtrans]

Another question.
Does anyone here have access to a scanner that will allow them to look at specific senders to see what they are reporting? I was looking around with my Autoenginuity package today and noticed that with the engine off my exhaust pressure sender reports about 25psi. I would expect it to report atmospheric pressure which for me here in Colorado would be around 12psi. 25 just doesn't make any sense. Once running at idle the reading is about 3psi higher. I expect this is somehow normal as otherwise I'd be expecting codes but I don't really know. That's my problem now. Autoenginuity supplies all this information, but nothing about what the correct reading should be. I'm also looking for the test procedure for checking exhaust pressure, what the pressure should be at a certain RPM, so I can determine if there are any issues with exhaust obstructions.
Thanks for the help!

 

[EDKtrans]

I figured out the exhaust pressure sender thing. In one of those, just as your falling asleep moments of enlightenment it hit me. The 25psi engine off reading would be right for inches of mercury. I hooked up my laptop this morning and I'm sure that's whats going on. Both the inlet air pressure and exhaust pressure readings are marked as PSI, but are returning numbers that are actually Inches Hg. The program wont let me change the units either. No big deal, I can do the conversion.

Another question.
Does anyone here have access to a scanner that will allow them to look at specific senders to see what they are reporting? I was looking around with my Autoenginuity package today and noticed that with the engine off my exhaust pressure sender reports about 25psi. I would expect it to report atmospheric pressure which for me here in Colorado would be around 12psi. 25 just doesn't make any sense. Once running at idle the reading is about 3psi higher. I expect this is somehow normal as otherwise I'd be expecting codes but I don't really know. That's my problem now. Autoenginuity supplies all this information, but nothing about what the correct reading should be. I'm also looking for the test procedure for checking exhaust pressure, what the pressure should be at a certain RPM, so I can determine if there are any issues with exhaust obstructions.
Thanks for the help!

 

[EDKtrans]

I put together a intake leak tester today and quickly found a couple of leaks. One, that's pretty bad is in a worn area on the short hose that comes off the turbo. I also felt a slight bit of air movement on the other side around where the hose connects to the intake horn. 400,000 miles on these hoses, I'm going to replace the set. Does anyone have any recommendations on good aftermarket hoses? From what I've read the factory ones are, like most of the parts for these truck, pretty expensive. I expect a hose set made to handle the heat and pressure of a modified truck should work just fine on my stocker.
If interested, this link is to a picture of my test rig. If you view it full size you can see a badly worn area on the hose where it rubs on the intake tube coming off the air box. That's the point of the biggest leak. I'm hopeful that the leaks could be the problem causing the high EGT's but even if it's not these hoses need to be replaced.

https://flic.kr/p/24KbzLH

 

[EDKtrans]

A quick update for anyone following along. I replaced the rubber bits in the turbo/intercooler/intake plumbing and the temps came down quite a bit, but are still higher than they would normally be. Now, instead of cruising on a flat stretch of interstate at 1300 degrees, I'm a bit below 1000. I'm going to hook up my pressure testing rig again and look for more leaks. When I had it on before it was blowing off the turbo at a bit over 10 psi, but by then I knew I had leaks in the hoses so I didn't bother testing at a higher pressure. I'm thinking I might have more leaks so I'm going to work on getting the test rig to stay in place hopefully up to around 20 psi and see what I have.
I'm also wondering about the intercooler itself. When I replaced the hoses I found the aluminum hot side tube was pretty well gunked up with 400,00 miles worth of oil from the crankcase vent system. The intercooler outlet side is clean and dry but I'm thinking there could be enough gunk in the cooler to cause a partial restriction. Anyone have experience with this? Sound feasible?

 

[StitchRipper]

Did you ever find out what was wrong and why the high egts