Exhaust Overheating Code (1966)

[96 EVO]

Yeah, they told him his DPF was cracked.

Or maybe the mechanic was on crack...... can't recall 🤔!

Edited September 4, 2021 by 96 EVO

[jacwjames]

Back in ~2006 I was involved in a restart of mines that had been shut down for ~4 years.   Eventually (somehow) I was promoted to Maintenance Manager.  The equipment that was still there and usable did not meet the new Mine Health and Safety Administration (MSHA) diesel particulate criteria.   We had to test and maintain records along with ventilation surveys etc.   Even most of the new equipment did not  meet the criteria.   We had to install DPF on pretty much all the equipment and purchase the equipment to be able to clean the DPF which was a high temperature oven and a vibrating table that would shake the soot out of the DPF while it was baking.  We monitored all the equipment with computer, would download the data at every service (essentially weekly), some of the newer equipment that came equipped with the DPF's did regenerate and we could actually see it on the printouts.  We had to keep detailed records of all of this  On the equipment, as the back pressure climbed on the exhaust system, we'e ultimately pull the DPF and put one of the spares.  Each engine by make, model, size had different DPF's.  We spent +$1M on all of this to bring the  mines in compliance.

What we learned over time is that the equipment that was run hard and hot would benefit from the DPF's and that they would have to pulled and cleaned a lot less frequently then some of the other equipment.  We also found that some equipment it would not work at all, we had to remove and operators would have to wear personal protective equipment (masks etc) to protect against the diesel particulate. 

So when all these types of systems were being developed the first generation of engines performed poorly.  This probably includes motorhomes that started to have this equipment installed.  I knew the Knoxville  Cummins Manager and would stop in and talk to him and he commented that the engine manufacturers were scrambling to develop engine to meet the EPA requirement (Tier engines) and it seemed that just when they got the bugs worked out of engines they would release a new Tier and they'd start all over again. 

So if you own a coach with this type of equipment I'd suggest you do your research and be proactive to maintain it. 

I guess I'll keep my 2002 with a ISC 8.3

[Gary Cole]

Interesting information Jim. How were you measuring the back pressure in the exhaust system?

[jacwjames]

4 minutes ago, Gary Cole said:

Interesting information Jim. How were you measuring the back pressure in the exhaust system?

This was part of the system we purchased along with the computers to read it with. 

Even though we dedicated people monitoring all these systems they were still difficult to keep operational.   We had 3 different mines with centralized warehousing where we stocked extra filters, refurbished would be sent out based on a requisition and old ones returned for cleaning and restock.  $$$$$$$$

The best equipment to run it on were the loaders & trucks, these were run hard ~7 hours a shift, 3 shifts a day, 365 days a year.  Worst equipment were service type vehicles (supply truck, pipe truck, Explosives trucks) the engines were never really stressed so they never got hot enough to burn off the DPM and the filters would plug really fast. 

[dl_racing427]

I've found over the years that the WORST thing you can do to an engine, gas or diesel, is to baby it.
Now I don't mean beating on it continuously, but they need high speeds and heavy loads to minimize deposits and prevent cylinder glazing and poor ring seal.

My daily beater is a 2004 Ford Focus, with the 2.3 Duratec engine.
It has almost 310,000 miles, and oil consumption is still not noticeable on the dipstick in a 10,000 mile change interval.

My typical highway cruise is 80-90mph.  It sees full throttle and 5,000+RPM at least once or twice every day, and sometimes much more.
The engine itself has never had anything beyond a cam cover gasket replaced.
I'm actually curious now just how long it will keep going. LOL

[Frank McElroy]

I've posted this information on other discussions but let me chime in with some information on the DPF system especially those in early 2008 model year coaches.

First, the only real way to sort out what is going on is to connect the engine ECM to the Cummins Insite software.  This will tell you when the latest software update was performed.  The early engine versions had lots of issues including inaccurate DPF temp calibrations that were resolved via software updates around 2009 - 2010.

Insite will also provide a DPF history report of the last ten regen cycles.  This will include time between regens, soot loadings via pressure and temp readings in all 3 sections of the DPF and tell you whether it was a normal or more severe soot load. 

If you drive at highway speeds you can expect to go about 100 hours between regen cycles.  If you are seeing regens say less that every 50 hours of engine run time, you are having the start of a problem that is generating soot and you need to fix that problem soon.  Don't wait for a check engine light to come on.  Could be the start of a bad injector, clogging EGR, sticking engine brake, sticking VGT turbo, or a failing air intake sensor.  When the problem gets bad enough, generally the first indication is a plugging DPF.  you may or may not see other engine codes.  But fixing the DPF generally is just a short term solution unless you also do all the diagnostics to be sure the engine isn't also generating soot.

The reason why there isn't a forced regen option on our coaches with fiberglass bodies is heat and lots of heat.  You need auxiliary fans to cool the DPF.  Also, a forced regen is only aimed at getting the coach drivable so you can get it up to highway speed to do a normal regen cycle and really burn up all the carbon so you get back to a normal 100 hours of engine run time between regen cycles.

[Gary Cole]

Frank is 100% of engine horsepower available during a regen and how much time does a regen require. Does exhaust backpressure increase significantly during the cycle? 

Edited September 8, 2021 by Gary Cole

[Frank McElroy]

To answer your question - it all depends on a number of factors. 

The engine ECM will decide how best to burn off the DPF soot and control running the engine to spray fuel into the exhaust to have a controlled soot burn but not so hot that it damages the DPF ceramic.  

If you are doing a regen with say a normal soot load say at the 100 hour mark, that means that there is minimal filter back pressure and you can still operate at full engine power - no derate - if you need to.  The time it takes to do a regen depend on the internal back pressures in the 3 section of the DPF.  If a normal soot load, operating at say 60-65 mph on the highway with the engine brake off, it should take about 30 minutes.  But if you have high soot load it could take an hour.  If you use the engine brake the regen is suspended.  If you get below about 35 MPH, the regen is also suspended. 

Also, when the dash light comes on, it is only telling you to drive under conditions to do a regen,  It doesn't mean that the regen is actually being performed.

Under certain driving conditions or if you have a check engine light with certain trouble codes, the ECM will suspend the regen operation.  Driving a DPF coach with a check engine light on is asking for trouble because you could very well plug up the DPF and then you will get an engine derate before a stop engine light.

The shortest time to do a regen would be by driving 60-65 MPH, no engine brake, and no full throttle hill climbs.  On my coach, I've seen regens last as little as 20 minutes on flat terrains or take 40 minutes in the mountains.  All my regens happen at 100 hour intervals.  Once a year I check the DPF regen history report using the Cummins Insite software just to be sure I don't have a problem brewing that would show up as shorter regen intervals or soot loading higher than normal.

[96 EVO]

11 minutes ago, Frank McElroy said:

 

The shortest time to do a regen would be by driving 60-65 MPH, no engine brake, and no full throttle hill climbs.   

Interesting!

I have always though a regen while on a 6- 8% climb would work best. 

[Gospel]

Okay I am learning about regen, I just purchased 2008 Monaco Knight in 6/21 and Just completed a 4500 mile trip with plenty flat area's for a regen. Never had a regen icon show up on instrument panel. Ist steep grade in the Big Horn NF the engine shut down with no warning. I tried a restart, it started no power and shut back down when i put it in drive, tried 2nd time same thing, 3rd time it started, put it in drive and away we went.  Had a 2nd & 3rd shut down with nothing showing up on the instrument panel. All on steep grades, running on semi flat land was no problems that I could detect. I did have the Stop engine/Aftertreatment Diesel particulate filter lights come on for a split second then go back out. Never came on again and only did it once. I stopped at a small shop in Colo and had them put a computer on and code 1966 came up, They erased that code. I have a background in as diesel mechanic but it been 50 years since I worked or thought about one. 

Have the ECM updated to the latest software, replace the three sensor for the DPF filter and see where I'm at but after reading some of the post I'm not sure, rather not reinvent the wheel so I asking for a 1,2,3 type of approach. I talked to the local Cummins shop in Austin, not impressed with the service advisor answers. 

Ready to act on it. 

[Gary M]

13 hours ago, Frank McElroy said:

To answer your question - it all depends on a number of factors. 

The engine ECM will decide how best to burn off the DPF soot and control running the engine to spray fuel into the exhaust to have a controlled soot burn but not so hot that it damages the DPF ceramic.  

If you are doing a regen with say a normal soot load say at the 100 hour mark, that means that there is minimal filter back pressure and you can still operate at full engine power - no derate - if you need to.  The time it takes to do a regen depend on the internal back pressures in the 3 section of the DPF.  If a normal soot load, operating at say 60-65 mph on the highway with the engine brake off, it should take about 30 minutes.  But if you have high soot load it could take an hour.  If you use the engine brake the regen is suspended.  If you get below about 35 MPH, the regen is also suspended. 

Also, when the dash light comes on, it is only telling you to drive under conditions to do a regen,  It doesn't mean that the regen is actually being performed.

Under certain driving conditions or if you have a check engine light with certain trouble codes, the ECM will suspend the regen operation.  Driving a DPF coach with a check engine light on is asking for trouble because you could very well plug up the DPF and then you will get an engine derate before a stop engine light.

The shortest time to do a regen would be by driving 60-65 MPH, no engine brake, and no full throttle hill climbs.  On my coach, I've seen regens last as little as 20 minutes on flat terrains or take 40 minutes in the mountains.  All my regens happen at 100 hour intervals.  Once a year I check the DPF regen history report using the Cummins Insite software just to be sure I don't have a problem brewing that would show up as shorter regen intervals or soot loading higher than normal.

Hi Frank

I recently had a Cummins Care shop do a print out because of the issues on my 09 recently. They were less than helpful on helping me understand the info. I was wondering if I scan it as a PDF and sent it to you, maybe you might help me understand it. Naturally after going to this shop, I was told I should not go there as they have a bad reputation. After constant calling about when coach would be done, two weeks to do a 5hr service.

[96 EVO]

I'll have to try and remember to take a screen shot of my engine hours on the Alladin, next time it regen's.

[Frank McElroy]

22 hours ago, Gary M said:

Hi Frank

I recently had a Cummins Care shop do a print out because of the issues on my 09 recently. They were less than helpful on helping me understand the info. I was wondering if I scan it as a PDF and sent it to you, maybe you might help me understand it. Naturally after going to this shop, I was told I should not go there as they have a bad reputation. After constant calling about when coach would be done, two weeks to do a 5hr service.

Gary, sure, send me a PDF file to my email and I'll call you to explain.  That file should be about 50 pages long.  Hopefully they gave you a complete report.  If they did not, see if they can email you the Cummins Insite file that should be stored on their computer.  You won't be able to open it but I can.

[Daryl Ammons]

On 9/9/2021 at 11:38 AM, Frank McElroy said:

Gary, sure, send me a PDF file to my email and I'll call you to explain.  That file should be about 50 pages long.  Hopefully they gave you a complete report.  If they did not, see if they can email you the Cummins Insite file that should be stored on their computer.  You won't be able to open it but I can.

Hey Frank I am having all sorts of problems. I think you responded to my question on wiring schematic.  
I was on my way from Grand Junction Co to Colorado Springs and the caution light came on that the coach was trying to do a DPF regen.  It stayed on and after pulling a steep grade it was still on.   I stopped and read about it in the manual.  The manual stated that it was trying to regen but unable to.  It said that if the stop engine light came on I would need to immediately stop.  Sure enough in about 10 miles the stop engine light came on.  I ended up on the side of the road calling a mobile mechanic.  He hooked his computer and forced a regen. He advised that I get it checked at Trans West in Fountain Co.  They said the DPF had been breached and it was due to over fueling.  Said I needed all new injectors and DPF.  I told them J wanted to do the least I could to get me back home to NC.  They said I would at least need to replace the DPF or it would come back on and defame the engine.  The 2009 Dynasty only has 60k miles so wonder why it would need injectors.  Code said exhaust temp got up to 1650 degrees.  Any input appreciated.  
I am going also include pictures of the codes the mobile tech found.  Also will include the estimate from Trans West.

Thanks 

Daryl

[Frank McElroy]

Daryl, there are three main failures that can generate soot.  It's the soot generation that is plugging your DPF.  If your shop can give you the Commins Insite EIF file, please send it to me.  I want to see the past ten Regen history.  I also want to see the history on the turbo actuator inactive codes.

From what I do see, I'd be concerned about the turbo actuator trouble code.  A bad turbo actuator and sticking turbo will generate soot.

Yes, a bad injector can generate soot and be bad.  Cummins has diagnostic tests to determine if individual injectors are bad by running the engine on two injectors at a time. And with the DPF disconnected if soot is generated. Do injectors pass this test?

The third main cause is a dirty EGR valve or associated sensors even though codes aren't present.  This would be far down the list after rulling out the turbo actuator and confirming injectors are good.

If your engine is really generating soot, that is the first problem to fix.  Once fixed, you then want to do a stationary DPF Regen followed by an OTR Regen and not need a DPF replacement.  But if the DPF was breached, unfortunately, it needs to be replaced.

Did this engine have an EGR or DPF delete installed?

[Daryl Ammons]

10 minutes ago, Frank McElroy said:

Daryl, there are three main failures that can generate soot.  It's the soot generation that is plugging your DPF.  If your shop can give you the Commins Insite EIF file, please send it to me.  I want to see the past ten Regen history.  I also want to see the history on the turbo actuator inactive codes.

From what I do see, I'd be concerned about the turbo actuator trouble code.  A bad turbo actuator and sticking turbo will generate soot.

Yes, a bad injector can generate soot and be bad.  Cummins has diagnostic tests to determine if individual injectors are bad by running the engine on two injectors at a time. And with the DPF disconnected if soot is generated. Do injectors pass this test?

The third main cause is a dirty EGR valve or associated sensors even though codes aren't present.  This would be far down the list after rulling out the turbo actuator and confirming injectors are good.

If your engine is really generating soot, that is the first problem to fix.  Once fixed, you then want to do a stationary DPF Regen followed by an OTR Regen and not need a DPF replacement.

Thank You so much for the info I will talk to them tomorrow and see what has been checked.  I will also ask for the Cummins EIF file.  They said the DPF was damaged so I okayed they replace it but I did not ok replacing the injectors.  The mobile tech did mention the actuator but the shop has not mentioned that.  If I try to make it back to NC is there possibility of damaging something more?  I have people there that I could trust.

[Frank McElroy]

I'll call you.

[Frank McElroy]

Update - great to talk with you over the phone.

Based on our conversation, and the fact that you have power lag after the Jake brake is turned off or after coasting and an inactive turbo actuator code, I strongly believe the root cause of soot generation is a sticking turbo/turbo actuator.  (BTW when having this power lag, the accelerator needs to be held for about ten seconds before a check engine light comes on.  During that time the engine is generating lots of soot.)

As we discussed, I'd do the following.

1) You already authorized a DPF replacement.  Ask to see the old DPF to see if the previous owner did a DPF delete by having a hole punched through the center of the DPF.  Let me know what you find out.

2) Try to get a copy of the Cummins Insite EIF file and send it to me.  I can then review the DPF Regen history and inactive fault code history.

3) Have the service center do an injector power load and injector cutout test using the Cummins Insite Diagnostics to confirm from the throttle snap test that you have a bad injector.  If the power load test passes and the engine can run on any two cylinders without belching soot, the injectors are fine. Either a bad turbo actuator or plugging EGR or EGR related sensors are the cause of the failed throttle soot snap test.

4) Because you have a history of VGT actuator code failures and a history of hesitation after applying throttle with the Jake brake on, I highly suspect a bad turbo actuator is generating soot.

5) If you decide only to replace the DPF and pass the injector power test but not replace the turbo actuator and drive home for service, do the following.  Leave the Jake brake switch off unless you need it. (In my opinion the advice from the previous owner to leave the Jake brake switch on all the time is very very bad advice.)  Do not drive the coach with rapid throttle movement.  No fast full on / off throttle.  Give the failing sticking turbo actuator time to work.  Drive 60-65 MPH.  If you detect any throttle response hesitation, back off on the throttle to give time for the sticking turbo to work. Keep an eagle eye on the turbo boost gauge. If after coasting or Jake brake use and you give it throttle and see the turbo boost drop vs rising, the turbo is sticking let up on the throttle.  Wait a few more seconds before applying throttle again.  If you still have a drop in turbo boost, pull over or shift the trans to neutral for a few seconds then back to drive.  The idea is to reduce exhausts gas pressure on the sticking VTG turbo mechanism so that the sticking turbo can work.  This will be easy on the engine and generate very little soot assuming your injectors test good. 

Very likely, following the above guidance will get you home for complete repairs at a shop you trust.

Posting this long description to help others who may experience the same situation.