Have a rubber tracked carrier we built with a 300hp CAT C9 ACERT, currently working at around 12,000 ft. ASL. When climbing slopes the engine tends to run out of power and when pulling down fails to recover when the load is removed. Anybody else know of anything similar? CAT dealer tech has checked for codes, replaced one sensor which changed nothing, so far no help. Unit is hydrostat drive so it should be performing better, even if it's derating it should still be capable of 250+ hp. Ideas? Thanks, Lantraxco
Is the fuel pressure staying up? Does that unit have an electric lift pump?
I don't know, not recording any codes, and I know there's a pressure sensor. I would assume the ECU would flag it if it was starving for fuel.... hmmm? No electric pump, no.
Faulty sensors don't always give a fault code. It's possible for them to give an incorrect but still valid reading. Check the run screen in ET while the fault is occurring and check if the displayed values seem reasonable. Are you getting logged event codes for engine derate? I'm not saying the the dealer's man wasn't any good, he may be a top mechanic and have checked all this, but all too often these guys come along, plug in ET and think it's going to do their job for them. You still need the knowledge to interpret the information. /rant
You're preachin' to the choir on that one sir. The computer can only tell you what it knows, you have to figure out what it means! It would make sense to me to observe what was happening under load, not sure if they tried that. Yeah, I've seen an older CAT engine where a sensor would fail on a long hard pull, but still be within it's normal limits so no fault codes... local CAT dealer near cooked their chassis dyno before they finally caught it. This machine is over a thousand miles from me and I'm getting information third or fourth hand from the boss in Virginia, so anything is possible. I was under the impression that an altitude derate would be displayed (if it had a display) but not be recorded, am I misinformed? I am not familiar with CAT's ECU software, nor ET so I'm just going by what I read here and there. Thanks for your help guys!
There are a few exceptions depending on software and application, but usually in ET you can view active faults, logged faults and logged events. Engine derates would be stored in logged events. There may also be software switches in the configuration menu which affect what the engine does (or rather what the ECM does) under certain abnormal conditions. These switches are set according to the application. Is this a new build/installation which you can't get working correctly or is it a previously good machine which has developed a fault?
It's a recent new build that has functioned perfectly to date, something in the neighborhood of 700 hours I think. This issue only came to light in the last week or so, first time it's had any work above 6 or 7,000 feet. Previously the machine would pull a slope until the operator got too scared or the hydrostats ran out of pressure and destroked, no lack of engine power. It was serviced within the last hundred hours, all new fuel and air filters. The engine is tagged as a marine Tier 3 unit, but sold to us by the local CAT dealer network for an industrial application. I have no idea what all the parameters are, other than the supposed horsepower and torque curves they stated that it was programmed for. The label on the engine stated altitude limit 10,000 feet, but since the torque and horsepower charts they gave me showed figures up to 15,000 I assumed that just meant it started to derate above 10,000? JSC25831 is the serial number.
Yair . . . lantraxco Is that some sort of a seismic jigger looking for coal? Cheers.
Good guess Scrub! Close but no cigar I think.... CPT rig, Cone Penetration Testing. They push an electronic cone point down into the ground and log the information from the sensor and also the resistance to penetration as they go. They do it in a grid and map the layers and geology, and any water tables. Mostly used to map an area for foundations or pylons or the like. They use these a lot for engineering the foundations for the big wind genereator towers, the access roads and the crane pads used for erecting them. The jacks lift the machine off the ground to get it dead level and insure all the machine weight is available for pushing. I think we're about 55,000 pounds total weight with full fuel. Where that picture was taken it was between jobs for mines, it was mapping dry tailings mounds and tailings ponds for the required reclamation reports to the government.
Yair . . . lantraxco Thanks mate, I'm a nosey old b*****d. (big grin) Cheers.
Aw Scrub.... I'm only 56, so I'm not really old old yet... but I been nosey all my life, I see a machine I don't recognise, I want to know what it does, just like you! I have matured some though, according to my Dad who is soon to be 85 Lord willing, I took apart every mechanical thing I ran across and never put any back together until I was past thirty! LOL :tong
We had loads of cases like this in the Andes with electronic machine engines working up to 17,000ft ASL. The software runs out of derate because the engineers think no engine is ever going to go that high. As we used to tell them - "You guys think you need to be in a plane to be at the altitude where this machine's working"......... "Altitude limit 10,000ft" means exactly that, the software is programmed to derate starting at typically around 3-4,000ft up to maximum derate at 10,000ft and that's your lot. It won't derate any more than that, and that will more than likely be why the engine is struggling at 12,000ft. Having been there and done that on a host of previous occasions no Diagnostic Codes is probably what I'd expect because the engine control is doing exactly what it was programmed to do based on actual atmospheric pressure and therefore sees no reason to throw a Code. It has derated as far as the derate map in the software exists and will stubbornly refuse to derate any further. We always begged the factory to put something in the software that logged a Code if the actual atmospheric pressure was less than the lowest atmostpheric pressure programmed into the software derate map, but as usual our pleas fell on deaf ears. When the tech came to check the engine out on ET did he by chance give you a Product Status Report and did that report show what the derate % was at the job site altitude..? It would be interesting to compare the actual derate vs the maximum programmed derate to see if it was maxed out. The % Derate should be available from the main ET screen. If you want some derate info on the engine PM me the Serial Number and your email address. I can probably get hold of a load of data on the engine. It might be worth your while to have the dealer contact Cat via DSN and ask if there is any alternative software available that permits higher altitude operation. It's worth asking the question but TBH I would be surprised if there was because generally a TIER III marine engine isn't expected to work at anything higher than Sea Level unless something really weird happens ......... As a suggestion; when planning an engine purchase for an installation that is likely to operate at any significant altitude ASL it's well worth giving loads of information about the proposed use and having the dealer check with the factory to see if the power unit will function adequately at that altitude. I recall one example of a fleet of four blasthole drills that were built for a mine in Argentina at 14,000ft ASL. The manufacturer never asked any questions and simply purchased the same arrangement of Cat 3512 engine they always put in that model of rig and shipped them to site. When they were put to work there were immediate complaints of lack of power and excessively high exhaust temperatures. The first words from the factory when we contacted them were - "If we'd been told where these engines were going we'd have recommended a 3516. You'll never get the power you want from a 3512 in that configuration at that altitude". The final solution (paid for by the rig manufacturer) was a really expensive fix I can tell you......... As a parting shot remember that altitude operation counts as a "Severe Service Application" just like running with high sulphur fuel and you should cut yoru oil change periods by at least half as a starting point. So if the manual recommends 500-hour oil/filter changes your max ought to be 250 at that sort of altitude. If you are doing oil analysis keep a close eye of the "soot %" in the analysis figures and don't let it get too high. It may be the case that at your lab the infra-red soot analysis may not be included in the standard analysis package so you will have to ask for it as an extra.
Serial number JSC25831 was delivered with a test spec of 0K4891 which appears to have a max altitude of 7500ft. (See attached PDF) View attachment JSC25831.pdf I'm not sure where the tier 3 marine tag comes in to this. Maybe post a pic?. I suspect the reference to 10,000/15,000ft comes from generic charts showing what C9's can achieve when appropriately assembled. Ultimately, I suspect you've answered your own question. Altitude may be affecting the engine's performance. Either the atmospheric pressure sensor is not reading accurately or your figure for working altitude is off. All that said though, you should see a logged event code for engine derate,
OOPS! Dyslexic I guess, sorry, the correct serial number is JSC25381, I transposed the 3 and 8. Supposed to be a 300 hp rating.
Alright, that's fine. Attached pdf. View attachment JSC25381.pdf 300HP with 8500ft max altitude. Nothing has really changed regarding troubleshooting. If the engine is derating, it should be logged.
I found the same info basically. This particular engine is rated to 8500ft max, despite the fact that on one of the tabs there is a derate chart based on combinations of altitude/ambient temperature that goes all the way up to 15,000ft. I suspect the software won't derate past the atmospheric pressure expected at 8500ft, even if the amtospheric sensor is registering lower. The pressure going below the lowest value in the software will not trigger a Diagnostic Code based on my experience.
In my defense, not that I'm making excuses, the subject of working elevation never came up, and of course the branch of the company this machine is assigned to apparently is the only one where they get work in the mountains, at least to my knowledge. An oversight on my part. Hopefully CAT can come up with some software that has an extended map as Nige suggested. In the meantime I'll kibbitz with these guys from afar and see if there's any other issues we can correct that will help. Thank you Gentlemen, we will continue this story of "As the sprocket turns" (Or not in this case! LOL)
Yeah, this would be funny if it weren't not. The salesman sent me that chart, rated happily out to 15,000 feet, then I see the sticky on the engine valve cover when we install it says something to the effect of "Altitude limit 10,000 feet" and now the real poop sheet shows 8,500? Who's on first? What's on second? Wow.
I think this confusion (8500 vs 10,000 vs 15,000) confirms that a question from the dealer to Cat via DSN in order to establish the actual maximum operating altitude of the particular engine installed in your machine is in order ........ my money's on 8500 TBH.
I'm betting with you, the factory poop sheet is much more likely to be correct than anything else.
If it is confirmed as 8500ft then that probably explains why at 10,000ft there were no serious performance issues, especially when you think that derate is based on atmospheric pressure as opposed to X thousand feet. However when you get way past the maximum permitted altitude all sorts of problems raise their ugly head. When the D10T first came out the factory had to come up with an engine software fix to get it to perform in the Andes.
Dumb question here, but would the changes to the engine for the higher-er altitude operation include a different (larger) turbo ? Sounds like the computer changes just lower the fuel delivery as the air gets thinner (when it's programmed properly).
Not a dumb question at all. Basically the "standard" software map will change the amount of fuel injected and the fuel injection timing BTDC depending on the input from the atmospheric pressure & ambient temperature sensors (amongst others). Generally to get a good burn when the atmospheric pressure is lower than the normal 14.7psi the fuel injection timing has to be advanced further away from TDC, often known as Advance with Altitude or AWA. However the standard software map will end at some value of atmospheric pressure and if you expose the engine to a pressure lower than that effectively what happens is that the software has run out of compensation and engine performance will suffer. Basically this is the situation the OP is in. If an engine is to be configured specifically for operation at high altitude then there are all sorts of options, turbos & injectors being just a couple of them. Another option is a larger engine, as per the example I mentioned in post #12 on Page 1. For example the High Altitude version of the Cat 785 truck has a 3516 in it rather than the usual 3512, and the High Altitude version of the 789 uses a 3516HD 76-litre engine (a la 793) as opposed to the standard 69-litre 3516SS in the standard model of truck. On mechanical-drive trucks it's often usual to modify the torque converter so that the engine will spin up faster to aid the initial truck movement. What you come across is a Catch-22 situation where you can't get turbo boost without RPM and you can't get RPM without boost. Drop the truck into 1st speed and try to take off loaded from under the shovel and the RPM will probably increase from 750RPM Low Idle to maybe around 950RPM and hang there, and the truck won't move. At that RPM there is not enough boost to get the turbo really spinning and so the RPM increases no further. We always referred to it as Flash Stall. Then the RPM will then slowly start to increase until it gets to a point that the turbo finally takes off and you're cooking with gas. The problem is that I have seen that process take up to 90 seconds - not good when you want production There's really no "one size fits all" solution, a lot of the High Altitude versions of machines were developed as a joint effort between the factory, dealer, and customer. Along the way there was loads of pain I can tell you .........
Yair . . . Nige Fascinating stuff, thanks for that explanation . . . and thanks digger doug for the question. The real world knowledge shared on this board is quite amazing. Cheers.
I second thanking Nige for his 'splanation, it was well recieved. My original question stemmed from the fact my neighbor was a diesel engineer, and I had inquired to him, about 5 years ago how infact, they would get a diesel engine to run in Tibett at 17,500 feet. IIRC this was before all the direct computor control of the injection process, his answer was they would change out some of the turbo's components for other ones (not a larger turbo) just some "inlet" parts, for more air, maybe some messing around with fuel injection, but he was not worried in any way.
Excellent information Nige. I seem to recall overheat being a big problem due to the thinner air not carrying as much heat away from the radiator and coolers? One problem with this machine I originally posted about, unlike a situation where a rock truck may spend it's entire life at one mine this unit may be working below sea level in Death Valley a month from now, so permanent changes to the hardware might be just as big a problem when it comes off the mountain. Extending the software map I think is paramount for now, after that minimizing parasitic power draws and maybe that will be enough to make the difference. It doesn't have to be fast, just make the trip. The actual work function can only draw a max theoretical of around a hundred horsepower so they don't have any problem getting their work done, it just doesn't want to climb the hills, lol.
Not necessarily as generally the ambient temperature at altitude is much lower so heat transfer is easier due to high delta. We generally used to fit Rockford fan clutches to larger engines wherever possible in order to reduce the parasitic load on the engine. A direct-drive fan on a 3500 engine can easily pull 100BHP. Best of luck with getting some software for it. A lot will depend on how persistent your dealer is with the factory. Issues with a single engine don't usually attract too much attention when literally hundreds of engines every day roll off the factory production line.
And when electronic controlled engines first started being sent down the deep mines, the software had to be re-written because the increased atmospheric pressure would take the sensor out of range.
Those software engineers aren't necessarily the sharpest knives in the box are they ......??
I don't know about the boys writing the software, I would think they work to the specs given them and that's all they can do. I would seriously doubt they have any remotely real world experience with engines at all, just writing code. Just like it never occurred to me the machine I put together would be working at elevations above 10K because of the kind of work they do, if you're not involved in the mining world, why would you think of it? On the other hand you would think CAT of all manufacturers would have enough experience in it's engineering ranks to always program to the reasonable limits of the engine's capabilities, plus or minus. Deere tends to use electrically controlled variable turbos, I wonder if they're any better at dealing with altitude....
Once you've been on the inside at Cat and see the massive amount of service letters that come out each month, you realise that their business model is "product development on the customers' time"
LOL! They obviously studied the General Motors business model!
It wasn't like that back in the day. Machines actually had most of the bugs removed BEFORE they were put on the market for general sale.
Must have been before my time Nige, I always thought CAT had the absolute best... best propaganda machine the world over, they kept telling everyone they were the best until most people believed it. Just one example that pops to mind, after one of many changes in undercarriage desing that turned out once again to no be an improvement in wear life, the only way they could sell some models was to give a free set of replacement rails and sprockets away with each new machine. To be fair when you're that big and doing that much the world around, how the heck can you possibly keep track of it all?
We have a mine here that we have had to put a fake pressure sensor (adjustable potentiometer) on the machines for them to run properly, they are well past 1000m below ground now. Cat won't be bothered with it so hence the need for hicky do dad solutions.
We had to do that on a 3412 PEEC genset once because it had run out of atmospheric pressure compensation. Worked too .......
Sounds like the computer was willing but the OEM sensor ran out of range?
More like the engine was willing, but the computer didn't know what to do with the truth. So what happens with a mechanical engine at high altitude. Guessing that with a turbo but no "boost feedback" to the pump, they just get a little smokier. Does a mechanical injection pump with aneroid or whatever have less power at altitude than without? because it's limiting the fuel more.
I'm not tracking, if you can manually adjust a pot and fool the computer into adjusting parameters so the engine runs well, is that not an indicator that the sensor was unable to track the atmospheric pressure properly?
The physical sensor should track the pressure just fine. It's when the pressure goes beyond certain parameters programmed into the software, the software thinks the sensor is lying to it and gives an error code and/or derates the engine. If you replace a sensor with a set value resistor or PWM signal generator, depending on the type of sensor, you can certainly fool the ECM into thinking the engine's working within acceptable limits when really it isn't, but, best case, the emissions will be off and at worst you could get problems with smoke and/or overheating. Incidentally, this is how a lot of the plug in engine HP boost harnesses on ebay work. By tampering with either the atmospheric pressure, boost pressure, fuel pressure or fuel temperature sensors, or a combination of all four.
Having been intimately involved with high altitude operation of electronically (and mechanically)-controlled diesel engines for the best part of 10 years I can assure you that it's not as easy as your neighbour is indicating. The issue of course is combustion, you can't burn more fuel per combustion cycle than a % of the amount of air you can cram in via the turbo, but in order to get that fuel to burn correctly some changes will more than likely have to be made to the injection timing to advance it further away from TDC in order to get a little bit more time for correct combustion. Part of the solution may be to increase the size of the turbos- personally I doubt if changing internal components would cut it - or even go to compound turbocharging (a Low pressure turbo blowing into a High pressure turbo). However you can only go so big on turbos before you run into problems caused by their sheer size. A mechanical-injection engine is somewhat easier to set up for any given job site. All you do is back the rack off and reduce the amount of fuel injected until you get an "adequate" amount of black smoke and exhaust gas temperatures are within safe limits. If exhaust temps are too high obviously you'll burn up valves and the downside of a mechanical engine is that not many of them have exhaust temperature sensors and don't give any warning that you're about to fry valves in one or more cylinders. A much more of a seat-of-the-pants approach but in truth you can do very little about the injection timing BTDC therefore you're missing an important factor in getting the best combustion that you can from how much air you can cram into the engine with the lower atmospheric pressure. Another turbo problem with the thinner air at altitude is turbo overspeeding. At some job sites I recall seeing atmospheric pressure around 8psi compared to sea level 14.7psi. Humans literally couldn't walk and talk at the same time at that altitude. The air is so much less dense that there isn't the same resistance to "spin up" of the mechanical components of the turbo cartridge. If you thought that "turbo lag" was an issue then you ain't see nothing yet until you get to high altitude and get into turbo overspeeding. The most common failure mode caused by turbo overspeed is a compressor wheel burst where the wheel splits neatly into 2 halves and you're left with the turbine shaft spinning like crazy but generating no boost. There were various improvements made over the years from cast aluminium wheels to forged aluminium but after a lot of testing the only thing that worked to give an adequate level of reliability (a low % of failures prior to engine removal for overhaul) was to manufacture the compressor wheels from titanium. As you can imagine that had a major effect on the selling price of the turbos and also had knock-on effects regarding turbo rebuildability because the tooling required for titanium compressor wheels was different to that for aluminium wheels.
So all he needs to do is buy a hopped up performance "chip" for it and let it lie to the engine until it makes enough power to get over the hill, right:drinkup That smart **s remark was in jest to CMark's post a couple above this. On a serious note, this has been very informative, and filed in my brain along with all the other things I may or may not use someday.
Wish that were true, if it is ship me one! LOL :tong