Power Problem with FM260

[JRhetts]

As some of you may recall, I have been trying to chase down a perceived lack of power on the Mitsubishi 6M60T1 engine in my Fuso FM260. I felt I could not pass as rapidly as I would prefer, and some really steep highway climbs reduced my speed to equivalent of other trucks. …After I pestered my nearby Fuso dealer, Mitzu agreed to replace the turbo unit.
I detected no major change.

After a lot of tinkering, consulting diesel engineers, and an abortive effort at dyno testing the rig, I came to the conclusion that:
I have a 245 HP engine, designed for longevity [came with 7 yr 250K mile warranty], powering 23,000 pounds of rolling weight, and it is never going to pass like some of the high-HP/high-torque pickup-based rigs I have driven.

 

[1leglance]

blackstone has always treated me well and I have used it to see if I am getting too much blowby or if my veggie oil setups were doing anything negative to my engines.
like you said there are a number of good places to go and it is worth the investment.

 

[Amesz00]

does the engine run EGR? i know of a similar problem with one of our customers MANs, would periodically for no reason use heaps more fuel (like as if it were towing 20t worth of trailer) and considerably less power. MAN did all the diagnostics and said its fine, nothing wrong with it. he then somehow tracked it down to the EGR control valves (or the actuators that control them) sticking one way. reckoned that when they work it goes fine, when they stick it goes like crap.
other than that, in performance terms, boost is made by engine load and heat. obviously there isnt a problem loading up the engine. heat comes from air:fuel ratios. if there were a fuel system problem, and it were starving of diesel (even only slightly), you would see less boost and less power.
just my 2c, sorry dont know anything about oil analysis.
andrew.

 

[alan]

EGR's are a constant source of problems with common rail diesel engines, toyota's,nissan's and mitsubishi's to name a few all suffer from clagged up inlet manifolds from the sludge that forms from the egr and engine breather fumes,block it off! better performance better economy.

 

[SkiFreak]

block it off! better performance better economy.

I'd love to, but how do you do this without the ECU having a hissy fit and reporting errors?

 

[alan]

we have never had a problem with codes appearing.

 

[PKDreamers]

Castrol have a service called Labcheck in Australia which I am sure they would have in other parts of the world.

 

[mog]

Has anyone had experience with using oil analyses to diagnose what is going on with an engine?

This is kind of a lemon to lime comparison but my 2 cents.
In aviation (jet) SOAP (Spectrometric Oil Analysis Program) checks are routinely performed every 150-flight hours and both pre / post heavy engine maintenance. It works outstanding and can predict problems BUT this is done fleet wide, routinely and across a fleet of 1000s (Garrett 731s in my case) engines so the database is huge. Doing it as a one off check would not be as informative of course. A lot of the predictions in the SOAP analysis is the types of alloys dictate which bearing(s) etc are having high wear. You would not have this database and I don't think Mitsubishi would either. If you had an oil analysis every oil change, I guess you could start building your own database, but that is a long-term project.
If wear (perhaps turbo bearing?) is a concern, you can buy an oil filter cutter (most aviation supply places carry them for light recip aircraft that use spin-on filters). So you can open-up your own filter and check the debris (and even weight it you like) yourself.
I'm sure the automotive labs will have some baselines that will be useful, when using them.
BTW, what is the max boost you are supposed to be getting? And how are you monitoring it?
Best of luck with the troubleshooting.

 

[jhrodd]

I don't think oil analysis is going to help much other than to show possible high soot or fuel dilution. Have you had it on a chassis dyno? The first thing I would do is see if it's making it's rated horsepower. An IR thermometer aimed at each cylinder might show one or more underperforming. Also pressure test the charge air cooler, I built a simple tester out of PVC pipe to regularly check my DD15's CAC. For big trucks the factory specs are no more than 5# loss in 15 seconds @ 30 psi mine always had zero loss in 15 minutes. 5 #'s in 15 seconds is a pretty big leak if you ask me but they won't replace it unless it's more than that.

 

[JRhetts]

This is kind of a lemon to lime comparison but my 2 cents.

I think both of your 2 cents are valuable and helpful. Thanks for the reply!!

(… in my case) … the database is huge. Doing it as a one off check would not be as informative of course.

Yes, my ‘database’ may only have an N=1, unless the lab I use happens to have data on other Mitsu 6M60T1s. What I have been hoping for is that one or more vectors in the oil results might be so anomalous as to give me something to follow up on. At this time I don’t have any promising leads.

 

[JRhetts]

does the engine run EGR? ...
andrew.

Andrew

Yes this engine DOES run an EGR. I very much thought it might be part of my problem, for example wondering if the turbo was not getting enough input to spin up to its rated max. However, according to Mitsu's diagnostic computer, the EGR is working properly, tho I cannot say exactly what sensors there are nor what measurement led them to that assertion.

Any suggestions for me to pursue? I can understand things pretty well once explained to me, but I have not studied diesel engines. As I said above, I am primarily a driver/explorer, not an engineer/mechanic.

John

 

[blackduck]

John
just a thought but you don't have an exhaust restriction do you
some time back on one of our boats that has an above and below water exhaust a bloody octopus got past the diversion gate built a home then shuffled off this mortal coil
V14 engine very high tech ran like a pig
we checked everything
and always landed back at the turbos
finally we looked at the exhaust and there was the problem
restricted exhaust which threw the induction right out and messed up the whole show
removed the 8 legged home wrecker and it ran like new

its worth a look ??

 

[whatcharterboat]

Maybe Andrew should check for octopus in the exhaust too if he wants to keep going through that deep water in his crewcab

 

[mog]

I'm surely not an expert and probably don't even qualify as a reasonable knowledge individual on diesels. Most of my experience is in fanjets (well kind of an axial turbocharger), but I'll put some thoughts out as catalyst for the experts.
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1.) Have you looked at the ‘controls' for the boost? Is the ECU seeing the correct pressure signal from the sensor? It sounds like your independent boost pressure gauge and the ECU are seeing the same number, so maybe that is fine. But if the turbo is doing its job compressing perhaps it or its control (wastegate) is being told to stop working too soon. You could bias the input data (voltage) to the computer for boost pressure (tell the ECU it is getting less boost then it is) to see if it can make the 22psi with its controls ‘off/modified'. If you intend to try that, drop me a PM and I will send you a schematic for that test, so you will not need a breakout box for the sensor wiring to the ECU.
2.) Have you checked the HOT side of the turbo system (exhaust)? Perhaps a muffler with a collapsed interior, a bent pipe or an exhaust brake that is not fully open (or bent/misaligned butterfly valve). If the hot side can not spool up the cold side, that of course will effect boost.
3.) As mentioned, it would be interesting to see what your delta P is from the outlet of the turbo to the intake manifold. I don't know were your add-on gauges reads from, but two reading, one at the turbo outlet and downstream of the intercooler (or as close to the manifold as possible) would be informative. On the FE/FG the allowable drop (delta P) is ZERO.
4.) With a ‘history' of injection problems, maybe a review there. If the engine is not making power because of a fuel issue, then turbo boost could be off. It is much easier to read the low boost, then to read low ‘power'.
5.) Perhaps this is a larger ‘fleet' problem and you are the only one paying attention to it. Mitsubishi is not going to be a bunch of help in that. I don't see them volunteering that “O- ya , 20 percent of the FMs are not making boost/power”. If you could check with other operators (maybe the other RUF uber-Fuso owner might be of some help), to see if there is an issue with your truck only, or part of a larger problem. It would sure give you some ammo to use if it is a fleet problem.
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Note- some duplication with others and suggestions for things you have already checked as per post # 10. I typed this last night off-line . . See I couldn't sleep thinking about your problem
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2a.) Has the compete inlet side to the turbo been checked? Something as simple as a clogged air filter could effect boost (less air in, less to boost). Or a rag left in the inlet during maintenance and only partly blocking the inlet? I had a pressurization problem (aircraft of course) once were I suspected the sensor line being blocked. Blew compressed air through, that was ‘fine', visually inspected the complete line's exterior looking for a collapsed section, that was ‘fine', ended up running a cable inside of the line and found it partly blocked. So while the compressed air would flow through it, the volume of air was reduced during operation effecting the control. Moral of the story is with airflow, it is not just pressure & flow, but volume (CFM) that is necessary

 

[mog]

I experienced [and still do] inability to hold highway speeds on even moderate hills;
I experienced [and still do] very long acceleration-to-pass times even on flat highway surfaces;

I have to say that those 'experiences' sound pretty baseline Fuso performance.
Your Uber-Fuso:
Weight.......HP (spec)..................Torque (spec)
23,300.......243 {96 lbs per HP}....516 {45 lbs per lb/ft}
My Fuso FG
Weight.......HP (spec)..................Torque (spec)
10,500......145 {72 lbs per HP}....275 {38 lbs per lb/ft}
No way can I even think of holding highway speeds on hills. Every hill is a downshift to 4th at least and long 5-6% grades bring the dreaded 3rd gear downshift.
Acceleration-to-pass, yup I did that once, we even took photos to prove it (it was a 'real' car, not a VW bus).
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I fully agree you should be getting your rated boost and rated HP/Torque, but even if you get a true 18% direct increase with boost at 22psi, my very non-performance FG at the weights and HP/Tq listed above has an 18% advantage in HP to weight, and 32% Tq to weight, and it sxxxx in the road performance aspect.