Diesel Trucks?

I recently starting working at a light duty diesel shop, and I really like the work. Man though, we suck at diagnosing them... I was wondering if anyone had any information on classes videos or anything that could help. Mostly what we struggle with is low power issues, but it seems like every time it turns into a parts cannon. Anyway, just looking from more resources on fixing these darn things.

Any specific brand that seems to be problematic?

The best I've found has been classes from ATG:

atgtraining.com/product-categories/produ...ine-performance-2011

atgtraining.com/product-categories/produ...l-common-rail-diesel

atgtraining.com/product-categories/produ...ramax-lml-lgh-diesel

The in-person classes and webinars are fun, but it's the training manuals that really shine. The formatting and organization is perfect for use by flat rate techs like me. I keep their 6.0/6.4/6.7L Powerstroke on my toolbox because it makes for a great reference when diagnosing.

Ok I will check them out. Well currently we have problems with a little of all of them. I guess I was thinking more general information about theory, but those manuals look pretty handy too...

Watching LBT-381 Light Duty Diesel Problems and Solutions on AVI, maybe that will indwell me with all the necessary knowledge (if only it was that easy...)

Let me know what you think of the AVI class.

Unfortunately, there is no ScannerDanner of light duty diesels, as far as I know.

Alot of the automotive principles for gasoline engines will translate to diesel engines.
The only differences are:
1.glow plugs versus spark plugs
2.Injectors being fired either electrically (uses fuel injection control module like ford) or mechanically via high oil pressure cummins, cat, Mercedes Benz,
3. Oil pressures are up to 100 times higher (need a 5000 psi liquid filled pressure gauge for testing)
4. Gears instead of timing chains
5. Must bleed air out of fuel system when changing fuel filter and clean prefilter.

But to answer the actual question youtube has several people that cover diesel engines and testing other wise nashville auto diesel school would be a solid option or a local diesel school. Also there are plenty of books available in print and digital.

That AVI course was decent. A good overview of the three major truck brands (light duty). Obviously can't learn it all in 101 minutes. My employer provided the subscription, so I'm not sure it would have been worth the money for just that specific course, but I see they have quite a few more dealing with specific systems, so I guess I'll start plugging away at those. Maybe I'll start a journal and write my own book: AJeep18's Diesel Engine Performance Diagnostics :whistle:

Hardtopdr2 wrote: Alot of the automotive principles for gasoline engines will translate to diesel engines.
The only differences are:
1.glow plugs versus spark plugs
2.Injectors being fired either electrically (uses fuel injection control module like ford) or mechanically via high oil pressure cummins, cat, Mercedes Benz,
3. Oil pressures are up to 100 times higher (need a 5000 psi liquid filled pressure gauge for testing)
4. Gears instead of timing chains
5. Must bleed air out of fuel system when changing fuel filter and clean prefilter.

But to answer the actual question youtube has several people that cover diesel engines and testing other wise nashville auto diesel school would be a solid option or a local diesel school. Also there are plenty of books available in print and digital.

Yes I do understand the basic theory, I am just trying to get a better grasp of diagnosing specific issues. (PIDS to look at, tests to do etc.) I will certainly check out Youtube. Free is always best!

Ok what issues would you be looking at?

Low power? This one can have several possibilities from cam and crank sensor issues, derated due to dpf plugged up, maf sensor issues, injector pressure regulator failing, high pressure oil pump failing/low pressure, injectors failing, injector tubes cracked leaking oil into cylinder, back pressure sensor stuck high disabling turbo, turbo not spooling up from bearing failure (typically higher mileage diesels which the give aways for this is oil in intake air charge tubes going to and from intercooler), fuel injection control module going bad (typically ford ficm where the voltage is low should be 48 volts) failing to fire injectors, Low compression.

Idling up and down while at idle? Back pressure sensor failing, back pressure sensor tube plugged up with carbon, plugged up dpf/cat

Most of these will have a data pid and one way to see a sensor not functioning correctly is with key on engine off and save data pids then key on engine running. data pids that dont change or are high koeo are good teltails of a sensor failure or further investigation on that circuit.

With common rail diesels with low power cmplaints the first things to look at tend to be
(1) MAF output
(2) Turbo Boost Hose Leaks
(3) Carboned up EGR
(4) Leaking Waste Gate
(5) Fuel Rail Pressure.

For difficult or non-starting on a common rail.
(1) Fuel Rail Pressure
(2) Injector Leak Back test
(3) Cam & Crank Sensors
(4) Glow Plugs

---

(unless you live in Alaska nothing like so important as on an old style diesel)


For rough running and misfire to identify the cylinder
(1) Injector corrections on scantool
(2) RPM for each cyliner.

Pico Automotive have some examples of guided test on CRD diesels.

Andy.MacFadyen wrote: With common rail diesels with low power cmplaints the first things to look at tend to be
(1) MAF output
(2) Turbo Boost Hose Leaks
(3) Carboned up EGR
(4) Leaking Waste Gate
(5) Fuel Rail Pressure.

For difficult or non-starting on a common rail.
(1) Fuel Rail Pressure
(2) Injector Leak Back test
(3) Cam & Crank Sensors
(4) Glow Plugs

---

(unless you live in Alaska nothing like so important as on an old style diesel)


For rough running and misfire to identify the cylinder
(1) Injector corrections on scantool
(2) RPM for each cyliner.

Pico Automotive have some examples of guided test on CRD diesels.

Is there a way to test the MAF? It moves up and down with throttle response but I am not sure how to test beyond that.

The hot wire type are really easy to check. The voltage output on the Hot Film type can be either 0v to 5v or 0.5v to 4.5v.
The engines I see are generally Bosch CRD1 and use a Hot Film 0.5v to 4.5v sensor.
You can test these with the car stationary engine running using either a multimeter or a scope.
Connect to the signal wire by back pinning at the sensor (Bosch usually yellow wire)
At idle you should see somewhere between 1.5 to 2.1v
Hit the gas pedal and increase rpm to near the redline and the voltage should initially jump to 2.5v or so then more steadily to just over 4v.
The fall back in voltage when the pedal is released is slower than the rise.
If you are using a scope you can see hash on the scope trace which is actually single induction pulses.

I have a nice scope capture from a Freelander TD4 that I will try and look out tomorrow but the Pico guided test show it all anyway

www.picoauto.com/library/automotive-guid...t-wire-turbo-diesel/

this is worth watching Injector leak off test

Understanding the different systems is the first thing you should undertake. Whether mechanical, HEUI, MEUI, or common rail. EGR and aftertreatment systems as well. Each manufacturer runs differently but if you grasp the theory of each system's operation then you'll pretty much be able to diagnose anything. Most of the issues that you are going to see are emissions related( i.e. aftertreatment and EGR), or part of a common pattern of failures that many of the same vehicle are going to have happen.
If you want to understand the different fuel and emissions systems I recommend checking out Adept Ape On YouTube. He's a knowledgeable CAT mechanic that posts many theory and operation videos. Remember that just because you aren't working on a Caterpillar doesn't mean it isn't applicable. CAT actually developed the HEUI system with International that's in some of the Ford trucks. And common rail works pretty much the same on ALL diesels.
I can try to find some info at work that could help you pertaining to Cummins, Perkins, CAT, Kubota, Deutz or Isuzu that won't specifically relate to a pickup but will at least educate you on what you need to be looking for. Cummins and Perkins factory training is probably the best training I've come across yet.
So, in conclusion, get familiar with how the different fuel systems work. Get VERY familiar with how aftertreatment and EGR systems work. Learn turbocharger operation and theory. Variable geometry turbochargers are common on all newer Diesel engines. Those are four of the biggest things you'll be dealing with.
Once you know theory, you'll be able to select your own PID's on the scanner because you'll know what to look at for the system you need to diagnose.

Any additional information you have would be great! Like you said at the end it is actually knowing what PIDs to look at that I guess is giving me trouble. We have been having lots of injector problems lately, is there any way to test them without removing them and having the tested? Not necessarily one that is non functioning but poorly functioning. I know Chevy has balance rates which can help, but is there anything to look for on other OEMs?

Ford offers data PIDs for their injectors if I'm not mistaken on the newer 6.7. It has been a bit since I've had to diagnose something on a Powerstroke because the majority of what we deal with at work is logging equipment, larger trucks, and construction equipment since we are a Hyundai construction/Bell Truck dealer and also Cummins, CAT, and Perkins engine dealer.
I can tell you from experience that several model years of the newer trucks whether a Ford, Chevy, or Ram have had issues with the Bosch injection pumps. Some of the Powerstroke's have issues with the injector hold down clamps breaking and causing misfires. Most injection issues you'll see on the 6.0 Powerstroke are very well documented already and primarily relate back to the high pressure oil system for HEUI system. You can always use a lab scope on diesel injectors the same way you'd test a gas injector. The wave forms are going to be a bit different because of a diesel's operation but scoping a known good for the heck of it will give you a general idea of how the patterns are supposed to look. I can't remember off the top of my head if my Verus has a functional test for Ford as far as injector testing is concerned. I know Cummins Insite software has the capability on certain engines for injector testing. We don't work on many Ram trucks but if one comes in we typically use Cummins Insite to diagnose an engine or emissions concern.
If you have a firm grasp on gasoline engine diagnosis, it is very easy to take that to a diesel once you get the theory down. If you're looking for more specific training for the Duramax, Powerstroke, or Cummins 6.7 or 5.9 I'd recommend checking out ATG's books from AESWave. They're expensive, but investing $100 in a book is nothing if it gives you the knowledge to advance you in your career.

To answer your specific question on testing injectors, it just depends on the engine you're testing them on. If the scanner doesn't have a contribution test or balance test then scoping them will be your best bet. If you're having problems with only one or two cylinders it shouldn't be hard to see the difference between a good cylinder and the bad on a two channel scope. The best way to test them is removing them and having them tested, but usually that involves a lot of labor. On glow plug engines, you can remove the glow plug on the "bad" cylinder and unplug the suspect injector to see if the injector is leaking. Sometimes getting to those injector plugs is more work than it's worth though. There are a ton of different ways that a diesel fuel system can be tested. I prefer using my scope whenever I can because getting to anything on a pickup diesel is a BEAR.
Also check out Science of Diagnostics, and Diesel Tech Ron on YouTube.

While not an injector problem, I did manage to diagnose a compression problem quickly with my lab scope. Sorry for the crappy quality photo.

I guess the problem we run into is not so much a dead injector as that is fairly easy to diagnose, but a set or several under or over fueling injectors, we always send them out to be tested but have gotten weird results lately (they said they were all great so we put them back in and they we leaking so bad it wouldn’t build enough pressure to start, and almost filled the manifold with fuel!) so I was wondering if there was a way to test this in the truck.