Diesel Diagnostics
Dealerships are automotive repair shops; independent workshops are automotive repair shops.
For years I have worked with both dealerships and independent workshops. As a local council apprentice diesel mechanic and for the entire length of my career as a diesel fuel injection specialist, I work with everyone in the industry.
Indirectly we have both dealerships and independent workshop subscribers assisting each other. I am told by several members they found out about Diesel Help from stumbling upon some of our technical bulletins when Googling. One our bulletins TB1048Hyundai iLoad IMV wiring fault P0253 Injection Pump Fuel Metering Control A circuit low has been a big draw card. The 2013 Hyundai iLoad fault turned out to be a common Hyundai technical bulletin and admittingly did assist confirming the issue our members were experiencing. Of course, we are not into plagiarism. As it turns out we spent a few days diagnosing the vehicle to enabled us to compile enough of our own evidence to create a bulletin reducing the possibility of a misdiagnosis.
During the diagnostics I had contacted our resident Hyundai dealer to find out the fuel line plumbing arrangement to confirm if we had air ingesting within the system. Willing to assist, the helpful workshop supervisor immediately asked me the fault? The workshop manager told me about the technical bulletin on the 2013 Hyundai iLoad. The engine starts ok and would only fault when deaccelerating and then accelerating soon after. This would occur at any time, hot or cold. The fault was a damaged wire rubbing on the engine mount. Rather than jump to the wrong conclusion, its best to diagnose to avoid a misdiagnosis.
Prior to the member joining Diesel Help, several tests were performed on the wiring without finding a problem. In diagnosing diesel’s, we have two ‘must have tools’. One being a diagnostic scan tool and the other is our Eliminator.
The Eliminator enables you to connect a separate fuel supply directly to the high-pressure pump’s inlet and outlet. The separate fuel supply will assist to determine if there is a supply or an engine system fault. During driving with the Eliminator, the vehicle faulted on several
occasions. This confirmed we had an issue with the Common Rail Diesel (CRD) system. During the test using clear hose, we had also noticed air bubbles in the return hose. This information is extremely helpful as air causes more than 50 percent of CRD fuel-related faults.
To narrow down where the air was entering, further investigation found air returning from the injectors when the fault was occurring. At first, we thought it may have been combustion entering via the injector nozzle holes. An on-vehicle injector return test was performed at idle and no air was entering the test vials during this test. I recalled seeing air ingested when testing a common rail pump on the test bench. This foaming of diesel fluid creates aeration from the sudden change of the Inlet Metering Valve (IMV) on a new high-pressure pump. This type of aeration is not so harmful as it dissipates quickly after it occurs.
FUEL PRESSURE DATA
The diagnostic scan tool is used to observe the rail pressure change during a fault. When diagnosing common rail diesel problem, I want to be able to read the desired and the actual fuel rail pressure. This way we can determine if the ECU is instructing the fuel pressure change or in something changing the pressure beforehand. I am using an image of our recently acquired laptop-based Delphi DS Diagnostic Scan tool to explain what data I am referring to.
DIAGNOSIS AND/OR EARLY DETECTION OF THE FAULT
Of the two wires to the control valve on the pump (red/black and yellow on this vehicle), it was the yellow found as the problem in this case. You must strip the convoluted tubing and tape from the wiring-loom about 350-400mm back from the plug to find the problem. The wire strands were ok, just the insulation rubbed away as you will see by the photos. Could not see anything from underneath the vehicle other than the loom disappearing over the engine mount. Removed the battery and other components from the left hand side engine bay to get a good look at the loom (but still hard to see as you will see in photo) and it was draped over the top of the mount but was held fast by an earth tab.
SOLUTION
Repair the wire with tape over the rub, re-tape the length of loom and refit split tubing. Also dress the loom away from mount.
SPECIAL NOTES
We have experienced several other Hyundai iLoads with similar issues yet different fault codes including P0670, P0253 and P0088. and the symptoms were engine would start but will not accelerate and produce excessive rattle evident. Another case it was found the red wire had rubbed and blown a fuse.
Refer to a wiring diagram for the fuel flow control valve is Y194. Looks like yellow wire earths through pin 77 of ECU. If red/black wire was rubbed it will often blow fuse F12.