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Td5 misfiring & cutting out (no oil in loom issues)


mturri

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My '04 Disco Td5 started behaving extremely oddly, subtly clunky at idle (feels as if the vehicle is being given hand pushes from behind), then normal when given throttle, but once boot is off the throttle the engine starts misfiring (not the typical 1 cylinder misfire but something rather massive) and comes to a stop. Engine re-starts as if nothing had happened but said behavior persists.

Nanocom read the following faults:

FAULT 27-01 injector 1 peak charge long (CURRENT)

FAULT 27-02 injector 2 peak charge long (CURRENT)

FAULT 27-04 injector 4 peak charge long (CURRENT)

FAULT 27-05 injector 5 peak charge long (CURRENT)

FAULT 28-03 injector 3 peak charge short (CURRENT)

FAULT 31-01 injector 1 open circuit (CURRENT)

FAULT 31-02 injector 2 open circuit (CURRENT)

FAULT 31-03 injector 3 open circuit (CURRENT)

FAULT 31-04 injector 4 open circuit (CURRENT)

FAULT 31-05 injector 5 open circuit (CURRENT)

Cleared these several times but they keep showing up each time the engine shuts down. Also worth noticing is that "Idle Speed Error" is now between +/- 12, whereas before was well within the +/- 4 range and the engine felt a lot smoother. All other fueling parameters are within specs, also no abnormal smoke, oil level normal, coolant level normal, coolant clean, etc.

All indications point to a rather radical oil-in-loom problem but... injector harness is practically new (replaced 2 months ago) and there are absolutely no traces of oil in connectors C0521-C0171 (injector harness to engine harness) and C0158 (red plug to ECU). Checked continuity in all 7 conductors (5 injectors + 2 grounds) from each individual injector connector to the ECU & found no conductivity problems at all. Also verified battery, fuse boxes (ECM and fuel pump associated relays & fuses), alternator & grounding at various points, all to no avail. Pulled ECU apart just in case... also completely dry.

Replaced fuel filter but no changes, engine still misfiring and cutting out on easing on or releasing throttle. Although shown by Nanocom as an electrical problem, it does have the looks of a fuel delivery issue, strange one though as it takes place when fuel demand tails off...

Fuel pump will be replaced next, followed by fuel pressure regulator (including gauze filter), but then...? CKP sensor? ECU?

Any thoughts more than welcome.

Regards

Matt

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I'd try and borrow an ECU to swap in and try that. As you say sounds like injector harness but you have ruled that out (probably - don't discount the fact that new parts can sometimes be dud...)

Was it a genuine harness?

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Update:

Replaced crank sensor, thought I had it since the metal tip was literally buried in oily muck & the car ran smoothly for quite a while, but eventually the misfiring & cutting out returned...

Currently waiting on new fuel pump, will open up FPR and inspect gauze filter. Also fixing up a device to be able to read fuel pressure while driving.

Installed injection harness is OEM, will try with the old one (nothing wrong with it, car had 90k miles and harness had never been replaced so more of a 'maintenance' replacement).

Won an ECU on fleabay but could be another month before I get it, meant to be the 're-mapped ECU' so let's hope it's not that...

Due to browser troubles this post went in twice. My apologies for that.

Regards

Matt

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  • 4 months later...

Back in July my Disco Td5 started misfiring & cutting out, not in the classic oil in loom way, but rather massively. Nanocom would show a scramble of the following fault codes:

FAULT 27-01 injector 1 peak charge long (CURRENT)

FAULT 27-02 injector 2 peak charge long (CURRENT)

FAULT 27-03 injector 3 peak charge long (CURRENT)

FAULT 27-04 injector 4 peak charge long (CURRENT)

FAULT 27-05 injector 5 peak charge long (CURRENT)

FAULT 28-01 injector 1 peak charge short (CURRENT)

FAULT 28-02 injector 2 peak charge short (CURRENT)

FAULT 28-03 injector 3 peak charge short (CURRENT)

FAULT 28-04 injector 4 peak charge short (CURRENT)

FAULT 28-05 injector 5 peak charge short (CURRENT)

FAULT 31-01 injector 1 open circuit (CURRENT)

FAULT 31-02 injector 2 open circuit (CURRENT)

FAULT 31-03 injector 3 open circuit (CURRENT)

FAULT 31-04 injector 4 open circuit (CURRENT)

FAULT 31-05 injector 5 open circuit (CURRENT)

Engine had been thoroughly maintained, injector harness replaced not long before and absolutely no traces of oil in wiring as well as critical connectors including the red plug. Checked continuity between each individual injector connector & the respective pin in the red plug. Checked ECU grounding, battery voltage, fuses, relays, etc. everything even remotely associated with the ECU was verified and found ok. Replaced CKP sensor, fuel pump, and controlled regulated fuel pressure was right (replaced FPR last year).

The cutting out gradually worsened over a 2-month period to the point at which the engine would stop altogether (without any previous misfiring) under high load and the check engine light showed up.

The fault code in this scenario was always:

FAULT 28-07 topside switch failed pre injection (CURRENT)

This new evidence pointed the finger towards the ECU so started looking for a replacement. Won a used one on fleabay and a few long weeks later fetched it from customs, plugged it in, programmed injector codes, learned security code and fired up the engine. Warmed engine up a bit and came down the driveway, but as soon as I let weight on the throttle the engine cut out immediately, would not take any load at all, over and over. Turned out the 'new' ECU was twice as buggered as mine! Could even see traces of dry oil around the four tiny ports on the back (eBlag dispute ongoing). Back to the start and another few weeks before I located a 'tried, tested & guaranteed' ECU off a breaker yard.

At this point the Disco was barely drivable so took advantage of the sit time and did several low key but time consuming jobs in preparation for a future remap. Pulled out and cleaned intercooler, radiator, hoses, etc. Blanked off EGR, modified exhaust manifold, changed out studs, replaced oil cooler, oil centrifuge & oil filter housing gaskets. Replaced suspicious clips, secured cables, installed silicone hoses; cleaned plugs, changed out engine mounts, springs, shocks, track rod, link rod, etc.

It was during this process that I noticed that the section of engine harness conduit going from the back of the battery compartment to the engine, had been rubbing against the ACE lines (right below the coolant reservoir), and it was literally mounted on top. More concerned about a potential leak development in the upper ACE line, wrapped it with a slit piece of hi temp rubber hose (engine harness getting moved around in the process).

Anticipating a frustrating journey drove the Disco to town for a wheel alignment session but experienced no misfiring or cutting at all. Drove it around lightly for another 5 days, still good! Took the highway and got rough with her this time but still not a single miss. Though uneasy about not knowing what the problem truly was or how it was involuntarily fixed, declared the Disco once again healthy.

Soon came a planned long weekend family trip and decided to take the now well behaved Disco. Drove about 70 km on a paved road and took a shortcut through a rough mountain pass with plenty of corrugated dirt sections, deep holes and rock outcroppings. About 30' into it the engine started cutting out again. It became progressively worse & to the point where even a small bump would cut the engine out! The difference this time was that the misfiring and cutting out were not random but in response to road surface features! Turned around & managed to get home giving the starter motor the day of its life, as well as infuriating the wife & kids…

With the ECU still weeks away and evidence that the problem could be laying somewhere else (although ECU was still ‘topsiding’ under heavy load and continuity was re-checked good between ECU and each injector… in static conditions), resolved to try out a different approach... Disconnected the plug going into the engine (C0171) and peeled off enough tape on the conduit going back to the ECU as to be able to freely pull a good 8 inches on the 7 wire bundle coming from the said plug. Cut the 7 cables about 6 inches from the injector harness connector (right before the conduit dives down through inlet manifold), ran heat shrink tubing, soldered 7 new wires, heat shrank, ran into 1/4" slit conduit, and taped & zip tied in place.

img01resize.jpg

img02resize.jpg

Then ran the conduit and the 7 cables inside down through the inlet manifold and followed the engine harness path all the way to the plastic receptacle where the ECU is housed. Pulled off the cables corresponding to pins 1, 22, 23, 24, 25, 26 & 27 on the red plug and cut, soldered, etc.

img03resized.jpg

img04resize.jpg

img05resize.jpg

Fired her up and never again has it missed a beat let alone cut out! Despite this, have a new engine harness on order as I have my doubts about the long term integrity of the soldered connections.

Here's where the engine harness had been chaffing against the ACE lines & suspect the conductors had been damaged:

img06resize.jpg

It's a low point therefore if any oil or dirt built up between partially peeled conductors then that could explain the ECUs topside switch failures (partial shorting between conductors at higher loads) and why they have not come back since the ‘bypass surgery’, though always keep the spare ECU handy just in case there was permanent damage inflicted to the ECU and it eventually decides to give up.

Put together the following diagram as to help me out in the process:

c0158toc0171bypasscable.jpg

Rgds

Matt

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  • 1 month later...

Here's a follow up on this post.

Whilst experienced no more misfiring issues, soon enough lost the A/C and tracked it down to a lack of conductivity between the A/C compressor clutch and the red plug. Again had to cut cables off the engine harness and laid in a parallel loom.

Two weeks later I happened to take the Nanocom for a ride and it came to my attention that fuel temperature remained still at 30°C...

Shortly after the new engine harness arrived and proceeded to replace it. Needless to say, the fuel temperature issue was immediately solved.

Had suspected the engine harness had become damaged by sitting over & rubbing against the ACE lines as marked by the red arrows:

1HTIMG01resizuFy.jpg

voFIMG02resizbWE.jpg

5vhIMG03resizmwT.jpg

And seen from below:

owlIMG04resizxWS.jpg

And was right... this is how the harness looked:

E3TIMG010resi7mm.jpg

After being cleaned out:

THdIMG020resinKy.jpg

bA9IMG030resiooW.jpg

F8SIMG040resiie4.jpg

Note the yellow cables are the injector conductors (no wonder the misfiring problems and shorting between injectors!)

Cheers

Matt

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  • 3 years later...

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