Td5 misfiring and cutting out problem finally solved!

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.

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.

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:




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:

Nice job m8 ..... i also have these "peak charge long" codes on injectors 1, 3 and 5(mostly coz after i erase them they come back randomly but always on 5) ..... I asked here and nobody answered what this code means.....the eldritch for me is that the car is running and starting as it should, without any probs......could u tell me something about these codes please?

I also got the same fault codes showing on my Def TD5. Had all the cutting out symtoms but in the end it was mainly down to gunk choking my fuel pump low pressure stage in the tank.

I'd changed every sensor and the injector loom etc. But still it continued. Only since I've replaced everything in the fuel system (and ran an earth wire from battery to ECM) has the problem finally disappeared.

Ron.

Sierafery,

I'm no expert and this could well be total blks but I believe the "peak charge long" and "peak charge short" faults essentially mean the ECU is not getting in the flywheel what it orders the injectors...

The ECU is constantly listening, through the CKP sensor, to the result each injection and stroke cycle produces on the flywheel. If injector signal delivery or fuel availability are compromised then a 'mismatch' occurs between what the ECU wants (commands) and gets. And it blames it on the injectors by saying the peak charge was off.

Fuel availability is an easy one and it usually boils down to a defective FPR or fuel sender.

Injector signal delivery issues can take various forms, including purely mechanical (my case), oil in loom (causing either increased resistivity along a single conductor or partial shorting between different conductors), insufficient grounding, etc.

Hope the above makes sense.

Rgds

Matt

Makes a lot of sense for me...thanks m8.....especially coz lately i observed that it began to appear oil in the ECM red plug again. It was sorted out once, now i ordered the o-rings for the injector loom and a new engine harness(it wasn't cheap at all)....will see what hawkeye says after replaceing these. As i said my car is running faultless but i better prevent some probs.

sierrafery said:

Makes a lot of sense for me...thanks m8.....especially coz lately i observed that it began to appear oil in the ECM red plug again. It was sorted out once, now i ordered the o-rings for the injector loom and a new engine harness(it wasn't cheap at all)....will see what hawkeye says after replaceing these. As i said my car is running faultless but i better prevent some probs.

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OH. I nearly forgot.

I also had problems with a lot of oil in the connectors for the CKP sensor. Also, the wires on the socket had beconme brittle and one was bare for about ¼ of an inch back from the plug and the other wire was cracked in various places. The wires were a little twisted in such a way that these wires were (I assume) occasionally shorting out the sensor. I did a temporary repair and insulated the breaks in the insulation which got me going again until one of the wires snapped off. I have since done a better temp repair by putting in two short lengths of fresh wire. The difficulty was thet wire which snapped had snapped off at the point where it disapeared into the plug so I had to cut back some of the plastic to get a little bare wire to solder my new wires onto. Should you discover this problem with your's, the plug for the bonnet switch on the Defender is identical to the one on the CKP.

Also, if you have oil in the loom, check the blue header connectors in the same half of the loom at the ECM's red plug. Rave doesn't show any in their photographs near the ECM (under driver seat) but I have two headers in there one of which was very very badly oiled up too. The cap comes off the header and it's easy to wash it out with de-greaser of your choice.

Finally, I also replaced three of my relays. When I opened the relays I found the contact points on them were badly pitted and worn out. Initially I simply cleaned them and "dressed" then with prudent use of a nail file until I got replacements.

I hope this helps.

Ron.

Thanks for your reply....that's why i decided to replace the whole engine harness...cos the old one is full of oil and it has some "tyred" parts(i.e the CKT sensor wiring...and others) ....i've replaced the injector loom two years ago and now i have oil in the engine harness again...i dont see the logic to replace the whole injector loom when the problem comes from the orings on the plug of it(the loom itself was struck out to lay in oil anyway)......i will replace only the orings and use some sealant too there then put the bran new "oilless" engine harness......i will spray the ECM plug with contact cleaner and let it dry well before off course.

Cheers m8s

Any old ECM/ECU looms can yu chuck in my direction plse. Am in involved in a "security" project and need a couple of old (non working/oily) looms to play with.

The Mad Hat Man said:

Any old ECM/ECU looms can yu chuck in my direction plse. Am in involved in a "security" project and need a couple of old (non working/oily) looms to play with.

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Mine is still working just that it's oily ....I'll replace it sometimes next week and will find some cheap way to ship it to u from Romania...and yours it'll be(yu'll get it as a Christmas present)....anyway i don' wanna put used parts on my landy ....PM me your full adress

The Mad Hat Man said:

Any old ECM/ECU looms can yu chuck in my direction plse. Am in involved in a "security" project and need a couple of old (non working/oily) looms to play with.

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Sorry mate, I plan to re-wire my old one so I have a spare.

Sierra, I simply used a generous blob of grease to seal my plug where it goes through the head.

Also, a tip for anyone changing their injector harness, wrap a bit of rag round your finger and wet it with WD40 then poke yer finger in the hole, the crap from the old o-rings wipes off dead easy.

Out of own experience it appears that those two blue o-rings in the injector harness cannon connector go under gauge fairly quickly (even if genuine or OEM) thus letting oil go around the male connector (injector harness side) and into the female connector (engine harness side). Have lately adopted the practice of cleaning the hole, as Clanforbes suggests, and then using hi temp silicone (gasket type) around the o-rings & male plug. No more oil in loom for a long time now.

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:






And seen from below:



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



After being cleaned out:







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

Cheers

Matt

Land Rover should be accountable for this stuff. Its just shoddy build quality and a fault caused by their cable routing/lack of shielding.

Guess I have all this stuff to look forward to at some point lol

Great post !

I've just suffered the oil in the injector wiring loom problem complete with the oil in the Red ecu plug on my disco td5 03.
I'm all set with the new parts - injector loom and cover gasket etc etc but what concerns me is the part of the loom that isn't replaced as it still has oil inside it ......... how long could this take to work it's way out ?

I've noticed with interest your rewire on the lower half of that loom, thinking it to be a possible fix if replacing the ' top section' doesn't solve the problem totally.
My line of thinking .......... totally replace all the contaminated wires.

Any thoughts ?

Regards

Colin.

The only "infected" wires are the five yellow ones connected to the injector loom... i'll quote a post of mine from an other forum coz it's relevant(and easyer for me to do that)

1. If there was a theory that the oil comes through the pins of the injector loom and te oring replacment is not the real fix i can say now, 8 months after i've replaced just the orings that there is not even a trace of oil in the upper harness plug(where it's connected to the injector loom)

2. Did this too myself for a friend who couldnt afford a new engine harness... 5 months ago.... it's also working....no oil from the "infected" harness reached the ECM since. >> cut the five yellow wires of the red plug near the plug as to have space(these are coming from the injectors) and use "clamps" to reconnect them(tin the ends of the cutted wires) ... clean the connector with contact spray and leave the ECM with the connector downward over night as to get rid of the oil from there

I dunno how they are named in english but here they are(of course use a cutter to separate 5 of them) http://www.marcofil.ro/detalii_produs.p ... odusID=155 ... click on the image to enlarge

The oil leaves the harness through this connectors and can't reach the red plug, also insures a good connection and isolation between wires......it's verifyed.
_________________

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After that a m8 said that these connectors are oftenly named "chocolate block connector"

Reading more ............ i think i'd better check my cables aren't rubbing on something ?!

The mis fire recently started on my 1998 136k disco qnd sure enough the loom and red plug were full of oil. Cleaned out and no improvement so looked under the rocker cover. Prodded all of the injector wires and found them hard and brittle, after which mis fire temporarily disappeared. Going to change the injector loom, partly to cure the oil leak but also in the hope that the misfire is caused by a broken conductor under the rocker cover. Has any one else found this?

If not I guess I'll work my way along the engine harness, soldering iron at the ready!!

Tuss said:

The mis fire recently started on my 1998 136k disco qnd sure enough the loom and red plug were full of oil. Cleaned out and no improvement so looked under the rocker cover. Prodded all of the injector wires and found them hard and brittle, after which mis fire temporarily disappeared. Going to change the injector loom, partly to cure the oil leak but also in the hope that the misfire is caused by a broken conductor under the rocker cover. Has any one else found this?

If not I guess I'll work my way along the engine harness, soldering iron at the ready!!

Click to expand...

replace the injector loom asap

Finally got round to changing the loom tonight. All better now. Nice to have 5 pots back . My engine loom doesn't appear to be threaded through the ACE pipes - it stays above them.

hi guys , not long ago I replaced my top loom , and the connecting plug , and later had to do a By pass on the lower loom , because of oil pressured to the red connector , the oil wasnt in the surround of the loom but actually within each individual wire , I used Trailer Cable 7 core , with 7 colours to make it easier , and ran it over by the egr valves and around the brake servo , down and under and into the large gator into the ecu area, ..
another job done ,,, only 5 more to do lol,
steve