Random D5 cylinder 4 misfire solved - check your D5

SwissXC90 · Feb 2nd, 2018, 18:38

So on my MY2009 185hp D5 diesel I would occasionally - as in once every few weeks or months - get a misfire on cylinder 4.
Never noticeable when driving, but logged in the engine ECU.
Very rare, and no discernible pattern to it.

So a few weekends ago, after chatting with a fellow forum member, I checked the fuel trim balance between cylinders - all very well within spec, and then decided to have a good close look at the injector electrics.

I removed the injector cover, and unplugged all the injectors and inspected the connectors.
All but cylinder 5 were clean and dry. Cylinder 5 had the start of white oxidation on it.
I used contact cleaner spray on all connectors and on the injectors as well, and got them all clean.
Tip: when still wet with contact cleaner, mate the connector a few times in and out so that the contacting surfaces of the pins have contact cleaner moving about on them. Helps to clean the mating surfaces.

I also cleaned all the dusty injector connectors so that the weather-proof rubber seal would mate well.
In fact, I cleaned everything under that injector cover as best I could.

I then inspected the wiring loom and found something I suspect was the root cause of the problem.
Most of the injector wiring loom is inside a plastic semi-flexible trunking, except where wires break out of the loom to go to an injector.
At these breakout points, the wires are protected inside a flexible braided sleeve.

Exactly on injector 4, the loom was hard pressed against the injector, so hard that the wiring loom had formed a molded curve as it went around the injector casing.
Given that the injectors can be at 90°C then the engine is running, and that the injector body is bare metal, I was not happy with that at all.

I cable-tied the loom back to the wiring loom guide, so that it was well clear of all injectors (and any other metal bodies where vibration and chaffing may occur).

Since that cleanup of injector contacts and re-positioning the loom away from the injector bodies, I have not logged a single ECU misfire.

I'm hoping I found the root cause of the problem and have fixed it for good.

At any rate, I recommend you check your injector wiring loom and make sure the loom is clear of the injectors.
And check the injector connectors for cleanliness as well, and remove any signs of oxidation using contact cleaner spray.

Whizzer · Feb 2nd, 2018, 23:59

Can't agree more!

Corrosion to the injector connections (cylinder 4 in my case) was the downfall of my trip to Austria last year resulting in abandoning my car at Stuttgart Volvo and continuing in hire car!

Fortunately not too expensive repair (new connector), just a pain!

I regularly remove these connectors and use contact cleaner as Swiss says.

Off to Austria next week - fingers crossed.

SwissXC90 · Mar 8th, 2018, 12:41

2 Month Update
It's been at least 2 months since I cleaned the injector connectors and re-positioned the wiring loom

Not a single ECU error logged in all that time... great!

Mijasman · Jun 30th, 2019, 11:30

Quote:

Originally Posted by Whizzer

Can't agree more!

Corrosion to the injector connections (cylinder 4 in my case) was the downfall of my trip to Austria last year resulting in abandoning my car at Stuttgart Volvo and continuing in hire car!

Fortunately not too expensive repair (new connector), just a pain!

I regularly remove these connectors and use contact cleaner as Swiss says.

Off to Austria next week - fingers crossed.

The electrical connector to number 5 injector on my 2006 XC90 is broken. In order to avoid buying a complete engine wiring loom, I am desperately searching for a replacement connector but am unable to find one. Do I really have to replace the entire wiring harness? I cant even locate a used harness.

Help please

SwissXC90 · Jun 30th, 2019, 14:29

Volvo can sell you a spare connector

Davidasherson · Feb 7th, 2022, 07:28

So delighted to find these posts. I have been told by mechanics that my car engine is perfect on the one hand to needing to replace the small turbo on the other! Gave up in the end. My misfire is so sporadic and I am sure it is electrical. There is one specific corner in which I can sometimes replicate the miss. Probably because of a shift in weight in the engine that causes the injector wiring to shift.
Will give it a try and report back.
Many thanks to all.

Feb 2nd, 2018, 18:38	#1
SwissXC90 Premier Member Last Online: Mar 20th, 2024 18:26 Join Date: Jan 2016 Location: Cross Country	Random D5 cylinder 4 misfire solved - check your D5 So on my MY2009 185hp D5 diesel I would occasionally - as in once every few weeks or months - get a misfire on cylinder 4. Never noticeable when driving, but logged in the engine ECU. Very rare, and no discernible pattern to it. So a few weekends ago, after chatting with a fellow forum member, I checked the fuel trim balance between cylinders - all very well within spec, and then decided to have a good close look at the injector electrics. I removed the injector cover, and unplugged all the injectors and inspected the connectors. All but cylinder 5 were clean and dry. Cylinder 5 had the start of white oxidation on it. I used contact cleaner spray on all connectors and on the injectors as well, and got them all clean. Tip: when still wet with contact cleaner, mate the connector a few times in and out so that the contacting surfaces of the pins have contact cleaner moving about on them. Helps to clean the mating surfaces. I also cleaned all the dusty injector connectors so that the weather-proof rubber seal would mate well. In fact, I cleaned everything under that injector cover as best I could. I then inspected the wiring loom and found something I suspect was the root cause of the problem. Most of the injector wiring loom is inside a plastic semi-flexible trunking, except where wires break out of the loom to go to an injector. At these breakout points, the wires are protected inside a flexible braided sleeve. Exactly on injector 4, the loom was hard pressed against the injector, so hard that the wiring loom had formed a molded curve as it went around the injector casing. Given that the injectors can be at 90°C then the engine is running, and that the injector body is bare metal, I was not happy with that at all. I cable-tied the loom back to the wiring loom guide, so that it was well clear of all injectors (and any other metal bodies where vibration and chaffing may occur). Since that cleanup of injector contacts and re-positioning the loom away from the injector bodies, I have not logged a single ECU misfire. I'm hoping I found the root cause of the problem and have fixed it for good. At any rate, I recommend you check your injector wiring loom and make sure the loom is clear of the injectors. And check the injector connectors for cleanliness as well, and remove any signs of oxidation using contact cleaner spray. __________________ XC90 R-Design MY2009, Black Sapphire Metallic. HP-Sound, RSE, Nav, Tel, ParkingCam, BLIS, ParkingHeater, RestHeat, Removable Towbar, Summer: CRATUS 20x8 on Pirelli Scorpion Zeros 255/45, Winter: NEPTUNE 17x7 on Continental WinterContact 4x4 235/65.

Mar 8th, 2018, 12:41	#3
SwissXC90 Premier Member Last Online: Mar 20th, 2024 18:26 Join Date: Jan 2016 Location: Cross Country	2 Month Update It's been at least 2 months since I cleaned the injector connectors and re-positioned the wiring loom Not a single ECU error logged in all that time... great! __________________ XC90 R-Design MY2009, Black Sapphire Metallic. HP-Sound, RSE, Nav, Tel, ParkingCam, BLIS, ParkingHeater, RestHeat, Removable Towbar, Summer: CRATUS 20x8 on Pirelli Scorpion Zeros 255/45, Winter: NEPTUNE 17x7 on Continental WinterContact 4x4 235/65.

Jun 30th, 2019, 14:29	#5
SwissXC90 Premier Member Last Online: Mar 20th, 2024 18:26 Join Date: Jan 2016 Location: Cross Country	Volvo can sell you a spare connector __________________ XC90 R-Design MY2009, Black Sapphire Metallic. HP-Sound, RSE, Nav, Tel, ParkingCam, BLIS, ParkingHeater, RestHeat, Removable Towbar, Summer: CRATUS 20x8 on Pirelli Scorpion Zeros 255/45, Winter: NEPTUNE 17x7 on Continental WinterContact 4x4 235/65.

Feb 7th, 2022, 07:28	#6
Davidasherson New Member Last Online: Sep 1st, 2023 10:37 Join Date: Feb 2019 Location: Durban	D5 misfire 2014XC 60 So delighted to find these posts. I have been told by mechanics that my car engine is perfect on the one hand to needing to replace the small turbo on the other! Gave up in the end. My misfire is so sporadic and I am sure it is electrical. There is one specific corner in which I can sometimes replicate the miss. Probably because of a shift in weight in the engine that causes the injector wiring to shift. Will give it a try and report back. Many thanks to all.

Feb 2nd, 2018, 23:59	#2
Whizzer Junior Member Last Online: Apr 1st, 2024 17:46 Join Date: Jan 2015 Location: Maidstone	Can't agree more! Corrosion to the injector connections (cylinder 4 in my case) was the downfall of my trip to Austria last year resulting in abandoning my car at Stuttgart Volvo and continuing in hire car! Fortunately not too expensive repair (new connector), just a pain! I regularly remove these connectors and use contact cleaner as Swiss says. Off to Austria next week - fingers crossed.

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