Member Since: 31 Dec 2021
Location: Taranaki
Posts: 271
Ignition coil buzz 4.0L Petrol V6
Hi all
I've just noticed that I am getting a high pitched electrical buzz in the vicinity of the ignition coils on my V6 petrol engine when key is turned to ignition on, but motor not running (It's probably buzzing with engine running but can't be heard above sound of the engine). I'm yet to unplug each one to work out which one is buzzing.
I have a sound recording but don't know how to attach to this forum.
Should I be concerned? Engine normally starts first attempt but I get an occasional crank but no start (it then starts on 3rd or 4th attempt) - is this the problem?
I can buy a coil on line for approx 50 pounds (about NZD$100) from UK lrparts which doesn't seem too bad. Looks to be an easy unplug and unbolt job.
If I replace is it better to replace one, or all 6 (just conscious of cost).
New battery installed 2 weeks ago.
All codes clear except B1C57-14
Any feedback welcome
Blake
18th Mar 2022 10:23 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4907
It's possible one or more of the coil pack spark plug insulators have degraded causing a HT short to earth. It could also be an actual coil pack failure or more than one!
However, there should be PCM (engine) fault codes to support this, if not it might just be a battery issue.
Start with checking the battery voltage and that it has an absolute minimum 12.3v before starting. Then go from there as per above but you should be focusing on the engine diagnostics rather than body, just make sure your IID is configured to include all modules.yµ (idµ - eAµ) ψ=mψ
19th Mar 2022 3:44 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 271
Thanks Prof
Battery voltage 12.4v ignition on, engine not running. Start engine 14.3v, drops back to 13.8 after a few minutes running. New Yuasa battery 2 weeks ago. Old battery only had 11.7v ignition on, engine not running. Didn't notice sound then but that's not to say it wasn't making the noise. I can't hear the noise from within the cabin, only hear it when bonnet is open and I'm standing there.
Sound is a high pitched whine, definitely an electrical type sound, sometimes constant, sometimes quivers/fluctuates in pitch.
I just tried unplugging each coil electrical connector in turn with ignition on, engine not running to see if I can isolate the noise to a particular coil. I can only however unplug 4 of the 6 coils. With the 3 coils on the left hand side the little plastic tab is facing you, so I can push that in to pull the electrical plug. The 3 right hand side ones the tab is facing to the rear, I can remove the front coil electrical connector, but not the 2nd and third coil on the right hand side. I can't get my fingers in there, even if I unbolt the coil. There is not a lot of free play with the wires, and I don't want to damage anything, after 16 years the plastic on the wires feels stiff and hard.
Anyway engine is running smoothly, running on all 6 cylinders, not missing a beat. Like you say no faults on the PCM. Maybe its best left untouched, engine starting first attempt.
I think I will purchase a spare coil and keep in the glove box, as a precaution though.
Thanks
Blake
19th Mar 2022 11:05 pm
Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1798
The whine type noise could also be one of the pulley bearing on the way, especially the idler one.
29th Mar 2022 9:00 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 271
Thanks Globtrotter for the feedback
I'm getting the noise when the engine is not running, but with the key in position II (ignition on, prior to cranking). The best way I can describe the noise is it sounds similar to a mozzie (Mosquito), high pitched zing.
It's obviously not a common issue (although most of the UK guys seem to have diesel or V8 petrol engines. The colonge V6 seems more common in NZ/Aus/North America.
I was wondering if the V8 petrol uses the same coils as the V6 petrol.
In the vicinity of the noise is also the Engine control module (ECM), and the fuse board and relays. Its hard to pinpoint.
I tend to agree with ProfsrG with his comment about coil pack insulation degrading. After 16 years the plastic is getting hard and brittle.
Like I say I'm not too worried, engine is running on all 6 cylinders, nice and smooth. Hopefully it's not a problem about to develop however.
Cheers
Blake
29th Mar 2022 9:37 am
Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1798
Could have a look when its really dark and see if there is any tracking
29th Mar 2022 10:17 am
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 271
Great idea. Thanks
29th Mar 2022 10:36 am
Gram-br
Member Since: 23 Apr 2021
Location: SAO PAULO
Posts: 15
My D3 gasoline V6 makes the exact same noise with the ignition on, engine not running. I thought it sounded like a small electric motor running, but there is no such thing under the hood, as far as I know.
Coil packs are too expensive here in Brazil to swap out just for curiosity, so I have not tried that.
Like you, mine starts and runs fine, no fault codes, so I am just putting it down to one of those 'LR things'.MY05 Disco 3 4.4 V8 HSE .... insurance write-off
Replaced with MY08 Disco 3 4.0 V6 base model
'98 Toyota Hilux SW4 V6 for playing in the mud
'03 Brazilian Nissan XTerra Diesel ... my overland car, sold
+ countless others
30th Mar 2022 10:09 pm
Naki Blake
Member Since: 31 Dec 2021
Location: Taranaki
Posts: 271
Thanks Gram-br, that's interesting you have the same noise. I think for time being I'm just going to leave as is.
I followed Globetrotter's suggestion, but couldn't see any tracking, sparking in complete darkness around the coils.
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