Suspect Diesel knock/pinking

Forum for Engine, Exhaust, Drivetrain, ECU
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Fifeplumber
Posts: 4
Joined: Sat Aug 14, 2021 10:12 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by Fifeplumber »

Hi I was wondering if anyone can help, I've got a j11 1.5dci, been getting a loud knocking under load but not present at idle, when starting the car from cold (bearing in mind the temps been rather warm lately) it hunts like it's doing a cold start, splutters when adding acceleration but eventually sorts itself out, garage said it's just diesel knock and to use premium fuel (used V-power) but made no difference, also when at 70mph on motorway it would start spluttering like it's getting starved of fuel, but again if I give it more acceleration it clears it. Had enough of worrying that I'm doing damage I took it to the garage again, they found that it was misfiring, @1400rpm they were getting a low fuel pressure on injector 2, backed off then back on the throttle and then it showed up low fuel pressure on injector 3, so they replaced both injectors, a few days on now and the knocking is still there all be it a smoother drive, but the starting from cold is still an issue, it's driving me insane as it's not losing any power which is strange and not showing up any warning lights. Previously before changing the injectors there was an egr fault logged, a glow plug fault logged, if anyone can shed some light that would be most appreciated

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MikeGC
Posts: 1850
Joined: Tue Feb 07, 2017 11:50 am
Location: Stockport
Qashqai Model: Mk.3 Qashqai - J12 (2021+) New Model

Post by MikeGC »

Welcome to the forum, I wish I could help.
No doubt someone will be along who will have more idea what the problem might be
March '22 - J12 1.3DIG-T 160 CVT Tekna+ with all wheel drive - Pearl Black
July '19 - J11B 1.3DIG-T 160 DCT Tekna - Vivid Blue
March '17 - Qashqai J11A 1.5dci n-connecta - gunmetal
September '14 - Juke 1.5dci gunmetal ascenta premium (red accent packs)
Fifeplumber
Posts: 4
Joined: Sat Aug 14, 2021 10:12 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by Fifeplumber »

Thank for the welcoming 😊, fingers crossed as I've already paid for 2 injectors that I'm now thinking wasn't the issue, or maybe part of the issue, n the bank balance isn't neverending lol
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calnorth
Posts: 2719
Joined: Mon Feb 11, 2019 2:01 pm
Qashqai Model: Mk.2 Qashqai Facelift - J11b (2017–2021)

Post by calnorth »

Fifeplumber wrote: Sun Aug 15, 2021 10:56 am Thank for the welcoming 😊, fingers crossed as I've already paid for 2 injectors that I'm now thinking wasn't the issue, or maybe part of the issue, n the bank balance isn't neverending lol
I'm not experienced with diesels at all...they were always noisy. However, the area of concern is probably described well in this article:

https://www.infobloom.com/what-is-diesel-knock.htm

Your starting problems look to be troubled around air/fuel mix and temperature. All at the right level and time. There are of course sensors involved to enable engine management to get the starting and running processes right.

Sorry cannot be specific but it needs a good diesel person to examine it.
Mk2 Qashqai Facelift - J11b (2017–and onward)
1.6 Dig-T N-Connecta
Fifeplumber
Posts: 4
Joined: Sat Aug 14, 2021 10:12 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by Fifeplumber »

It's never really been a loud diesel that's what the annoying thing is with having this issue, there's also like a drone/dull vibration coming through the car aswell at idle, going to see if the garage could check out a few sensors, namely the knock sensor and the map sensor, also maybe query the crank sensor
Fifeplumber
Posts: 4
Joined: Sat Aug 14, 2021 10:12 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by Fifeplumber »

Well turns out injectors 1&4 were faulty aswell 😔, but on the plus side it's back to being nice n quiet, no knocking and don't have to have the radio on to drown the sound lol, downside is it cost £1150 to get all 4 injectors changed
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