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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #1
I finally got the plugs and filters from Mopar Parts online and having the shop manual CD really helped. With 30k on the plugs they were still at .60 mm which is .0236. I didn't expect the spec to be that narrow. A good chocolate brown color. 168 in/lbs torque. The engine cover has little lanyards on the bolt covers to keep from losing them which I thought was a nice touch. Having a magnet plug socket also helped a lot. Uncliping the connectors was the most stressful part of the whole job but easy enough in the end. All in all a very easy job anyone can do.
 

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Thanks for the write up. Where did you get the shop manual CD?
 

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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #3
I'm pretty sure I got it on Ebay, not cheap though 150 or so. And thanks.
 

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The question I have is why change these plugs so early?

What does Alfa recommend? Jaguar says 160,000 km (100,000 miles ) even for my supercharged engine.

Iridium tipped plugs do not erode as copper or even platinum tipped plugs used to do. Have a very close look at the plugs you removed. You will see a bright strip of silver coloured iridium around the verynend of the centre electrode and the tiny bit of iridium welded to the gap side of the ground electrode. The colour of the rest of the plug really isn't relevant any longer because that colour reveals only the actual heat range experienced by those particular plugs, which depends on how you drive. The technical heat range of iridium plugs is quite broad so we no longer worry too much about whether a particular engine is running too hot or too cold centre electrode temperature.

They last so long because the gap doesn't change.

In fact, nobody is sure how long they can actually last. 100,000 miles is arbitrary. Japanese makers like Toyota remain super conservative and recommend plug changes at 60,000 miles, or six years which is pretty weird since age doesn't affect plug life.

Um, that would be why using such expensive plugs makes sense in the first place.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #6
I only play an engineer on tv so take this with a grain of salt. Yes the gap was the same as the new ones and if it was just a matter of gap I'd leave them in. From the looks of them it's easy to say they take a beating and although the ceramic insulator was intact and the color was good plugs are judged on more than gap. I would think that as the plug ages the likely hood of it not meeting it's design parameters increases. Thus the 30k service interval Alfa recommends. I'm not trying to convince anyone of anything, just thinking out loud more than anything.
On another note I also got a cabin air filter and there is no way anyone could change that without instructions. Holy Cow, it's 4 times more involved than changing 4 spark plugs. Panels to remove, connections to disconnect, battery to unhook.



WARNING:
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbags, airbag curtains, knee blocker, seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect the IBS/negative battery cable assembly from the negative battery post, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to take the proper precautions could result in accidental airbag deployment.



  1. Disconnect and isolate the negative battery cable. If equipped with an Intelligent Battery Sensor (IBS), disconnect the IBS connector first before disconnecting the negative battery cable.
  2. Remove the right front floor outlet (Refer to 24 - Heating and Air Conditioning/Distribution/OUTLET, Air/Removal and Installation) .
  3. Working on the right side of the HVAC housing, disconnect the wiring harness (1a) from the retainers (1b).
  4. Release the retainer (2a) and remove the cover (2b) for the cabin air filter.

  5. Remove the cabin air filter (1) from HVAC housing by pulling the filter element straight out of the housing.
 

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I recently changed the plugs on my daughter's boyfriend's Audi Q5... 210,000 km, most likely never replaced. As you said, the trickiest part is unplugging the connectors. I found 6 plugs gapped at .080'', twice the recommended spec. I installed new dense iridium plugs, all pre-gapped correctly. He couldn't believe how it ran after.

I wonder if the wide open gap was a result of wear or if somebody had been in there. The .080 was very consistent...
 

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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #8
Good question. The photo is one of my plugs with 30K and I was struck by the amount of discoloration up the threads. If the Audi plugs had 80k on them perhaps the amount of discoloration if there was any might be more pronounced? I just got back from a run to town and I could and I was surprised I could notice the extra performance just from replacing the plugs and air filter. I've never noticed that much of an improvement in any of my other cars I've had over the years but this was so much I could not help but notice. I'm sure some is in my noggin but still quite a difference.
1654852
 

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2020 Giulia TI,1988 Milano Gold Auto
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My 2020 2.0 Giulia owners manual specifies 60,00/6 year plug replacement. Guess Alfa decided to adopt the Japanese schedule after all.
 

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From Michael's comments, I conclude the plugs at ,080 gap had been tampered with. I expected the threads to be stuck after 10 years, they offered no resistance - they almost felt like they were not tight enough. The owner or PO (his father) have never held a wrench in their lives, so it was done by somebody they PAID to fix the car.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #11
I did save my old plugs so I guess when I turn over 90,000 I can put them back in for thirty more. Thirty more, 30 more... almost sounds like it could be a song about my Alfa:)
 

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The best guide to servicing is the manufacturer's recommendation.

If Alfa specifies 30,000 miles (50,000 km) then that's the change interval I would use. It seems very short for iridium plugs although there are two designs of iridium plug and only one of those two has the very long service life.

The picture of the iridium plug is of the shorter service life version. The long life version has a needle sized centre electrode and a similar "slice" of the same diameter material welded under the ground electrode forming the gap.

NGK markets the former type as Iridium IX and the latter as Iridium Laser. NGK welds a disc of platinum under the ground in the Laser version. I've seen long life Denso plugs using a tiny piece of iridium "wire" identical to the centre electrode welded to the underside of the ground which I understand extends the service life of those plugs to 100,000 miles.

The two designs are interchangeable but the long life plug is much more expensive.

For my supercharged Jaguar which develops 340 bhp from its 3.0 litre engine the change interval is 160,000 km (100,000 miles) with no time interval. Just checked NGK parts listing and sure enough they specify ONLY the laser iridium plug: change interval 100,000 miles. Interestingly, the specified plug is also "indexed" which formerly was only racing engine specification. That means the orientation of the gap is critical. The manufacture requires that when the plug is threaded fully in and torqued EXACTLY to spec the gap faces a particular direction. None of this: "screw in hand tight and then an additional quarter turn" estimated installation torque! You need an in /lb torque wrench.

Plugs are interesting devices. In the old days we changed the copper core plugs in our turbo engines every second oil change: at 2x7,500 km ( yup, conventional oil and the filter were all used up in 4,000 miles and the plugs gone in 8,000 miles). Mind you, ten years earlier that was the tune up and oil change interval for a pedestrian OHV engine!

Don't remind me about points and condensers.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Discussion Starter #13
I noticed the plugs do have a small disc attached/welded under the tip of the electrode on the ground end. You can sorta see it in the photo, live much more so. I'm sure those are the factory plugs and perhaps the later models have the longer life versions hence the 60k. They came from MoPar Parts Online and were in a Genuine Alfa Romeo Parts box and not a NGK box. Really good information, Thanks!
 

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I know plugs are made by plug makers and not car makers, although who owns the plug makers is another issue. The brand name on the OEM plug might not be the name of the actual plug maker.

Maybe Alfa specified a conservative plug replacement interval for reasons specific to their engine.

There is no doubt it is wise to follow the engine maker's recommendation in preference to that of the plug maker. The engine maker tests their own engines. Engine makers may follow the advice from their parts suppliers but the engine maker makes those decisions about what's best practice for their particular engine.
 
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