L77 - AFM/DOD improved over time. But high oil consumption?

[CliveSS]

There are many posts relating to AFM/DOD lifter failure. Also several posts on the improvements made to AFM/DOD over time - (thank you Monstar). I am interested in AFM/DOD, not so much from a performance point of view but really to understand any potential reliability issues which are likely to arise from the system.

My unmodified 2006 VZ Thunder auto has an L76 with AFM/DOD hardware that is not activated. From what I have gleaned the hardware consists largely of: softer profile cam (than non AFM/DOD, special valley plate containing solenoids (VLOM), two part lifters on 4 cylinders.

On my auto transmission L76 motor (and I understand on L76 and L77 manual transmission models) the AFM/DOD is disabled by the factory settings to the ECU software. In essence the solenoids in the valley plate/VLOM do not actuate. They are in a permanently closed position and hence oil under pressure is not diverted to the two part lifters. The lifter pins are therefore permanently in the default locked position and to all intents and purposes operate as a "normal lifter".

It is widely reported that AFM/DOD lifters in early L76/L77 motors have issues with sticking. In other words the main lifter spring (not the latch pins spring) will be stuck in the compressed position. The effect is that the lifter and push rod assembly are in a shortened state and float between the camshaft lobe and the valve rocker. A ticking or clattering sound results from the lifter and push rod assembly being bounced off the rotating camshaft lobe. Damage to camshaft and lifter will likely occur if the problem is not addressed.

As a sidebar, my L76 motor has AFM/DOD disabled and since the lifters are not subject to opening and closing I assume that they would not be subject to "sticking". They would not need to be replaced or upgraded - bearing in mind that I am referring to a stock motor with no performance mod's. Hence any ticking noises coming from any (L76/L77) deactivated AFM/DOD motor is unlikely to be due to faulty lifters. Would anyone like to comment on this?

Returning to the matter of sticking lifters, there is a very informative AC Delco u-tube clip (Oct 2018) explaining the operation of AFM/DOD lifters. It explains that lifter failure is almost always a symptom and not the cause of engine damage. It can be caused by a mistimed switching event brought about by low oil pressure VLOM issues etc. etc. That seems to support other posts which report persisting problems despite replacing damaged lifters. Watch the video clip for details.

I have seen another u-tube clip (don't recall title or date) which suggests that the lifter bores are extremely tolerance critical. The bores should be checked before replacing lifters.

As per para' 1, Monstar notes that AFM/DOD systems have been improved over time. If I am reading his posts correctly it appears that by VF series 1, L77 motors will have a set up as good as it gets. They incorporate Delphi II lifters and several other mod's to increase efficiency and reliability.

However there have been several posting about high oil consumption on some engines. Low km's units and apparently in good order where high oil consumption would not be expected. I am unsure whether that is only on AFM/DOD active motors or if it also applies to de-activated systems? It seems that high oil consumption is associated with AFM/DOD enabled motors.

I read on another forum/post (don't recall title or date) that high oil consumption on AFM/DOD active engines is a direct result of AFM/DOD. It appears that on extended low throttle/light load freeway cruising (when 4 cylinders are de-activated) the de-activated cylinders are subject to excessive oil build up (and/or petrol?) which burns when the cylinders are put under load and the cylinders are re-activated. Over time/mileage the piston rings "gum up" resulting in high oil consumption.

I would appreciate any comments on the above; particularly in relation to high oil consumption issues. Any comments at all would be useful, but the following info might help to shed some light on the issue(s):-

Engine: e.g. L76/L77
Mod's or standard
Model year:
Total km's
Oil consumption
Auto or manual
DOD present or not
DOD enabled or disabled

If you've read the post to this point you must be keen! Hope some useful information comes back.

 

[Ron Burgundy]

Wow that's long post...

Does you engine have any issues / unusual noises ?

 

[CliveSS]

Wow that's long post...

Does you engine have any issues / unusual noises ?

Why?

 

[Ron Burgundy]

Why?

Because I am struggling to see what the actual question is ... What is the issue ?

Unless it's simply a broad discussion around the topic you raised ?

 

[CliveSS]

Thanks Ron,

Yes, the point of my post is "to understand any potential reliability issues which are likely to arise from the system". I used the example of my own L76 to provide context, not to resolve a specific issue.

My long post provides (hopefully) some useful information for those interested in DOD. Also some assumptions; some of which may be erroneous. Any relevant feedback is welcome.

I have bolded text in para' 5 which invites comment. Also para' 11 asks for further comments.

Hope that clarifies.

 

[Skylarking]

Don’t know technical details about AFM/DOD but if any concerns exist about oil consumption, the question that pops into my mind is how much is consumes between services?

If it’s more than the amount between the high and low marks on the dipstick (1 litre?) between services (15,000kms) then I’d consider it a fault which Holden should fix under Australian Consumer Law (ACL) statutory warranty, even if outside manufacturers warranty period.

The whys and why nots of oil consumption are not really relevant as any more than 1 litre per 15,000 kms is outside service intervals which would indicate something is wrong. And when one buys a car it comes with a certain service schedule which can’t be changed after the fact (that would be a bait and switch) so Holden can’t suggest intermediate top ups between service; that won’t hold.

As for deactivated AFM/DOD hardware, and ticking noises, if there is any abnormal noises Holden needs to sort it out under ACL as an engine should last much longer than the manufacturers warranty of 3 years 60,000kms. Heck, maintaining scheduled services should allow the engine to work for more than a decade without valve train rebuilds. If an engine with deactivated AFM/DOD hardware has a higher failure rate for the AFM/DOD bits than the other parts of the valve train, then obviously Holden has mis-stepped by taking the cheap software approach rather than producing a different variant of hardware (without AFM/DOD) - so I’d expect Holden should handle the issue under your ACL statutory warranty.

Having said that, mainly due to AFM/DOD’s need for super clean oil, and as extra insurance, I would consider doing a mid service schedule oil & filter change (as many forum members often recommend).

So, buy from a dealer and allow ACL statutory warranty to work for you rather than worry about a potential engineering issues or non event.

 

[abuch47]

https://www.sae.org/news/2018/05/gm-2019-v8s-with-dfm-system
https://www.wardsauto.com/2019-10-best-engines/2019-winner-chevy-silverado-62l-ohv-v-8-dfm

 

[426Cuda]

Interesting thread CliveSS.
I've owned my auto VF Redline since new (Oct 2013). It's been moded most of its life and has always enjoyed a good romp across the tacho type workout. Mods include headers, hi-flow cats, 2.5" exhaust, OTR CAI, engine and trans tune. Roughly 260rwkw. The tune included broadening the AFM band / parameters and also making the most of the E85 flex fuel capability (st my request and also as suggested by Pir4te / Monstar).
I've had no real issues with the car to speak of.
Engine: e.g. L76/L77
Mod's or standard: mods as above + brakes ;-).
Model year: 2013
Total km's ~87,000
Oil consumption: too small to measure. I.e. negligible.
Auto or manual: Auto
DOD present or not: Present, active and tuned for
DOD enabled or disabled. Enabled.
Oil changed at ~ 8,000km intervals (Penrith HPR 5W40 Enviro).
Usually run on a 70/30 ratio of e10 & e85 respectively. Gets good economy, and power for about the same prIce as 91RON. It runs better than new.
Cheers,

 

[Forg]

Because if you averaged out the availability of E85 across all of Sydney it would round to 0, we use PULP98 in our bought-new-by-us 2014 SSVR.
Opposite of 426Cuda's, dead stock & my wife putters around in it so it probably doesn't get enough exercise.

In case this is what you're after:
Engine: L77
Mod's or standard: Stock.
Model year: 2014
Total km's: ~29,000
Oil consumption: too small to measure. I.e. negligible.
Auto or manual: Auto
DOD present or not: Present
DOD enabled or disabled. Enabled.
Oil changed at ~ 4,000km / 9mth intervals (whatever the mechanic I trust uses).

 

[krusing]

I know this is a VF thread, But my L77 is the same as in a VF,
I have a 2012 Series 2 Calais Wagon, Built July 2012, and use it as my work Car,
Purchased it in June 2013 from a Dealer, with 16,900 k/s on the clock,
it was ex-GM [Executive] Car that was based at Port Melbourne, was in immaculate condition,
Ticked all the boxes at the time.
I have never missed a service [scheduled services of 15,000k's up to 90,000 k/m's]
Where now I have done them myself at every 10,000 k's since they charge you $100 for 7 litres of oil, and $90 p/hour.
And they usually don't actually check/do everything on the service list.
I did replace the DOD Filter earlier in the year as I had a noisy lifter,
[especially when its cold, but not as notable when it gets hot, but still a little bit noisy]

In case this is what you're after:
Engine: L77
Mod's or standard: Stock.
Model year: 2012
Total km's: ~163,000
Oil consumption: Could be 1/2 Litre > 1 litre depends on City driving or Country Driving
[doesn't get to the low mark between services]
Auto or manual: Auto
DOD present or not: Present
DOD enabled or disabled. Enabled.
Oil changed at ~ 10,000 k's - 5w-30 Penrite, or Shell full synthetic [what ever 5w-30 is on special at supercheap]