Chevy's Dreaded Displacement on Demand bit my Silverado last week

[Sigblaster]

I miss the good old days when I could work on my ‘70 Chevy Nova 302 small block V8 in front of the frat house I lived in. Water pump takes a ****? No problem. Need to adjust the points? No problem? Need to change spark plugs? No problem. Hell, even a leaky valve cover gasket can be a real pain in the ass these days. When I worked on my own car back then it was all familiar because it was like working on dad’s sprint car. This **** sucks.

My first car was a '73 Pontiac Ventura. Piece of garbage, but I could fix it it cheap and easy, if I needed to. I never did, just sold it to the scrap yard when I was tired of it.

2nd car was a 1966 Impala survivor. I did work on that, and it was simple, cheap, and easy. Raise the hood, so much room under there, get your work done and get back on the road.

3rd car was a restored 1966 Impala. Gorgeous car. Lost the mechanical fuel pump somewhere around Elizabethtown KY. Long story short, hitched a ride to E-town, got the part, replaced the fuel pump at the side of the road and it lasted for years until I sold her.

Since then, it's been up and down. Mostly down. Cars have gotten smaller, which means less room under the hood, and they're not designed with maintenance in mind. You have to be a contortionist to work on newer vehicles, and sometimes you have to pull the pack to get to the basic parts.

The US government did this to us. They set out to kill the shadetree mechanic, and they did that.

Some of you may have read about the death of my '06 Pathfinder. I really wanted to get an old school, air-breathing, classic piece of Detroit metal. But I'm too old for that now. Got a modern car with a warranty. Can't imagine having to pull the pack to change the oil pan if I hit some road debris, or reprogam a computer when it goes all HAL 9000.

 

[Nazgul]

Wife bought a new Jeep pickup for herself when she retired in 2021. Can't say anything bad about it. I found a 2020 JL Wrangler and bought it. Have to say I haven't had so much fun in a vehicle since the 1971 Chevelle with a 454 of my youth.

My JL has the same 280 hp engine her truck has. The truck pulls our camper like a champ. Went to pass some one the first time in the Wrangler and found myself going 90 mph! It is quick.

First trip was to visit family in Chicago. On the way back the 4 WD fault light kept coming on. Research showed all kinds of fixes that involved new wiring harnesses, sensor/switch replacements and programming issues. Found a Jeep Tech who said "Push all the fuses in the box in tight". There are 59 dozen fuses in the box so I went to work and pulled/reinstalled all of them. Problem fixed.

Don

 

[Jaybird1980]

You can easily tune out MDS on the Ram, or put it in tow/haul mode, or manually select your highest gear (the tranny will shift normally, since the gear select only means it won't shift above that gear).

There's not much reason to do so in the Ram, though, unless you get a vibration from the MDS. The lifter/cam issues in the RAM are the same as in the non-MDS hemis and there's been no indication it happens more readily on one or the other.

Who has the tuner to get rid of it on a 15 and up?

Tow haul mode changes all the shift points. I do the manual select of gears but it's a pain. I want it gone so that if someone else drives it they don't have to do the hokie pokie button dance.

 

[Leadeye]

I can remember when"displacement on demand" was what you told the engine shop when you said "bore it and stroke it".

 

[Hoosier Carry]

I hate that cylinder deactivation crap. It's just another thing to break. They're still doing it. I do like getting near 23 mpg on the hwy with a V8 when gas is $4/gal. It's not that important. But I'd rather not have something else to go wrong.

Yeah, I bought a truck to tow and haul stuff, not to drive all over the interstates and worry about mpg. Give me full power Scotty! I don’t need a “Vegan” truck that whimpers in 4cyl!!

Seriously though, after buying a 50thousand dollar truck and having Uncle Sam rape me over Gas prices all year long, do you think I am worried about an active fuel management system that throws a few bucks back my way? Woppdeedoo! Turn that stuff off and use that engine.

 

[HoughMade]

I took the old Silverado for an extended "test drive" yesterday afternoon and made sure I hit all the parameters that would have previously caused cylinder deactivation. She ran fine...perfect, in fact.

I then brought it home and changed the oil and installed a billet oil cooler bypass cover that I have had sitting around. This is a common oil leak area. I found a cover from Jegs that uses an "O" ring instead of a gasket, so I'm hoping that....only one of the oil leaks, is taken care of. Even with a few leaks, it has never run low on oil because we check it at least once a week and make sure it always stays in the dipstick crosshatch.

If I had to do it over again, maybe I would have listened more to the DoD complaints and had it disabled 100,000 miles ago.

As old tech vs. new tech, I like having a truck that ran 234k without an internal engine problem which still make compression like it has 50k and gets 22 MPG on the highway and only ever needed expected brake replacement, hubs and oil changes before hitting 230k.

That just would not happen with a carbureted anything running dinosaur oil. I remember when cars were used up around 100-120k miles with normal maintenance. Now people buy cars with 100k on them and rightfully expect that they will run another 100k without too much trouble.

I have a code reader and if you know how to use it, you can still do the work at home. Many things are simpler than they were 45 years ago (probably not 55 years ago)....but maybe it's not simplicity, it's familiarity. I'll get familiar with what I have to get familiar with to get the job done.

 

[BiscuitsandGravy]

Speaking of checking your oil... Search for the 'I do cars' channel on YT. You'll see what oil starvation looks like/results in.

 

[snowdrifter]

Speaking of checking your oil... Search for the 'I do cars' channel on YT. You'll see what oil starvation looks like/results in.

I stumbled across his videos a few months ago and got hooked. He makes some really entertaining teardown videos. The carnage in some of those engines is unbelievable.

https://www.youtube.com/@I_Do_Cars

 

[daddyusmaximus]

I picked up a 2011 suburban a few months ago (after seeing how nice my daughter's 2014 was) and instantly the DOD started pissing me off. I just didn't like the way it sounded and felt when it kicked in and out. Went and got me a Diablo Sport tuner for it. There's an option you can select to turn it off, so now I have a V-8 100% of the time. I'm hoping this will prevent problems like this from sneaking up on me. So glad the Jeep I'm building (1980 CJ7) is old school technology. It will have a Holly Sniper fuel injection on the Mopar 360, but most of it is just old school plug & play stuff.

 

[jamil]

I stumbled across his videos a few months ago and got hooked. He makes some really entertaining teardown videos. The carnage in some of those engines is unbelievable.

https://www.youtube.com/@I_Do_Cars

It showed up in my feed too. I mean, you wouldn’t think watching an engine being broke down for 45+ minutes would be that interesting. It’s kinda therapeutic. I usually have a short attention span and end up quitting most lengthy videos after a few minutes. I usually watch those straight through.

 

[Sigblitz]

@HoughMade
Good job on that. I like this because I like doing things myself. And I learned something new.

 

[Sigblitz]

I guess I didn’t realize some of the cathedral port LS engines had the DOD. I thought they had all switched to square port by then.

I knew Mopar was using old stock on new models in the 70's. My wife's Ford truck has old stock on it, and it's a pain to find the correct parts. It's a common thing on new models.

 

[Brad69]

@HoughMade
Yes DOD on GM’s is the Devil!

My wife’s 2011 Escalade had the 6.2 with DOD Diablo tuned that out ASAP.
It went 170,000 no issues when it was traded.

My Scat Pack MDS worked great you never felt it
just a slight tone change.
Unbelievably a 6.4 engine could get 28 mpg!

 

[HoughMade]

@HoughMade
Yes DOD on GM’s is the Devil!

My wife’s 2011 Escalade had the 6.2 with DOD Diablo tuned that out ASAP.
It went 170,000 no issues when it was traded.

My Scat Pack MDS worked great you never felt it
just a slight tone change.
Unbelievably a 6.4 engine could get 28 mpg!

My current truck is a Ram 1500 5.7L. I can't tell when it goes into 4 cyl. mode. I could hear it on the Silverado from the beginning.

 

[Bugzilla]

I can't complaint too much, it did make it 234,000 miles before causing a problem.

So almost a year after the Silverado transitioned from my daily to my teenage son's runabout, it started tapping...more like knocking, pretty loud (but not as much as rod knock). It also threw a code for a cylinder 4 misfire.

Some of you may know that this is the tell-tale sign for a displacement of demand lifter getting stuck in the collapsed, 4 cyl mode because cyl. 4 is one that deactivates. This can destroy the engine if run too much in this condition.

The standard shop solution is replacing lifters, a $2k job that involves pulling the heads, IF there hasn't been too much damage already. Then, it can happen again unless you delete the DoD which can cost over a grand, leaving you with a $3k solution on what is probably an old truck (mine is).

But then there's the "backyard" solution. There's a guy with a YouTube channel and a shop in South Dakota that has developed a technique to "release" the stuck lifter (special tool, $38). Then, you have to keep it from ever going into 4 cyl. mode again. So, with that tool, an intake manifold and valve cover gasket set and the electronics to turn off DoD and many hours, you too have about an 80-90% chance of fixing it. Sometimes it doesn't work, or it has gone too far for the "trick". I probably spent $200 in total, but I did some other maintenance since I had it apart.

The trick is essentially this- you have to take the intake manifold off (no small feat) then there is a plate under it called the VLOM (Valve Lifter Oil Manifold). When 4 cyl mode is called for, high pressure oil is directed though this manifold to the 4 cylinders to turn off. Oil pressure forces pins in the lifter in and the lifters collapse, turning off the cylinder. The computer also shuts the injectors off.

You take the VLOM off. Then there are passages in the block valley leading to all of the cylinders that get deactivated. I hear that the intake lifters are pretty much the only ones that fail.

You know what cylinder is your problem by taking off the valve covers and there should be a super-loose rocker. Take the rocker off on the affected valve, then in the oil passage in the valley, put a specially shaped tool, a punch of sorts, down the passage to the lifter- then tap on the punch...sometimes harder than you think is prudent and if it works, the push rod will shoot all the way out of the engine bay when it releases.

Then, you disable displacement on demand. You do this mechanically and electronically. Mechanically, the special punch comes with a bushing that you drive into a passage in the VLOM that blocks oil from being send to deactivate the lifters (the lifters are are not lubricated through the VLOM, just the cylinder deactivation). Then, you can get the computer reprogramed or, I went cheaper and got a thing that plugs into the OBD2 port and deactivates it so the signal is never sent to the VLOM and injectors are not shut off.

It's a very involved job, but she is running fine now. However, I will be selling it soon and we need a more fuel efficient car for when my son starts driving to Griffith for welding school.

Here is a video and the website for the guy where I got the tool.



https://www.crazedperformancerepair.com/

Or just buy a Ford and drive it!

 

[Brad69]

5.4 all that needs said!

 

[firecadet613]

Or just buy a Ford and drive it!

Hemi > EcoBoost.

 

[indiucky]

Twenty years into the apocalypse:

them: Man...that dude's an amazing mechanic...tractors, woodworking tools, trucks, small engines, lathes, whatever....he's just good at it....a natural.....so what'd he do...you know...before??"

me: you wouldn't believe me if I told you....

 

[Bosshoss]

Or just buy a Ford and drive it!

Ford had a very interesting version of DOD by blowing out sparkplugs when they weren't needed.

 

[Jaybird1980]

Ford had a very interesting version of DOD by blowing out sparkplugs when they weren't needed.

Absolutely.

When you want to remove them you can't get them out. When you want/need them to stay in you can't keep them in.