SOLVED! Disabling DOD

[Jkb242]

Everything I have read on the subject of oil consumption with the 5.3L is that it is often related to DOD. I realize This may vary somewhat widely but if temporarily disabling DOD is pretty straight forward I could access its impact in my particular case. Is re-enabling it just as easy as disabling without any glitched? I’m concerned that as the oil is burned and passed through the exhaust, there could be damage to the CATS and the O₂ sensors causing them to fail.

Thanks!

 

[northcreek]

Everything I have read on the subject of oil consumption with the 5.3L is that it is often related to DOD. I realize This may vary somewhat widely but if temporarily disabling DOD is pretty straight forward I could access its impact in my particular case. Is re-enabling it just as easy as disabling without any glitched? I’m concerned that as the oil is burned and passed through the exhaust, there could be damage to the CATS and the O₂ sensors causing them to fail.

Thanks!

Oil consumption has also been reported to be caused by low tension piston rings and valve cover breather issues. I deleted my DOD using the Range OBD port plug in device. This worked okay but, I eventually removed it because I was having trouble with my monitors not resetting. I logged 120k miles on that without consumption or DOD issues so my advise would be to sit tight. You could get a tune if you have your heart set on DOD delete.

 

[Mooseman]

If you just want to disable DOD temporarily, you can do so by unplugging the vacuum sensor on the brake booster near the master cylinder. Its only purpose is to monitor vacuum to enable DOD. You will get a CEL and code for it but you'll now what it's for.

 

[Jkb242]

Thanks guys. As always really appreciate the input. Indeed I could have the breather issue that was mentioned. I never changed the bank 1 valve cover that included a PCV connection to see if that was an issue but it too is related to the action of DOD is it not?
What about the concern I mentioned regarding early failure of the CATS and oxygen sensors (oil in the exhaust).
Thanks!!

 

[northcreek]

I never really bought the breather thing, seems like GM was buying time with that. If it was breather location as they claimed, why didn't the problem exist right out of the box?unless it was the cumulative effect that it caused on the rings. My son took his truck in for EOC and the dealer fix was a soak it with top end cleaner. I don't think that we've seen a lot of Cat replacements and O2 sensors are cheap and should be replaced at regular intervals anyway.

 

[Jkb242]

Interesting indeed. I agree that the O₂ sensors are relatively inexpensive but because of the location, unless you have a lift, they are not an easy or practical replacement for the average home DIY on the 5.3L. It just seems there must be some degradation to the CATS considering the addition of oil in the exhaust. That’s my main concern regarding DOD oil contribution to the exhaust stream.

 

[Mike534x]

The driver side valve cover seems to be a 50/50 fix, in regards to helping alleviate the oil burning issue. DoD is disabled on my Envoy, but I still experience 1-2.5 quarts of oil burned between each change. Though my rear main seal has a bit of a leak, so I'm sure some of my oil is going there as well. All I can think of is replacing the valve seals, or doing a soak with GM Top Engine Cleaner overnight to see if that helps it out. I had my driver side upstream O2 sensor fail last year, and that thing was a pain to get at! GM thought it was a good idea to stick the connector near the top of the transmission . I will say though, seeing the original last 190k miles was pretty good all things considered. My cats are next to be replaced, the passenger has a bit of a rumbling noise when hot and sounds like a coffee can full of nails if you bang on it.

I will say, that on my Dads 06 Yukon the valve cover replacement helped with most of his oil burning and puts in roughly a little over half a quart between each change.The 5.3's are odd engines, some burn oil while others don't. When I had my 05 Avalanche, it never used oil between changes, while my Dads Yukon used about the same amount as my Envoy until the valve cover replacement.

 

[Jkb242]

The driver side valve cover seems to be a 50/50 fix, in regards to helping alleviate the oil burning issue. DoD is disabled on my Envoy, but I still experience 1-2.5 quarts of oil burned between each change. Though my rear main seal has a bit of a leak, so I'm sure some of my oil is going there as well. All I can think of is replacing the valve seals, or doing a soak with GM Top Engine Cleaner overnight to see if that helps it out. I had my driver side upstream O2 sensor fail last year, and that thing was a pain to get at! GM thought it was a good idea to stick the connector near the top of the transmission . I will say though, seeing the original last 190k miles was pretty good all things considered. My cats are next to be replaced, the passenger has a bit of a rumbling noise when hot and sounds like a coffee can full of nails if you bang on it.

I will say, that on my Dads 06 Yukon the valve cover replacement helped with most of his oil burning and puts in roughly a little over half a quart between each change.The 5.3's are odd engines, some burn oil while others don't. When I had my 05 Avalanche, it never used oil between changes, while my Dads Yukon used about the same amount as my Envoy until the valve cover replacement.

Great thanks for sharing your experience. I gain a bit more insight from other member experiences and I really appreciate it. Thanks!!

 

[Sparky]

I bought my 07.5 Silverado with 128k on it and I discovered it barely used any oil. Super happy... until suddenly one day a long while later on my way to pick up lunch my low oil light came on. The heck? It was down 2 quarts not even 50% into my oil change!

I disabled AFM with a handheld tuner shortly after and the oil usage dropped back to 1/4 qt in 5-6k miles like it was before (and my mpg was no worse, maybe slightly better, go figure). Not sure what happened that it suddenly went bonkers and drank oil but it stopped after simply tuning it out.

Now the truck has 221k on it and I usually have to add a almost a quart halfway through an oil change. But hey, it has high miles (and some minor leaks). It still has all original AFM stuff installed (though disabled via tune). Runs great.

Not going to guarantee that your oil usage is due to AFM or the valve cover (I never touched mine, not sure which it has, I just know it leaks a little bit!). Just my experience.

Side note @Mike534x - as far as I know I still have original O2 sensors. I've never touched them, anyway! And this truck was totally original everything when I bought it except front brakes and the passenger side manifold bolts! Even the spark plugs were original I found when I pulled one at 150k to inspect for oil fouling - stupid me for assuming that the previous owner had replaced them on schedule I guess. It never ran bad and it didn't change a thing after new plugs were in, even though the old ones were fried with gaps the size of the grand canyon.

 

[mrrsm]

...and here is some more support (non-official) for this informed approach from a GM Parts Dealership:

Is Your 5.3L V8 Engine Eating Up Too Much Oil? We Have Two Solutions For You. | Auto Parts Express

Are you Experiencing faster oil Consumption rates on a GM Engine with Active Fuel Management? Here's What you can do to Fix it.

www.gmpartsonline.net

 

[Jkb242]

I bought my 07.5 Silverado with 128k on it and I discovered it barely used any oil. Super happy... until suddenly one day a long while later on my way to pick up lunch my low oil light came on. The heck? It was down 2 quarts not even 50% into my oil change!

I disabled AFM with a handheld tuner shortly after and the oil usage dropped back to 1/4 qt in 5-6k miles like it was before (and my mpg was no worse, maybe slightly better, go figure). Not sure what happened that it suddenly went bonkers and drank oil but it stopped after simply tuning it out.

Now the truck has 221k on it and I usually have to add a almost a quart halfway through an oil change. But hey, it has high miles (and some minor leaks). It still has all original AFM stuff installed (though disabled via tune). Runs great.

Not going to guarantee that your oil usage is due to AFM or the valve cover (I never touched mine, not sure which it has, I just know it leaks a little bit!). Just my experience.

Side note @Mike534x - as far as I know I still have original O2 sensors. I've never touched them, anyway! And this truck was totally original everything when I bought it except front brakes and the passenger side manifold bolts! Even the spark plugs were original I found when I pulled one at 150k to inspect for oil fouling - stupid me for assuming that the previous owner had replaced them on schedule I guess. It never ran bad and it didn't change a thing after new plugs were in, even though the old ones were fried with gaps the size of the grand canyon.

Sparky that’s very informative and most interesting! My consumption currently is worse than yours now and is worrisome because I believe it must have some effect on the CATS. I agree completely the 0₂ sensors should NOT be a frequent change and well into the 150k miles point of longer IF there are no other contaminated in the fuel. Someone I greatly respect here suggested a temp disable on AFM simply plugging off the vacuum at the brake booster to the AFM sensor which I might try for a couple of oil cycles. I don’t have a tuner and did not want to involve a clueless dealer since most are (MHO) especially if I could approach your results between oil changes.thanks again terrific experience feedback!!

 

[Mooseman]

Just unplug the sensor and leave the sensor in the brake booster as-is. I might experiment with the idea of pulling the sensor out and leave it to atmosphere and plug the hole in the booster. Might prevent the CEL and stop DOD at the same time but have a feeling it will just throw another code. I only have the Caprice to experiment this on but it works the same way.

 

[Jkb242]

I read through the super information in the Sticky posted by Mooseman wow super informative informative!! Sadly I never realized a permanent DOD delete was so costly nor did I realize the work that drove this cost. I am very interested in the temp disable solution using the vacuum boost disconnect. Are there any pictures of the AFM sensor connection to this vacuum connection that could be posted?
Concerns:
1) instantly effective, nice but given that In my case I have no engine issues, no misfires, no lifter clicking and no noticeable detection when AFM goes in or out, am I in any way “kicking at that damn snake” risking any sort of “negative feedback”? I’m just looking to cut the oil consumption that is believed to be a result of even this temporary AFM disable.

2) Any concerns when reconnecting the vacuum to re-engage AFM.
If there is any risk with this temp procedure I really would appreciate knowing now given that I have no know AFM/DOD related issues now but oil consumption. I don’t trust “random luck. Even when I lived 4hrs drive time from my driveway to Vegas I NEVER WENT THERE!
Thanks indeed so very much!!

 

[Mooseman]

1) No. It's when it's activated that it could fail staying in a collapsed state. if it's isn't allowed to collapse, it will work as a normal lifter and should last as long as the others.

2)No but I wouldn't run it for an extended time to avoid wearing it and getting the failure.

Just disable it and be done. There is only one sensor on the brake booster to disconnect. Eventually, you can get a tune and get it disabled permanently and get a perfomance boost at the same time.

 

[Jkb242]

Did you see an improvement in oil consumption based on your previous with this temp disable. About how long would it be safe to run the temp disable.
Thanks for your assistance

 

[Mooseman]

Yes I did but I do have a leak too. The Caprice is also disabled like this but it didn't have oil consumption issues. You could run it disabled like this forever AFAIK.

 

[Jkb242]

I have looked over the brake booster vacuum Lund for the AFM/DOD sensor but I can’t locate it. I took a picture to show how the 1/2” booster line entering the rear of the intake manifold.

Also not show is the vacuum line from the driver side valve cover looks like a location for the classic PCV but there is not one there. Inside this valve cover must be the location of the baffle that was designed to take its place. I mentioned this because the second picture showing the absolute manifold pressure on top of the manifold is wher the valve cover port is connected. Is that indeed correct?
Much thanks!

 

[Mooseman]

It's not on the line but on the brake booster itself, near the master cylinder.

My Saab isn't in use right now but I'll try and have a look and take pics of those hoses as well as that sensor on the booster. The one on top sure looks like it's been "repaired" or modified.

 

[Jkb242]

The line on top has been repaired. I think it might have been a semi rigid plastic hose to the valve cover that broke or cracked which I replaced with a neoprene hose. Because it was a simple slip fit with no barb to secure it, I installed SS hose clamps. Regarding the AFM sensor near the master cylinder, is this sensor on the engine side of the firewall. Thanks for pictures when you can post.

 

[Mooseman]

Yep, on engine side, right next to the master cylinder.

 

[Mooseman]

Caught some pics today. The sensor is just to the right of the master cylinder.



Also got some pics of the hoses. It connects to the rear of the driver side valve cover for the PCV system.

 

[C-ya]

@Jkb242 for some real-world numbers, my truck was using 6 qts of oil between changes (5,700-6,000 miles). Once I turned my DOD off via a Lime-Swap tune (member here, $99 tunes), it dropped to 3 qts for the first oil change interval after the tune. It is now about 2 to 3 qts between intervals. I think my engine was pretty bad and I never expected it to get back to zero consumption, but I am happy to see it reduce to what it did.

I think you will not do any damage by disabling it for a time for the test. I had my tune done at 156K and I am at 207K now. Other than the CEL, you won't even notice it. Mine was very quiet when kicking in and out. I had to be near a curb or between city buildings going about 30 mph to hear it engage. It was very subtle, but noticeable once I knew what to listen for. If you can coast a bit when you are between buildings, shift to neutral while still rolling then put it back in drive. You should hear a difference in the sound. Windows down, of course...

In case you aren't catching it, you are simply unplugging the sensor that is mounted on the brake booster as shown in @Mooseman 's picture. You are not disconnecting the vacuum line. DO NOT DO THAT! You will have a very hard brake pedal if you have no vacuum, and possibly no brakes due to the stiff pedal.

 

[Jkb242]

@Jkb242 for some real-world numbers, my truck was using 6 qts of oil between changes (5,700-6,000 miles). Once I turned my DOD off via a Lime-Swap tune (member here, $99 tunes), it dropped to 3 qts for the first oil change interval after the tune. It is now about 2 to 3 qts between intervals. I think my engine was pretty bad and I never expected it to get back to zero consumption, but I am happy to see it reduce to what it did.

I think you will not do any damage by disabling it for a time for the test. I had my tune done at 156K and I am at 207K now. Other than the CEL, you won't even notice it. Mine was very quiet when kicking in and out. I had to be near a curb or between city buildings going about 30 mph to hear it engage. It was very subtle, but noticeable once I knew what to listen for. If you can coast a bit when you are between buildings, shift to neutral while still rolling then put it back in drive. You should hear a difference in the sound. Windows down, of course...

In case you aren't catching it, you are simply unplugging the sensor that is mounted on the brake booster as shown in @Mooseman 's picture. You are not disconnecting the vacuum line. DO NOT DO THAT! You will have a very hard brake pedal if you have no vacuum, and possibly no brakes due to the stiff pedal.

Uhm, never would have taken thus go be associated with DOD given it’s mounted to the booster in a way that appears to be metering the vacuum in the booster but there is no penetration into the booster it’s simply a place where the electrical signal to the DOD fees was “saddled” merely for convenience. Ha, who would have thought? Thanks very much.

 

[Jkb242]

I’d like to Mark this thread resolved but haven’t figured out how to do that. Is this something I can do as the OP?

 

[Mooseman]

Done. It has to be done by a mod after so many days.

There are several conditions that have to be met for DOD to activate, one of which is a certain amount of vacuum in the brake booster. By killing the sensor, no DOD.