Displacement on Demand Users

[SilverG]

Try this scanner config. It has the DOD status bit logged (at least for my '07 5.3) and I have the KR histo set up to try to catch DOD KR. Since I could not find a filter PID for DOD I just used Throttle % < 25. Does anyone know how to filter to only DOD?

The first change I made was the TPS Max by slowly moving it up. I am currently at 20% (6% stock). I also set the max hyst to 1.5. Next the biggest gain came by adjusting the DOD high octane up by 1 accross the board and +2 in the cells I am in the most. My last change was to drop both Vac tables (4th gear) by -4 in the sweet spots and feather it out on the ends. My mpg is up by 1-2 with these changes. Like others have posted, I can now accelerate in V4.

[Syclone2356]

Try this scanner config. It has the DOD status bit logged (at least for my '07 5.3) and I have the KR histo set up to try to catch DOD KR. Since I could not find a filter PID for DOD I just used Throttle % < 25. Does anyone know how to filter to only DOD?

The first change I made was the TPS Max by slowly moving it up. I am currently at 20% (6% stock). I also set the max hyst to 1.5. Next the biggest gain came by adjusting the DOD high octane up by 1 accross the board and +2 in the cells I am in the most. My last change was to drop both Vac tables (4th gear) by -4 in the sweet spots and feather it out on the ends. My mpg is up by 1-2 with these changes. Like others have posted, I can now accelerate in V4.

Thankyou sir,

I just saved that file and I'll log my truck on the way to work tommorow.

I really need to set up my replies to auto subscribe me to the threads, just stumbled across this tonight.

Tony

[SilverG]

What cylinders are firing for DOD? I bumped up my timing by 1-2 in my cruise cells and now I am seeing some KR. I can’t hear it so I am not sure it is real or fake. The interesting thing is it is almost always #6. Is there anything special about #6? I have read that #5 & #7 are the two most likely to run lean (non-DOD). Not sure if that is true or not. This weekend I am going to pull the plugs and see if I can notice anything different. For now I backed the timing down 1 and it appears to be less KR but also less MPG. I have scans if anyone is interested.

[Penguin]

What cylinders are firing for DOD? I bumped up my timing by 1-2 in my cruise cells and now I am seeing some KR. I can’t hear it so I am not sure it is real or fake. The interesting thing is it is almost always #6. Is there anything special about #6? I have read that #5 & #7 are the two most likely to run lean (non-DOD). Not sure if that is true or not. This weekend I am going to pull the plugs and see if I can notice anything different. For now I backed the timing down 1 and it appears to be less KR but also less MPG. I have scans if anyone is interested.

The cylinders that shut off are #1, 4, 6, and 7. I am not sure about 5 and 7 going lean, that may be a throwback to the old engines where 5 and 7 scavenged each other as they fired in sequence (18436572) but these engines have different firing order (18726543).

Please keep us updated, I set my DOD at 15% TPS, Hyst at 1.0%, high octane timing up a bit, and also lowered the vacuum tables. Truck runs good, can't tell when it switches but mileage has gone up easy 1-2 mpg all in town.07 RCSB 5.3 with 3.73's.

[SilverG]

Well I removed my plugs last weekend and found somthing interesting. My #6 was gapped to something like .1! The electrode was almost a 45 degree angle. I gapped it to .04 like all the rest and put it back in. I have not had a chance to log it since I fixed the gap.

Given what I found, are you sure #6 does not fire in DOD?

[Penguin]

Well I removed my plugs last weekend and found somthing interesting. My #6 was gapped to something like .1! The electrode was almost a 45 degree angle. I gapped it to .04 like all the rest and put it back in. I have not had a chance to log it since I fixed the gap.

Given what I found, are you sure #6 does not fire in DOD?

Straight from GM Service manual as of today. First sentence spells it out, but I pasted some extra reading in there...




Cylinder Deactivation (Active Fuel Management) System Description

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.

When commanded ON, the ECM will determine what cylinder is firing, and begin deactivation on the next closest deactivated cylinder in firing order sequence. The Gen IV engine has a firing order of 1-8-7-2-6-5-4-3. If cylinder number 1 is on its combustion event when cylinder deactivation is commanded ON, the next cylinder in the firing order sequence that can be deactivated is cylinder number 7. If cylinder number 5 is on its combustion event when cylinder deactivation is commanded ON, then the next cylinder in the firing order sequence that can be deactivated is cylinder number 4.

Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing. The pin housing contains the lifter plunger and pushrod seat which interfaces with the pushrod. The outer housing contacts the camshaft lobe through a roller. During V8 mode, the locking pins are pushed outward by spring force, locking the pin housing and outer housing together causing the lifter to function as a normal lifter. When V4 mode is commanded ON, the locking pins are pushed inward with engine oil pressure directed from the valve lifter oil manifold (VLOM) assembly solenoids. When the lifter pin housing is unlocked from the outer housing, the internal pin housing will remain stationary, while the outer housing will move with the profile of the camshaft lobe, which results in the valve remaining closed. One VLOM solenoid controls both the intake and exhaust valves for each deactivating cylinder. There are 2 distinct oil passages going to each cylinder deactivation lifter bore, one for the hydraulic lash-adjusting feature of the lifter, and one for controlling the locking pins used for cylinder deactivation.

Although both intake and exhaust valve lifters are controlled by the same solenoid in the VLOM, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event. During an intake event, the intake cam lobe is pushing the valve lifter upwards to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve. However, when cylinder deactivation is commanded ON, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately, and deactivate the exhaust valve.

By deactivating the exhaust valve first, this allows the capture of a burnt air/fuel charge or exhaust gas charge in the combustion chamber. The capture of exhaust gases in the combustion chamber will contribute to a reduction in oil consumption, noise and vibration levels, and exhaust emissions when operating in V4 mode. During the transition from V8 to V4 mode, the fuel injectors will be turned OFF on the deactivated cylinders. The ignition system secondary voltage or spark is still present across the spark plug electrodes on the deactivated cylinders. If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, and then return to V8 mode for 1 minute.

Switching between V8 and V4 mode is accomplished in less than 250 milliseconds, making the transitions seamless and transparent to the vehicle operator. The 250 milliseconds includes the time for the ECM to sequence the transitions, the response time for the VLOM solenoids to energize, and the time for the valve lifters to deactivate, all within 2 revolutions of the engine crankshaft.

The cylinder deactivation system consists of the following components:
• The VLOM assembly
• Eight special valve lifters, 2 per deactivating cylinder
• The engine oil pressure regulator valve for cylinder deactivation operation
• Gen IV cylinder deactivation engine block
• The ECM
Valve Lifter Oil Manifold (VLOM) Assembly

The cylinder deactivation system uses an electro-hydraulic actuator device called the valve lifter oil manifold (VLOM) assembly. The VLOM is bolted to the top of the engine valley, below the intake manifold assembly. The VLOM consists of 4 electrically operated Normally Closed Solenoids. Each solenoid

ETCETCETC

[SilverG]

Thank you. So basically if I am seeing KR on #6 while in DOD it must be false knock and nothing to worry about. I thought it was interesting that they continue to fire the spark plugs on all 8. I will say the plugs were a little darker than I would have liked. I scraped off a little carbon on the plug ends.

[Penguin]

Thank you. So basically if I am seeing KR on #6 while in DOD it must be false knock and nothing to worry about. I thought it was interesting that they continue to fire the spark plugs on all 8. I will say the plugs were a little darker than I would have liked. I scraped off a little carbon on the plug ends.

I too thought it was interesting they keep an exhaust charge in the cylinder and also keep firing the plugs.

Its kinda odd that the only cyl you see KR on in DOD has a plug that is messed up on the gap. I'd be very careful....now that you re-gapped it, does it still have KR in DOD? Was there any physical damage to the plug at all? That's just too big of a coincidence to ignore...no idea though how you could get KR without the cylinder working though...??

[nycblazer]

5.3 and 6.0 have DOD, 6.2 does not.

First of all i wanna say WASSUP to everyone, this is my first post.

i have a 2007 Cadilac Escalade 6.2L engine with VVT & DOD.

[gmtech16450yz]

I believe it was only the early '07's that had DOD, the later ones and '08's do not.

Oh and I don't care what somebody does in their tune tweaking AFM, you're NOT going to get 25mpg at 70mph in a full size crew cab truck unless you're going down hill or you have about a 60mph tail wind.

AFM timing is usually pretty close to maxed out stock, you might be able to get another degree or two, but not much more. Non AFM spark tables are a different story.

[Texsrt4]

I believe it was only the early '07's that had DOD, the later ones and '08's do not.

Oh and I don't care what somebody does in their tune tweaking AFM, you're NOT going to get 25mpg at 70mph in a full size crew cab truck unless you're going down hill or you have about a 60mph tail wind.

AFM timing is usually pretty close to maxed out stock, you might be able to get another degree or two, but not much more. Non AFM spark tables are a different story.

wow, i don't know what to say. I guess I should just start

1. DoD is available on the NBS trucks, which means '07 and up. The '08 and '09 trucks and suv's have it as well
2. Timing is off everywhere in the 4cyl DoD mode, worse than it is in the 8cyl mode. You can add as much as 5 degrees, and even more in the high octane mode before you start running into the detonation cycle.
3. Without knowing anything about the DoD system, how can you make the claim that it is impossible to get good mileage? That is interesting. If you think you can't add timing, it means you are not, and therefore are not seeing the benefits. It is evident you haven't adequately tuned a DoD vehicle, nor have you looked at my posted map and compared it to a stock map. I really suggest you do so before making comments regarding my integrity on here. I have posted my tune and had several people PM me, thanking me for helping them improve their mileage.

Don't believe me? I really couldn't care less. But don't go around providing wrong information, people will take it as the gospel truth.

[gmtech16450yz]

Sorry, I guess I'm just an idiot.

You'd think I would have learned something after 30 years working on cars (estimating I've worked on easily over 50 thousand cars), 25 as the lead driveability tech in two top level GM dealerships, thousands of hours of factory training and testing, dozens of certifications including all ASE engine, advanced emissions systems, fuel management and electrical certs, 3 years working on a pit crew at the Indy 500 (stock block Chevy no less), restoration of collector muscle cars (several sold at Barrett-Jackson) and track support/ tuning/ service work on several historic Trans-Am cars, some valued at over $500k.

By the way, the DOD comment was related to nycblazer's having an '07 6.2 with DOD (or AFM, which it's actually called). I believe my comment was correct, only the early '07 6.2's had AFM. And ALL '07 on up trucks and SUV's do not have AFM. I only worked on 7 late model GMC's today, so since I have so little knowledge on these things I could be wrong.

I'm sorry I stepped on your toes, I'll leave this thread now.

[Texsrt4]

Sorry, I guess I'm just an idiot.

You'd think I would have learned something after 30 years working on cars (estimating I've worked on easily over 50 thousand cars), 25 as the lead driveability tech in two top level GM dealerships, thousands of hours of factory training and testing, dozens of certifications including all ASE engine, advanced emissions systems, fuel management and electrical certs, 3 years working on a pit crew at the Indy 500 (stock block Chevy no less), restoration of collector muscle cars (several sold at Barrett-Jackson) and track support/ tuning/ service work on several historic Trans-Am cars, some valued at over $500k.

By the way, the DOD comment was related to nycblazer's having an '07 6.2 with DOD (or AFM, which it's actually called). I believe my comment was correct, only the early '07 6.2's had AFM. And ALL '07 on up trucks and SUV's do not have AFM. I only worked on 7 late model GMC's today, so since I have so little knowledge on these things I could be wrong.

I'm sorry I stepped on your toes, I'll leave this thread now.

See, I'm confused now. Because you seem to have a long pedigree of experience, but you failed to realize that AFM, or DoD (as it is labeled in the HPTuners Software) is available on '07 and up cars and trucks. You were incorrect in making claims about timing information, and you were incorrect in mileage claims.

I have no doubt that you are a competent mechanic, nor do I doubt the list of experience you have, but because you have wrenched on carb'd motors in the past doesn't mean a thing when it comes to programming GM EFI.

No where did I state ALL trucks have AFM, just stated it was available. Do some more research, use the software and my base tune, its in the repository, and see for yourself. I have nothing to hide, nor anything to lie about. What benefit do I gain by lying on here? Nothing, so why would I do it? Exactly. Give it a shot, what do you have to loose?

[waynehartwig]

wow, i don't know what to say. I guess I should just start

1. DoD is available on the NBS trucks, which means '07 and up. The '08 and '09 trucks and suv's have it as well
2. Timing is off everywhere in the 4cyl DoD mode, worse than it is in the 8cyl mode. You can add as much as 5 degrees, and even more in the high octane mode before you start running into the detonation cycle.
3. Without knowing anything about the DoD system, how can you make the claim that it is impossible to get good mileage? That is interesting. If you think you can't add timing, it means you are not, and therefore are not seeing the benefits. It is evident you haven't adequately tuned a DoD vehicle, nor have you looked at my posted map and compared it to a stock map. I really suggest you do so before making comments regarding my integrity on here. I have posted my tune and had several people PM me, thanking me for helping them improve their mileage.

Don't believe me? I really couldn't care less. But don't go around providing wrong information, people will take it as the gospel truth.

Mind sharing your tuen with me? So I can see what your doing to get the increase? I'm all for better MPG!

[edcmat-l1]

Sorry, I guess I'm just an idiot.

You'd think I would have learned something after 30 years working on cars (estimating I've worked on easily over 50 thousand cars), 25 as the lead driveability tech in two top level GM dealerships, thousands of hours of factory training and testing, dozens of certifications including all ASE engine, advanced emissions systems, fuel management and electrical certs, 3 years working on a pit crew at the Indy 500 (stock block Chevy no less), restoration of collector muscle cars (several sold at Barrett-Jackson) and track support/ tuning/ service work on several historic Trans-Am cars, some valued at over $500k.

I'm sorry I stepped on your toes, I'll leave this thread now.

That's overly impressive.
50,000/30 yrs = 1666.66 cars per year/2500 hours (typical work year is 2000 hrs, dealership is usually more) = .55 cars per hour. That's a helluva average. Where did you get time for 1,000s of hours for training? And the extensive amount of time it takes to restore cars to BJ level?

You either never did any heavy line, had no driveability cars that presented a challenge, or are waaaaay off on your 50,000 car estimate.

Sorry, just hate chest thumpin.

[Jtbrewer]

[Jtbrewer]

Anyone have any luck with the MPG yet?

[04blackgmc]

im tweaking it on my g8.. nice gains so far i would so 2mpg or so highway