99_SS_LS1

iTrader: (4)

Ok. That could be the difference here. I've never tuned an auto car, but I do know for a fact that manuals do have it. My 2k SS enters it all the time. I can hear it, feel it, and see it on my wideband gauge.

I don't have any logs to post.

RPM WS6

iTrader: (3)

Ok, I just did some quick research and discovered that DFCO does in fact exisit in the LS1 world (I was wrong about that). Your insistance has caused me to learn something new today. Thanks.

However, in all my time scanning and tuning various A4 LS1s, I've never seen/felt/heard it be active. I suppose it's possible that the activation parameters are very hard to reach for an A4 car. I live on super flat land (IL), so perhaps while scanning I've just never reached the coasting parameters to see this system in action. The biggest "hill" we have around here is a speed bump.

I have to assume that DFCO in the A4 cars is very much like Torque Management in the M6 cars, meaning, it's there for both trans types but it only really affects one of them.

99_SS_LS1

iTrader: (4)

Hey, that's cool man. Glad to hear it. That's why we're all here, to learn.

Yeah you're right, its probably pretty hard to hit the enabling parameters in an automatic as they come setup from the factory. Especially if you have a cam with some overlap. It'll never pull enough vacuum. However, headers alone will cause it to enable very easily.

Try doing a scan and downshifting manually. It'll go into dfco then, you'll see the o2's drop to zero

RPM WS6

iTrader: (3)

I am definitely going to try this next time I have a scanner hooked up. My two current LS1s both have stock engines, so things should still work the way the factory intended.

I read that some of the newer tuning programs allow changes to this sytem. I've got a very old version of LS1 Edit, and I've never even seen a screen/tab for this.

After 12 years of messing with these cars, it's rare for me to discover anything new, but once in a great while it does still happen.

safemode

iTrader: (1)

Could it be that auto's dont have it because they aren't locking the torque convertor so they have to actively keep the trans pressure up when "coasting" just like it does when idle? That would seem pretty plausible, since at low rpm the engine would not be kept moving by the trans

The Mighty Texan

iTrader: (4)

Wow, this proves you learn new **** everyday. Pretty crazy glad you brought this up 99!

SSCAMARO02LS1

My apologies... Still hard to believe tho.

Mr Incredible

I know it's hard to engage the DFCO on my F250 Super Duty. You have to really mash the gas and then let off for the scangauge to read 9999 on the mpgs. I do not recall ever having it engage on the Camaro. Which is not to say it didn't, but I sure don't recall it.

The scangauge is currently in Daughter's truck. I'll get it out sometime soon and see how hard it is to get the DFCO to cut in with the A4. It'll be a pain since I ran the wire to be pretty much permanent and out of sight. The scangauge has infinitely more use in her truck than the simple gauges in it.

gta3uzi

It would be interesting to see if it will engage in drive instead of overdrive as you wind up doing a lot more engine braking in drive.

Mr Incredible

And I tried just that thing. Here's the story...

78 miles out and back. Outbound was open highway. Back was 2 lane state highway. Avg temp was around 46 degrees. Wind was 20-30 knots from the side each way. Free mods only. Ported TB. 3.23 gears. Hooker cat-back. Tires at 34psi. Windows were tinted. Coffee was hot. Cigar was cheap.

Outbound.
23.2 mpg avg
32.9 mi
3538 max rpm
66 mph avg, mostly 77mph but a lot of 65 mph construction zones.
Maximum deceleration mpgs from 77-85 was 140. Foot off gas, no braking, simple deceleration from speed.

Back.
25.2 mpg avg
38.7 mi
3211 rpm max
63 mph avg
47 mph avg

Going through small towns at 45mph brought decel mpgs of around 80-100 from 60 to 45mph.

Coming back through town brought decel mpgs of around 70-90, depending on what mph you start decelerating from. The faster you start your decel, the more mpgs you have. But, when thinking about fuel economy, it takes gas to get to a higher speed so you aren't saving anything.

I tried decelerating using 3rd gear manually, and it was a bit worse. I decelerated heavily in 2nd gear (major acceleration and getting off the gas) and it was not only not better, but again worse.

I found no DFCO under normal and slightly not normal driving conditions. DFCO engages, in any car/truck that may have that feature, when certain programmed conditions are met. It varies with the make/model/year. Obviously, not all vehicles have it. Many do. When DFCO kicks in the injectors are turned off and no fuel is presented to the cylinders. When the gas pedal is again pushed, certain RPMs are met, or other programmed indicators are observed, power is restored to the injectors and they again inject.

The best bet to save gas is to accelerate at a moderate rate to reach your desired mph and to decelerate (coast) as long as you can when coming to a light or a turn. Let the momentum you've paid for in gas money work for you. Pushing on the brakes simply turns your money into heat.

Invariably, there will be somebody telling you to get a hybrid and that you don't deserve to own an LS1, blahblahblah. Whatever. There are as many reasons to own an LS1 as there are people that buy them. I enjoy the power and great looks, and have gone fast before. I don't need to race everywhere I go anymore. My money is much better spent for beer money and paying for cable. For daily driving I just hop in the 40mpg CRX. It really burns my wife that I can get 40mpgs out of my $900 CRX and she gets 45mpgs out of her $29,000 Prius. But then, I paid for both, so it doesn't matter as much to me.

Hope some of this was helpful.

RPM WS6

iTrader: (3)

Great post, Mr Incredible.

It seems that the A4 LS1s either don't have an active DFCO system (it may be present in the PCM as a supported parameter, but just not active for the A4s), or that it's extremely difficult to make it activate.

This is consistant with what I've seen, scanning many A4 LS1 cars. I've never seen a situation where the O2 vaules were consistant with scheduled engine shut-down at a time where speed was above 0mph.

I will do a follow up test in the future with my scanner, and graph O2 values under high vacuum coasting conditions (including manual downshifting, and coasting from high speeds). I'm sure I've looked at these values before, but indirectly while scanning for other things. This time I will be looking specifically at O2 values under these conditions.

RPM WS6

iTrader: (3)

Hmmm.... just had a thought about this. I'm not sure that manual downshifting would be a way to make this activate. Logically, I think the only time this system could work for an A4 would be when the TCC is engaged, and that's only going to happen in D/OD. So dropping down to lower gears (engine braking) probably isn't going to bring the system online (if it's even present for the autos).

Mr Incredible

I downshifted manually into 3rd, and 2nd at lower speeds, and could not get any DFCO. I didn't do anything crazy since that's not where you would really go during any kind of driving approaching normal. I would think if it takes some really contorted driving to engage DFCO, it would be merely for science and not usable in real world driving.

Mr Incredible

Anybody with an M6 LS1 know anybody with a scangauge?

Scar

I don't mean to come off as a dick or anything, but you seem like a dick. Seriously man if you think I'm mistaken say so, that doesn't mean that you have to be so damn sarcastic and condescending about it. It's really not a difficult concept, by going up a hill you are creating potential energy, when you go down it you use that potential energy to turn the engine rather than utilizing the gasoline that would normally turn it. I'm probably taking this a bit wrong and I have had quite a decent serving of bourbon this evening so I'm probably making an *** of my self.

Schedule a water test with your local city water department immediately!
Oh, but have a good day.

Time for more

Jays_SSZ28

iTrader: (2)

All f bodies have DFCO, A4 and M6.
All you need to do is run with a wideband and you'll see it go lean under certain deceleration maneuvers.

Heres a '99 A4:

gta3uzi

I wonder how well DFCO works on Corvettes... Somebody should go ask them.

SSCAMARO02LS1

U did take it wrong, and I did apologize in the thread above.
Never said or implied that u were mistaken, just said I was having a hard time understanding it. It was explained better by others in this section, therefore I expressed my apologies. Relax man and go have another bourbon while I try to learn some more.

Thanks to those who explain / teach us guys, who are green about some things, and are trying to learn more every day. Nice info.

safemode

iTrader: (1)

So then i guess the next step is asking why it's so hard for A4's and if the pcm can be edited in a way that makes more use of it without bad side-effects.

RPM WS6

iTrader: (3)

If it could be engaged more easily without ill effects, I imagine the factory tune would be setup for that. This is a fuel savings measure, so it's logical that the factory tune would take advantage of it as much as possibile without creating negative side-effects on driveability.