new $EE tuning thing!

**Thatdudeorion** · 08-08-2016

Did some additional testing thanks to the benefit of the EGR override and I can now see that the factory EGR tuning does tack on an additional measure of timing advance when the EGR is active. Let's say something like 7* when EGR DC is 100%, may not be an exact number but whatever.

So lets talk for a second about EGR...
I think I've been thinking about it wrong the whole time, and I'm now convinced like 91ss eluded to that any gains in MPG that people are seeing with increased EGR duty cycle is due primarily to the added timing advance that can be run due to the cooler combustion temperatures. So I have overridden the EGR to 0% and added back the additional timing I was missing via the AutoSpark in $EEx, and thus far initial testing looks good! Can't wait for the new efficiency measure in the next Beta!

**steveo** · 08-09-2016

Originally Posted by Thatdudeorion

Can't wait for the new efficiency measure in the next Beta!

might be a bit to finish that project, but every few days i throw a bit more code at it. i've been a bit distracted.

lately my time has been tied up tuning sportbikes, which it turns out is way harder than tuning cars; and that's where my energy is going right now. i've tuned a ton of old carb bikes, but didnt' prepare me for this...

you know how you can add or subtract 10-15% of fuel from a car and you don't really notice "too much of a difference" beyond the subtle stuff like throttle response?

try tuning an engine that runs a 5% fueling threshold between studdering horrible barfing raw fuel out the pipe, and losing all of your torque so it feels like a 50cc scooter, and wants anywhere between 12:1 and 18:1 afr for max power depending on what kind of mood it's in...

also imagine a world where header primary length, a few mm of velocity stack height, or even a few mm of exhaust baffle diameter is more extreme of a torque band shift than changing cams and porting heads, and requires up to 30% of fueling change in narrow bands?

it's crazy stuff to say the least, and the japanese engineering nutjobs that build these crates run some kind of alien math to design them.

my current bike has VE that looks like a broken roller coaster but makes damn near 4hp per cubic inch and revs to 18000rpm.

great practice, though... i think im going to come back to the car world and be an excellent tuner.

20160723_204121 by Steve, on Flickr

**91ss** · 08-09-2016

Originally Posted by Thatdudeorion

So I have overridden the EGR to 0% and added back the additional timing I was missing via the AutoSpark in $EEx, and thus far initial testing looks good! Can't wait for the new efficiency measure in the next Beta!

Cool, you beat me to it! Looking forward to the results. But I'd like to stress again that it's this going to be combo dependent. YMMV, literally lol. Results with a stock cam may want the egr flow with the timing. The goal is to find the right advance to achieve MBT. Going beyond starts to become counter productive. Energy starts fighting the rising piston if ignited too soon. It's possible that the egr flow lets you get to that MBT advance that you would not be capable on the octane of the fuel alone.

Not sure we'd have a one size fits all solution, but with enough data points, might end up with some good starting points for general approaches or recommendations.

Steveo - fun on tuning those bikes. He, did you ever run them through Engine Analyzer sim software? Be curious if it shows that finickyness.

**Thatdudeorion** · 08-17-2016

Yep, I agree the goal is to get to MBT, and I do have concerns about too much advance, or at least more advance than what's really necessary...without a dyno it's really tough to tell what's perfect, and then even if you do, it's only for a certain point on the timing map.

And I agree about it being completely application dependent. According to the wiki on EGR functionality, one should be able to achieve at least equal performance/economy if not increased economy with it versus without it, primarily due to the reduced pumping losses which come with having to open the throttle wider to account for the inert EGR charge displacing some combustible charge and thus reducing power at a given throttle opening, but that just doesn't seem to be the case for at least my LT1 with stock f-body cam.

Other engines (I'm thinking smaller, lower output engines) may be affected more strongly by pumping losses may indeed show greater increases in mileage with the EGR flow allowing greater throttle blade openings/pumping loss reductions.

It is also possible that my EGR valve is gunked up and not really passing 100% flow even when the solenoid is commanded to 100%, which may be skewing my results, but at this time, I'm just leaving it commanded to 0% all the time and adding my own advance adder to compensate.

And it seems like my opti may be going out or needing a cap and rotor at the very least, so my quest for 40MPG will surely not be completed til I work up the cojones to tackle that job. Need to get to work on aero mods in the meantime.

**steveo** · 08-18-2016

Yep, I agree the goal is to get to MBT, and I do have concerns about too much advance, or at least more advance than what's really necessary...without a dyno it's really tough to tell what's perfect, and then even if you do, it's only for a certain point on the timing map.

as far as efficient timing advance goes, due to its combustion chamber design and unique cooling system, you'll find that under light loads, the lt1 has a particularly wide flat area between the two timing advance points of 'just enough timing to burn everything' and 'too much timing, and power loss starts'.

really big. in terms of power and feel, on my car i could -barely- tell the difference between 35 and 65 degrees in cruise range. but you could see it on a vacuum gauge for sure, if you held steady throttle and varied timing.

don't be afraid to experiment with a crapload of timing in cruise range. the combustion temperature and stress on internal components is very low when the engine is unloaded. a bit of detonation will not blow stuff up or melt pistons if you aren't running like that for hours. in my experience your car will protest with surging and bucking and feeling 'strained' way before it hits the point of knock anyway.

your experience may vary.

**Thatdudeorion** · 08-22-2016

Originally Posted by steveo

as far as efficient timing advance goes, due to its combustion chamber design and unique cooling system, you'll find that under light loads, the lt1 has a particularly wide flat area between the two timing advance points of 'just enough timing to burn everything' and 'too much timing, and power loss starts'.

really big. in terms of power and feel, on my car i could -barely- tell the difference between 35 and 65 degrees in cruise range. but you could see it on a vacuum gauge for sure, if you held steady throttle and varied timing.

don't be afraid to experiment with a crapload of timing in cruise range. the combustion temperature and stress on internal components is very low when the engine is unloaded. a bit of detonation will not blow stuff up or melt pistons if you aren't running like that for hours. in my experience your car will protest with surging and bucking and feeling 'strained' way before it hits the point of knock anyway.

your experience may vary.

Yeah, this has been pretty much my experience exactly, and I have tried to use the MAP readings to get it dialed in, and I think without a steady state dyno we're probably just going to have to accept 'close enough' particularly in my case as I don't think there's more than 500' of contiguous level roadway, and heck, even if there were, I still don't know how close I could get it, as even at closed-throttle idle, the MAP readings jump around quite a bit whether you're tweaking timing or not.

**atlantadan** · 08-23-2016

I've got a Caprice with the LT1 and try as I might, I can't get this program to work. It errors out every second or so, and then logs an issue with the data stream. I'm going to start pulling the same fuses I pull to flash using TunerCat (which works), but does anyone have any other ideas?

**steveo** · 08-23-2016

if you can find out specifically what fuse you have to pull to get it working, that might be a start to us figuring out why it just doesn't work on some b-bodies.

some experimentation is definitely required to help get this working, as nobody with programming ability that uses eehack seems to own a b-body.