flyinfatman

Well, i took the car to the dyno and she tuned out great. This translated perfectly to the track. During the race, the engine/tune/computer performed flawlessly. The throttle response was better than the best mail order chip i used. and the power, well, shes a healthy baby... see below.

Now comes the hard stuff. I want that last 10%. Our fuel mileage was abysmal! 6mpg. with an average race runnign around 800-1000 miles, houston we have a monentary problem! The engine lives between 2500-5500 rpm with the majority of the sweeps from 3-5k. on the dyno i had the engine tuned to a 12.7 AFR from 2-5k with the last few 100 rpms getting steadily richer. Since i have data from the track, i know that my dyno tune is roughly a half point richer on the track. Next trip to the dyno I plan to set the tune to a much more aggressive AFR (13-13.5-1) and pull more fuel on top. That alone will produce better results but there are other issues i want to sort out.

My AE is not right or at least not good enough to give me the fuel mileage i desire. When the throttle is rolled in or punched im seeing a huge rich spike in AFR and im wondering how much of this "spiking" i can tune out. please see the attached graph from the track run. How realistic is it to never see the spike into the rich area. Is it possible for me to hit this perfectly with little overrun into the rich? Which AE table affects this the greatest. Is it the delta TPS or the delta map? how much am i off by? how much is too much to remove from the AE table that controls this? Id love to see a near perfect tune from another EBL user, I don’t have anything to compare my tune too.

Im going to attach some shots of the analysis screen to describe what im seeing and trying to unsee/fix so to speak. First off, two data sets will be shown. One is off the dyno final run, and the second is a few practice laps around the track. (I cant wait to wire in a 2 axis accelerometer!).

The dyno run shows a full on punch and the resulting spike to rich then the climb to my tuned AFR. notice the spike from lean to rich to lean to my set AFR.



The Track run shows an up-shift from second to third. The variation in the AFR here is what im trying to negate.



Many thanks in advance!

Ronny

iTrader: (1)

I would pull 10% out of AE vs TPS and same for MAP and check the result. Then repeat again and again. This past tuning season I pulled a lot of AE out as my fuel pressure is quite high due to N20 added begining of season. Remember you can tailor the AE by RPM as well. I found adding more AE under 2000 rpms vs over 2000 was helpfull. I think I am at 10.5/1-11.0 at the richest point I see.

When you pull too much AE you will get a lean pop. Going from rich to lean on AE is what I prefer.

Are you TBI?

flyinfatman

yes sir, 350 TBI with 61# injectors at 25 psi.

Ronny

iTrader: (1)

AE is in multiples of 61 usec

RBob

iTrader: (1)

If this is on a 350 then reduce the two AE PW tables by 27%:

AE - MAP PW
AE - TPS PW

That is to multiply all entries by 0.73

Note that this recommendation is based on you not having previously changed the AE tables.

If the engine is a 305 then multiply the above tables by 0.65

This will rough in the AE tables due to the increased injector flow, further tuning is likely required.

RBob.

flyinfatman

i am extremely glad i asked. I would have been pulling these down by 2% until infinity.... as soon as i get a chance to get over to the dyno i will be spending my time playing with the AE and on off throttle transition.

I have been considering adding another 500 - 1000 rpms to the tune to allow us a little more over rev down the straight. The current set up is pulling out 10 degrees of timing at 5000 rpm to prevent any of my over zelous drivers from spitting out rods. as it stands now we have to feather the last 500 feet of the straight because the engine signs off. this is a double edge sword for me though, as once i increase this they will continuously ask for more until we reach rod fatigue levels. RPM stands for ruins peoples motors.

flyinfatman

one last question while i have your collective attention. what is the best way to deal with PE, and why would i ever want to enrichen my mixture once set?

for your time i give you..... 4th gear wheel spin at speed. Yea i like the EBL way too much.

Ronny

iTrader: (1)

There are 4 PE settings based on gear. I believe mine are set at 13.00 initially in first and 12.6 in 4th gear of 4.

Dyno is always beneficial in setting a tune for max perf.

PS... this should be in DIY-Prom

flyinfatman

Ronny,

Sorry for posting in the wrong area. the mods can move this if they like. i certainly dont mind.

Now about PE,

if the tables are based on gear, and there for speed, how would the computer know when to add PE if i dont have a VSS hooked to the EBL? i guess im wondering if this is functional for my set up or if this is some left over item from emmisions legality. If indeed its not useful for me how would i go about eliminating the variable so its one less thing i have to tune around?

Ronny

iTrader: (1)

You can make all the values the same. I am not sure if it works off a VSS. I always though it was gear based. You might find info at dynamicefi intro tuning part 2.

RBob

iTrader: (1)

Without the VSS the ECM can't calculate which gear is in use. The ECM uses the ratio of engine speed over vehicle speed (N/V) to figure which gear is used.

Since you are likely always in open loop don't need PE mode. I wouldn't use the "SA - PE vs Gear/RPM" table either. Set up all of the required SA in the main & extended SA tables.

Same with the desired AFR, use the open loop table.

Setting the "PE - TPS% Enable Threshold" to 100% should also disable PE mode. Of course you lose the PE Enrich over time, but you may not require that feature.

RBob.

flyinfatman

Rbob,


as always you have excellent support on this computer. I just want to pick your brain a little more. what would you suggest for an all out race car trying to get every ounce of power and MPG?

Right now, I'm just trying to get the optimal gas mileage at wide open throttle. Its a hard concept for me to grasp tuning wise. usually we are talking about lean burns on small throttle openings in high gear on the street. At this point the only thing i can think of to improve MPG is setting the tuned AFR at wide open as lean as possible with out hurting power or inducing detonation. Then as i was inquiring above making sure the motor does not enrichen.

at 6 mpg we have to be able to make an improvement somewhere. this is not some hulking beast of a motor it was built with reliability in mind while producing consistent performance as a second thought. with out tipping my hand to everyone on here, its making around 300 ft ibls to the wheels at 3200 rpm. this should be getting better gas mileage in my mind. am i off base?

RBob

iTrader: (1)

Run a non-projected spark plug and one that is as cold as can be and not foul out. Optimize the spark advance.

As far as leaning it out, well, that is a double edge sword. Can get more power and better mileage, but at the risk of melting or breaking a piston.

If there are times the driver is completely off the go-pedal can shut off the fuel. Can do this in the VE table,or use DFCO. Set the DFCO delays to 0 seconds that that it will be entered immediately. Then adjust the DFCO IAC steps for the desired level of engine braking.

To use the VE table for this just zero out the cells at the RPM range at 20 KPa.

RBob.

flyinfatman

you have just blown my mind yet again. i had no idea that i could adjust the compression braking via the EBL. My brake set up was thrown off after the swap to the new engine and EBL, we had to dial wayyyyy back on the proportioning valve due to rear lock up under compression braking before a particularly nasty 90* left hander. you have just solved a problem and probably didn't even know it.

looking at tuner pro, adjusting the IAC DFCO step up from 40 to 80 would reduce the compression braking?

10-4 on the DFCO set to 0% TPS. there are precious few seconds where the throttle is off completely. From the lap logs its averaging 56% tps over 1 lap. the track im setting up for is flowing and fast. it only has two major braking zones on 2 miles. The beauty of this set up on the track is the response. the TBI/EBL provides crisp accurate input from the throttle. even with my crap over fueled/tuning skills.

with a 22 gallon fuel cell and another day on the dyno, i think we will be contenders.

Thanks Rbob! and Ronny as well!

p.s One other thought crossed my mind. In trying to tune for best performance and gas mileage at this level, would one try to use as much spark advance as possible and match the fuel needed, or go for the leanest AFR possible and as much spark advance as it will take? by no projected spark plug i assume you are referring to an electrode this is more recessed into the threads? care to share a part number for an 882 head?

i appreciate the time spend answering my questions! Many thanks.

RBob

iTrader: (1)

Setting the TPS% for DFCO to 0 will likely disable it. The delays are these:

DFCO - Enable Delay
DFCO - Delay Between DFCOs
DFCO - MAP Enable Delay

Set those to 0.

Also increase this parameter to 43 KPa:

DFCO - MAP Increase to Exit

Yes to reducing the compression braking by increasing the IAC - DFCO Steps. Note that this is only in affect during DFCO.

You can also play with the throttle follower (TF) steps. This is when the IAC opens as the throttle opens. Can change how quickly the IAC closes back down, along with a delay (when it hits the maximum) before it starts to close.

Yes, the electrode doesn't extend out as far. In the standard resistor plug the Autolite 144 is the coldest one with a non-projected tip. To go colder need to use non-resistor racing plugs.

From AR135 (next down from 144) through AR 132 (coldest). Note that these are 14mm, 5/8" hex, .460" reach, tapered seat.

RBob.

KurtAKX

You can go far enough with timing under some conditions to reduce power without getting knock. You'll waste fuel if you go that far with timing. Since you have some dyno time at your disposal, you have a really good tool to optimize bsfc at WOT.

Ronny

iTrader: (1)

I believe the OEM's spend countless hours on dyno for SA to make optimal. WOT SA is the best MPH at a specific time frame. Say 20 sec at WOT for a safe A/F(approx12.8). Same could be said for all other MAP/RPM cells but not being WOT. Vacuum comes into play as well. I believe the highest VAC is desireable. Few of us have that unlimited access on dyno. I am using an aggressive SA table from a LT4 and it has zero knock. My heads I feel are similar in compression and design. Works for me.