Tuning the EFI 393W

[EricLar80]

The purpose of this thread is to document the tuning process I am currently going through. Although I am far from an expert, I thought that it would be helpful for those that may have interest in self-tuning. This first post will focus on the background, and I will add posts covering what I have learned and what I have been trying out.

A few years ago I put a fuel injected 393W into my 1973 Bronco. At the time, I put together a very simple tune using the moates quarterhorse system, and Binary Editor software. Surprisingly, by just changing a few things to match the modifications I made, I was able to create a tune that worked pretty well - easy starting, semi-stable idle, and no pinging/pre-detonation or other fueling/timing issues.

All was fine until a few weeks back that I was talking to Lars and I decided that it was time to invest some more time into the tune since I know that it is far from optimized. The main focuses that I have are to smooth out the idle, fix the lag that is present from idle to about 1800 rpm, and adjust fueling since it is rich to be on the safe side. My EFI 5.0L ran extremely well, so I have high expectations from the 393W and it just isn't there yet.

Here is the current set-up of the engine/trans:
- 351W stroked to 393W
- Windsor Sr (Roush) heads by World Products (200CC; 2.02/1.60 valves; cast iron)
- 9.0:1 compression ratio
- Explorer Serpentine
- Lightning GT40 lower intake; Explorer GT40 upper intake
- MSD TFI distributor
- Lightning 90mm MAF sensor
- 75mm Summit throttle body; some massaging to the upper intake to blend the two together
- 30lb Ford Fuel injectors
- stock style fuel pressure regulator (39psi)
- LC-1 Wideband O2 Sensor and Gauge
- 1 1/2" primary shorty headers
- Dual 2 1/4" exhaust
- 4r70w transmission

I have spent countless hours reading about tuning the ford system, and these by far seem to be the best sites...

The 'write ups' section of this site is awesome. I give a major shout out to the guy who runs this site: 'Decipha'.
http://www.efidynotuning.com/
http://forum.efidynotuning.com/

This is a message board with a lot of great info if you search, but it can be difficult to get tech feedback from the 'gurus'. They don't seem to be too interested in Broncos... Most people use Moates and BE. They seem to point people in the right direction, but wont hold your hand. So you have to be willing to read and reread everything, compared to this site where a lot of people are very attentive to the newbie.
http://www.efidynotuning.com/

Based on the time I have spent over the last few weeks modifying my tune, I can honesty say that the power of tuning is amazing. Seemingly subtle changes can have profound effects on the way the engine behaves, which, of course, is a double edged sword. Hence the reason I started this thread in the hopes that it encourages others to take the plunge!

More to come...

Eric

 

[EricLar80]

We'll start off with a few definitions (as I understand them):

Strategy: An overall set of parameters that can be changed within a specific computer. The MAF fox-bodied mustangs follow a 'GUFB' strategy that is carried throughout the models. This is probably the most common strategy for people like us to start from.
Calibration: Calibrations are computer specific; A9L (manual)and A9P (auto) use the GUFB strategy, but have slightly different calibrations to accommodate the differences.
Template: Summary of smaller changes to the calibration that a tuner would typically send to a customer, essentially a way to adjust all of the necessary items in a calibration while keeping the rest of the calibration the same

If you are in the same situation that I was, creating a tune for an engine that never came from the factory from Ford, the first step is to make all of the base adjustments that will allow you to create a 'base tune'. That first time firing the engine up was pretty gut-wrenching.

Borrowing heavily from this site, here are the minimum things to adjust in a tune before you fire it up:


[PID] Variable Comment
[SARCHG] Cubic Inch Displacement Input your actual engine size
[FN036] MAF Transfer Input your actual MAF flow data from your flow sheet
[ALOSL & AHISL] Injector Slopes Input your injector's manufacturer's recommended values
[FN389] Injector Breakpoint Input the injector manufacturer's recommended fuel breakpoint
[FN367] Injector Offset Input the manufacturer's recommended voltage offset values
[FN035] Load Scaling Populate the Y-axis with your engines expected peak N/A load values
[FN348] Crank PW Multiply the Y-axis as a percentage of the stock 302 cubic inch and 19 lb/hr injectors values by doing, 19/(new injector size) * (new engine size)/302=0.xxx

For my base tube I started with the regular A9L calibration (GUFB strategy) and modified the above parameters according to my engine. Note that I have an A9L computer, so that was a logical starting point.

Note that, in the page I linked to above, the author has created what he calls the A9L2 calibration - essentially what he believes is an easier starting point for people like you and I. Since starting to tune a few weeks ago, I have been working from this base A9L2 calibration. In my opinion, it is a good starting point because he removes a lot of the oddball spark/advace tables that Ford had been using. From the factory, the A9L calibration jumps around and interpolates from various spark tables and it is hard to tell what section of the calibration the computer is referencing for the spark that is being demanded. For example, there is a sealevel and altitude spark table; depending on the elevation that you are at as measured by the barometer sensor, the computer will find some middle spark value between the two. By eliminating the altitude table, you know that it will only look at the sealevel table. Of course, you have to be aware of this if going up to the mountains, but you can work on that once you have everything working as intended at sealevel.

The above may seem like a step back because EFI is supposed to adjust automatically for all driving conditions (such as elevation), but I think the major barrier to the layman is that there are too many things to consider. So, limiting the variables is a good thing to get started on a base tune.

Next, I will get started on explaining the method of determining the values to enter for the base tube per the list above. The SARCHG is the easy one, the cubic inch displacement of the engine, and in my case I put in 393.

Next, FN036...

Eric

 

[EricLar80]

FN036 - MAF transfer table

Before I get into it, I do want to say that you need to make sure your engine is mechanically sound. You cannot tune out mechanical problems with the engine. Vacuum leaks, compression problems, whatever are not able to be worked around. To the best of your ability before tuning, fix those problems first otherwise you will be very frustrated.


A lot of people are familiar with the MAF sensor and it's output is the basis for every single important calculation that determines how the engine runs. The mistake that a lot of people make is using 'calibrated' MAF meters (supposed to calibrate to a certain size fuel injector) with their stock tune. This essentially tricks the computer into scaling the MAF with the fuel injectors, but ignores every single other parameter that the MAF contributes towards, most notably spark. The computer has a table that it looks at (FN036) that compares a measured voltage to an expected amount of air (in pounds/hr). Of course, more air means more fuel.

Lets assume you went from 19lb injectors to 24 lbs injectors and got a calibrated MAF to compensate without any additional tuning. The new MAF will get the computer to think there is less air coming in than there actually is, thereby reducing the amount of fuel the computer tells the injectors to supply and keeping the air/fuel ratio in check. Obviously, you dont get any actual benefit, in fact you most likely made things much worse since the load scales are now completely off, especially if you have made other modifications like heads, cam and intake.

Compare this to actual tuning - you get new injectors and enter the slopes/breakpoint as documented by the injector company. Done (with a little refinement). And now you have the capacity for additional fuel if you engine inhales more air due to upgrades.

Also, if you decide to upgrade your MAF, you can do that just as easily. I decided to use the 90mm lightning MAF. It is known to be very accurate based on the commonly available settings. It is especially accurate at low RPMs, which is important because you really lean on the MAF for idle stability. The more resolution and accuracy at idle, the better. You could even use this MAF for a lightly modified 302 without issue, so long as you enter the transfer function.

Here are the settings I have set for the lightning MAF (entered into FN036):

Volts Air (pounds/hr)
15.9998 1741.934
4.9070 1741.301
4.6389 1474.846
4.4431 1302.174
4.2480 1145.026
4.0530 1002.769
3.8569 873.502
3.6621 756.591
3.4670 650.770
3.2710 555.404
3.0759 469.226
2.8811 391.919
2.7339 339.009
2.5879 290.850
2.4409 247.128
2.2949 209.742
2.1479 176.791
2.0020 148.910
1.8850 124.198
1.7090 102.653
1.5630 84.277
1.4160 67.802
1.2700 53.861
1.1230 41.188
0.9771 31.049
0.8540 23.445
0.7319 16.792
0.6350 12.990
0.5620 11.089
0.0000 0.000

If you plot that series of numbers out, it will give a curve that looks like the one here:

So, following the story above, if you decided that the stock 55mm MAF from the mustang isnt enough, you could easily put a new MAF in place, enter the known/documented transfer curve into the tune, and have a properly running engine. Of course, a little refinement may be needed based on your intake, etc.

Easy.

 

[EricLar80]

Alosl, ahisl & fn389

Although fuel injectors are advertised by a single variable (eg - 30lb), there are 3 parameters that actually matter: High slope, low slope & breakpoint. Much like the MAF, you want to have high resolution at idle, which is why I went with modest fuel injectors (30lbs) for my 393. Looking back, there are larger injectors that have good low-end delivery that would have also allowed a little more room on the top end.

Hi Slope (AHISL) - this is the value that you enter that is closest to the advertised flow rate. This is the amount of fuel in pounds/hr that the injector flows at steady state.

Low Slope (ALOSL) - when an injector first opens, it squirts fuel at a rate that is higher than the advertised rate because it is under pressure. For this reason, you enter this number so the computer can adjust for the difference. This is especially at idle when just a little bit of fuel is used.

Breakpoint - this is the point (measured in pounds of fuel) that the injector moves from the low to the high slope. At idle, the computer will be using the low slope heavily (even more so with larger injectors), and move more towards the high slope as the engine requires more fuel. The higher the difference between the high and low slope, the more sensitive a tune will be to the breakpoint. See the plot below.

You can see how the injector slope is slightly different at the bottom of the plot, this is the low slope, highlighted by the red line. The main length (highlighted by the white line) is the high slope. The intersection of these two is the breakpoint. Even if you have the right hi slope (easy to tune), it can be moved around by the low slope and breakpoint. A higher low slope (steeper), would get to the breakpoint and transfer to the high slope more quickly. A different breakpoint will shift the high slope up and down.

The computer always uses the low slope number in any delivery of fuel, even at wide open throttle (WOT). For this reason, the low slope and vreakpoint is extremely important for fueling.

If you look at the information provided by ford (in my case m-9593-bb302 injectors), you can see at this link that there are values for the parameters above.

AHISL: 0.008542 (lbs/sec)
ALOSL: 0.010023 (lbs/sec)
Breakpoint: 0.0000132400 (lbs)

In order to convert the slopes to lbs/hr, you need to multiply them by 3600. (60 seconds in minute, and 60 minutes in an hour, so 60x60 = 3600)

AHISL: 0.008542 (lbs/sec) = (.008542*3600) lbs/hr = 30.7512 lbs/hr
ALOSL: 0.010023 (lbs/sec) = 36.0828 lbs/hr

Note that the high slope (30.7512) is actually different than the advertised 30lbs. Not incredibly so, but still notable. The numbers above are what you will enter into the calibration.

For breakpoint, you will enter the number in the tuning software assuming x10^-5. So, in our case:
0.0000132400 lbs => you will enter 1.32400

Note that the decimal moved 5 places over. It is extremely important to move it 5 places; don't assume it is x.xxxx

FN389 is a table, so you will enter in 1.324 (in my case) for all positions.


Well, I think that is enough typing for tonight. I will continue going through the various initial base tune parameters in following posts, then move onto more meaty subjects related to fine tuning. Hopefully someone will find this useful!

Eric

 

[xcntrk]

Dude great thread and bookmarked for future reference!

A couple questions; why did you go with the moates quarterhorse over the TwEECer-RT system? I have no preference between the two but noticed Tweecer offers an advanced custom tune option. You give them your motor build specs and they supply a base tune. You then run a few pulls, log some data and send it back. They update the tune based on the log output and send the update. You do this 3 times for $250. Sounded like a great base to start from, what do you think?

Also, with the MAF scaling, you say that you need to make sure your engine is mechanically sound before getting into larger MAF, injectors, etc. For a new EFI build or conversion, would you recommend using the stock parts (i.e 65mm MAF, 19# injectors, etc.) first and get the OE EEC image running smooth before upgrading for more fuel & air?

Great thread thanks!

 

[EricLar80]

The moates system is newer than the tweecer, so there are a few advantages. The major advantage is that you can make uodates to the tune while data logging, and there are 'hacks' that you came access in binary editor with quarterhorse that you don't have access to otherwise. The hacks allow you to change fuel types, disable adaptive or closed loop, and a quite a few other things. These can all make tuning easier. Of course, the QH is way smaller being just a chip, whereas the tweecer is like another computer with a harness, I believe.

In terms of buying a tune online, you can easily do that with the QH as well. In fact, I know you can get the same deal for about $100, where they will give you a base tune and then one adjustment based off of a datalog. This is from various tuners, not the moates people.

I was actually trying to say that you should fix any mechanical problems before trying to tune at all. Establishing a base tune is fine, but going any deeper than that and you want to make sure things are right. It can lead you down the wrong path otherwise. For example, take something simple like a small exhaust leak at the header flange. Even though the engine will run fine, the computer will think there is more air left over because the O2 sensors picks up the oxygen getting into the exhaust. This will cause the computer to adjust to be more rich, which will incorrectly clue you to adjust injector settings to be more rich in future tuning.

You can start from a known base point if you like, it may make it easier, especially if you have a stock size engine. Once you change the aspiration characteristics, such as adding significant displacement, you will have to make adjustments. It is always nice to know something is running before you change from there if you can, but I wouldn't buy two MAFs or sets of injectors for that purpose.

Eric

 

[blakerj10]

Great thread... Thanks!!

Will be going down this path as well.

Can you change injector firing order with the QH? Trying to decide if I should swap my cam to the 351 firing order before putting the engine back in.

 

[EricLar80]

Great thread... Thanks!!

Will be going down this path as well.

Can you change injector firing order with the QH? Trying to decide if I should swap my cam to the 351 firing order before putting the engine back in.

Yes, there is a setting in the QH that you input the firing order and you would be done. No need to get your hands dirty.

Eric

 

[00gyrhed]

WOW, I took mine to a mustang tuner that was highly recommeded. I have never been happy. I have a rough lopey idle and shouldnt, I have ignition ping at low rpm before the transmission downshifts. It has been back 3 times and even though it runs great once you are driving it and if you only put it in OD once you are on the highway and then never let your RPM get below 1500, I think it could be much better.

You want to come to TX and tune mine for me?

I really dont ant to have to spend all the time figuring this all out and then never use it again.

 

[EricLar80]

I think that Decipha guy is located in Louisiana; not sure how close that is to you. You might want to try and reach out to him and see what he can come up with for a base tune over the internet.

Do you have the QH system, or a SCT chip, or Tweecer?

I was able to make my idle a lot smoother by messing around with the idle air parameters. It's not something that I mentioned for the base tune, but something I will cover later when I get to the tune refinement part.

By the sound of what you are saying, your problems are probably load/loadx related. Essentially how much work the engine is doing vs how much it thinks is possible to do at any given time; it is part of the FN035 function. If the load setting is still scaled for the 302, but you have the 393, then the computer thinks the 302 is ingesting tons of air and doing a lot of work for the RPM you are at and changes timing accordingly. Depending on various settings, this could cause it to advance timing and cause pinging. Load scaling is supposedly extremely important, which is why it is part of the base tune.

Eric

 

[Ourobos]

WOW, I took mine to a mustang tuner that was highly recommeded. I have never been happy. I have a rough lopey idle and shouldnt, I have ignition ping at low rpm before the transmission downshifts. It has been back 3 times and even though it runs great once you are driving it and if you only put it in OD once you are on the highway and then never let your RPM get below 1500, I think it could be much better.

You want to come to TX and tune mine for me?

I really dont ant to have to spend all the time figuring this all out and then never use it again.

I'd find a better tuner. Through an automatic, I squeezed 416 rwhp out of my last 393, approx. 540 at the flywheel after tuning.

 

[EricLar80]

FN367 Function

Moving on to more of the base tuning and initial fire of the engine.

***Note that all of the injector settings (slopes, breakpoint, offsets) are different for each injector. It is important to obtain the spec sheet for your specific injector. ***

Table FN367 is very simple. Using the same injector spec sheet as before, you will obtain the scale at which the injector fires fuel as it relates to voltage. The injector offset is listed under section FNPW_OFFSET in the spec sheet.

As background, the injector will open more quickly with a higher voltage (engine running) than with a lower volatge (engine off or starting). This, of course, affects how much fuel will be injected at any given time.

Once you have this table entered, it is not likely that you will play around with it any more. Unlike slopes & breakpoint, where we are going to go back to them after initial drives.

Eric

 

[EricLar80]

FN035 Load Scaling

A good link for this topic: http://info.efidynotuning.com/scaling.htm Ignore the scaling airflow stuff towards the bottom if you are naturally aspirated and using a large enough MAF for your engine.

***note: you need PRLDSW to be set to 0 for the following to be true*** See the link above for an explanation.

This is where things start to get more interesting. FN035 is the Load Scaling Table that we were talking about a few posts back. Essentially, using the engine displacement that we entered in SARCHG, and the values we entered into the MAF transfer curve, the computer is attempting to estimate what loading the engine is under at any given RPM. I think it is based off of an assumed brake specific fuel consumption calculation. So, if you have a really large engine ingesting a ton of air at a low RPM, but you have settings entered for a smaller engine, the computer thinks the engine is operating at a higher efficiency than it really is and starts doing weird things.

Where the engine makes peak torque is where you expect there to be the largest loading. For those with flat torque curves, the peak loading can be for a relatively long period of time. At idle, the loading will be relatively small. In my case, I start around 55, then quickly move up to 75 ~1800rpm, then 90 or so at about 3k rpm and carry that until ~4800 rpm where it starts to drop off.

There are two parameters to familiarize yourself with - Load & Loadx. Load is the actual load the engine is under based on the BSFC calculation. It is recorded in the tune as the absolute maximum loading the engine is capable of at any given RPM and should always be less than 100 on naturally aspirated engines. It is possible to be slightly over 100, however. You start with some assumed values based on your cam/heads, etc - I did some research into other, similar engines to mine to find base values.

Loadx is the percentage of loading, while driving, that the engine is actually under at that exact point in time. So, lets say at 2000 rpm, the your engine is capable of a loading of 70 - you would enter 70 in the FN035 at 2000 rpm. If, while driving, you were just cruising around and had a load of 40, then you are operating at a loadx of 40/70 = 57%. You should never have loadx of more than 100% when naturally aspirated (but you will if you try to run a 393 running on a 5.0L tune).

Load is used in the spark calculation, and spark is where a lot of power/heat is made, thus it is important to fine tune this later to get everything you can out of the engine.

Once the base tune is completely established, you will go for a few test drives to verify that you have set up FN035 with the correct peak loading. This can be done by logging an idle to redline WOT acceleration in 2nd gear. Do this a few times for a good average and update the table. I personally went a little light to start in case the spark advance was not correct, and did a few progressions of load scaling until I felt that I had the numbers where I thought they should be.

Please note that you will want to go back and revisit this table as you continue to refine your tune. As things get dialed in, numbers will continue to shift slightly. Or, you can call it good after a few good passes if you prefer.'

Eric

 

[76Broncofromhell]

This is the greatest thread I've read! I've called Moates and bugged the Mustang tuner crowds to try to get these kind of answers and never gotten them.

Please continue this thread with your knowledge! I've book marked it on every internet capable device I own.

 

[mp]

I have a GT40 EFI 408W in the works--will be following this thread. Thanks for the input!

 

[Letsgocrawling]

I'm doing the exact same thing right now, I've had issues with my mass flo efi system forever. But with the help from the efi guy here on clbs my problems are coming to a end thanks to him! The quarterhorse seems to be new tech, as i've gotten info from another tuner that does'nt use it---where the differences are, are notable---one tuner to the other. My deals probaly not the norm because of engine size but that's what got the efi guys attention to help. Through his help i'm machining a custom 4" id tube for the maf slot sensor, this system is like the original mass flo setup that i purchased 5 years ago---kind of, it's all inside the air cleaner and yes it's tall but i already have the hole in the hood. With plenty of discussion the one idea of it being there could be a issue,it is soft now, we concluded it will work mainly from a custom tube to feed air and fuel #s through the throttlebody. The inlet and outlet will be 5" should flow 1000cfm easily. The new tune will come from flow conversions from a flow bench. Colorado connected to Tucson via the internet---go figure. El8 thanks for the info and with your help the eb brothers will benifit from the efi's ability! I'm planning a thread about the same stuff with pics of the build and so on. It will probaly sound a little generic so bear with me, hopefully the efi guy will chime in and make it a graph;D I hope to have the tube done this weekend

 

[EricLar80]

FN348 Crank Pulse Width

Thanks for the words of encouragement, everyone!

Moving on to FN348, crank pulse width... This one is relatively simple. The intention is to update the amount of fuel that is used during cranking depending on the size of your engine vs the original 5.0L (302 ci), as a function of temperature. Similar to a choke, this function increases the amount of fuel being delivered during cranking when it gets cold.

***Note: there is no need to adjust this table if you have a 302 and are using the A9L or other fox body computer***

The stock A9L computer has these settings:

Temperature (F) -- Crank Pulse Width (seconds)
65534 -- 2.00
180 -- 2.00
150 -- 2.30
70 -- 5.70
40 -- 10.50
20 -- 14.15
0 -- 21.89
-20 -- 38.76
-65536 -- 38.76

In order to adjust it for your engine size (you can leave this alone if retaining the stock 302 displacement), you multiple values in the crank pulse width column by the percentage difference in engine size. In the case of a 393 vs a 302, the 393 is (393/302 = 1.30) 1.30 times larger.

So, the new values will be:
Temperature (F) -- Crank Pulse Width (seconds)
65534 -- (2.00 * 1.30) = 2.60
180 -- 2.60
150 -- 2.99
70 -- 7.41
40 -- 13.65
20 -- 18.39
0 -- 28.46
-20 -- 50.39
-65536 -- 50.39

This should be a pretty good starting point for the engine to make sure it cranks easily.

Easy.

 

[EricLar80]

First Drive

Ok, you have the new engine all built, the EFI system installed, and your new base tune completed and uploaded into the tuning chip. It is a good idea to run a few tests and check a few things before you fire it up for the first time.

Here is a list of things to look at:

1. Verify that the distributor is installed in the correct orientation: http://info.efidynotuning.com/ignition.htm (this establishes the correct injector firing timing)
2. Verify that you have 39 psi at the fuel rail. You can hot wire the fuel pump to have it constantly run and check the pressure at the Schrader valve on the fuel rail. If you have more or less pressure, you need to scale things appropriately.
3. Verify that the fuel pump runs for 3 seconds and then turns off when you turn the ignition on. This is the computer priming the pressure. If it runs continuously, the tune may be corrupt and needs to be fixed before attempting to start it.
4. Verify that all the sensors are correctly attached to the wiring harness
5. Verify that you have many good, solid grounds. This is extremely important since a lot of the sensors measurements are referenced to a ground measurement. An unstable ground measurement means you have an unstable sensor measurement.
6. Anything that may have seemed out of place during installation.
7. BASE TIMING MUST BE SET TO 10 degrees BTDC WITH THE SPOUT REMOVED!! Set it there, lock it down and never look back. Any future timing changes will be done in the tune itself. Trust me, it is easier and more accurate. If you dont have it at 10 degrees, then your injector firing will be off. Not a huge deal, but the whole goal of tuning a custom tune is not try and trick the computer.

When you first fire it up, it would be nice to have a wideband O2 sensor if not just to see that everything is working correctly, or at least working on the safe side of things. It is better to have too much fuel than not enough since running lean can cause engine damage pretty quickly. At idle you are seeking 14.7:1 ratio when using gasoline. Many fuels today have 10% ethanol (E10) - this fuel runs a little richer, approximately 14.1:1. The computer can adapt for this difference automatically if things are close enough in the tune so don't worry about this too much.

When you crank, then engine should start pretty quickly if you allowed it to prime a couple times by cycling the ignition on/off. Let the idle settle in and observe it's characteristics. If you need to break in your cam/lifters, you will need to go through that procedure - keep an eye on the air/fuel ratio to make sure it stays around 14.7:1 while you break it in. A little richer (less than 14.7, perhaps as low as 12 or 13) is ok.

If everything seems to be ok, then take your Bronco for a test drive and be easy on it until you see that everything is working normally. You want to keep an eye on the temp gauge (keep it below 220). Keep an eye on the the wideband; it will dip below 14.7 under moderate throttle and WOT. It may spike lean on deceleration. Pay special attention to any predetonation - if you hear it, either bump up the fuel octane or pull timing (2-5 degrees) proportionally to severity. Predetonation has a particular metallic sound - kinda sounds like a tap on a muffled cymbal.

Go on a nice, quiet first drive for like 30 minutes and datalog the whole thing. If you can datalog, tuning will be much, much, much easier. Uploading this datalog into eecanalyzer will help with making future tuning decisions, and the route that I am using. It has easy tools to play with filtering the data for specific things (WOT runs only, for example). It will also help with adjusting slopes and MAF curves.

You get back from your drive and you think "now what?" To be continued...

 

[EricLar80]

Getting the engine started and driving seemed like the hardest part, but it may have been the easiest.

Due to various circumstances, I drove around on my base tune for 3 years; I likely put a few thousand miles on over that time period without any driveability issues. It was stable and I felt comfortable for the time being. Fast forward to a few weeks back, and I was still driving it that way.. then I started going back and forth with Lars. This motivated me to look into the tune further and eventually brought me here.

There is a thousand different ways to approach tuning from this point forward. As mentioned before, what got you here wasn't so bad. The hardest part, frankly, is getting the idle right. You read about it all the time on this site and others - people have unstable idles - loping, arrhythmic, dying when coming to a stop, overheating. Idle is inherently unstable...

It is probably the wrong way to do it (since I am far from professional), but the approach we are going to go through together will be the 'circle the drain' method. That is to say: as you adjust the tune, it may require you to go back and readjust something you already looked at. It may seem tedious, but that's how you refine the tune.

Here is an outline of the approach we are going to take to the tune:

• Part 1: The tenets of tuning - things to always remember
• Part 2: Initial fuel curve adjustment
• Part 3: Initial Load scale
• Part 4: Spark
• Part 5: Initial idle adjustment
• Part 6: Dialing in the fuel curve
• Part 7: MAF curve adjustments
• Part 8: Dialing in load scaling
• Part 9: Dialing in the idle

Eric

 

[KyleQ]

Very nice thread!