by: Michael Decipha Ponthieux
Posted: 2013-01-02
Last Updated: 2018-05-12

Stoich (fuel type)

Before a vehicle can be tuned especially a highly modified vehicle, the base changes must be made in the calibration file to incorporate all changes that the vehicle has been subject to. The most important aspect of custom tuning is getting fuel correct first so the actual air/fuel ratio commanded matches what the engine is actually getting. Before any 'tuning' can begin the ecu must have the correct stoichiometric air fuel ratio entered into the calibration data. The stoichiometric ratio is the ideal ratio in which all energy in the fuel is consumed. A numerically lower stoichiometric ratio consumes more fuel (lower MPGs) as compared to a fuel with a numerically higher stoichiometric ratio (higher MPGs). In EEC-V and newer ford ecu's there are two seperate stoichiometric scalars that must be changed to reflect the actual fuel being burned.

Below is a chart of the more common fuels and TYPICAL stoichiometric air/fuel ratios for that fuel.

Typical USA Pump Gas
Pump Gas Non-ethanol14.64Does not exist in most parts of the USA
Pump Gas E1014.08typical fuel at most pumps in the USA
Sunoco Race Fuels
Sunoco MO2X UL (clear 97)14.52.7% oxygenated
Sunoco 260 GTX (98)14.4
Sunoco 260 GT (clear 100)13.93.3% oxygenated
CAM 2 GT 10013.9alternate name of Sunoco 260 GT
Sunoco 260 GT Plus (light blue 104)13.74.8% oxygenated
Sunoco Standard (purple 110)14.85
Sunoco Supreme (blue 112)14.95LEADED
Sunoco MO2X (green 112)14.52.7% oxygenated
Sunoco HCR Plus (orange 114)14.8
Sunoco Maximal (red 116)15.01LEADED
Sunoco MaxNOS (yellow 116)14.9
Turbo Blue Race Fuels
Turbo Blue Unleaded (clear 100)13.93.5% oxygenated
Turbo Blue Unleaded Plus (lt. blue 104)13.74.5% oxygenated
Turbo Blue (blue 110)14.7
Turbo Blue Advantage (lt . blue 112)14.9
Turbo Blue Extreme (orange 116)15.0
VP Race Fuels
VP Street Blaze 100 (orange 100)14.02 - 14.16
VP C10 (clear 100)14.535
VP C12 (green 108 MON)14.45 - 15.00
VP C16 (blue 117 MON)14.775
VP Q16 (yellow 116 MON, 120 RON)13.43
VP C23 (blue 120 MON)14.935
VP C44 (purple 99 MON)12.87 - 14.93
VP 110 (purple 110)14.40 - 15.09
VP 11314.26leaded / oxygenated
VP MS10314.265
VP MS109 (clear 105)13.415
VP Import (clear 120 MON)14.155

If you have any corrections or additions to add to this chart please email us to keep this current. The above are TYPICAL stoich AFRs, fuel blends can vary from pump to pump and source to source.
Ford fuel control can be broken down in to 3 modes.

Cranking PW

Cranking PW is the actual pulsewidth in msec the injectors are fired for every pip signal. If you have difficulty starting and suspect the cranking PW are too high (i.e. too rich) hold the throttle to the floor during crank to shut off the injectors and verify. Cranking PW do not have to be perfect, typically +/- 25% of ideal will suffice with no ill effects. In summary, If you dont have to hold the key in the crank position with the starter engaged for long to get the engine to fire then your cranking pw is fine.

Base Fuel

Lambse (Tuning Step 1)

The first step to tuning is dialing in fuel, and the ecu controls fuel with LAMBSE!!! If you've never tuned an engine before its imperative that you understand fuel CAN ONLY be dialed in on a WARM ENGINE. A cold engine can require significantly MORE fuel than a stabilized warm engine. Lambse is a derivative of LAMBDA or the "AFR" (air/fuel ratio) the ecu is demanding. When fuel is dialed in your wideband will match your lambse. YOU CANNOT ADJUST FUEL IN ANY WAY SHAPE OR FORM UNTIL YOU KNOW WHAT YOUR LAMBSES ARE!!! with null multiplier's your LAMBSE will be what your demanding in your fuel table(s) (the base fuel table FN1362 is my preferred table) you adjust your fueling to make your wideband MATCH your lambse, again, you adjust your fueling to make your wideband MATCH your lambse, repeat, you adjust your fueling to make your wideband MATCH your lambse you adjust your fueling to make your wideband MATCH your lambse

DO NOT change the maf curve to get the wideband to spit out the afr you want adjust the maf curve or injector values to get the wideband to spit out the afr the ecu is telling it to (LAMBSE) the LAMBSE is the Lambda (AFR) the ecu is DEMANDING, if your lambse is 1.160 at WOT and your wideband reads 0.990 lambda at WOT then you are RICH and you need to pull some fuel out just for clarification, the 1.160 lambse at WOT was my example to show you that the wideband reading means nothing if you don't know the lambse, no one in their right mind would demand 1.160 at WOT, 0.875 is more like it, to further that, most engines running at 1.160 at max engine effeciency aren't usually too happy and usually sputter breakup pop misfire etc.. likewise, if your LAMBSE at WOT is 0.550 and your wideband reading is 0.850, you are LEAN and need to add fuel. Again, no sane person would demand 0.550 Lambse at WOT (im using this extreme to express the importance of LAMBSE!!! This process is how you dial in fuel, YOUR FUEL IS NOT DIALED IN UNTIL the wideband lambda matches the ecu's lambse when this happens your fuel trims "KAMRF" will be very near 1 in closed loop at all conditions and the lambse that the ecu is demanding during closed loop will be the actual lambda measured with a wideband. Once more, you adjust your fueling to make your wideband MATCH your lambse for all conditions, the lambse is the AFR the ecu is demanding. So keep in mind, multipliers modify lambse, THEY ARE INCAPABLE OF DIALING IN FUEL, for example, if your wideband is reading 0.92 and your lambse is 0.88 your fuel is off by ( 0.92 - 0.88 = 4%) changing the WOT fuel lambse multiplier from 1.000 to say 0.96 will reduce your LAMBSE from 0.88 to (0.88 * 0.96 =) 0.84 and since your fuel error% is 4% for this example, your actual wideband lambda would drop to ( 0.84 + .04 = ) 0.88 That will give you a wideband lambda of 0.88 but lambse is now 0.84, thus .88 - .84 = 4% error still. Thus as you can see you hadn't changed fuel any as your fuel error% is still off, the ONLY two methods of ADDING MORE FUEL is by either INCREASING the MAF flow or by REDUCING INJECTOR SLOPE(S)

Even with known values fuel is seldom dialed in, thus the need for custom tuning. I find typically most of the time its lean at the very bottom end at idle and lean on the big end at WOT. Usually the mid-range is fairly close.

If PRLDSW=0 and FN035 is scaled properly as per the
Scaling Write Up your fuel table should be set as follows: FN1362 Base Fuel Table


if you input the actual flow values for your injectors from a flow bench as well as the maf values from the flow bench your fuel will probably be off a tad, it should be perfect in a perfect world but we don't live there. A flow bench has nothing to do with injectors or a curve or anything, a flow bench just measures flow, a good starting point but thats it Free reving an engine to dial in the maf meter is a very valid and effective means of creating the curve down low, you can typically dial it in enough to drive it out of state This is maf not speed density, the maf measures airflow, it doesn't matter if your engine is at 2v on the maf at a steady 60mph cruise or if its at 2v on the maf free reving at 4500 rpm. Its still flowing the same amount of air, a non lab-spec wideband is not as accurate as a narrowband at finding stoich, a narrowband ONLY measures stoich You can't use them to dial in fuel for anything other than stoich, however, you can should always use the narrowbands to verify the wideband is accurate If the narrowband voltage isn't over 0.8 volts at WOT then it would be wise to start snooping around and questioning the wideband could also be a faulty hego ground (check out
Hego for more details).
  • Changing the injector slopes DOES NOT CHANGE LAMBSE.
  • Adaptives does not change anything, it only closes the gap from lambse and afr
  • PW is irrelevelt, thats the beauty of mass air, if the fuel is dialed in at 180kg/hr then its dialed in at 180kg/hr, rpm or pw is irrelevent
  • Fuel is proportionate to airflow the ecu will adjust pw for the rpm to reach the same lambse, thus mass air flow
  • Think of the breakpoint as an amount of fuel, because thats exactly what it is, in the older ecu's with a breakpoint function the breakpoint does
    actually get effected by rpm but its very minute, this is exactly why you can't convert from a breakpoint scalar to function
  • in open loop, lambse1=lambse2

    Injector High Slope

    The Injector HIGH Slope is the actual flow rate of the injector, typically this would be the same value as the injector is rated for (ex: 30lb injector would have a high slope of 30, a 60lb injector would have a high slope of 60, etc...) Although, its typically common for most injectors to have a high slope slightly less than their rating as well. A 36lb injector will usually have a high slope of 34.2, this is due to the fact that most injectors are rated at 43.5 psi but operate at only 39.15 psi

    Injector Low Slope

    The Injector Low Slope accounts for non-linearities at low pulsewidths, at low pulsewidths most injectors act as larger injectors spraying or drooling more fuel, so to compensate you will have a low slope typically with a value HIGHER than the high slope but not always. Typically the low slope is approximately 15% larger than the high slope on most injectors. So a 30lb injector would typically have a low slope of (30*1.15=) 34.5, a 60lb injector would have a low slope of (60*1.15=) 69 or so (excluding the siemens deka 60lb injectors which are very linear at low pulsewidths). The further apart the low slope is from the high slope the more influence the breakpoint will have, thus IT IS IDEAL AND HIGHLY RECOMMENDED to have the low slope AS CLOSE AS POSSIBLE to the high slope when dialing in unknown injectors; this will insure your fueling is not doing anything odd at the breakpoint. However, the low slope can SOMETIMES be less than the high slope on older larger injectors. This isn't as common on newer style injectors.

    Injector Slope Tuning

    The injector slopes can be thought of as global fuel multipliers. A smaller injector slope (smaller injector size) will spray MORE FUEL than a larger injector to deliver the same air/fuel ratio. Thus, decreasing the injector slope will RICHEN the fuel mix. This can ONLY be done when the MAF curve is correct and measuring airflow accurately.

    Fuel Pressure

    Changing the fuel pressure will change the Injector Slopes and Voltage Offset for ballpark quick adjustment, I compensate 1% per psi, so if you up the pressure from 40 to 60, i would multiply the slopes by 1.20 if I drop the pressure from 40 to 20, i would multiply the slopes by 0.80, if i went from 40 to 45 the i would multiply by 1.05 not exact, but good enough for government work, also keep in mind most injectors are rated at 43.5 psi where as a factory ford fuel pressure regulator will regulate the injection (delta) pressure at 39psi

    MAF Transfer - Dialing in the MAF

    Incorrect injector settings will usually only cause inconsistent fueling at the bottom of maf curve usually below 2.0 mafv. In most cases everything from 2.0 mafv and greater will have a consistent fuel error% if the maf curve is accurate. To test that the maf curve is accurate, simply make a half throttle log accelerating from idle sweeping through the maf voltage up to about half throttle at 6000 rpm. If done correctly you should have a smooth mafv increase from idle voltage up to about 3.5 mafv or so (dependent upon meter). Now you simply calculate out your fuel error% ( lambda / lambse ) at each mafv point and compare your error percentage. If you come up with a constant error% for everything over 2.0 mafv, then your maf curve is accurate!!

    For example:
    If during your mafv sweep your LAMBSE is at 0.888 and your wideband reads 0.960 but stays there CONSISTENT then the maf curve is accurate! You can very simply reduce your high slope and get your 0.960 wideband reading down to exactly 0.888 that the ecu is demanding (LAMBSE). LAMBSE's in closed loop are based purely on hego feedback, when in closed loop your lambse's will jump around to hit stoich (make the hegos switch.) Once it does, adaptives will update the KAMRF's. When in closed loop you do not need to dial in fuel, the KAMRFs will do that for you!!! Then once you've gathered sufficient KAMRF data you use that info to dial in your fuel.

    Note: The highest MAF voltage in the MAF transfer must be the maximum the ecu allows!!!! NO EXCEPTIONS!!! This will be 16 volts for EEC-IV and 5.12 volts for EEC-V The MAF curve must be in chronlogical order, thus all numbers must be in order from least to greatest, YOU CANNOT HAVE A LOWER FLOW FOR A HIGHER VOLTAGE!! else the ecu will reset everytime it reaches that point.

    For those that do not have a known maf curve, I recommend to dummy down the maf transfer to only a few points like so:

    etc, everything below set to 0v and flow = 0, you can now work your flows much easier, thats decipha's 2nd law of dialing in a MAF

    why bother with adjusting 30pts on a maf curve if you can change just 3 injector values and your fuel is perfect every time? with a known curve you can calculate hp from airflow, you'll also find that the transients are much more accurate and the vehicle just runs 'smoother' your afr will also be much more consistent, you wouldn't need to run the curve threw anything to straighten it out as it would already be perfect, also you can use the hegos to see where your WOT fuel is, if your kams are at one then you don't even need a wideband as your wot fuel is perfect, for newer 94+ ecu's that have inferred load you wouldn't have to spend hours dialing in inferred load as the only changes would be where the engine became more effecient, typically 3/4 throttle on up, that way if your maf sensor ever fails you can still drive the car with no problems, you can also find if you have any turbulance in your intake piping as the maf curve would have spikes in it, you can then clock the maf and know exactly where its happiest at
    so if you can get by with dialing in fuel using the slopes and breakpoint, that is your best bet

    Fuel Error% - Calculating Fuel Corrections

    Fuel error percentage can be calculated using the following formula
    LAMBDA - LAMBSE + KAMRF = Error %
    So for example, lets say our engine idles at .45 mafv, with the engine at a warm stable idle, the wideband lambda jumps between .98 and 1.02 lambse's are jumping between 1.14 and 1.18 kamrf is at 0.945, we then have

    1.00 - 1.16 + 0.945 = 0.785

    Calculate the fuel error percentage at each mafv point in your maf curve, if the corrections are not linear (indicating an incorrect injector value) then apply those corrections to your maf flow.
    So with that, (for this example) we would go to the 0.450 voltage point in our maf transfer function and multiply the flow by 0.785 for our new reduced flow rate.

    Wideband/Narrowband Tuning

    A narrowband will report a stoich switch before a wideband will, if it doesn't then something isn't right. A widband (WBo2) is nice but it not absolutely necessary to dial in fuel, with a known curve you can watch the kams peal the fuel curve into place the easy way to tell if your maf transfer is correct is that your wideband AFR will stay consistent, if your fuel is constantly jumping all over the place then your maf transfer is off, but if your LAMBSEs are static (one value) and your AFR is off by a percentage then you can make that correction with the SLOPE(s)

    for example, lets say you have your fuel table setup so that from 0 to 75 PERLOAD your LAMBSE is 1.000, at 90 to 105 perload LAMBSE is 0.875, 120+ load LAMBSE is 0.800 (see A9L2 for example) with all lambse multipliers null (set to 1 = no effect on lambse) including the global open loop fuel multiplier scalar null (set at 1.00) your lambse will be what we demanded in the fuel table at WOT lambse drops to 0.800 (perload exceeds 120) yet the wideband stays consistent reading 1.058, you can very easily drop the high slope from say 40 to 34.5 and in the next pull the WOT wideband will be exactly 0.800, now everything over the injector breakpoint is going to have a kam correction of 1.00 since your linear flow fuel is dialed in !! The only 2 variables remaining are the low slope and breakpoint, I start off by setting the breakpoint high, say 0.000020 (GUFB = ~6) for example, then adjust the low slope to get idle right where it needs to be, I then re enable closed loop and let the hegos and adaptives dial in the fuel, once the kams have learned you can organize the mafv numerically in the datalog and see how the kams have adapted, if you have a kam correction less than 1.00 in the lower voltages of the maf curve then you know you need to increase the low slope, REMEMBER, you must dial in the low slope BEFORE you can dial in the breakpoint as it will be constantly moving once you have the low slope dialed in and the high slope dialed in you'll see exactly where the breakpoint is as the KAM's will not be 1.00 in that MAF voltage range

    Open Loop / Closed Loop

    In open loop the lambse's do not respond to hego feedback, the lambse calculated from the fuel table(s) and multipliers is what you get since the hegos are cold during startup all ecu's crank into open loop fuel mode, one can logically figure out that since the hegos can only report STOICH = 1.000 lambda, that open loop must be entered at WOT and high loads as well where enrichment is needed (more fuel than stoich) So short, in open loop the hegos are just ignored but they can still give you insight on if your lean or rich by the voltage they are reporting. At WOT the hegos should be reporting 0.800 volts or more indicating your not lean. If you see them drop below that you know your lean unless the hegos heaters aren't getting power.

    During closed loop the ecu constantly adds and subtracts lambse to get the hego to switch if the hego is lean ( < 0.4 volts) then the ecu drops the lambse to enrichen the mix until the hego switches rich ( goes above > 0.4 volts) once the hego has switched rich, the ecu then increases lambses to get it to switch lean again in a never ending closed loop once the hegos are controlling fuel correctly, the ecu will save that fuel correction in the KAMRF data and use it the next time the ecu is in that cell (load and rpm range) the narrowbands and ecu can dial in your fuel much more accurately than a human can by looking at a wideband and making adjustments
    See the
    HEGO Write Up for more details.

    Closed Loop Tuning / KAMRF (LTFT)

    KAMRF is the absolute fuel error% at that specific mafv which is how much fuel it took for the hego to reach actual CL stoich reported by the hego VS what you told the ecu it should be there is no fuel table for closed loop since its value is stoich = hego switch voltage point of .4 volts which can never be wrong you can apply the KAMRF as a direct multiplier to maf flow at that specific mafv, just make sure you remain at that mafv for at least 10 seconds and the lambses are switching above and below 1.0 so you know the kam's are mature and accurate.

    By datalogging and comparing MAF voltage to KAMRF we can dial in fuel perfectly but since the hegos only report stoich they can not be used to dial in WOT fuel... or can they? the beauty about mass air is that you tune the ecu to the peripherals not specifically to the engine by this i mean you don't dial in a VE table to calculate fuel like you would in a speed density setup once you have your maf and injectors dialed in, so long that your not exceeding their capacity, your fuel will be exactly where you set it

    its highly recommended to have a wideband for dialing in WOT but if you don't have a wideband you can still dial in your fuel by letting the hego's do it for you the ecu will default to open loop at WOT, in order to force closed loop at WOT you MUST set the WOT Breakpoint (threshold) to max either 5.1 volts or 1023 ad counts since relative_throttle position can never reach that the WOT flag will never be set, you must ALSO disable the OL vs RPM and OL vs ECT functions from forcing you into open loop the easiest way to do this is to set the time delay scalars to 20 seconds, you can now use the hegos to dial in WOT fuel, you must pull a few degrees of timing out to prevent a bunch of heat in the engine, an engines burns hottest at just a tad leaner than STOICH, and we all know HEAT MAKES POWAH so by pulling out say 6 degrees or more you will reduce the amount of heat in the engine and make it safer to beat on at STOICH
    for example, with a dialed in low and high slope your kams might look like this

    at 1.5 mafv and below, the kams fluctuate between 0.97 to 1.03 which is perfectly acceptable
    at 1.8 mafv kams=1.05
    at 2.0 mafv kams=1.06
    at 2.2 mafv kams=1.04
    from 2.3 to 5.0 mafv kams fluctuate between .98 and 1.02

    you then know you need to reduce the breakpoint to give it a little more fuel where the slopes meet which is approx. 2.0 mafv in the example given

    think of it like this

    low slope=low load, cruise and idle
    high slope=high load, wot and aggressive acceleration
    breakpoint, is the center of where it mixes both together

    in every tune i make, i demand a set value across the table for a specific perload for example: I demand 1.000 (stoich) up to a perload of 75% of the maximum engine load (no boost) and 0.875 at perloads of 90% and greater I drop the lambse to 0.800 at a perload of 120+ (n/a engine can't reach perload greater than 100% when FN035 is dialed in "PER DECIPHA") the O/L fuel table fn1362 and the stabilized fuel table fn1360 do the same thing, only different is stabilized table has rpm input instead of ect, at startup the base fuel table is used regardless until the ECT stable flag is set in which it switches to the stabilized fuel table fn1360, as long as you reasonable values in the tables for it makes no difference tune wise
    Note: The RPM vs Load Open Loop Function is ONLY ACTIVE once the ECT Stable Flag is set, setting the function to all 0s will not force open loop until the ECT Stable flag is set. the lambse is the afr your telling the ecu you want, if your lambses are 0.850 at WOT and you want them at 0.800 you need to go to the fuel table and change it from 0.850 to 0.800 in those cells its very difficult to get the fuel dialed in with closed loop throwing you around, once you get your fuel right you can then allow closed loop and adaptives to do their thing and dial your fuel in perfect, only a narrowband can dial your fuel in perfect, unless you want to get a lab spec wideband and spend hours makes decimal changes to your fueling

    KAMRF is the LTFT (long term fuel trim).

    STFT = Lambse

    Short Term Fuel Trim is the lambse difference from stoich (1.000 - lambse) * 100 , It is the exact same representation of Lambse.

    To put this into perspective, lets say at WOT we have a LAMBSE of 0.800
    1.000 - 0.800 = 0.2 * 100 = 20 (STFT)

    Now, lets say we have a negative STFT value of -18
    1.000 - (-18 / 100) = 1.18 LAMBSE

    as you can infer, a negative STFT means its removing fuel, so lambse will be greater than 1.000 (leaner)
    a positive STFT means it is adding fuel, so lambse is less than 1.000 (richer)
    So lets say for example, we have a STFT of 15

    1.000 - (15 / 100) = 0.85 (Lambse)

    for quick reference heres a table to break it down and help understand it better
    -11.010 = [1.000 - ( -1 / 100)]
    -21.020 = [1.000 - ( -2 / 100)]
    -41.040 = [1.000 - ( -4 / 100)]
    -81.080 = [1.000 - ( -8 / 100)]
    -121.120 = [1.000 - ( -12 / 100)]
    -161.160 = [1.000 - ( -16 / 100)]
    -181.180 = [1.000 - ( -18 / 100)]
    -201.200 = [1.000 - ( -20 / 100)]
    -251.250 = [1.000 - ( -25 / 100)]
    01.000 = [1.000 - ( 0 / 100)]
    10.990 = [1.000 - ( 1 / 100)]
    20.980 = [1.000 - ( 2 / 100)]
    40.960 = [1.000 - ( 4 / 100)]
    80.920 = [1.000 - ( 8 / 100)]
    120.880 = [1.000 - ( 12 / 100)]
    160.840 = [1.000 - ( 16 / 100)]
    180.820 = [1.000 - ( 18 / 100)]
    200.800 = [1.000 - ( 20 / 100)]
    250.750 = [1.000 - ( 25 / 100)]

    E-85 Adjustments

    If you've previously tuned your vehicle for pump gas and are switching to E-85 the following are the minimum changes that should be made when switching fuels.

    reduce stoich_afr "z_afr" to e85
    shoot mbt timing to it
    kick up the crank pw by 25%
    drop the 90+ load lambses (top 3 rows) by 0.05 lambda

    Dial her in from there.


  • Multipliers and fuel tables only modify lambse, THEY DO NOT DIAL IN FUELING!!
  • You can use the wot fuel multiplier if you want, in fact I use it on a lot of my mail order tunes, but remember though its a multiplier on lambse it cannot dial in fueling. So remember if your demanding 0.888 and your wideband is saying 0.820 even if your in boost, your running rich, once again the purpose in this write up is to emphasize that the wideband reading is useless without knowing the lambse, there is no possible way to know if your rich or lean since its relative to lambse
  • If you want a WOT AFR of 0.800 and your wideband reads an AFR of 0.800, yet the LAMBSE is 0.860 (the computer wants 0.860) THEN YOU ARE RICH and you need to change your fuel table to 0.800 instead of 0.860 and then reduce fueling so your wideband then reads 0.800 again which would coincide with your lambse, since your 6% richer now if you just changed the lambse to 0.800 without changing your fueling you'll be down to 0.740 lambda
  • LAMBSE is the AFR the ecu is demanding, widebands read the actual lambda, thats why you dial in fuel by getting the actual lambda (wideband) to match the commanded lambda = "LAMBSE"
  • Side Note: Table rescaling has no effect on FUELING, for the record, no one has to rescale any tables, its ONLY done to gain more control, if you want to do it the quick way you can simply increase the SARCHG (cubic inch displacement scalar) and adjust your tables accordingly, same principle
  • LAMBSE is the afr you tell the ecu you want, once fuel is dialed in correctly, the wideband will spit out the same value as LAMBSE
  • The lambse should be whats in the fuel table unless your in closed loop and its varying around stoich or if theres a multiplier thats modifying the lambse, like the wot multiplier, global fuel scalar, startup enrichment, lug multipliers, etc..
  • The injector slopes have nothing to do with lambse
  • Its often easiest to get fuel close in open loop then enable closed loop and use the kams to mold the fueling into place perfectly
  • The older ecu's used lbs/rev as a variable for the breakpoint (half the engine cylinders), where as with the newer ecu's its static thus the single breakpoint lb fuel scalar

    Startup Enrichment

    Startup Enrichment is the additional fuel needed to stabilize the engine for every startup, better known as a "Choke" in carburetor's. If you haven't dialed in base fuel yet then you can't dial in startup enrichment yet. Once your base fuel is dialed in for startup fueling compensation you have to dial in the startup enrichment "lambse subtractor" table.

    Also note the other big contributor to startup is dialing in the isc multiplier table(s) fn1861 / fn1862n / fn1862d.

    This is covered in the

    Cold / Startup Enrichment Write Up

    Resetting the ECU / KAM Memory

    Once your fuel has been dialed in, the KAM memory will not need to be reset.
    It is NOT recommended to reset the KAM memory for any purposes, the adaptive memory can ONLY benefit the tune.
    An unintentional memory reset such as a loss of battery power will not warrant any tune adjustments.
    If the vehicle has been sitting for an extended amount of time without the engine ran, so long as the injectors and MAF
    sensor remain the same as it was when tuned, no tune adjustments are required.

    Keep Alive Memory SHOULD ONLY be reset when fuel modeling has been changed
    this will occur under the following conditions:
    • MAF Transfer Function adjustments greater than 5%
    • Injector High Slope adjustments greater than 0.5 lbs/min
    • Sarchg (CID - Engine Size) adjustments greater than 50 cubic inches

    Adjustments made to LAMBSE in the fuel tables WILL NOT require KAM to be reset.

    to reset KAM's do any of the following:
    • The easiest method is to change the kam clear scalar to clear then hit update, then change it back to normal and hit update again, key must be on
    • OR... you can select an empty tune slot with the key on then select back to the tune
      for example, (if using BE) open up hardware >> moates config >> select tune slot 7 which should be blank, the pump will run, then select tune slot 8 again and the pump will shut off (if thats where you have your tune written)
    • OR... or you can write a corrupt tune to it like a CBAZA tune to a GUFB ecu for example
    • OR... you can disconnect the battery for 30 minutes
    Any of these methods will reset the learned adaptive fuel KAMRF's and idle air ISCKAM corrections.

    Retuning Required

    Retuning is required under any of the following circumstances

    • MAF sensor changes - all changes must be made in the MAF transfer ONLY
    • Fuel Injector changes - all changes must be made in the injector parameters ONLY
    • Fuel Pressure changes - all changes must be made in the injector parameters ONLY
    • Cylinder Head Replacement - spark table and peak load function must be updated
    • Camshaft Replacement - dashpot MAY need to be updated
    • Base Timing changes - Ignition timing (spark table) and injector timing must be updated
    • Fuel Grade changes, ex: E-85 or 87 Octane - AFR parameter and/or spark table must be updated

    Tuning Fuel Blind - No Fueling Feedback

    In some cases you will run in to some vehicles that do not cooperate. In these instances often the hegos are non-functional and an aftermarket wideband sensor either isn't possible due to the setup or just non-functional or reading incorrectly. In most instances it is due to burning oil and/or cam timing events or large exhaust with poor velocity. In any case in order to dial in these setups you must return to the old school carburetor style methods of dialing in fuel by feel. This is my method that works for me.

    First you will have to force open loop which goes without saying if you have incorrect or no hego feedback.
    Force OL Then simply go play with the maf transfer to get the engine running as best as you can. Without having any way to read the afr you cannot dial your fuel in so you have to tune it like a carb and adjust the maf transfer to see if the engine likes it or not. The best way to do this is to get the engine up to operating temp then at idle go adjust the maf flow at that mafv your idling at by reducing the flow multiplying it by 0.95 and updating. Continue to reduce the flow in 5% intervals until the engine starts dropping rpm and you will also see IPSIBR starts shooting up to add air to maintain idle. You have now reached the lean best idle fuel. Now multiply the flow by 1.05% to give it back 5% to make her happy again. At this point you've now reached the leanest point the engine will happily idle at and you've dialed in that maf point. Now use the throttle to reach the next mafv point and start over again. Dial in each point as well as you can until you reach the highest mafv point possible. Then to dial in those higher points you have to drive the vehicle. Hold the maf stable at that next mafv while driving and dial it in. Keep repeating until you reach half throttle. After half throttle it is safer to add fuel in 10% intervals by multiplying the flow at that mafv point and all the points above it by 1.10 until you've reached the point where adding fuel seems to slow the engine down or make it not as responsive. At that point remove 5% and your at the richest best fuel point for enrichment fuel and WOT. This is a tedious process so be patient. If a dyno is not available and street tuning is required its always best to have someone ride with you if possible to make operating the vehicle and tuning safer and easier.

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