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Message: <blockquote data-quote="rz5.0" data-source="post: 1219856" data-attributes="member: 12700">Fuel 101by Michael Decipha PonthieuxLast updated: 8-26-2013Lambse (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 will require significantly MORE fuel than a stabilized warm engine. Lambse is the AFR (air/fuel ratio) the ecu is demading. When fuel is dialed in your wideband will match your lambse. YOU CAN NOT 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 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 AFR the ecu is DEMANDING, if your lambse is 17 at wot and your wideband reads 14.5 at WOT then you are RICH and you need to pull some fuel out just for clarification, the 17:1 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 17:1 at WOT 13:1 is more like it, to further that, most engines running at 17:1 at max engine effeciency aren't usually too happy and usually sputter breakup pop misfire etc.. likewise, if your LAMBSE at WOT is 8 and your AFR(wideband) is 12.5, you are LEAN and need to add fuel again, no sane person would demand 8:1 AFR 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 matches 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 AFR 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 multipliers modify lambse, THEY ARE INCAPABLE OF DIALING IN FUEL, for example, if your lambse at WOT is 13 and your wideband is reading 13.5, your fuel is off by (13.5/13=1.038%) changing the WOT fuel multiplier from 1.00 to 0.96 will reduce your LAMBSE to 12.47 (13 * 0.96) and your AFR will drop to 12.94 , HOWEVER, the gap between lambse and the wideband will still be off by the same percentage (12.94/12.47=1.038%) thus you hadn't dialed in fuel as your fuel 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, typically its lean on the big end, take a stock supercharged lightning for example, they demand 12 LAMBSE at WOT yet they only get 14 AFR why i bring up the lightnings? I find that just incredible and since they come stock with the 90mm meter thats many folks use which BTW has the maf curve dialed in perfect on the trucks side note: typically reducing the high slope to 34.5 and the low slope to 36 on a stock lightning will have the fuel perfectly dialed in!!! NOTES: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 hego101 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 SlopesThe injector HIGH slope is the actual flow rates 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...) the low slope accounts for non-linearities at low pulsewidths, at low pulsewidths an injector acts as a large injector spraying more fuel, so to compensate you will have a low slope with a value HIGHER than the high slope. Typically the low slope is approximately 15% larger than the high slope. 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 etc... now 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, this will insure your fueling is not doing anything odd at the breakpoint changing the fuel pressure will change the slopes 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 1.2 if i drop the pressure from 40 to 20, i would multiply the slopes by 0.8, if i went from 40 to 45 the i would multiply by 1.05 not exact, but good enough for government work MAF Transfer - Dialing in the MAFits very easy to tell if the maf curve is accurate, at wot with a steady lambse, your AFR will stay consistent if your LAMBSE is at 13 and your wideband AFR is 14 but stays there consistent then the maf curve is accurate, you can very simply reduce your high slope and get your 14 AFR wideband reading down to exactly 13 that the ecu is demanding (LAMBSE) it to be LAMBSE's in closed loop are based purely on hego feedback, when in closed loop your lambse's will jump around to hit stoich 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!!! once you gather sufficient KAMRF data you use that info to dial in your fuel Note: The highest MAF voltage in the MAF transfer must be maximum the ecu allows!!!! NO EXCEPTIONS!!! This will be approx. 16 volts for EEC-4 and approx. 5.1 volts for EEC5 The MAF curve must be in chronlogical order, thus all numbers must be in order from least to greatest, YOU CAN NOT HAVE A LOWER FLOW FOR A HIGHER VOLTAGE!! else the ecu will reset everytime it reaches that point for those that don't have a known curve i recommend to dummy down the maf transfer to only a few points in half volt intervals like this: 16.0 volt = 1600 5.0 v = 1600 4.5 v = 1200 4.0 v = 1000 3.5 v = 800 3.0 v = 600 2.5 v = 400 2.0 v = 200 1.5 v = 100 1.0 v = 50 0.5 v = 25 0 v = 0 0 v = 0 0 v = 0 0 v = 0 0 v = 0 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</blockquote>