spittybug wrote:If I understand the concept of the enhanced acceleration enrichment, the purpose of the "stuck to walls" and "sucked from walls" parameters is to add or subtract fuel based on what has been commanded by the VE table versus what is shown to have actually been combusted (by the 02 sensor). Is that basically right? In a perfect world, if the VE table was spot on for the right amount of fuel at each load/RPM condition, the transition from one to another would be supplemented or reduced by an amount of fuel that is stuck or sucked, right? Would over richening it a little bit would be akin to selectively enrichening the transition for power versus economy?
So, if you had your VE table dialed in for your advance table and AFR targets by having run VE analyze with gentle driving, and were confident that it was as good as you were going to get it, the difference between your true AFR values and your target AFR values are what needs to minimized.
Is there perhaps the means to analyze a log file, calculate the AFRtarget minus AFR actual (is this a variable that already exists perhaps?)
spittybug wrote:Thanks for the really quick response!
What is the purpose of telling the ECU how much fuel is getting pulled or added? What does the ECU do with that information?
Is there a variable that already exists for AFRtarget minus AFR actual? You say that this can be done in the log viewer, but I'm struggling without a definition of all of the variables. Does such a list of definitions exist?
It runs it through the wall-wetting equations and uses that information to determine how much fuel is actually going to go into the engine, and modifies the length of the squirt to make sure that the VE-commanded amount of fuel actually gets into the engine (as opposed to getting stuck on the intake port walls).
spittybug wrote:I successfully created a variable I call DeltaAFR which shows me how my AFR (as sensed) compares to my target. It helps show me how much I'm off, and it is a fair bit! It is defined as [AFR Target 1]-[AFR] so positive values mean I'm richer than target. Mainly I'm showing rich, but with occasional very lean spikes when I come off deceleration and then go open throttle. How much of a lag is there (time wise) between Target AFR 1 and AFR I wonder? My LC-1 is located a foot from one bank of cylinders, right near where the crossover pipe from the other side of the engine joins in. It's probably 3 - 4 feet from that bank. Any good way to determine that delay?
I'm not changing anything yet though. This shows me what I need to do is turn off the EAE and gently tune again. A couple of my target AFR transitions could be better placed too. Then I'll run this analysis again and it should show me close to 0 for the differential I hope. THEN I'll turn on EAE and see where I go astray. That should hopefully give me guidance as to where to "add or suck".
My language was less than perfectly chosen... when I said that fuel was added or subtracted, I was trying to ask if indeed the pulsewidth was being modified to account for the fuel that is sticking or coming off... the overall net fuel delivered doesn't change, but more is being added when the ECU is being told that it is getting stuck on the walls and some is being removed when told it is coming off the walls; all to ensure that the amount we want (VE table value) is indeed what makes it into the engine. Did I say that better?
Using the scatter plots I've looked at DeltaAFR against RPM and I think I will find it very useful once I do the above. Is there a way to set the X and Y scales on both scatter plots and the normal log graphs? I'd like to center DeltaAFR around 0. These kind of analytics are very powerful and really help to visualize what is going on. Thanks for the good work!
I'm going to use mapdot since I want to be able to share my efforts with the stock Delorean conversion guys who don't have TP sensors. I also find the TPSdot too noisy in my past experience.
spittybug wrote:Made things a little bit better again today. Without a dyno, I'm just driving and logging and checking my AFRs.
I tried EAE with the lag turned on.... DISASTEROUS.... rendered car totally undriveable. I have previously tried to go up on the number of squirts (set at 2), but with no luck; it just kills the car.
Transitions from very low map levels to high still make me go off the chart lean for a quick spike. I don't feel it in the car, but I see it on the logs. It must be affecting acceleration performance too. I tried upping the % added to walls at the lower half of the MAP range, but all that seemed to do was make me richer in steady state; didn't help the acceleration spikes.
I don't have standard AE turned on as I found it difficult to avoid herky jerkies. Perhaps I need to set a mapdot threshold >100 and then play with that enhancement curve? Or am I doing something wrong with the EAE?
spittybug wrote:Doesn't look like I can go 6 squirts since I would fall down to 3ms per squirt (total REQfuel = 18ms). If I go to 3 squirts, it goes to the recommended minimum of 6ms and the idle pulsewidth will probably be right around 2ms. I'm running simultaneous on the banks.
Will try shortly.
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