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Before you buy any Self Learning EFI system, please read!

Discussion in 'FAST Support Forum' started by pbp1, Oct 5, 2015.

  1. pbp1

    pbp1 Member

    Joined:
    May 19, 2009
    Here is some information that I think would be helpful to anyone shopping for an aftermarket EFI system.

    All Self Learning aftermarket EFI systems use manifold vacuum as a measure of engine load. This is measured by the MAP sensor. Manifold Vacuum on a running engine has an inverse relationship to the load that the engine is under. At a given engine speed, as the load is increased, the vacuum goes down.

    At Wide Open Throttle, the vacuum (or pressure) inside the manifold is roughly zero. At that point, the vacuum or pressure inside the manifold is equal to the atmospheric pressure (No vacuum, and no pressure).

    At Idle, when the throttle plates are closed, there is some vacuum present in the manifold because the downward movement of the pistoms is sucking against the backside of the closed throttle plates.
    Anything that puts load on the engine will decrease this vacuum. For Instance, it you had a vacuum gauge connected to the intake manifold of an idling engine, and the A/C compressor comes on, even if the engine RPM stays steady, the vacuum will drop.

    Manifold vacuum is an excellent reference for engine load!

    Engines with long overlap camshafts and/or low compression and/or small displacement can make low vacuum at idle. This is why vacuum assist power brakes are not reccomended in these applications.

    The total range for vacuum in our atmosphere is from zero (atmospheric pressure) to 30 inches of vacuum (high vacuum). Most stock or moderately cammed engines will generate 15 - 20 inches of vacuum. An engine with a long overlap cam can make as little as 2-4 inches of vacuum.

    The issue with an engine that makes less than 7 inches of vacuum is that when the ECU is trying to measure load, it only has a vacuum range of 7 inches or less from idle to wide open because the idle vacuum is very close to the wide open vacuum. This senario tells the ECU that the engine is almost at full load when in fact it is idling. Because the ECU is told that the engine is at full load, guess what it does? It throws a bunch of fuel at it to handle the reported high load.

    For a Self Learning EFI system (any brand!) to work properly, the engine needs to produce a bare minimum of 7" of vacuum at a warm, in park idle. I would prefer that the engine makes 10" just for added margin of error.

    If you have an existing running engine that you are considering converting to EFI, you can simply connect a vacuum gauge to it and see how much vacuum it is making. If this is a new build, consult with an engine building professional or your camshaft manufacturer with all your engine specs and ask them to make a camshaft reccomendation that will produce a minimum of 10" of vacuum at idle. Bear in mind that a lot of factors come into play concerning the production of manifold vacuum. Engine displacement, compression ratio, how well the rings and valves are sealing, Camshaft duration, Camshaft lobe separation, idle ignition timing, idle fuel mixture, intake manifold and intake port design, efficiency of the exhaust system, all play a part in manifold vacuum.

    With a laptop tunable system like the XFI Sportsman or XFI 2.0, you have the ability to re-scale the tables in the system to get back the load resolution lost by the idle vacuum, but this does require some tuning experience, or a willingness to learn about tuning.

    If you are looking to purchase a Self Learning EFI system, please have a conversation with the dealer or retailer that you are considering purchasing from. If you are an installer or dealer of EFI systems, please have this conversation with your customer before the sale. This will help ensure that the end user gets the best system for his or her application.
     
    ThePCSurgeon and maxwell like this.
  2. Lance

    Lance Member

    Joined:
    Feb 11, 2011
    Location:
    Central MI
    If I may add.....

    Also keep in mind with any "self learning" system that the O2 sensor feedback is everything. Any errors measured by the O2 sensor will ultimately affect the calibration and quality of tune. As they say; Garbage In = Garbage Out. So, it's important that the location of the O2 sensor is optimal and that no air leaks are possible before or immediately after the O2 sensor location in the exhaust plumbing. Flex-tubing, slip fit collectors, bad header gaskets, cracked headers, open headers, poorly welded O2 bungs, etc., are all potential problems that can cause a false lean indication to the ECU with the ECU attempting to richen the mixture up in both short term correction and long term correction (learning). These issues will typically be more pronounced at idle and cruise.

    In my experience, most of the problems encountered are a result of either too little vacuum signal and/or exhaust leaks.

    A little about self learning: The learning process is fairly simple. If the measured AFR is different than the target AFR, the ECU attempts to correct the error in the short term (O2 correction) and in the long term (learning). If the engine is obviously running rich at idle/cruise, yet the O2 is indicating a lean condition, this is a problem and it will severely affect idle quality and drive-ability.
     
    Last edited: Oct 5, 2015
  3. Steiner

    Steiner Member

    Joined:
    Aug 20, 2015
    Location:
    Lyman, SC
    Great post. It should be stickied.

    However, you should clarify this:

    ...as I do not believe it to be a 100% true statement. It should be noted that a self learning FAST system requires this due to its tuning methodology and allowable user interface. There are self learning systems out there that can deal with large low vacuum cams because idle vacuum is taken into account and scaling is adjusted based on cam type input and/or there are other options for idle cell parameters, and on some of these user tuning is also an option when the normal input parameters are not enough to sort it out.

    Personally, I think FAST should just make the Sportsman unit the base EZ ECU since apparently it works with the eDash already and has a self-tune option. There are several manufacturers with self-learning systems that are also user tunable (at a lower price point in a few cases). Sure, the ones with user tunable options may wind up having just as many issues as the "hands off" type but I think the percentage of users who can get some of their issues fixed is much higher on the ones with the tuning option. I realize sometimes it's necessary to save people from themselves though.
     
  4. TurboNova

    TurboNova Active Member

    Joined:
    Jan 30, 2009
    Location:
    Lake Havasu City AZ.. but mostly travel tuning
    Easy Clarification, don't put Self Learn systems on anything that has less than 10" of vac min. Don't put a self learning system on something with a cam lobe center of 106-110 generally it will have too much overlap and not enough vac. If someone wants to be successful with a self learning system they should be building a mild street engine with a mild cam that makes lots of engine vac and a good sealed exhaust. Cam lobe centers in the 112-116 being better, preferably the 114-116.
     
  5. Lance

    Lance Member

    Joined:
    Feb 11, 2011
    Location:
    Central MI
    I wouldn't want to pick a manifold vacuum number and call it a limit as the perceived limit is different for different applications and for different users. However, in my experience, anything less than 10" of vacuum starts to be a compromise. The compromise is typically sacrificing some drive-ability. The less vacuum, the lower quality the drive-ability will be. Since the term "drive-ability" is a little arbitrary, it's up to the user to determine what's acceptable or not. In any of the self-learning systems using MAP to derive engine load, the lower the vacuum, the smaller the signal to noise ratio. Even re-scaling the range doesn't always help as you will effectively be amplifying the MAP signal along with any noise.

    That said, the applications that may be in the marginal range may have better results with the Sportsman over the EZ but will have to do a little more work to achieve the desired result. Alternatively, those wanting a more simple bolt-on, with a milder cam and less tuning intervention, will probably be happier with an EZ.
     
  6. Steiner

    Steiner Member

    Joined:
    Aug 20, 2015
    Location:
    Lyman, SC
    Then don't market it solely as a system that "supports stock-to-1200 HP engines" with no caveats. Responsibility lies with the manufacturer just as much as the customer.
     
  7. pbp1

    pbp1 Member

    Joined:
    May 19, 2009
    Supporting up to 1200hp, and working with any engine up to 1200hp are two very different statements. ANY system has caveats. This is why it is important to make an informed decision when making a purchase like this. The horsepower limitation of ANY EFI system is the flow capacity of the injectors. The EZ 2.0 throttle body will flow a total of 592#s per hour at 45psi. This is enough fuel to support 1200hp at 90% duty cycle.
    If a person only looked at this one attribute of the system, I agree that they may or may not make the best decision. This is exactly why I started this thread. To help anyone make a more informed decision.
    Just trying to offer some educational information!
     
  8. TurboNova

    TurboNova Active Member

    Joined:
    Jan 30, 2009
    Location:
    Lake Havasu City AZ.. but mostly travel tuning
    Maybe or just lack of education in the whole industry. Just because it will support 1200 hp of fuel does not mean a self learning system will work on that engine, I agree. But that is a selling point that they all make. The biggest issue is the end customer who buys this stuff from Summit who has no tech support and a large lack of knowledge in the EFI area, then the issues are brushed off on the dealers who didn't sell it to that user and the general FAST tech line. IN general there is good support from FAST but it is hard to fix everyones issues over the phone and often you don't get the whole story.

    I can say from experience, I personally will not sell any Self Learning systems not matter what the manufacturer is to somebody with an aggressive engine with too much cam. From what we have tested the less than 10" rule is a go no go for me. It is not worth the time to "try" to make the system work. I have also had the inverse issue where the engine was 100% stock and made too much vac, like pegging the sensor in the hi vac area during cruise which was also causing a problem. In that case there is only two other FAST choices which is the Sportsman XFI or XFI.
     
  9. Steiner

    Steiner Member

    Joined:
    Aug 20, 2015
    Location:
    Lyman, SC
    pbp1, yes I agree and which is why I said good post earlier. The problem is it's on the user forum and probably 99% of customers only find a user forum AFTER they have a problem. I've said it before elsewhere but an issue with a lot of places is that engineering and marketing are usually not always on the same page or even in the same building.....probably because they might kill each other. ;)
     
  10. pbp1

    pbp1 Member

    Joined:
    May 19, 2009
    Thanks Steiner!
    Education on the part of the manufacturer, and taking advantage of the value of a qualified dealer on the part of the consumer are both part of the solution.
     
  11. ThePCSurgeon

    ThePCSurgeon New Member

    Joined:
    Mar 25, 2015
    Location:
    New York
    Great information, thanks..
     
  12. gary beauregard

    gary beauregard New Member

    Joined:
    Sep 13, 2014
    Location:
    NY
    Posted by Turbonova: "important with a manual trans, you can't tune in each gear.... you are wasting your time. Pick a middle gear like 3rd on 5 or 6 speed and make it spot on. Then you will have to let the ecu correct the other gears using closed loop"...."I would not put it in learn mode, since it will constantly be tuning each gear. Just tune in one gear and let the closed loop take care of the difference in each gear. You also have to keep the O2 correction + and - high 25% on both sides to let the ecu fix the fuel."

    How does the ez1 and ez2 work in these situations.
     
  13. Steiner

    Steiner Member

    Joined:
    Aug 20, 2015
    Location:
    Lyman, SC

    I believe they just set different learn gains for each area (idle/cruise/WOT, which are based mostly on RPM and MAP to set those areas I think) so that the ECU only tunes to within a certain percent of dead on......Like having the gain set so that the ADL value only needs to be within 13% at cruise and maybe 5% at WOT (just using those numbers for example. So, the mapping does not have to be dead on.....at cruise for instance if closed loop has to add 10% to hit your target AFR, it will not change anything in the learn value or map because it's within the 13% range already. It gets "close enough" while letting closed loop do the bulk of the work afterward. At WOT in each gear the fueling is going to be more similar between gears than it is at cruise or low loads.

    I don't want to speak for Brian but I think he recommends doing it the way he does because when you are able to datalog and tune yourself, you can get to a spot where you're "close enough" much faster than if you let the ECU do it. By tuning it to dead on in the middle gear with a manual, you have to assume that lower gears will need less fuel and higher gears will need more fuel so your map is set up to where you're kind of in the middle so you've got good + and - range for closed loop to work on both sides of that. If you get too tight with the learn gains and transport delays and let learn take over, then what can happen is that it may adjust the learn values in one gear and then it winds up being a ways off in another gear so then it gets there and adjusts again so the learn values will oscillate. This is a problem because closed loop acts much faster than learn....you could hit a spot where you're maxed out on closed loop but still not at AFR target, and since the ECU has to see a certain amount of closed loop adjustment for a certain amount of time then the learn value may not change for many cycles, then when it does it may show up on the other end. When this happens you might have a certain spot in a certain gear where there's a hiccup or overly lean/rich condition over and over that may or may not fix itself with time/conditions. I don't know if this makes sense, sometimes stuff in my head doesn't make it out my mouth or fingers right. Brian will certainly be able to add to it and correct it.

    Bottom line is we get used to driving our dd cars that the OEM's spent countless hours tuning with O2 sensors that each cost probably cost more than our entire EFI systems in each individual bank using more sensors and other stuff than we have available to get it to act the way it does. Then we read the magazines and marketing material and might start to think that we can just bolt on an all-in-one unit on any old engine and it'll just turn our junk into the same driving experience. If you have the tools, you can get close but all the engineers on earth can't put that into one little computer with $100 worth of sensors that will do it for you.
     
    Last edited: Oct 6, 2015
  14. gary beauregard

    gary beauregard New Member

    Joined:
    Sep 13, 2014
    Location:
    NY
    "This is a problem because closed loop acts much faster than learn....you could hit a spot where you're maxed out on closed loop but still not at AFR target, and since the ECU has to see a certain amount of closed loop adjustment for a certain amount of time then the learn value may not change for many cycles, then when it does it may show up on the other end. When this happens you might have a certain spot in a certain gear where there's a hiccup or overly lean/rich condition over and over that may or may not fix itself with time/conditions."

    This makes sense, maybe the self learning is not best suited for manual trans.
     
  15. Steiner

    Steiner Member

    Joined:
    Aug 20, 2015
    Location:
    Lyman, SC
    Well, with a purely self learn system like the EZ you kinda have to have it since you're relying on the system to build your base table. There's always the possibility that some spots could be off further than what the O2 correction limits are set for. Something has to be there to at least get the tune close so O2 correction is not working so hard so often. It's kinda like sitting at the table for dinner, you want the main course you're shoveling in your mouth right there under your nose but the drink, salt and pepper, condiments, etc that are part of it all need to be spread out within easy reach around it.
     
  16. TurboNova

    TurboNova Active Member

    Joined:
    Jan 30, 2009
    Location:
    Lake Havasu City AZ.. but mostly travel tuning
    EZ 1, EZ2 have the closed loop corrections set really wide. One of the issues is since it is constantly learning, it will keep learning in each gear as you drive. It works since you still have closed loop and learn active. It would be nice to turn learn off once you have one gear tuned and just let closed loop correct.

    I would agree it works better in an automatic trans.
     
  17. Darrell A. George

    Darrell A. George New Member

    Joined:
    May 26, 2015
    Location:
    Hoschton
    This key point from the original post tells me why I've struggled so hard with my EZ EFI 1.0 multi-port FAST system. Nowhere in the documentation or any of the dozens of online videos does it warn of the issue the EZ system has with low idle vaccum. My car only makes 5 to 6 inches, and as I transition from idle to motion the AFR goes fat (10) the plugs load up and it stumbles until the ratio improves. Mostly I fight with 1st and 2nd and can't come out of the turns hard on the throttle or the AFR will dip into the 10s and load the plugs. The car can not be raced this way.

    So, I spent a large sum of money and wasted untold hours trying to get this system to work. Even the guys on the FAST support desk never offered this as a possible cause. And I purchased this directly from FAST, I told them my HP numbers and that it was going on a road race car, but never was I asked about the size of the cam. So now I guess I have wasted all this money.

    Selling this without a warning and not teaching the sells desk techs to ask key questions is not right, it's just bad business. I was sold a product I can't use, thanks guys, it does not even work as a boat anchor, it's just junk for me. And for all the other people out there having trouble with the EZ system, this is probably the key contributor.
     
    gunther19820 likes this.
  18. Darrell A. George

    Darrell A. George New Member

    Joined:
    May 26, 2015
    Location:
    Hoschton
    Sad part is, even the FAST sales team is not asking the key questions when they sell the product.
     
  19. Les Duncan

    Les Duncan Member

    Joined:
    Oct 5, 2014
    The usual answer is " it's just business, move on " I just stored my car without an engine, basically worthless, I threw over $20,000 into the wind and I don't have the
    boat anchor, since I made a deal to recoup some $$$ selling system and add on parts to install shop at 50-75% off retail. The next purchaser of this product will be
    none the wiser as to whether it will work and the dealer representing FAST and the install shop will have profited again, caveat emptor.
     
  20. Les Duncan

    Les Duncan Member

    Joined:
    Oct 5, 2014
    I was lead to believe that I WAS going to get the same or better driving experience in my classic car with BBC and FAST EZ EFI 2. The agent who sells the product sells it this way.
    This is bad business and misleading at the very least.................. they are just selling systems thinking it will just work on everything, not so much. By the way the O2 sensor is
    well over a $100 for decent product but if you have reversion and header leaks what's the point?
     
    Darrell A. George likes this.

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