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I found that the current RPM limiter is a bit harsh,still much better than fuelcut only,but not that nice that some stock cars already have.I do not know how they really work,but maybe together we can find out.I know that some of you are much more interested making VEMS controlling idle valves flawless and so on,but i think that BASIC ENGINE OPERATIONS,such as RPM limit,are more weighty.So i think we should find out how those Hondas,BMWs limit their RPM with such little hysteresis,and almost no jerk. I think that they do not cut all the ignition,but just cut some cylinders ignition event ,so the engine will not lose all its power,and movement. Please write here your comments! I don't want to argue here, but IMHO getting the engine to idle is more like basic operation than smoothing rev limit ;-) Sure,but i installed VEMS approx a year ago,and since then it runs smooth,without any kind of idle valve,just with opened throttle valve.And there are other type of supported idle valves (and not one!!) that works.I think its not that hard to install one of these (as i did earlier with other standalone system.Just my 2 cents. - You're right, there are well controlled valves already, however supporting a new one is always a big plus (and a big help for every BMW owners), if not too much work. I even didn't ask the firmware team to get support for mine, just did my measurements and own development on the firmware to support my IAC valve. (Getting help and comments from others though) Now I've got a good-working code, which finally has been merged to v30, but something is wrong now (with the merge probably), that's all. We're seeking the bug, not a big deal. ---- i did a little search,so this is how others do: TEC3: New Dual Rev Limiters with ‘Triple Smooth Technology’.. 1st step retards timing to a negative -12º degrees.. 2nd step cuts coil current in half.. 3rd step coil current and fuel are cut-off.. all three steps occurring within milliseconds! 034EFI: A dual stage rev-limiter is implemented in Iic to provide a smoother, more accurate rev-limiter of engine speed. In addition to the standard fuel cut rpm limiter, a programmable timing retard is also used to pull power before the fuel cut is realized. Thus, the driver will begin to anticipate the fuel cut by feeling power drop off as ignition timing is pulled back. Timing values from 0 to -50 can be used to accomplish this. For more information, see the Tuning Manual. AEM: Soft Cut Rev Limiters Utilizing user programmable stages, the EMS offers 5 distinct modes of rev limiter. With ignition retard, programmable partial cylinder cut of fuel and/or spark and full cut of fuel and/or spark, the combinations are limitless. MSD: Soft Touch Rev Control For points and OEM Ignition systems The Soft Touch Rev Control, PN 8728, is designed to be used on standard points ignition or inductive ignition systems. This means that the PN 8728 can be installed on engines with a GM HEI Ignition, Ford or Chrysler electronic ignition, any standard breaker points systems or even with an MSD 5 or Blaster Ignition (non-CD ignitions). The Soft Touch Rev Control is adjusted with plug-in modules and is supplied with 6,000, 7,000 and 8,000 rpm modules. When the engine reaches your set rpm, the Soft Touch circuitry kicks in and drops the spark to certain cylinders. These cylinders are fired on the next cycle to prevent fuel from loading up in the cylinder. This limiter produces very accurate and smooth, backfire-free rev limits. Can be used on 4, 6 or 8-cylinder engines with inductive ignitions. http://www.teglerizer.com/fi/bem/Basics%20of%20engine%20management.htm Most EMS systems implement a rev limiter, some allow a soft-cut where the engine selectively misfires followed by a hard-cut a little higher up where the engine simply stonewalls. Some limiters cut off all fuel at the prescribed engine speed, withholding it until you're 500 rpm below the limit. Other rev limiters cut off the spark (or injectors) of individual cylinders one after the other, progressively cutting more and more until the hard-cut limit is reached so that you can barely feel that you have reached the maximum allowable rpm. These soft limiters mean that the car can be used right to the rev limit without a worry. Normally the EMS will maintain the tacho signal consistently to ensure that it doesn’t go crazy. Often the rev limiting is coupled with a shift light that warns the driver that the rev limiter is about to operate and he should change up a gear. With batched and grouped injection systems, selective cutting of fuel can be dangerous since the fuel is not injected at the optimum time for each cylinder and it is quite possible for a cylinder to induct only a partial charge of fuel which could result in detonation and resulting damage.
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