I have always read and been told that the stock limiter cuts the fuel not spark. One of the reasons users buy the 6AL is for the rev limiter.
Ian
I have always read and been told that the stock limiter cuts the fuel not spark. One of the reasons users buy the 6AL is for the rev limiter.
Ian
Caught a typo after sending: for the PIP cutoff calculation, the formula's constant needs to be 6006250/maxrpm = PIP.Originally posted by fanglemeister
Here is an excerpt from Ford's A9L binary:
PIP 961 # Minimum PIP period (PIP = 6250000/maxRPM)
In other words to use eec-tuner to set my internal rev limiter for 6k rpm cutoff, I would set the PIP value to 6006250/6000 = 1001.0416
Setting the no fuel rpm limiter lower than the PIP limiter works as anticipated.
Also, most people like using the MSD etc. because it is a "soft touch" rev limiter, the eec PIP limiter cuts all spark and when it comes back on it causes a backfire more often than not. For this reason I set the no fuel and no spark limiters at the same rpm. I try not to get anywhere near the limiters of course, only hit them on a missed shift (not that I ever let that happen!) ;)
OK very good, it is nice to have a EEC tuner on the board.
Very good point on the soft touch.
Ian
Hey maybe you're right, I'm just quoting what I've been reading in books for years. As far being incorrect on the fuel cutoff theory I think you're incorrect. For what you claim to take place with nothing but air in the cylinder, the only way that can happen is if the fuel cutoff kicks in when a fuel injector is either completed it's cycle or never started one, and that goes for each cylinder. Odds are when the fuel cutoff does kick in, there will be at the very least one fuel injector right in the process of injecting fuel when the cutoff occurs which will cause a lean condition.Originally posted by fanglemeister
This info isn't correct. I've been running an eec-tuner on my car, and combing through the eec-tuner archives, since last April, & feel like I have a pretty good handle on things at this point.
Factory rev limiter: at least in the A9x strategies, eec cuts the PIP signal at 6250 rpm, in other words this is an ignition cutoff, not a fuel cutoff. There are also fuel cutoffs in the stock eec programming, which in oem form are set so high up that hopefully you will never hit them! Here is an excerpt from Ford's A9L binary:
PIP 961 # Minimum PIP period (PIP = 6250000/maxRPM)
HALF_FUEL_REV_LIMIT_ON 8000 # Turn on half-fuel rev limit
HALF_FUEL_REV_LIMIT_OFF 7500 # Turn off half-fuel rev limit
NO_FUEL_RPM 7000 # Max RPM (no fuel)
As for cutting all fuel being lean, this is also incorrect. You have to have *some* fuel being injected to be lean! Pure air is just that, pure air - nothing else is there to cause detonation. This is why Ford set it up to cut ignition first, and then cut all fuel. Not sure why they even stuck the half fuel lines in there, since the total ignition and fuel cuts come before this could ever happen. BTW I have set my PIP cutoff at 6k rpm and it works just like the oem cutoff at 6250, which I only ever hit when a crappy floormat caught my throttle pedal. (once!).
P.S. Lets not turn this into a pissing contest OK. Seems every time a debate starts it turns into mudslinging. We're all here to help each other. BTW I'm not so sure how reliable the factory limiter even is. I know plenty of guys that have gone past 6250rpm and nothing happened ( except for valve float:D )
Further info on this: the half fuel cutoff is a remnant from the DA1 speed-density setup. On the DA1 the factory rev limit scalars are set to:Originally posted by fanglemeister
Not sure why they even stuck the half fuel lines in there, since the total ignition and fuel cuts come before this could ever happen.
Rev Limit Half Fuel OFF 5000
Rev Limit Half Fuel ON 6000
Rev Limit Maximum (No Fuel) 6200
And to clarify this term "half fuel", the DA1 guys say this limits all fuel to half the cylinders, not half the fuel to all cylinders, sort of like the MSD soft touch but with fuel instead of spark.
I'll try some experiments with my tuner and see what happens with the half fuel set lowere than total fuel cut. At part throttle, and low rpm of course.
Well, I'm certainly no expert, just relaying what I've learned thru changing eec parameters with the tuner over the past year. I don't profess to understand all the details of the factory rev limiter. For instance, I have no idea if it uses a soft touch strategy, or cuts it completely. There's no indication in the binary that I can see.Originally posted by TheHawk05
Hey maybe you're right, I'm just quoting what I've been reading in books for years. As far being incorrect on the fuel cutoff theory I think you're incorrect.
And I did not mean to say your advice to run an MSD soft touch was incorrect, just pointing out that the factory limiter is not a fuel cutout, and also that cutting *all* fuel won't neccessarily lead to engine damage.
Your advice to run a soft touch of some type is in fact good advice - I have a Crane HI6S myself, as a backup. :) I had a buddy who was running a Mallory tach with the POS built in rev limiter, used to backfire like all hell when it cut the entire ignition out. The eec doesn't seem to backfire badly when you hit the rev limiter, fwiw.
Agreed. Sorry I sounded pissy, I'm just a stickler for accurate info. That deal with guys running past the rev limiter, this could be several things - depends what year car, the T4MO (SN95 GT) is setup to rev to 7000 rpm. I guess Ford depended on valve float as a rev limiter. Also, I trust the eec more than the factory indash tachometer, as far as counting revs. The tuner is nice because you can record datalogs off the eec.P.S. Lets not turn this into a pissing contest OK. Seems every time a debate starts it turns into mudslinging. We're all here to help each other. BTW I'm not so sure how reliable the factory limiter even is. I know plenty of guys that have gone past 6250rpm and nothing happened ( except for valve float:D )
PS I like your Tbird, very nice car!!!!
Hey man not to worry, you didn't sound pissy at all! I only said that so things don't get out of hand. Some people have a very poor attitude and aren't open minded at all and when someone corrects them or challenges their theory they take it personally and start getting sarcastic with remarks and what not ( Obviously you're more mature than that )I've had several bad experiences on other forums because like you I'm a stickler for accurate info and too nice for my own good sometimes when I try to help people with lessons I've learned from my own experiences so they can avoid making mistakes. A couple of times it's resorted to schoolyard mentality with name calling and the whole bit on their part and I'd hate to see that happen here. I've really enjoyed my short time on this board so far and everyone here seems to have a common goal and thats to make this forum a collection of helpful people and good experienced advice. Hopefully we can get more people like yourself on here who have experience with the TWEECER and other Electronic tuning devices because that kind of knowledge can be invaluable when it comes to tuning a blower car to run it's optimum.;)Originally posted by fanglemeister
[B
Agreed. Sorry I sounded pissy, I'm just a stickler for accurate info. That deal with guys running past the rev limiter, this could be several things - depends what year car, the T4MO (SN95 GT) is setup to rev to 7000 rpm. I guess Ford depended on valve float as a rev limiter. Also, I trust the eec more than the factory indash tachometer, as far as counting revs. The tuner is nice because you can record datalogs off the eec.
PS I like your Tbird, very nice car!!!! [/B]
P.S. Thanks for the compliments on my Bird, they are always appreciated and never taken for granted. Welcome to the board as well:D
Tell the truth guys, you are acting civilized because you fear my wrath! :D
Seriously though, great info and a great topic!
Ian
Well that's one of the great things about forums on the net. they provide a place to clariy misinformation. like you Ian, I was always told that the factory EEC cut off fuel at 6250rpm to act as a rev limiter and I've read that in just about every Mustang magazine I can think of. Maybe we need a Ford engineer in here to clarify it for us
:)
Final reply on the rev limiter subthread, the tweecer and eec-tuner lists on groups.yahoo.com are as of recently being combined; in the near future the previous tweecer-only list will be converted into an installation and hardware troubleshooting list for both tuning methods, and the eec-tuner list will be just that, dealing mostly with issues of tuning, i.e. modifications to the various oem software calibrations. Some people don't like the mailing list format, but what's nice about the tuner list is that you can set your member preferences for no mail delivery, and have access to the message archives. Enjoy...
http://groups.yahoo.com/group/EECTuner/
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