Joe Harlan
New member
I am prety sure the DPFI is a 2 injector throttle body type that probably doesn't get major support but I find the insode of the boxes aren't much different.
Gains from ECU Mods
- Thread starter MMiskoe
- Start date
I am prety sure the DPFI is a 2 injector throttle body type that probably doesn't get major support but I find the insode of the boxes aren't much different.
lateapex911
Super Moderator
Keep in mind the history involved here...from the begining, carbed cars were classed taking into account the gains that carb tuning and ignition advancing would present. Also keep in mind that in many cases, those changes are rather rudimentry. While you might be able to gain power in one part of the curve, you lose it in another in lots of carbs that weren't designed with racing as their ultimate goal.
Then came ECUs. The cars were classed based on the assumption that the ECUs would remain stock. But certain cars showed overly impressive gains, and after much hand wringing, it was decided that they must be "chipping", and there is no way to police that.......sooooo... the rule was changed, with the intent to allow "chipping" or, where that wasn't possible, additional boards could be added to acheive the same ends....and to ensure that the changes were simple, they threw in the "fit's in the original case" clause.
So, now we have cars that are:
Carbed, and running jets and tweaked timing
(At the weights set under the presumption that they would jet the carb and tweak the timing)
or- (in some cases)
cars that are running complete standalone control systems.
(but are running at weights that were set presuming stock ECUs...no chip OR complete control system)
Is this the way it should be?
And, in answer to your specific question, obviously yes, it would be fair...in the cases where the weights were set under the "no chip" presumption.....
Ahhh, fine...but...how do we know which cars were, and which cars were not classed under the "no chips" presumption????
Well, we don't, and I can't imagine being able to determine that. I know a few, the ITA CRX is one, but anything short of knowing every car is too little. And on top of that, we have no way to know how much weight was added (or not added) in the initial classification to account for the gains (or lack of gains.)
So going back is veeeeerrrry hard.
Another reason the current ITAC has a large proposal for PCA adjustments before the CRB.
zracre
New member
the re-chipping is neccesary for some cars to go over 108 mph...240sx comes to mind...and the rev limiters on some cars need to be adressed in the ecu...times a changin...electronics are advancing daily and we need to find a compromise that is in the best interest of the IT community. someone brought up megasquirt...a simple cheap system...im sure there will be more of that type soon for most cars...once we get away from trying to self police electronic gizmos we can look more for the obvious...
ShelbyRacer
New member
Joe et al,
On non-OBD2 stuff it's not hard to do. The easier thing is putting in an EEPROM and making a way to bootstrap it in its regular position. Then you simply power the right pin and reburn in place.
The real problem with a lot of this stuff is getting decent communication to/from the ECU. With the stock ECU, you NEED to be able to see what the block-learns are doing so that you can determine what the computer is really trying to do. BIG advantage for open-loop based controls. It's one thing to change the program, but a significant difference to be able to see what effect the changes had and how the computer is attempting to deal with them.
For those who don't do this, I'll give you a scenario (for those who don't care, stop reading here).
You determine that you're, let's say, 10% rich at X rpm and Y load. So you go in and pull 10% of the fuel at that point. A few things may occur:
Bad-
You may not have enough resolution not enough data points) so changing this makes a lean condition somewhere else close by. The computer then adds fuel to this entire block of RPM/load points. You're back where you started at the point you looked at, back to fine at the lean point, and all the other close-by points are now even more rich.
Worse-
You might have been OK at part-throttle but the WOT enrichment put you rich. You now add even more fuel and the problem gets worse. See, if you're rich at part-throttle and the computer pulls fuel out, it will ignore that compensation at WOT *and* add the acceleration enrichment. If you're lean at part-throttle, it will ADD the compensation *and* the enrichment.
Or-
You manage to lean it out too much due to mixture pollution from near-by rich or lean points. You get a ping or two, and the computer pulls out timing advance *across the board* until it's ready to try again (this amount of time can be changed if you know how and where).
Worst-
You thin out the part-throttle fuel curves after playing with the acceleration enrichment, and now wind up lean at WOT at certain points, and BANG, stuff breaks.
The OE ECU is always trying to compensate to reach its own target, and that can change depending on anything from weather to driving style. You not only need to know the net result, but also you need to see and log how the computer is trying to "fix" things. This goes for ALL OEM ECU's of all generations.
So what do aftermarket units do? They jump when you say jump (even if you tell it to jump into a pit of fire...) with no arguements. Can you make an OE unit do this? Yeah, but you have to find all of the little things it already "knows" and change them.
Think of it like trying to teach someone to race when they already "know" more than you about driving... (I don't know ANYONE like that...) It's actually easier and faster to start with someone with no pretenses and no bad habits. All you instructors out there- imagine what it would be like if you told your student what to do and they did it every time with no arguement or hesitation... Unfortunately, you'd also have to tell them what the steering wheel was for too...
But hey, I can probably get you better gas milage from the OEM ECU compared to a Motec...
ShelbyRacer
New member
So I meant to ask youse guys...
What about the cars (and I think there's more than one) that are running a stock carb, but have a distributor with no provision for changing advance? There currently, if I read correctly, is no clause to deal with this.
ITCS D.1.a.6 talks about *fuel injected* cars specifically, and D.1.e requires the original distributor (which in most cases is too small to allow mods inside- since there never were weights or vac canisters...).
And I know the one car I'm thinking of was classified before the ECU rule...
Joe Harlan
New member
Whos cares. Pinning the weights is common and a vac advance unit is a drivability tool more than anything. The minor losses in the power curve from a fixed advance won't been seen by most race engines on the track. Keep in mind if you fix the timing at 36 degrees on a six you don't want to spend much time lugging it around.Originally posted by ShelbyRacer@Nov 29 2005, 02:35 PM
So I meant to ask youse guys...
What about the cars (and I think there's more than one) that are running a stock carb, but have a distributor with no provision for changing advance? There currently, if I read correctly, is no clause to deal with this.
ITCS D.1.a.6 talks about *fuel injected* cars specifically, and D.1.e requires the original distributor (which in most cases is too small to allow mods inside- since there never were weights or vac canisters...).
And I know the one car I'm thinking of was classified before the ECU rule...
[snapback]66981[/snapback]
Matt Rowe
New member
But the point is the ECU guys get the advantage of tailoring fuel AND spark curves. An advantage also accessible to vacuum/mechanical advance distributor people. But those running a spark only computer are shut out. And of course all of this was affected by a post classification change for many cars. So as far as who cares? The guy who CAN'T legally make the same adjustment that everyone else can. Meanwhile they see a select group that can take advantage of fuel and spark tuning than was never anticipated when those car was classed. Maybe not a huge deal but certainly an overlooked inequity in the rules. And you wonder why some of us could car less about motecs vs modified stock computers? <_<
Joe Harlan
New member
Matt, I would venture to say that the carb fixed dist system is very limited in numbers. Sometimes it is just up to the competitor to deal with poor design issues when they pick a car. The other choice is to pick a class for that car that allows those types of mods needed to correct those issues. I think you would be a little shocked at some of the timimg maps used in a performance engine and how close to fixed they are above 3000rpm.
Matt Rowe
New member
Joe,
Having tuned some motors before, I wouldn't be all that shocked.
But with all your experience with tuning EFI you should also know that driveability does matter in a race car and a fixed timing curve does cost a little in a game where .005 sec at every turn can make a difference.I have no doubt it's a limited problem and have accepted it, but again don't expect me to have any sympathy for guys with an ECU that say they can't tune their car because no one has put in the development time to crack the ECU codes. At least they have a legal option to do so. Also, knowing this particular limitation is fine if you are extremely familiar with the rulebook before picking a car, but having been told timing is open and then finding out there is no legal way to adjust it is somewhat different.
Again, not my biggest concern and certainly not what keeps my car from the sharp end of the class, but it is an inequity in the rulebook, and you original comment of "WHO CARES" wasn't exactly friendly. Of course I could always propose a rule change, but I would hate to see how that would get twisted, provided the rule even gets approved when everyone remembers how screwed up the ECU policy has become. Who would want to open the door even more? :119:
Joe Harlan
New member
Originally posted by Matt Rowe@Nov 30 2005, 10:10 AM
Joe,
Having tuned some motors before, I wouldn't be all that shocked.
I have no doubt it's a limited problem and have accepted it, but again don't expect me to have any sympathy for guys with an ECU that say they can't tune their car because no one has put in the development time to crack the ECU codes. At least they have a legal option to do so. Also, knowing this particular limitation is fine if you are extremely familiar with the rulebook before picking a car, but having been told timing is open and then finding out there is no legal way to adjust it is somewhat different.
Again, not my biggest concern and certainly not what keeps my car from the sharp end of the class, but it is an inequity in the rulebook, and you original comment of "WHO CARES" wasn't exactly friendly. Of course I could always propose a rule change, but I would hate to see how that would get twisted, provided the rule even gets approved when everyone remembers how screwed up the ECU policy has become. Who would want to open the door even more? :119:
[snapback]67046[/snapback]
Matt I think you and I are saying the same thing I think we are just kicking different rocks to get there. I don't care about one or the other as long as it is considered in the classification of the car, and should something change it should be reconsidered. I am also gonna say it again. Not all cars are race cars some cars were meant to car blue haored old ladies to the weekly bingo game and nothing more sure we could classify them but one of several things will happen.
Somebody will complain the cars is a POS< -----almost gauranteed
Somebody will ask for adjustment knowing the car was crap going in<-------see above
Somebody will think the ad-hoc was nuts for even considering it.
Or last but not least.
One will win the ARRC with a blue haired old lady driving it and the Adhoc will be in trouble again.....
Matt Rowe
New member
Joe, I'm not sure I can argue with anything you just said. Unless you were trying to imply that my car shouldn't be a race car. Cause them's fight'n words!
Of course, with all of this talk about re-"processing" all the IT cars and classes everything should be reanalyzed with the same criteria. That alone should go along way to getting everyone on close to the same playing field. The rest I'm content to try and make with superior driving and car prep. What a concept!
Of course, with all of this talk about re-"processing" all the IT cars and classes everything should be reanalyzed with the same criteria. That alone should go along way to getting everyone on close to the same playing field. The rest I'm content to try and make with superior driving and car prep. What a concept!
Joe Harlan
New member
Haha, No I said not all cars should be IT race cars. I worked on your car once in race car trim. It was 1994 if I remember correct and it was a red IMSA GTU car, we did pretty well until getting knocked off by a back marker. Really trick stuff with a Chrysler ECU of all things....lol I think every cr out there can be raced I just don't think they all can be IT raced......Originally posted by Matt Rowe@Nov 30 2005, 06:50 PM
Joe, I'm not sure I can argue with anything you just said. Unless you were trying to imply that my car shouldn't be a race car. Cause them's fight'n words!
Of course, with all of this talk about re-"processing" all the IT cars and classes everything should be reanalyzed with the same criteria. That alone should go along way to getting everyone on close to the same playing field. The rest I'm content to try and make with superior driving and car prep. What a concept!
[snapback]67078[/snapback]
