cbender

I need some advice from those of you who who know more about fuel-tuning than I do and who have some knowledge about the AEM engine management system.

I discovered at Summit Point last weekend that my V-AFC doesn't do a very good job of fuel-tuning in VTEC when I'm giving the car moderate amounts of throttle. At mid-throttle, the turbo's giving less than full boost and the car runs rich and sputters. That results in uneven power. In turn (pun intended) that unsettles the car, making it frighteningly squirrely at speed after apex.

My understanding (which may or may not be correct) is that between narrow throttle (in which the ECU runs in close loop mode -- so it's constantly revising the fuel map in response to the readings it gets from the front O2 sensor) and wide-open throttle (in which the ECU just runs the stock fuel map, which is then modified by the V-AFC) the ECU extrapoloates between the closed and open-loop fuel maps.

If that's correct -- and, again, I'm not sure I've got this all right -- then it would seem to me that the options for smoothing the power curve are (i) to modify the definition for WOT (reducing the throttle percentage at which the ECU shifts to just running the fuel map, rather than extrapolating, using the V-AFC) or (ii) to buy an aftermarket EMS, like AEM's. Anything I do, of course, I'll need to test out on a dyno, in order to insure that the car never runs lean, unless (I think) I buy a wide-band O2 sensor.

I'm looking for any and all suggestions, including advice on where to buy the gear (if I go that route), as well as some help in understanding these issues.

Thanks!

Rieger328Ci

I'm stuck in the same situation as you. I was thinking about buying the AEM EMS because I heard that Todd will be able to give the SpeedCraft customers the settings for free and all we need to do is fine tune it.

vapors2k

sounds too good to be true considering the problems other members had when they were promised base maps but all they got was a dead start when the motors wouldn't start b/c the base map was not right.

GPW02S2

Let me know when Todd comes out with that AEM EMS setting thing..

cjb80

An aftermarket computer is very important in my opinion with any sort of turbo for this car. The stock timing is very advanced and therefore when in boost you're running on the edge. Everything mentioned above is resolved pretty easily as well...

The Speedcraft tune is only good if you're using stock injectors with the Vortech FMU. I would be pretty surprised if they just gave it out for free. It takes a long time to get a tune to the point where you can give it to a customer.

There is alot of time involved in getting the car close to stock, and even more time involved in getting it to run perfect (like stock.) There are so many different conditions that a daily racecar can be in. Hot, cold, humid, A/C on, engine temp, etc.

I have my car running really well now, it's taken me a while -- making little tweaks here and there, and large improvments are made, but I still have some more time to spend getting it perfect.

I recommend it to everyone, but don't expect that you can just take it to someone and have it perfect unless they are very experienced with the EMS. I would say you should get it if you're willing to learn how to make tweaks yourself. (Which means you need a wideband also! )

Chris

cbender

Thanks to all of you for the advice.

Just to be sure I understand what I'm getting into, are the only "costs" to using the AEM EMS the following: (i) the time required to take the base maps and fine tune them (CJB, I'm running stock injectors with the Vortech FMU, so I can use Todd's base maps), (ii) the fact that if I continue to use the Profec B to control boost, the temperature gauge becomes an "idiot" light (meaning it's on fully after the engine passes a threshold, but off fully before that), (iii) the time required to install the thing (which sounds pretty easy, even with the wideband O2 sensor, although I'm mechanically pretty clumsy), and (iv) the money. I already have a laptop.

Is there anything else I'm missing? Will I give up any functionality -- MILs, headlight warning buzzers, controls, etc.? Will the MIL be turned on ALL the time for some other reason?

If I buy the AEM EMS -- and, it seems almost necessary to also buy the wideband O2 sensor -- what's a good and which vendors should I approach?

Again, thanks. I'm in WAY over my head on this one, but I just can't live with how the car runs -- the sputtering is bad enough on the street (where it's easily avoided by going WOT whenever I'm in VTEC), but on the track it's a nightmare (where the uneveness of the power unsettles the car at higher speeds with the suspension already fully loaded).

Your help is much appreciated.

busaboy

Check posts by Hams2000, and call Dave at R and D motorsports randdmotorsports.com. R and D did extensive dyno tests on an s2000 with the AEMS unit. They might sell you their maps.

cjb80

Basically, you need to have a wideband if you're going to do your own tweaking and tuning. I recommend the Motec PLM, which is what I am using. Retail is about $1200 and you can get it directly from Motec.

I dont have the temp guage working at all on my car. Todd set his tune up to work that way, that's not default. I really don't have that much interest in setting it up because I know not the flog my car unless I have driven it for about 5-10 mins.

The MIL will not be turned on all the time for unless you have a problem. The EMS doesn't care about fuel tank pressure, catalitic converters, etc. And you only need one O2 sensor for it to run.

I think that about covers it. I am surprised that Todd would give his maps away for free, because it takes a long time to develop something like that. Also, you can't expect to just plug the EMS in, upload the map and work a well as the car that Todd tuned it on...

Chris

PS- You need a timing light, which you can get at Sears for $60-$70

schwett

i don't think the ecu interpolates between closed loop and open loop values; from what i have seen it is an instant transition. you can see this from a datalog in which the o2 sensor reading bounces up and down and up and down, and then, at a preprogrammed map and tps value, just goes flat. if it interpolated, i would expect it to keep bouncing but with a smaller and smaller bounce each time.

i would guess the problem you're having is that on a normal honda, at part throttle, the map is somewhere in the 10-15" range, and tps is 2 or 3 volts; corresponsing to 50% or whatnot. you have a map limiter somewhere, to prevent the ecu from seeing boost. at that same part throttle range, you are generating some boost, so the map signal being sent to the ecu is full atmospheric. this is causing the ecu to open up the injectors a lot, despite only partial throttle (the ecu relies much more on map than tps in open loop.) to make matters worse, if you have a rising rate fmu, those few pounds of boost are jacking up the fuel pressure. too much fuel at part throttle.

anyway, i assume you are running the stock injectors. if aftermarket injectors are an option (and i would never do a standalone or FI honda without them) you could run the infamous VAFC hack. oddly enough, it works extremely well. everyone i know who has done it reports extremely smooth transitions into boost. it does nothing for timing though, so be sure you've got that covered by another device (whatever your kit came with i would guess.)

i personally think ditching the entire ECU is overkill when all you really need to do are adjust fuel and timing curves. the headaches of tuning the AEM for all the various conditions that CJB mentioned are a byproduct of this. i used the EFI system PMS on my built and supercharged h22, and was very pleased. it is a piece of cake to install and tune. you don't need to screw with anything you don't want to, because you start with the stock ECUs maps and values, and simply modify. e.g., you tell it to retard 1/2 degree of timing per pound of boost. you can then go back into the software and fine tune that to put back a degree or two at a particular point in the power curve. you can throw in injectors that are twice as big, tell it cut the injector pulse in half across the board, and you'll hardly know the difference. takes about 30 seconds. it's a simple matter then to tell it to add 3% of fuel per pound of boost.

anyway, i like the system a lot. it's programmable on the fly from your laptop, unlike hondata, and it's cheap and easy, unlike AEM. it's not very trendy though.

http://www.efisystems.com/pms.htm

you definitely want the optional software. used ones are pretty easy to come by as well. new the whole setup, harness (no cutting required), controller, software, and the main box should cost you around $1100.

[QUOTE]Originally posted by cbender
[B]I need some advice from those of you who who know more about fuel-tuning than I do and who have some knowledge about the AEM engine management system.

I discovered at Summit Point last weekend that my V-AFC doesn't do a very good job of fuel-tuning in VTEC when I'm giving the car moderate amounts of throttle.

Rieger328Ci

[QUOTE]Originally posted by BlackS2000Turbo
[B]For those of you who are interested, Speedcraft has tuned a turbo S2 with an AEM getting an additional 25 hp from that upgrade alone.