AEM EMS question

To guys with AEM:

Do you use "boost fuel correction table" for WOT and "Throttle Inj Correction table" for cruzing? (this will cose the fuel map not to be gradual but every column in fuel map from top to bottom would be the same) OR don't use boost correction table and you have nice gradual fuel map?

Some tunning shops would die by their boost comp tables and others would say the oem style maps are better.

I went throught 4 config files/tunning and with boost comp tables the car is WILD (high low end tq). It is had to drive because it just wants to go fast and when you in traffic it is anoying. The regular map makes NSX drivable just like OEM but when on boost it lifts off, but the power kicks in on higher rpms.

I just want to find out what strategy those high HP nsx take?

PS if you are using AEM EMS check your "LS8" output under /options/configure outputs. My tunning shop over looked it. This turns on the engine fan. (it is not on in base map from aem) My was set off for all the time.

Here is fuel comp. High TQ. On my car when dyno 275tq 295hp on 4psi

Same car 280hp on 4psi I don't have the tq but feel of pants was diffrent. If you look at it those fuel maps look tottaly diffrent. First time I look at it I thought is is screw up map. I use wideband 02 feet back so I'm always in 12.5 AFR on boost and 13 AFR when on vac.

Then I guess the boost comp is the way to go on nsx

Yes, you right LS8 is radiator fan but if not specified in the outputs (default) it will be controlled by thermo switch after thermostat (I think). I could not find seperate controll for the engine fan only. But when activating the LS8 output lets say after 190F it will turn on the engine fan with radiator fan. Maybe there is other output for only the engine fan but I could not find one.

Thanks,
Dave

Jeez...Dave, you are doing all the R & D for me Get it tuned and completely drivabe for 6-8 psi and then make sure you save the map file, I will need that!

...I'm still looking for a good time to make a trip up to Jersey to see your set-up in person bro! I'd love to take some snap shots and maybe get a ride. My set-up will be similar to yours.(with your blessing of course)


-- Kevin


PS: How is that oil feed & return line set-up (to the turbo) going for you so far ?

I believe that the original intent of the Boost Fuel Correction table was just that, to allow slight changes in fueling at boost without changing the main fuel map. This could be done to adjust for various track conditions and environments. I don't think it was intended to make major changes to the main fuel map. However, I've seen tuners use it exactly for this purpose. I think it makes "tuning" quicker and easier on the dyno as all they need to do is produce one good set of numbers across the X axis (same load but vary the rpm, usually at zero vacuum) and just copy those numbers up (boost) and down (vacuum) the y axis. This characterizes the all-important WOT (no boost) volumetric efficiency curve for that engine and establishes the baseline AFR. At this point they simply add a known (from experience) set of "adjustment factors" using the Fuel Correction Table to adjust fuel for all the other load conditions. I’ve seen corrections factors that result in a very linear progression from load point to load point (same rpm) and some that add a slight curve. In any event, the car should be quite drivable at this point with minimal dyno pulls. All that’s left is tweaking the AFR for various driving conditions such as off idle and cruse. This is where they use the Throttle Fuel Correction table to lean things out for better fuel economy and drivability based on throttle position. Again, I don’t think the Throttle Fuel Correction was designed for this purpose. It is usually used were an engine has individual throttle bodies (no way to get a good manifold pressure or air flow readings) and where drivability and economy at partial throttle are not a concern (NA drag racing, sprint cars, etc). Without a MAP or AFM, throttle position and rpm is the only way to determine fuel requirements. Otherwise, the Throttle Position sensor input is only used for mode changes and accel/decel operations.
Bottom line, this kind of tuning approach is just another way to achieve the same thing but quicker. And quicker is important when a shop is trying to make money. Just a note; this kind of tuning is best done on an eddy current dyno where you can hold the load steady and vary the rpm and vise-versa. What way is better? Hard to say. With a little math and an Excel spreadsheet, I’ve been able to reverse engineer all the various tables and create a main fuel map that looks very similar to the more traditional maps provided as baseline calibrations with all PNP AEM EMSs. The only negative things I have noticed is that because a Throttle Position sensor is typically much more sensitive than a MAP sensor (even if filtered) the AFR can vary significantly if you have a shaky throttle foot. In addition, the Throttle Position sensor now becomes a major component in determination of AFR (at least to the % open specified) and therefore any failure will affect engine operation more so than the more traditional fuel mapping approach. On the other hand, it allows the tuner one more way to “fine tune” the AFR by simply adjusting the Throttle Position sensor within its slots. Just some ideas.

Thank You for explaining the two diffrent methods I didn't know the details of it. Thanks again.

Every config file coust me $400 and now there is an AEM engeneer that is going to be on East Coast in NJ and I'm considering having him tunne my nsx. But it is a lot of money and if he will not make diffrence then I don't know. I had my dyno tunned with the boost comp tables but the car just don't feel natural. It is eather fast or faster. In traffic it is such a pain to drive and my nsx is my daily driven car.

Is there a some kind of hybrid config to use traditional map with some boost comp correction?

If I decide to tune again I want to know what to ask the tunner. To me it simes that nsx is happier with the boost comp tables.

But does the o2 feed back corrects the fuel map too on WOT?

Thanks

PS I left the turbo oil feed/drain like I had it before for now.

You need to be more specific when you say "fast or faster" Is the idle speed too fast, does the car hesitate and then jump forward? Does it misfire? Is it jerky? Does it happen when accelerating lightly, moderately or heavy? Etc. If yours is tuned with Boost and Throttle Fuel corrections you'll probably need to tweak the throttle fuel table a bit in combination with the ignition table. If you don't want to dive into the AEM software, a simple thing you can do is play with the throttle position sensor, as it can richen up or lean out the mixture somewhat if tuned as above. Just mark the housing to the throttle body so you can get it back to the same position if need be. If it's been messed with before, you won't need to grind off the factory "don't fiddle with" screw heads. Also, be prepared to adjust your idle speed as it will probably change as well (use the stock TB adjuster).

As far as the 02 feedback is concerned, it depend if you have stock or wideband O2s sensors. If stock, the feedback will only adjust fuel ratios around 14.7 to one +/-. This typically only occurs just above idle during light throttle cruse mode and the AEM software should be programmed accordingly (not even close to WOT conditions). However, there are programmable constraints on HOW much the system can adjust the AFR when it deviates from 14.7 to 1. If the constraint is too tight and the fuel maps/trims are too far off, it'll never be able adjust the mixture enough to zero in on 14.7 to one.

If you have wideband 02s then the feedback system can control the AFR from just above idle to WOT if that's how you program it. Again, if the constraints are too tight and the fuel maps/trims are too far off, it wont be able to hit the target AFRs programmed by the tuner.

The idle is 900rpm's and it is very stable. When I press accelerator quick while driving it will hesitate and then jump forward. When I press accelerator gradually it speeds up with any hesitation. Also what I notice half a throttle with boost comp tables is like 3/4 or more oem setup. So when I just press the accelerator a bit it revs higher then it used to be. When just getting off the traffic lights and after just tapping the accelerator it is in 3,000 rpm's and with my stiff comptech II clutch I have to watch out not to drop it too quick or I will look like stupid jerk burning tires on traffic light. But when I want to go quick and start from 1st gear accelerating hard it pulls very smooth. Only when I just let my foot off the accelerator and then press back quick it will jerk 2 or 3 times and then it moves forward fine.

I have installed the AEM dual wideband. One sensor before the turbo on the "Y" joint and one after the turbo on the down pipe. The one after the turbo is set as the O2#1

How can I tell if it is misfiring? and if it is then I guess I have to get colder spark plugs like 8 or 9?

My throttle fuel correction line starts deep in then it goes to 0 around 50% throttle. Can I maybe send you my config file so you can see maybe something wrong stands out in there. I didn't use the adjuster screw on the throttle body.

Thank you,
Dave

Just for kicks, try disableing the 02 feedback and let it run open loop using the tables as is. I think it's "fuel", "02 feedback control", "options" and just un-check the 02 control box. I personally don't like using 02 feedback (narrow or WB) as it masks bad maps and if a sensor goes south at boost. . . . . bang! Just monitor your AFR using parameters and your laptop to make sure you don't go too lean. Check the AEM WB 02 manual, I think you want to trust the sensor downstream of the turbo, but double check. Mark.

Send your cal file to [email protected] and I'll take a look.