Piggyback on SC 996 -problems in closed loop?

Hi Am going to install a supercharger on my 996 and are looking at piggyback systems, I have found AEM F/IC controller that seams to have alot of nice tuning options -almost like a stand alon system. The only thing that conserns me is the NB O2 sensors on the stock ECU. As I understan the ECU going in closed loop when runing on light loade and then the ECU always tune the fuel to hit lambda 1 target -right? when I SC the engine I want to run a little bit richer then lamda 1, wich I can control with the piggyback, but will the factory ECU give me error codes when it cant control the fuel to get lambda 1? -in closed loop Is there anyone how knows exactly when the ECU is in closed loop? The AEM F/IC can "fool" the ECU by rise the lambda signal by 0,xxx volts but there is only one chanel for that, as I understand the 996 engine hase 4 (!) NB O2 sensors #&%�*^&#�... Here is the AEM F/IC http://www.aemelectronics.com/engine...oller-f-ic-12/ Any other suggetions? BR Erik

Quotes source post: 9677249

A stock DME goes into and out of closed loop mode at various times. The exact rquirements for this are not public, as far as I know. With the right test equipment one can monitor this closed/open loop status. Briefly, upon cold start and roughly until the secondary air injection pump shuts off the DME is open loop mode. Then it switches to closed loop mode. The DME stays in closed loop mode except under hard acceleration at which point it switches to open loop mode and enrichens the engine's fuel mixture in an attempt to satisfy the driver's torque demands. As soon as the hard acceleration event is over, or the torque demand by the driver drops below some threshold, the DME switches back to closed loop mode. During periods of closed throttle coasting the DME will switch to open loop mode. The SC because it pumps more air into the engine the engine requires more fuel. I can't say if the stock fuel system is up to the task. You'll have to rely upon the SC maker and its knowledge. The converters are most efficient when fed a very specific air fuel ratio: Approx. 14.72:1. Even a tiny bit above or below this and the converter efficiency drops off dramatically. Feeding the converters the right blend of exhaust gases is job #1 of the DME. A piggyback DME can add more fuel but the main/factory DME -- if it is in closed loop mode -- will see a decrease in oxygen content of the exhaust gases at the #2 O2 sensors (the ones after the converters) and lean the mixture to compensate. This leaning will be visible at the #1 sensors, from their voltage levels and the short term fuel trims and eventually the long term fuel trims, if leaning is needed for a long enough time to have this adjustment transferred to the long term fuel trims. If this occurs -- the piggyback DME adding fuel and the stock DME subtracting fuel -- obviously the two electronic devices can work at cross purposes. You'll have to ask the SC maker and the maker of the piggyback DME about this. They may have a suitable workaround or I may be wrong and this is not an issue. However, absent any change/customization of the stock DME's behavior either from a re-flash or some connection to the piggyback DME I do not think I'm wrong. The SC setup can still be made to work but the SC and any custom re-flash of the stock DME and a piggyback DME must be a very well integrated combination of hardware, electronics, along with a fuel system capable of feeding an engine with a SC on it. Remember the SC takes HP to drive. So an increase in say 50hp measured at the rear wheels means the engine is actually putting out more than 50hp over its stock output. The extra hp is being consumed by the SC. In the case of a 50hp bump the engine may be making close to 100hp over its stock output. Sincerely, Macster.

This is a DIY project and I have knowledge on SC and turbocharging on older cars with older ECU. Is there some way to make the DEM to stay in open loop? I can now feel that the car is running stronger (totaly stock) before its in running temp (around 70 degrees) probably when its in open loop and runnnig a little bit richer of course I going to change the ejectors to bigger that can deliver the new right amount of fuel. Theses kind of application usually deliver around 420 Hp at crank when charging 6 PSI

Piggyback computers are not a good tuning choice for these cars. You would be much better served teaching yourself how to write your own software by downloading the .bin files from the factory Bosch ECU and modifying the hexidecimal values in the maps. It's not as bad as it sounds, I promise. I highly recommend you check out the forums on www.nefmoto.com , which is a forum dedicated to Bosch ECU tuning (mainly the B5 Audi S4 platform, but there are plenty of resources for other makes as well).

OK thats sounds interesting but as I understand in the Motronic ME 5.2 you cant flach in real time -you have to take the DME out and read to it with the engine swith of So it feals like it going to take ages to map it on the streat as I have done with other cars with the AFR reading as help. thanks Capt. Obvious

Real time flashing is not possible with the Motronic ECU. You tune it by taking logs, adjusting the tune per the information you collect logging, reflashing the ECU and repeating. Sure, it takes a little longer than playing with the piggyback on the fly, but the end results WILL be more powerful, smoother and reliable. A full ECU flash takes about 3 minutes and can be done via the OBD port, so it's not really all that time consuming either.

Oh as I have understand the ME 5.2.2 can NOT be flashed by the OBD port ? -but you say it can do you have any ex�erience of flashing? what program is best to use? Can you recomend some software proram for the ECU programing (that not cost 3000 Eurolik the Swiftech for exampel) BR Erik

I have a decent amount of experience with ME7, as I wrote my own software for my old S4. Can't say a lot regarding ME5 though. Check out Nefmoto like I said earlier, they have a flash tool developed by the owner of the site that is *free* and there are many threads about which software and hardware to use. It cost me under $50 to get all set up to write my own software.

The problem is I need a xdf file so a can edit the Map in TunerPro and that a havent find for my ECU, otherwise I must use program like WinOls or Swiftech thats cost ridiculous amont of money. -Anyone have a xdf file for ME 5.2.2 ??

-Anyone have a xdf file for ME 5.2.2 ??