Originally Posted by EvO9 PiPER (Post 9032646)

hmm. so it is possible to get a nice tune for daily driving and have it last?
the only reason i havent done sd yet is because i herd re-tunes are required more frequently.

this would be done on a pure daily driven street car that never sees track time so thats also another reason. im not really trying to squeeze out as much power as i can from my current setup but would like better drivability...specially with the vta tial

Originally Posted by JohnBradley (Post 9032653)

I honestly feel the car should be checked 2 times a year or whenever parts change regardless of whether its MAF or SD. SD really needs the tune checked with part changes, but at least in my experience it can go longer on weather. The main thing to be kept in mind is what extremes the car is driven in. Here in the NW its pretty average most of the year and that could be a reason why my tune stays consistent. We do get extreme cold snaps in winter from time to time and heat waves in the summer. I drive the car through all of these but I dont rip on it all the time in the cold or extreme heat. If you got tuned (lets say in AZ for instance) in the middle of winter and race a lot in summer it would be in your best interest to get it checked when you do the bulk of your racing.

Originally Posted by EvO9 PiPER (Post 9032663)

im in texas. pretty hot summers, mild winters.

i dont really plan on adding any more performance parts so i think if i get a summer tune and winter tune i would be set. ughh...time to rip off that manifold again and drill in that iat:rolleyes:

thanks for the assurance though{thumbup}

Originally Posted by Jack_of_Trades (Post 9037129)

Excuse my ignorance here but couldn't you set the ECU to use the Fuel Temp Sensor during startup and then switch over the the IAT after a determined time or something? It seems the Fuel temp sensor shouldn't be subjected to as much engine off/heatsoak,no? I just figured that its already in the car and all...

Originally Posted by Jack_of_Trades (Post 9037129)

Excuse my ignorance here but couldn't you set the ECU to use the Fuel Temp Sensor during startup and then switch over the the IAT after a determined time or something? It seems the Fuel temp sensor shouldn't be subjected to as much engine off/heatsoak,no? I just figured that its already in the car and all...



Either that or use an ambient air temp sensor and build an IC efficiency table per RPM?

I haven't messed with SD (first time will be next week though) so forgive any stupid questions.

Originally Posted by JohnBradley (Post 9029392)

I never did publicly thank Sean@FFTEC for telling me I didnt know what I was missing out on with SD.

Thanks dude {thumbup}

Aaron

Originally Posted by JohnBradley (Post 9028583)

So after much thinking about how to explain what true Speed Density is vs what we do here for instance, how AEM's are often setup, etc. I came up with the following idea, just explain what everything is and remove doubt.

MAF - if you dont know this one its a volume sensor. Thats it. Ours have IAT and a baro comp to make it more accurate but it simply measures volume entering the engine. If there are boost leaks its inaccurate, doesnt like VTA (letting metered air leave without pulling fuel), all the stuff we know.

Alpha-N - TPS x RPM. That is all that is with no VE compensation (i.e. boost). If I tell it that at 100% throttle and 6000 rpm it does it at all boost levels independent of air volume.

Speed density - estimates air mass by pressure vs temp. Then applies this to a 3D map. The "3D" we already have, its Load (pressure or volume) x RPM with a set value in each cell. Every point can be fine tuned so this is really Alpha N with compensation. Any VE changes needs a retune, doesnt matter the system. It only knows pressure and rpm not what the true mass of the air is (it has a trim table and most get ignored above certain levels).

THEN THERE IS WHAT I DO (and many others at this point).

I use the fuel temp sensor to mimic an IAT since its already in the car. The IAT reads gross temp not average. It can heat soak, be subject to a meth jet to close, all sorts of little issues. The actual trim table in the Evo ECU really isnt setup for IAT trim anyway. It has an algorithm that allows for minor alterations to fueling since its set for a MAF, and then trims timing vs air temp.

Fuel temp is more or less constant. The fuel heatsoaks going thru the rail hits the tank and then is sent forward again. It takes 15 minutes to get full heat into the fuel system (ask anyone with an A1000). It is a rough average of engine bay temp which is what the MAF does factory. I have done exhaustive testing and see no more than 5-6* variation from fuel temp as a source to what the MAF would read in the corner of the engine bay.

Now for the term everyone has been waiting for, Boost Comp. This is what MAFs do, most SD setups (AEM, Motec, Autronic, Vipec, etc.) do for fueling. It assumes VE is more or less constant until you hit backpressure in the turbine housing, head flow, cam size, and VE starts to drop off again.

I set the fueling at 16psi and in our maps this is 180% load or so. The values are constant out to 38psi. Hyper Boost Compensation is the proper name. Retuning is as easy as altering either the max boost portion of the MAPVE table to allow more or less fuel vs pressure, and in some cases the tip in portion of the MAPVE (121kpa column).

There is no such thing as true speed density. I havent seen any AEM ever do this or any other standalone. GM is the closest to True SD and its because tada they use a MAF as well to judge volume vs pressure.

Do I do it right? I dunno. Does it work well when its setup, I build a good map, and then work that map on each and every application? Yes. Are there advantages and disadvantages? Of course, before I had the MAF comp vs Coolant the cars DID NOT love life cold. The IXs were better but not perfect, the VIIIs didnt like me.

....to be continued....