Guys, please help me understand something. On a stock tune, the MAP Max Delta above BP vs RPM values are 0, but on tunes that are FI, I see these values ranging from 15 to 40 inHg. Can someone explain what this does and how it work buy modifying it please?
The ECU uses this table to determine the maximum manifold pressure that can be seen by the vehicle for purposes of determining the maximum load on NA and Supercharged vehicles.Originally Posted by R8Bill
The equation is:
Max MAP = Baro + This Function * Baro/29.92 (i.e. its corrected for current Baro)
This MAP is then fed into the desired aircharge function (i.e. the Speed Density function) to get a cylinder aircharge and load.
This MAP value that is calculated and the aircharge are used in various functions throughout the ECU for predicting or limiting possible airflow values. As such, its a good idea to try to get it close to what you are expecting to see as your maximum.
So do you log the manifold pressure and use this formula to calculate the delta offset? Is the goal to get a new calculated load value that calculates close to say 1.5 load if that is what you have for a the max load value for WOT calculations?
The goal is basically to put in the highest boost you could ever see at a given RPM, so yes ideally you have a MAP sensor, and a way to get the most load on the engine for a given RPM so you can hit the highest boost (i.e. a steady state dyno holding you at a given RPM). Don't even think about load at this point necessarily, just think of this table as maximum boost you can hit.
Its up to your speed density section to then convert this into an actual maximum load, which will require you to also log MAP/Airflow and fix your various mapped points to be correct.
Can you give us an example on how to make this work. Here is a log of the MAP sensor for a given RPM range.
MAP-01.jpg
Sure, so lets say those are your maximum MAP values you saw for RPM.
You'd subtract whatever Baro is (lets assume its 14.7psi), and that value would go into that table.
Assuming your example is in PSI:
2000, 0.5
3000, 4.8
4000, 8.2
5000, 14.1
6000, 18.2
One thing you could do is log your MAP sensor channel, plot it out vs RPM like that, but use the Maximum value function instead of average over the whole range to get the maximum MAPs you saw at any given RPM.
It'd get you roughly in the ballpark.
Ah, I see and makes sense!! So you could create a Math and subtract this MAP sensor value from the Baro value to get your delta automatically.
MAP-002.jpg
But if this is your max, should you add a value to this to give you some room, maybe a few PSI?
Do you have a write up on how you create new speed density tables to create new load values?
Last edited by R8Bill; 12-13-2017 at 04:33 PM.
Interested in this too - does it hurt anything to go even 5psi over what you might ever see? Also interested in the SD part
Thank You
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
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So I was curious about the speed density too. I actually loaded the Roush speed density tables to my tune today versus the stock ones I had, thinking they are calibrated for higher boost in order to get the load values down to work within all other tables like spark and torque as their tables only go to 1.5 load. I also used my MAP delta math values and added 25% to give me some room. This log I just did, I still see load values as high as 2.5 at around 14psi of actual turbo boost so nothing really changed IMO. I would love to figure out hot to tune these speed density tables to re-calibrate load. Yeah, I could just make new spark and torque tables to work for load values up to 2+ but it might reduce my resolution. (Yeah, I have some knock and need to adjust maf some still, just wanted to share)
Log-BossTT-V3-012x.hpl
You will see P0068 codes if you exceed this.
Eric Brooks
HP Tuners, LLC
All you need to do is count the air molocules entering each cylinder from 2000 to 6000 rpms under WOT. Then you can set up SD tables perfectly. In the past Ford has relied more on MAF data than SD tables because it's both easier and more accurate to measure the airflow than to guess at it based on manifold pressure. I haven't really looked at Ford factory blower or turbo tunes to be sure, but I would suspect speed density to be a supplement type of thing. In this case it appears to be more of a check on max boost.
I have found that if you put this value too low (upon accell) the car will bog and die, as well if you shoot too high at lower RPM's the car will attempt to meet a threshold of boost not attainable at that time so it will cut in and out. Seems the best response will come from Dialing it in as close as possible. My car has a 10PSI Setting as well as a 7.5PSI so im playing with the values to see if it will make a difference in load and response.
Guys I've stickied this as I think this table is actually pretty important to adjust and knowing how it works is essential.
It doesn't have to be perfect, it just needs to be done in two weeks...
A wise man once said "google it"
So I have a 2011 GT500 and have an issue with the factory boost gauge not reading correctly. My current values are 0.0/8.0/15.0/22.0/24.0/24.0 for rpm 500/1000/2000/3000/4000/6500. The boost gauge currently lands right before 10psi and with my understanding 24.0-14.5 = 9.5 which is right where my gauge stops. With current pulley setup car should be seeing 12-14psi. Could the factory boost gauge not be functioning correctly due to the map max being limited to 24? Or am I thinking of it backwards and because the max delta is set too high the calculated value for boost is not reading correctly? Thanks
Last edited by whty8911; 04-05-2018 at 07:46 PM.
Please post or send me your tune, it seems like a sensor problem as from what ive experimented it seems like the car will not cut power if it goes past those parameters. I have yet to see it on a stock car though.
Here are three files that Ive worked with. One is a copy of my current tune file. One is a short 2nd and 3rd gear pull on the street and the third is an excel file with current maf transfer curve vs stock and also on sheet 2 of the file ive documented every change in my current tune vs a stock 2011 gt500 tune. I appreciate all the help in advance. Thanks.
Last edited by whty8911; 04-09-2018 at 08:13 AM.
On another note. This is my current setup.
2011 GT500
2.5" VMP upper Pulley
90mm idler pulley
65MM TB
Stock manifolds with no cats, x pipe and flowmaster outlaw mufflers
Tune from BAMA
I have a JLT 123MM intake I am going to install but was trying to work out a few issues first
Triple pass HE
Interesting stuff!
The base calibration I am using had these values set a bit low for my combination. (no error codes have been thrown though)
I'm curious whether you want this set accurately to actual boost (as if the value is leveraged for calculations), or whether you want to build in headroom (like it is only for error checking).
From what I have read previously in this thread is you want it set as close to accurate as possible. Highest possible boost seen at that given RPM but using that theory and the current values that have been inputted are nowhere close to the boost levels I should be getting.
Last edited by txtailtorcher; 04-12-2018 at 07:23 PM.
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