Well, i am fixing to get EFILive and a WB very soon (a month or less). I downloaded the software so i could view my tunes and logs that my tuner sent me. I have been messing around with the screens and settings for a couple of days, and bothering the crap out of Dewmanshu with a bunch of questions via PM. I guess i will just start posting up questions that i have here in hopes i can start puting this all together. I still dont understand the meaning of stuff like .."SPEED DENSITY', "TWO BAR", and stuff like that so hopefully i can start getting my thoughts in order. I am pretty tech savvy so i hope i can pick up this stuff at a decent rate. I dont know where to start with questions, but looking around at the tables in my tune i noticed this screen. Are these numbers accurate, and why would they limit my engine torque to 500lb/ft?

 

It is used by the traction control system if equiped. If this calculated value is exceded then it pulls timing. I believe the MAX value is 640 that the code can work with.

This may be totally wrong but that is what I remember anyway!

 

this wasn't located under the "traction control" sub catagory. It was under the "torque limiting" sub catagory, so i was assuming that it was going to retard timing if my engine torque exceded 500ft/lbs....which i am sure it is. Not really sure, just stabbing at a few things that i dont understand.

 

I would think it has to do with tq management to save the crappy stock 4L60E. The traction control (I think) uses a calculation in relation to MPH and RPM. If you RPM is higher than it should be for the MPH the PCM is reading it assumes tire spin and pulls timing. I had this issue after I went from 3.73 to 4.10. I had to turn the traction control off or I couldn't get over 20mph, LOL! Easy to tune around this issue.

 

Why? Because they think 500 lbs. of torque is enough. Cuts down on the warranty claims etc. And you're partially right about the timing, but remember the PCM has control of your throttle also. That max engine parameter is a "Global" setting, meaning it has precident over all other limits, and is always in effect unless disabled or raised beyond reach.

Keep in mind that our drivetrain has significant differences from any other GM gassers. Things that apply to the Gen III small block, traction control systems, or 4L60E have no bearing on the 2500HD w/ 8.1 and Allison. I know that's not what you want to hear but a lot of the techniques on tuning the computer are the same. Just do a head check on whether the advice applies to your rig or not when you get it.

I know you don't want to hear anything else from me until I can prove it. LOL

Vernon

 

However very good advice Manic Mechanic. LOL kinda like saying that...Manic Mechanic. Sunday Sunday IT'S MANIC MECHANIC VERSUS...LOL Sorry, been drinking, err still drinking.

You'll find most of us bring this value up to it's max, 640. I am not sure how your sceanrio, 8.1 & allison, would make a difference.

Your pcm doesn't see boost. More specifically your MAP sensor can't see boost. If it could (2bar map sensor), your pcm would need to have it's operating system upgraded. That mean's 2 bar. 2 bar folk can tune fueling tables to what specific boost they are in. You can't, you are tuning around the MAF and PE tables for WOT fuel.

You'll find doing some searching (not being a dick, just pointing out some good reading material) in this section there has been some real good write ups and explanations on the topics. TurboBerserker and dc_justin has done some great expalantions of a few things that are mysteries to most recently. Of course they're others, but those two stick out to me. 1slow, flyer, crash...and so on.

 

LOL, i just noticed his name was "manic" mechanic.....i always thought it was "maniac" mechanic.....LMAO!

Oh, i have been reading and searching......i didnt take that as a dick move at all. Im trying to read all i can, but its tough. I can read it, but i dont always know what the hell im reading.

So would i benifit from jacking the number up to 640, or does it even matter?

 

I suggest this, if you have the time and patience, once you get your software, log...log, oh and then log some more. Learning how to log different things. Then, if you haven't already learned how to log different advance(spark) PID's somebody will help ya, what I'd be curious is just what timing that setting is taking from me. By logging all spark PID's you should see how much tq management is taking from you. On HPT we have a PID for just that, TQ Advance *. If the pcm is pulling timing due to TQ management this PID will tell me.

So, before you change the setting, understand why or when it does what it does. This time consuming "figuring" things out is what will speed up your learning process. IMO. That's the long answer, short answer...LOL, yes change it to 640.

 

dewmanshu! You started without me! Runs to grab a brew.

Before I loose track of my thoughts I should at least help with the other two questions you had that I forgot.

MAP (manifold air pressure) sensor and bar. (short for a barometer). Max atmospheric pressure at sea level is one bar. This is approximately 14.7 PSI and the same pressure we live with and don't usually equate with pressure. The MAP sensor your engine is built with is designed to provide the most detailed readings between 0 and 14.7 PSI. Higher pressures than that either run out of reading or loose acurracy really fast. This small pressure range scale provides the fuel injection with the most accurate scale for manifold pressures that will be incountered in design use. When you bolt a supercharger on you exceed the design limits. So you want to swap in a MAP sensor that spreads the reading over a wider scale. Upto 2 atmospheres (or 29.7 psi) you use a 2 BAR MAP. A 3 BAR MAP would scale upto 3 times atmospheric pressure. With the MAF working it can still work with higher pressures because it's using the MASS of air reading to determine fuel needs after the pegged MAP.

But if you switch to SD (speed density) you are no longer measuring the MASS of air molecules you are now relying on measuring the air pressure and temperature (density) in the intake to now calculate the mass used at any RPM (speed). So with the MAP then being charged with such a higher role in fuel need calcualtions it's reading must be widespread enough to handle higher pressures of boost (pressure above 14.7 absolute). The main benefit to SD is the elimination of the MAF and any restriction it imposes on the intake of air. Accuracy is less with SD but power potential is greater.

Vernon

For what you've stated your intentions are for the truck keep the MAF and avoid SD.

 

cool, thanks for the definitions and the help. The searching/reading continues.......