How is this 'reaction' any different than the original CL MAF tune?

 

The CL MAF tune uses knock sensors as a secondary fail safe that shouldn't be required in most cases. SD either already has too much timing reduced in order to avoid engine knock @ colder temps (less power than could have been had @ around stoich & while accelerating to WOT) or the knock sensors are pulling timing due to engine knock that would not have occurred w/ CL MAF.


Do you not know or are you trying to prove some kind of point? If the latter, I'm bored w/ this & am done. Not worth arguing about.

 

I just don't know. I'm curious as to the differences between MAF and SD.

What in SD calls for 'reduced timing' and why is this timing not reduced while in running a MAF?

Why would the EXACT same timing curves in in both tunes cause one to knock and thus reduce timing but the other not knock?

 

GM has used speed density for years in factory cars without any problems. It most be said that the trend has been towards MAF systems and that usually the factory performance cars have a MAF (even the old GN's had a MAF system).

My understanding for the duel system of SD and MAF isn't just for a redundent system. The GM ECU using inputs from both systems during normal operation. The MAF system is very good at predicting airflow in a steady state system and not very good at metering airflow speeds that are highly dynamic. The SD system excels at dealing with rapid airflow changes but isn't as accurate at steady state as the MAF. The GM engineers know this and use a blending of the two inputs while going down the road depending on the state of the airflow.

In theory you should be able to tune the timing curve for temperatures effects (I believe there is a table (or 2) for adding/subtracting advance from the main timing table depending on the temperature). I would suggest looking at the EFI live forums for this kind of info.
Good luck!

 

It's not just MAF, stock uses all inputs, MAF, 02, temp, MAP, ECT...etc. Uses feedback from theses sensors to fuel properly. SD doesn't have 02, MAF feedback. So, it can run leaner in cooler temps which can lead to engine knock. Knock sensors then reduce timing to eliminate knock. However, it only adjusts after there is knock. Next post you see is a guy asking about how his ring lands got chipped. This is one way.

A SD tune can be set up conservatively where normal driving conditons up to WOT use reduced timing or rich fueling so that there isn't a lean condition in cooler weather. So, wether it's knock sensor reducing timing, rich fueling or reduced timing tables; under the curve power is sacrificed.



Answered above. One adjusts fueling from all feedback sources. This is what closed loop means. SD is the most open loop of the big (3) tuning practices. Has the least amount of feedback. Biggest loss of measurement is from the MAF. IMO, unless your racing or out of engine bay room, there's no major benefit to tune without the MAF. So, also IMO, OL MAF is the better solution for street cars. Open loop MAF is open loop in that it does not trim fueling based on 02 sensor feedback, but does uses airflow & pressure mesurement. They all can use ECT, IAT feedback. They all do use MAP feedback.

Some tuners will get into ignition spark on time tables & injector pulse tables in an effort to improve large temp swing SD tuning.

As noted originally,
There are loosely (3) popular types that owners choose for tuning; stock, OL MAF, SD. Unless, you have a dual tune, there are power sacrifices made one way or another if running the same SD tune in 0* & 90* temps.

 

Wow, I sure didn't mean to start a missing match but I am really appreciating the great feedback and info.
I've decided to leave the MAF in the system at this point. If I have to do anything later (if I go with boosted power) then I will cross that bridge then.
I am building this with 99% factory parts and want low maintenance, good street manners and reliability. The factory included it for a reason. I'll use it.

But please keep the info coming. I have a lot to learn still.

 

So my new setup will include a FAST 102. I can either spend the money on a new TSP 100mm MAF or my tuner says he will tune SD for basically the same price as a new MAF. I am leaning towards the SD tune. What do you guys think? Engine is LS1 with H/C and kooks full exhaust.

 

go speed density and never look back my car has seen 0 degree weather and 100 degree weather and it does just fine i run a wideband all the time to monitor my air fuel ratio and it stays the same no matter what the temp outside is or how the weather is the key to a sd tune is to have a good tune and not do a half way tune also i leave mine where it will go into open loop still and leave my ltft enabled and front 02 reading so the pcm will still relearn weather and temp changes i would never go back to maf no matter what i love sd so much i am currently doing 2 lsx swaps right now both stock motors and i will be sd tunning them

 

I totally agree, i notice no differences with temp with my SD tune.

 

can you explain this a little further. sorry im still trying to learn about tuning.

 

I'm learning too. I'd like to hear more as well.