any benefits to getting your car tuned this way, my car wasn't switched over to speed density when it was tuned, and i have been more than happy with the tune, but back around home here they are converting bolt on cars to speed density tunes, is this necessary and at what level can you know longer use the maf. I just don't understand why you would eliminate it unless you just needed to.

 

I meant to put this in the tuning section can someone transfer it there for me please, sorry about the mix up.

 

It is also expensive, I see no need for it unless high hp applications..

I asked my tuner the same q.. he said they have to keep the car a couple days.. drive it.. log.. tune.. drive it again.. log.. tune.. long process to learn MAFless

If I'm wrong, hopefully someone will correct me

 

so with SD u would have to constantly adjust to different conditions?

also how does a MAF play a role with an auto tranny?

 

i wondered this too about the having to retune the car for different weather conditions to get the optimum performance, but i wasn't sure about everything. but the guys who have tuned the cars i talked about didn't probably spend an hour tuning them and sent the guys on there way. When I got my car tuned, which i still use the maf the guy wanted to keep it for least a day to make sure everything was as near perfect as it could be. And i had no objections to his request. Tim from Redline in Festus MO did a great job with my car.

 

the stock maf is good to 500rwhp

 

The IAT still accounts for weather changes. If your forced induction its going to be higher any ways >_< You can also cut certain tables in half to trick the MAF into reading more

 

No you wont have to keep getting retuned due to weather. Perfect example:

I tuned an 02 Automatic WS6 back in the summer. MS4, PRC LS6's, and all the typical bolt ons. It is running a closed loop speed density tune and has been for months. The other day he brings it to me because he said it would not go into OD and he had a ses light. Now we are in 30* temps. I started up the scanner to check the code and while I had it open I opened up the histogram and looked at his fuel trims and nearly all of them were -3.

I disabled a code, flashed it, and sent him on his way.

As for shops spending an hour tuning. That tells me that you are paying for a wot tune only. They may also apply changes to certain tables that they use on masses of cars with similar mods as well but not a custome tune for your car. No way to do a full tune including building a VE table that quick.

 

yea i figured with the cars being sent on their way that quick it wasn't getting done exactly the way it should. I paid the money to have mine done the right way.

 

so the iat accounts for the weather changes for the tune. Also is there any benefit to speed density tuning, i mean is it easier to work with or what? I mean is one better than the other because i have seen plenty of high horsepower cars running mass airflow sensors?

 

like pat g he has spent tons of hours tuning his ta

 

I see no reason to get rid of the mass air flow sensor until my tuner says It would benefit me to do something different, I was just curious why these other tuners would choose to give them a speed density tune, I mean a lot of cars are bolts ons they are tuning, but some are head and cam cars, but like I said in an hour or less these cars are being sent back home with the owners supposedly ready to rock. I just think they are getting ripped off.

 

Wow. I had him tune my car and he said there was a bunch of crap wrong with my previous tune. I then sold the car and the guy that bought it went to get it tuned by Tim and guess what he told that dude. "there is a bunch of crap wrong with your tune". Thats funny since he was the last guy to tune the car that he tuned himself. What does that tell you?

Not really knocking on him, but sometimes his work is off and on. I wouldnt go back to him for a tune, ever. I hear he has to ask some of the other tuners in the area for tips. LOL

 

Ok guys, this is pretty simple. The basics of the internal combustion engine has not changed in over 100 years. Getting the proper (calibrated) air/fuel mixture is what you are looking for.

Your LSx base vehicle has two airflow measurment systems going into the motor...MAF and MAP(SD). They both have to work in harmony, ie. be calibrated (tuned) for total system accuracy. To do one, without the other is to do things half baked.

EFI Alchemy uses Craig Moates Road Runners with a portable wideband O2 for realtime calibration.

We do all of our tuning on a flat rate basis-assuming all systems are ready for tuning.

The realtime capability allows us to pinpoint deficiencies in a timely manner.

In short, we can do amazing things with our tunes but we cannot fix a broken vehicle with them. Read- If there is a problem, like an exhaust leak, we will stop the tuning process and seek a physical / mechanical remedy (at a shop hourly rate) and then resume the tuning process.

This is the only fair way to do business. If your vehicle is working properly, our knowledge and, equipment will allow us to tune your vehicle in a short order as these LSx based vehicles are very predictable when they are working correctly.

Two NA vehicles that have the same performance mods side by side, one SD and one running a MAF, the performance btw the two should always be the same.

We tune in SD first and then tune / calibrate the MAF. The only limitation of the MAF is with respect to the fact that the software is limited to +500 grams of airflow-Forced Induction.

 

This is not exactly what you are asking but these are a couple of reasons why someone may want to run in open loop vs closed loop. You can run either MAF or SD or you can run filtered MAF below 5000rpm + VE table (SD) since a MAF is not real accurate at quick throttle transitions in low air flow conditions. Unless you are doing your own tuning it is safer to run in closed loop. But if you do your own tuning and have a wideband there are some benefits to open loop. Closed loop always has your car staying around 14.7:1 AFR for emissions purposes (part throttle not WOT). This 14.7:1 AFR is all based off of what your narrow band o2 sensors are telling your computer. If you run in open loop you can setup your car however you would like. Idle at 16:1 AFR and have it set to do low throttle cruising around 15.5:1 afr. You can gain some decent fuel mileage running in open loop, but if you do not keep an eye on things you can ruin your car.

14.7:1 AFR is not for best fuel economy but rather best emissions. Your o2 sensors switch your AFR from 14.5-14.9 to help burn off certain types of gasses. One type of gas burns off around 14.5 and the other burns off around 14.9. It's purely for emissions and its not the best your car can run while constantly switching your AFR back and forth. Anyways this is all just part throttle / idle stuff and wide open throttle will all be the same no matter if you are running closed loop, open loop, MAF, SD or whatever as long as they are all running at the same AFR. Hope this some what helps. Also some have cars o2 sensor problems when you add a big nasty cam. The stock narrowband sensors will give false readings because of the overlap of the cam. This is when a SD tune is required.

 

He uses the same tune and tweeks it to each car depending on the mods. To say people are getting ripped off is a little one sided, while Im not trying to defend the person in question, all I can say is My car ran faster then the Average bolt on LS1. Unfortunately I dont have the slip for it so I never posted it, my fastest pass to date on motor was a 7.8x@91mph with an ok 1.7ish 60ft and this was in summer time weather. I beleive its his preference to tune in SD since thats what he's use to. For you there is no reason to retune you car unless you start some wrenching on it

 

oh i understand I just wonder how in depth these tunes are when the cars are in and out of the shop in minutes, not hours. Maybe these guys just work incredibly fast, and maybe not, but thats besides the point i just wanted some info on the speed density side of things and wondered why they choose to tune that way. Thanks Doc and Nitroused383 for the info.

 

Youll get alot of people for it and against it. I was wondering about the weather change also, but be it -5 below or 105..raining or snowing, my pile runs perfectly fine

 

so how often would u have to re-tune a car on speed density?

like seasonal?

 

Really a good speed density tune is not going to change much from day to day. Some of you guys act like it would be the end of the world if your temperature or elevation changed. I guess a lot of you forgot millions of people drove carburetored engines and never once changed the jets while traveling.

The only real time I would see the need to change your tune is when they add 10% ethanol into the fuel around winter time. This is only if you desire max performance though.