I’m trying to tune my first engine build using Dan Maslics “Master EFI Tuner” book with HP Tuners (basic). I’m using Case Study 3 and can‘t get past the first step. I’ve set my ECM up by his criteria and am not having any luck tuning the Idle MAF AFR calibration. My target AFR is 12.5 and my actual reading is 14.5. I keep adjusting my “MAF Airflow vs. Output Frequency” (from 3,000hz and lower) to richen the mixture to equal 12.5. Each time I do, the STFT (reads -45 after 2 ) keep pulling more and more fuel out but my wideband always reads an AFR of 14.5. Does any know why this is?

 

Why are you trying to get it to idle at 12.5 a/f ? If your not in open loop the o2's are going to be trying to correct your fuel back to 14.7. 14.7 is what you want at idle and part throttle.

 

That's what it seemed like to me to. The book's setting is supposed to be putting the ECM in open loop. Is it not? Should I just disconnect the MAF? The AFR was set that way because that is what the book set the target AFR at.

 

I have never read the book so I have no idea what it says. Setting AFR at 12.5 for idle doesnt make any sense, 12.5 a/f for WOT makes sense but not idle.

 

Post the tune.......

 

You need to force it to open loop in order to tune the MAF. Do a search on HPTuners for instructions on how to do this...

 

Its just a safe way to tune, its set to 1.17 in open look eq ratio. When you crank it up the chances of it going lean are rare. You leave your stoich table alone. When you change it back to normal operation your eq ratio goes back to 1.00 and it all falls in to place. I tune this way and its great. I've read a few of the tuning books and the mast book is my favorite.

 

12.5 at idle isnt a safe way to tune, to rich is just as bad as too lean. Stoich doesnt change unless your running a different type of fuel, you shouldn't be changing stoich on a normal tune in most cases.

 

Maybe you should pm the OP and tell him how its done since all you seem to be doing is saying I am wrong and not offering "the right way to do it" Sorry OP for wasting posts, I will not be replying to the thread again.

 

I normally would stay out these kinds of threads but I'll reply to clear this up. Its not practical to explain the whole tuning process or to answer every single tuning question out there. Read my 1st post in this thread I just quoted and is in BOLD, it says what he should shoot for. It seems like everyone that have posted have been trying to help the guy except you, you gave him advice that doesnt make sense and are now all bent out of shape. If you can explain why commanding 12.5 is better than 14.7 I have no problem apologizing. Instead of commanding 12.5 at idle it makes better sense to command 14.7 in open loop and tune it for that a/f ratio since thats where the O2 sensors are going to be trying to correct to in closed loop anyway.

 

Here's my tune.

 

Did you post your mods list?

1st your going to need to put it in open loop (OL).
Then command 1.0 (EQ Ratio) or 14.7 a/f ratio on your EQ ratio table

If you dont put it in OL the o2 sensors are going to use fuel trims to try to correct the fuel to 1.0 EQ ratio or 14.7 a/f. Then you can start the process of tuning your VE table and MAF. Thats not every single step, but will get you going. I'll look through the tune some more tomorrow, just saw those things right away.

 

Sorry, here they are.

LS1 / 3.908” bore
Mahle pistons / 4 CC valve relief
6.125” rods
PRC Stage 2.5 5.3L CNC Ported Heads 10.72 cr.
Melling high pressure pump
Crane cam 1449591 / .551” lift, 286 duration (224 @.050“)
Comp cams 918 valve springs
Comp cams pushrods
LS6 valley cover
LS6 intake
LS2 timing chain
Injectors / 0280155811 (24508208), 42# @ 58 PSI.
MAF / 89873788221
1 ¾” long tube headers
Ported 75 mm. MAF ends and throttle body

 

in engine.fuel,open&closed loop,you have short term trims enabled in open loop.so your o2 sensors will use short term trims to correct a/f ratio to stoich.you need to disable if you want to see what the maf is doing. but,you better reset maf values to original to start with or it most likely wont run due to the changes you made.