The long quest of a good tune for my project. ( Lot of infos )

Hi, my name is Alex. Sorry but it'll be a very long first post but I want to make everything clear as possible.


I started three years ago my first car project which included a 1989 fox body mustang and a LQ4 engine. With very limited knowledge at the moment I managed, after a lot of research, to make a quality build which satisfied me for the money spent in it. I just want to say that I am not a car builder or top tuner, just a guy who love cars since the first time I went to a racetrack. I took my time to buy quality parts and install them via instruction, I do not like shortcuts

*Here's a bit of info about the car*
-1989 ford mustang LX (used to be a 4 cylinders car)
-Team Z k-member kit
-1998 8.8'' cobra build rear-end with 3.27 gears
-Rear disc conversion
-Moser axle
-Rear interior all stripped
-etc...

*Here's a lot of info about the engine*
Engine ;
-2003 LQ4 from a 3500 Express van (100% rebuilded)
-4.020'' bore
-Stock style piston (stock compression)
-Stock crank
-Stock Rods
-Melling oil pump
-220/224 112*LSA .575/.575 camshaft
-F-body oil pan
-317 head with .600'' capable springs
-Stock 1.7 rocker
-Trick Flow push-rods

Air ;
-4'' intake tube
-85mm truck MAF (PN; 25168491)
-Stock throttle body (no coolant)
-Edelbrock pro-Flo XT

Fuel ;
-LS3 injector
-LS1 returnless pressure regulator
-Walbro 255LPH high pressure pump

Exhaust ;
-1 5/8'' to 3'' long tube headers
-2 1/2'' cat back with H-pipe setup
-Cat delete
-Rear o2 delete

Transmission ;
-2003 4L80e
-Internal dual feed
-Sonnax boost valve
-Sonnax pressure regulator valve
-FTI 3200 single disc converter
-HD2 shift kit

I probably forgot a few things but that's the big part of the setup.

For the tuning part, I paid a local tuner to get my VATS disabled and play with my fuel trim/table to get the car running. I went with him for a street tune at the drag strip and he ajusted the fuel with my wideband setup. I went three time at the dragstrip and my best time is a 13.34 @ 105mph. I have a hard time talk to the guy to get the thing fixed and that's bother me to have spend all those hours of research and hard work and have a so-so setup because the tune is not on point. I grew some balls and bought HPTuner MPVI2 and started collecting some info on how this works. I started messing with HP Tuners 3 days ago. I try to read alot and I am ready for some headache !

The problems ;
-Not so good time at the drag strip ( 13.34@105 )
-Bouncing wideband when cruising on highway
-Weird shift when moderate acceleration
-Pretty sure the lock-up setting are wrong. I had to pull the pan 2 months ago and saw lot of clutch material on the magnet.
-When WOT, I start with a 12.4 AFR then move up to 13.1 AFR (max 10 seconds pull)

I plan on updating this thread as much as possible. Maybe someone else is in the same kind of position that I am and this thread could be good info.

I joined the actual tune in this message. I think I saw 2 bad things in this tune. The first one is that my wheel size have not be corrected to the right ratio and from what I've read this can ''mess up'' the transmission tune. Second thing, I am pretty confident that my MAF table is not the good one since I have a 85mm and my tune seems to be setted for the stock one. I will make a change each day, post the modified tune and a data log. If you guys want to participate that'll be cool.

If you read all that, you are a warrior. Thank you ! :worship:

It's late at night so I can't type a whole story here but lots of things were not done. Certain features left enable that should be disabled.

The airflow model doesn't look like it was changed at all. There is no set MAF curve or VE table for fueling. All those changes have to done using a wideband o2 sensor. If you have a wideband you'll want to start logging that so you can make the proper changes.

And get the gear/tire ratio thing squared away, you don't want the wrong information in there.