I am just completing my first round of mods on my '98, Vortex, Supermaxx headers/cats/xpipe, Halltech air bridge and LS6 manifold.
( heads & cam later in the summer )
I had planned on getting a dyno tune when I'm done but it's going to cost as much as HP tuner would. I was wondering, with the mods that I have, could some of you folks help me out with a tune if I purchase HPT. I'm trying to squeez this all in before my next Time Trials on the 12th ?

 

If mine comes this week I will help walk you through a basic tune. I ordered last Tuesday and still no package. They must be back ordered or slow to ship.

 

You should go get a Dyno run with AF meter. You will want to know how rich/lean your car is so you can know where to start. Log the dyno run on your scanning software, so you can compare the AF on the dyno sheet to what is happening inside the PCM. This should give you an Idea of where to start when you compare logged street sessions to your Dyno run.

Good Luck.

 

You can also use a portable wideband such as the Innovative Wideband setup to tune the car on the street. Which will probably give you better results than tuning with a dynojet and then fine tuning on the street.

 

James G,

You don't really need a dyno until you have tweaked on the car using your datalog. Here is a very basic and effective way to do so.

Using HP Tuner:

1. SET UP YOUR SCANNER TO DATALOG
File->Connect
Scan->Start Scanning

RPM
O2 BANK 1 SENSOR 1
02 BANK 2 SENSOR 1
STFTB1(Short Term Fuel Trim)
STFTB2
LTFTB1
LTFTB2

Post or send it to me.

2. IDLE/LOW END and to setup for wot
After warming up your car to operating temp, you need to ~ZERO your STFT.
You should already be very close though your airbox will throw it off.
If your idle fuel trims are > 0, decrease your "Injector Flow Rate vs KPA" until they are close to zero. (Note a decrease in the flow rate indicates the engine has smaller injectors and will cause an increase in fuel enrichment)

3. WOT
Make a few WOT passes in 2nd or 3rd and check the o2 voltage at WOT.
Lets just say 0.925v to 0.945v is a good starting point. Less voltage=leaner, higher=richer. For my car, 0.945v is ~ 12.7:1 A/F.


Now, gets a bit more complex:
Note the following about HP Tuner: The injector flow rates in HP Tuner are setup in KPa. This means the value to the far left of the table is 0 vacuum or WOT and the value to the right is IDLE or max vacuum. You can scale your fuel curve by adjusting this.


Knowing that you already have it set for idle, do the following:
1. If the WOT run indicates enrichment is needed, DECREASE the values to the far left of the table (0 vac, wot) otherwise increase them. You should carefully scale this through idle. For example, if a 4% change is required at wot, then scale it roughly 2% in the center of the table, etc.

2. Granted, some will tell you to use the WOT PE RPM table and that is fine.
Just note that the PE table is setup to select a commanded air fuel.
For example, at 6000RPM, the value in a PE table might be 1.22 on a Z06. That represents a commanded fuel of 14.682/1.22 = ~12:1 A/F. If your injector scaling is correct from above, your PE table = Wideband value. This is not absolute as there are obviously are areas the pcm enrichs/enleans fuel, but it will get you VERY close.

4. ADJUST SPARK
Cut the data below using "copy" and paste this to the far left and upper block
of your spark table. This will only work in HP Tuner.

Example: high octane spark table for 91 octane w/aftermarket cam (if no cam increase low load spark; aftermarket cams with ground in advance increase cylinder pressure, ie cause pinging at low load):

http://home.comcast.net/~booth.p/high_octane_spark.txt

 

Almost forgot. When setting up spark, note that your car will probably never see more than 0.76gm/cyl airflow nor 11000hz maf. Spark data is scaled in mg/cyl and the maf in hz.

 

This all great advice and I really appreciate it. I'm going to do a baseline dyno early next week and I I'll order HPT at the same time. The only thing I worry about right now is I'm adding Supermaxx system and Z06 manifold
the week before my next time trials. I don't want to screw things up.
I guess I'll take things in small bits and hopefully I won't start throwing codes.
I'll post results soon, thanx again

 

What do you recommend here? It looks like leaning out my LTFT's may have made me too lean at WOT. I've made small adjustments in the WOT pe table, but it's still not getting enough fuel. I did this over a bridge, not on a dyno

WOT PE table:

1.203 1.203 1.203 1.197 1.192 1.167 1.167 1.222 1.239 1.307 1.344 1.314 1.427 1.438 1.39 1.392 1.405 1.45 1.212




After some adjustments, still too lean:

1.203 1.203 1.203 1.197 1.192 1.167 1.167 1.222 1.255 1.35 1.355 1.357 1.457 1.459 1.479 1.48 1.485 1.45 1.212




I still need to make adjustments to the PE table, but how much?

 

You are way too rich. I would put the stock PE data and injector rates back in and start over. Is your car supercharged? Get the o2 sensors down to around 925mv at wot. I believe stock is aroun 890 and that is exactly where my stock car ran best.

 

Too rich? My AFR's were around 14.x on the dyno...I was under the impression higher voltage from the o2's means leaner too