Tuner Cat info for LT1's...what I've found...

[80LS1T]

Ok I have been searching the web tonight for info on how to use Tuner Cat and have found some pretty usefull info that I thought I would share!

 

Here' and explination of the ECM Constants(Original Link)...

 

Cylinder volume: Expressed in millileters per cylinder.

*Here are a couple of formulas to get you the correct value to put here:

Cubic Inches / 61.5 = Liters

Liters x 1000 = Milliliters

Milliliters / Number of Cylinders = Milliliters per Cylinder

 

Injector Flow Rate (Injector Constant):

For the stock 24lb injector GM has set this value to 24.91.

To figure this for injectors other than stock you need to take the square root of your fuel pressure divided by the pressure the injectors were rated at, then multiply by the size of injector. Example, if you still have the stock fuel pressure regulator on your car, the LT1 fuel system operates at ~43.5psi.

Now to figure the injector constant for a Ford/SVO 30lb injector you'd take the square root of 43.5/39 and then multiply by 30 and end up with a value of 31.68. The 39 represents the pressure at which Ford/SVO injectors flow was rated at.

This can also be applied to other fuel injectors if you know what pressure they were rated at.

 

MAP Threshold to Enable WOT:

This is the minimum map value that the computer must see in order to declare wide open throttle.

 

EGR enable controls: If you’re keeping the EGR system, leave these tables stock.

If you’ve removed the EGR system, the easiest way to disable it is to set the EGR enable minimum rpm to a very high rpm, or the EGR enable maximum rpm really low.

 

Fan thresholds:

These are the engine coolant temperatures that the ECM must see in order to kick the fans on. For the stock 180* thermostat the fan turn on points are 226 for the low speed and 235 for the high speed. A good starting point for either the stock or an aftermarket 160* thermostat is to set the low speed fan to come on 20* after the thermostat has opened, and the high speed to come on 6-8* after the low speed. It is best to experiment and see what you‘re car likes best. Use the Fan 1 On Threshold (Low MPH) and the Fan 2 On Threshold (Low MPH) for your turn on temperatures.

The Fan Threshold High Speed (MPH) allows you to give the computer a mph value to distinguish between the high and low speed fan turn on points. This gets pretty interesting.

For example, you drive a lot in stop and go traffic and are consistently driving at 35mph and under. You can set your high speed threshold to 35mph and then at every speed under that the low mph fan turn on temps are active, and at any speed higher than that the high mph fan turn on temps are active. That way you can kick the fans on earlier at lower speeds to make up for the lack of airflow coming across the radiator while you‘re sitting in traffic. Then once your at a speed that allows the radiator to see more airflow the high speed turn on temps take control.

 

Fan Hysteresis Low/High Speed: These values are the temperature changes that will turn the fans off. If you’ve set the hysteresis to 3, then the fans will not turn off until the coolant temperature is 3 degrees cooler than the fans turn on point.

 

Fan control turn-on points based on oil temp are not used in our ECM’s since it takes no input of oil temp.

 

There are also values for fan turn-ons based on A/C pressure. I have not messed with these values as I don‘t see an advantage to it.

 

Fuel Cut-Off and Resume Speed: This is a MPH based setting that is your speed limiter.

 

Fuel Cut-Off and Resume Rev Limiter: This is the RPM based setting that allows you to change your rev-limiter.

 

VSS Diagnostic Enable Minimum RPM:

Not sure exactly what this does, but I’ve been wondering if you set the rpm on this to it’s maximum value if the computer would not be able to activate the limp mode that causes the OBDI 1st-2nd shift problem. I’ve always been under the assumption that the no-shift is caused be a hard launch on sticky tires that would cause the VSS to lose it’s signal and set the trans into limp mode.

Try it and see if it works for you.

 

CARS or the Skip Shift Funtion: The easiest way to disable this is to set the enable rpm to it’s maximum value. Skip shift disabled.

 

Low PRNDL Upshift/Downshift Speed Threshold:

These tables are used when you select 1st gear manually on the shifter. If you set the Upshift Constant to 35mph the computer will automatically shift the car into 2nd gear at 35mph even if the shifter is left in 1st. Excellent as a safety feature.

Set the Downshift Constant to a value lower than the Upshift. If you set the downshift to 20mph and try to downshift the car into 1st at a speed higher than that, the computer will not let the car downshift.

 

Maximum Line Pressure: This is the maximum amount of transmission line pressure that is allowable on the A4 cars. I think that this value can not be over-ridden by the other transmission tables.

 

Kickdown Mode Enable/Disable TPS Threshold: These are the TPS values that are used to activate the kick down mph and rpm tables that control wide open throttle shift points.

 

Minimum Coolant Temp for Closed Loop: This is the minimum coolant temperature that the car will switch from open loop to closed loop.

 

Minimum and Maximum BLM: These are the highest and lowest block learn multiplier values that the computer will use in order to adjust its fueling requirements.

 

BLM Cell Map Boundary Hysteresis and BLM Cell RPM Boundary Hysteresis:

The BLM table has boundaries for both RPM and MAP. These boundaries determine where on the grid (which BLM Cell) your sitting at.

Stock BLM Cell MAP Bounadary is: Low 32, Mid 50, High 80.

Stock Cell RPM boundary is: Low 700, Mid 1200, High 2000.

Example: Suppose though your crusing right around 1200 RPM and going slightly above and below it... so suppose your doing say 1175, 1200, 1225, 1200, 1175, 1200 etc. You don't want the computer constantly switching boundaries. These two hystersis settings come into play here. in order for you to be "IN" one of these cells you must leave another cell by an amount over the hysterisis value. For either the MAP or RPM. This is used similar to fan hysterisis - you don't want your fans switching on and off rapidly as your engine temp goes above and below a certain value all the time, so you give it a hysterisis value of a few degrees celcius.

 

DFCO Enable RPM Threshold and Enable Map Threshold: These 2 values are really used together to activate the deceleration fuel cut out mode. If engine rpm is above the RPM threshold and MAP is above the MAP threshold when you let off the gas and TPS goes to zero then DFCO will engage.

 

DFCO Disable RPM Threshold and Disable Map Threshold: These are the 2 values that will disable DFCO. They don’t need to work together like the enable values for this feature so if either is obtained DFCO disables.

 

DFCO Disable RPM Decrease Threshold: This is an rpm based value that if the car decelerates faster than, DFCO will disable.

 

DFCO Enable Coolant Temp Threshold: The is the coolant temperature that the car must reach before it can activate DFCO.

 

DFCO Enable MPH Threshold: This is the speed that the car must be above for DFCO to activate.

 

DFCO Spark Retard: This is the amount of spark retard that the computer will use in order to slow the car down when DFCO is enabled.

 

Knock Retard Enable Coolant Temp: This is the minimum engine coolant temperature that the computer will start to retard timing when it gets input from the knock sensor.

 

Burst Knock Enable % Difference Air Threshold: I think that this is the percentage of airflow difference (measured by the maf sensor?) that the computer must see to enable burst knock.

 

Burst Knock Enable Coolant Temperature Threshold: This is the coolant temperature that the car reach before burst knock can be enabled.

 

 

Here's a site with LT1 files but I'm not sure if you can load them with Tuner Cat or not? They might be for LT1 Edit? LT1 FILES

 

Some theory on how to modify your PE table(power enrichment)...

 

From Tunercats help file:

PE %Change To Fuel/Air Ratio Vs. RPM

This table is percent change to Fuel/Air Ratio used when in power enrichment (PE) mode Vs. RPM.

 

The values from this table and the PE % Change To Fuel/Air Ratio Vs. Coolant Temperature are summed to arrive at the Power Enrichment Fuel/Air Ratio.

 

The resulting air / fuel ratio can be calculated as follows:

 

PE AFR = 14.7 / (1 + %Change vs Cool/100 + %Change vs RPM/100)

 

For the selected RPM, suppose the percent change to Fuel/Air Ratio from the RPM table is = - 5.1 and the percent change to Fuel/Air Ratio from the COOLANT table at the selected coolant temperature is = 22.7, then the approximate Power Enrichment AFR would be:

 

14.7 / (1 -0.051+.227) = 12.5:1 AFR

 

Basically, for every 1% that you adjust the %change vs RPM table, the A/F ratio changes by 0.147. For example, if you are running 11:1(rich) and want to get to 12:1, subtract about 7% from the tables. Do the opposite if you are running lean.

 

 

Here's a great site with some pretty good info on using Tuner Cat.

 

From what I have found....you should tune your Air/Fuel ratio and then adjust your timing. What a lot of guys do is use a program like Datamaster to help adjust their timing. What they will do is record a run and then advance the timing(with Tuner Cat) a little(say 1 degree at a time). Then make another run and see if the PCM retards the timing at any point. If it does pull the timing back down 2 degrees at that RPM range. Repeat as necessary. This seems to work well for others.

 

That's all I have for now but if I find any more info I will be sure to post it!

 

Guy

[Danno74Z]

Hi Guy,

 

Thanks for posting information on Tuner Cat. That Camaro site has a ton of great info on the LT1. I found this site which helps explain the basics of PCM tuning - http://www.lt1howto.com/articles/pcmtuning.htm

 

Have you downloaded Tuner Cat yet? I thing you can use it for 30 days free and then have to pay the $90 to register and the definition file.

 

Danno74z

[strotter]

You know, of course, that you'll never "finish" your tune, don't you? It's a never-ending quest. Eventually, you'll get tired of fiddling, or it'll be Good Enough, but there will always be some little things that'll bug you and you'll get out your tuning gear and fiddle with it just a little more. I've spent three years tuning my '7730, and before that my '7747, and I just keep coming up with more things I want to try. I actually ended up writing an ALDL monitor program of my own, because there were things that the other programs just didn't do.

 

FYI, there's a great deal of tuning info on thirdgen.org in the DIY-PROM forum, as well as some very useful FAQs. Once you get past setting your BLMs and have a rough timing curve, you're going to need to fool with things like tip-in, throttle follower behavior, transition behavior, so on and so on. Excellent fun and food for plenty of deep thought.

[80LS1T]

Here's another great site with tons of guys that really know what they are doing!

 

http://www.monodax.com/forums/tunercat-obdi-hardware-software/

 

Guy

[80LS1T]

I just found another program for tuning your VE table which will help with part throttle drivablilty. Its call VEMaster and its free! It adjusts your VE tables up to 3000 rpms for you till you get to the 122-125 BLM's. Looks pretty sweet!

 

http://www.akmcables.com/vemaster.htm

 

I'm going to use it and see how it works out!

 

Guy

[80LS1T]

Ok I just found the best site I have come across for how to tune your LT1(probably very similar for LS1's too)....

 

 

http://www.lt1pcmtuning.com/tips.php

 

 

Guy

[strotter]

Here's a guy who, despite the name of the blog, has thought about tuning his LS2 a great deal. Analytical details a'plenty.