General Tuning Information for New Tuners

[n0dih]

I drew up a design in 83 when I was in 10th grade..... And the part that frustrates me is that I didn't know where I could do something with it or how to, and now the Sturman Digital Valve is very similar.... It ran the Pikes Peak Hill Climb in a 7.3L PSD one year.

My idea was I could take any size engine and have a very economy tune to a very aggressive tune all by the cam "size", adjust LC, LS, Lift and Duration, even installed position all from a ECM. Have the ECM control it all with timing, fuel, etc. Essentially that Corvette could have NASCAR like power and Honda economy. (assuming the rest of the combo like head flow, intake, exhaust, short block, etc could handle it). But it would be soooo easy to have a 600 hp engine getting 20 mpg on the highway and have 600 hp on tap the moment you nail the loud pedal.

Originally Posted by Programmer

....
5. Electronic valve timing ( can't prove it). We dreamt of electronic valve timing ever since Honda came out with it in the early 90's...

[Programmer]

There was a mockup somewhere back in 1979 (I think) for the 2.3L Mustang...electronic solenoids for the valves from what I remember. I think it was in Popular Mechanics, or Popular Science...way ahead of its' time...
I'd worked on an idea similar to Rhoads lifters...only a lot 'looser'. LOL...needless to say, it was much like fitting piston wrist pins to rods in a vise. You think it's a good idea, you think you know what you're doing, and it might work for the short term, but you know you're going to have to get it done at a machine shop later for real...

[n0dih]

I guess that was my problem, as a youngin, not having access to large amounts of development $$, not having resources, still playing with springs, weights, jets and rods and not even have looked at an EFI engine in person yet, the idea was good, but so overwhelming I had no idea where to go with it.

My idea was to have the solenoids do the lift and duration, so you could have a super mild duration "cam" for low rpm operation and just "move" it up the rpm range as you needed it. I had no clue how and no parts existed....

Someday have to get back in the idea of it and make something happen.... Maybe a DOD engine would give me some fun to play with....

Yeah, learned that one, tried to do simple things like rod bolts in by hand on my 455. It seemed just fine, but I lost the instructions that said to resize the rods after I did it. I ate the crank in 300 miles....

[gassr]

Originally Posted by Programmer

Much of this info is outdated and just wrong.

The topic of this thread is "ECM ABBREVIATIONS, a general description of BASE PULSE WIDTH, as well as a general/brief description of TORQUE MANAGEMENT" .

Under Torque Management, "The engine power output... Note: This is not throttle valve angle reduction, it is ignition timing retard or "backing off".

You are stating that one paragraph (or part of it) is not accurate? OK, someone can alter that one paragraph. In an attempt to stay on topic, how should it be reworded? How 'bout the rest/majority? Are the acromyns or PW description accurate?

[AJxtcman]

This is a start
I have more to add to this.


Torque Management,Traction Control Reduced Torque, and Torque Reduction.

Cadillac Information. (Similar to Corvette’s)

96 to 99 Information

Torque Management
Torque Management is a function of the PCM that reduces engine power under certain conditions. Torque management is performed for three reasons:

• To prevent overstress of powertrain components.

• To limit engine power when brakes are applied.

• To prevent damage to the vehicle during certain abusive maneuvers.

The PCM uses manifold vacuum, intake air temperature, spark retard, engine speed, engine coolant temperature, A/C clutch status, and EGR valve position to calculate engine output torque. It then looks at torque converter status, transaxle gear ratio, and brake switch inputs and determines if any torque reduction is required. If torque reduction is required, the PCM retards spark as appropriate to reduce engine torque output. In the case of abusive maneuvers, the PCM may also shut off fuel to certain cylinders to reduce engine power.

There are five instances (listed in the service manual) when engine power reduction is likely to be experienced

• During transaxle upshifts and downshifts.

• Heavy acceleration from a standing start.

• If brakes are applied with moderate to heavy throttle (input supplied by the Extended Travel Brake switch).

• When the driver is performing stress-inducing (abusive) maneuvers such as shifting into gear at high throttle angles.

In the first two instances, the driver is unlikely to even notice the torque management actions. In the other cases, engine power output will be moderate at full throttle.

When the PCM determines that engine power reduction is required, it calculates the amount of spark retard necessary to reduce power by the desired amount. This spark retard is then subtracted from the current spark advance. In the case of abusive maneuvers, the fuel injectors for cylinders 1, 4, 6, and 7 will also be disabled for a period of time.

Traction Control
Traction Control is a function of the PCM and the EBTCM that reduces front wheel slip during acceleration by applying the front brakes and reducing engine power. Refer to Brakes for an explanation of the EBTCMs role in traction control. The PCM continuously sends out a PWM signal that indicates the torque output of the powertrain. This signal, referred to as the Delivered Torque signal, is used by the EBTCM to determine what action is required when it sees the front wheels slipping. The EBTCM may decide to apply the front brakes only or apply the front brakes and request reduced torque output from the powertrain. The EBTCM requests reduced torque using another PWM signal. This signal, referred to as the Desired Torque signal, is used by the PCM to determine if the EBTCM is requesting reduced torque output from the powertrain. If the EBTCM requests reduced torque, the PCM will disable between one and seven fuel injectors to achieve this.

Desired Torque will normally be a 90 percent duty cycle signal to the PCM. When the EBTCM decides to request reduced engine power, it decreases the duty cycle of the Desired Torque signal by the amount of torque reduction required (90 percent duty cycle means no torque reduction, 10 percent duty cycle means 100% torque reduction). The PCM responds by shutting off fuel to one or more cylinders depending on the percent torque reduction requested. The PCM will not shut off any fuel injectors if any of the following conditions are present

• Coolant temperature is below -40°C (-40°F) or above 131°C (268°F).

• A low coolant level is present.

• Engine speed is below 600 rpm

The disabled fuel injectors will be re-enabled one by one as the need for traction control ends.

Several DTCs disable traction control when set. They will also trigger a TRACTION OFF light or message. The PCM traction control override also disables traction control and triggers the message. To diagnose a Traction Off light/message, diagnose any DTCs set first. Then check the traction control override and, if active, deactivate the override. If the TRACTION OFF light/message is still present, refer to Brakes for further diagnosis.


On 96 to 99 FWD Northstar’s when the T/C is turned off the PCM starts the car in second gear to reduce torque output
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PCM

Fuel Shut-Off Mode
The PCM has the ability to completely turn all the injectors Off or selectively turn Off some of the injectors when certain conditions are met. These fuel shut-off modes allow the Northstar powertrain to protect itself from damage and also improve its driveability.

The PCM will disable all eight injectors under the following conditions:

Ignition Off (prevents engine run-on).
Ignition On but no ignition reference signal (prevents flooding or backfiring).
High engine speed (above red line).
High vehicle speed (above rated tire speed).
Extended high speed closed throttle coastdown (reduces emissions and increases engine braking).
The PCM will selectively disable up to four injectors under the following conditions:

Torque Management enabled (transaxle shifts or abusive maneuvers).
Traction Control enabled (in conjunction with front brakes applying).
Low coolant condition (protects engine from overheating).
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Traction Control System (TCS)

Traction Control
Traction control will not have any effect on the operation of the vehicle until the control module detects one or both of the front wheels rotating faster than the rear wheels. At this time the electronic brake and traction control module (EBTCM) will request the powertrain control module (PCM) to reduce the amount of torque applied to the drive wheels. The PCM does this by retarding timing and selectively turning off fuel injectors (up to a maximum of 5). The EBTCM will apply the front brakes, thus reducing torque to the front wheels. Once the front wheels begin to rotate at the same speed as the rear wheels, the system will return full control to the driver. During the traction control mode, if the brake is applied to only one front wheel, most of the torque from the engine will be directed to the other front wheel which will improve the traction of the vehicle.

The braking is accomplished by closing the TCS master cylinder isolating valves, this isolates the master cylinder from the rest of the system. The TCS Prime valves open to allow the pump to get brake fluid to build pressure for braking. The drive wheel circuit solenoids are energized as needed to allow for pressure hold, pressure increase, or pressure decrease.

The TCS may be deactivated by the driver if desired. In order to deactivate the TCS with the engine running, depress the traction control switch. The system will remain deactivated until the ignition switch is cycled, or the switch is pressed again.

The EBTCM output (Desired Torque signal) is sent to the PCM as an input. When the PCM has a value of 100% the input is a 90 to 95% PWM at 128 hertz signal from the ABS/TC pulled low.
If the PCM has a constant 90% PWM signal. The PCM will not reduce Torque in this part of the program. It can reduce torque from the torque management, but it will not be from wheel spin.
If you add a PWM driver that hold the circuit at the 90 to 95%, but can be switched back to the cars system with a flip of a switch. Then you have a good piggy backed system.

On a 2000 to 2003 FWD Northstar if you turn off the T/C the PCM will reduce the torque output. This is similar in theory to the earlier cars starting in second gear. So don't turn off your T/C!

If a T/C DTC is set the PCM will reduce torque output!

I disconnected the ABS/TC module on a 2003 car and it ran just a tick slower. I thought that it was a fluke. No it was slower. It may have been a .1 of a second, but it was slower. The PCM will set DTC's for open circuits and the PCM does not receive that all important State Of Health (SOH) code from the ABS/TC module.

I tried to test the stall speed in a 2003 DHS. To do this you place the car in gear, apply the brake to hold the car, and mash the gas. The car would rev to 1800 RPM's and then start to drop off. Then if I held it for more than say 5 seconds it would kill cylinders. pretty soon it was 1500 RPM's

When the PCM see a brake pedal input and a TPS angle increase the PCM retard the timing (the first RPM drop) then the PCM shuts off cylinders via injectors. Just listen the your exhaust. We figured this out at the track. Try to launch with the gas and brake you really add to your time. Tell the guy running the dyno he can not use the brake and gas!

I made up some 1K resistance connectors for the dyno. We change a few wheel bearings a year. I started to cut the connectors off of the old ones. I soldered in the resistors and then just clipped them on for the dyno. I had no DTC's set or messages, but we only made 200 RWHP. Is this because the ABS and the PCM wheel speed did not match? I am not sure if this caused a reduction in power. I will take a data logger next time.

[AJxtcman]

Engine Torque Reduction Tables
These are the tables inside of the PCM's program!

IAT:
Yeah The Intake Air Temp sensor will reduce torque on a Northstar. It will revamp timing and shift speeds. When it is cold out lets just say 30° out and you get that Ice possible message on your DIC. Nail the gas and at 30 MPH, it will only drop into 2nd. If it is 50° out you will get it into 1st gear. If the temp is 90° out the PCM is trying to protect the trans and it reduces more timing on shifts. If the car is hot under the hood say 160° you would get detonation so they pull out timing. If you get some cold air going in to it the PCM will add some back without getting detonation.

IAT Spark Correction vs IAT vs MAP:
This is one of the tables used for above

Brake Torque Control:
This will reduce timing, reduce injector pulse, and shut down injectors

AC Clutch Engagement and Release:
This will reduce or increase timing, reduce or increase injector pulse, and reduce or increase IAC counts

TCC Engagement and Release:
This will reduce or increase timing

DTC Torque Reduction:
This can reduce timing, reduce or increase injector pulse, and shut down injectors depending on the DTC set

TCS

Traction Control Spark Retard vs RPM:
This table is the setting for the amount of spark retard at a RPM when the T/C is active.

Traction Control Spark Retard vs Desired % Torque Reduction:
This is the factor table for the desired amount of reduction.

Traction Control Aggressive Spark Retard vs RPM:
Think of this as when your on ice.

% Torque Loss vs Spark Retard:
This table is the reverse of the other table and tells the PCM how much torque is lost for a given amount of spark retard.

% Torque Reduction When Traction Control Disabled:
This is the table for the % reduced when a DTC is set, the T/C is off, no SOH message received, and the PCM receives a message stating that the T/C can not control traction.

Desired Torque Failure Limit:
Number of invalid desired torque reads out of Desired Torque Pass Limit reads which will set a fault.

Desired Torque Pass Limit:
Number of desired torque reads which will set a pass if Desired Torque Failure Limit invalid reads have not been reached.

Traction Control Re-enable Time:
This is the amount of delay before the system return to normal.
When I test have test driven some early CTS’s that have a very long delay. Like I can count 2 thousands before the PCM returns the power.

Engine Protection:

Low Engine Oil Pressure:
This will shut off all the injectors and or the Fuel Pump

Camel hump Mode AKA Over Temp:
Shut off cylinders to cool the engine

Over RPM:
This will reduce timing, reduce injector pulse, and shut down injectors

Misfire Balance Timing offset:
Adjusts the timing to prevent damage from internal torsional stress when the engine is misfiring.

Vehicle Protection

Vehicle Over Speed:
Shuts off injectors

Extended Brake Pedal Travel:
This will reduce timing, reduce injector pulse, and shut down injectors

Wheel Speed Sensor Failure:
This can reduce timing, reduce injector pulse, and shut down injectors depending on the system and the VSS

Catalytic Converter Protection

Misfire Detection:
This will reduce timing, reduce injector pulse

Catalytic Converter Over Temp
This will reduce timing and Vehicle Speed (Shuts off injectors), Change Stoich to stabilize converter temp

The 4T80E has a full set of Torque Management Tables also.

Drivetrain Abuse Management
This will reduce timing, reduce injector pulse, and shut down injectors
Examples: Neutral drops, Over Speed Governor, Trans Slip

Garage Shifts:
Reduces Trans Line Pressure via the trans PCS

Trans Upshift and Downshift Torque Reduction:
Trans PCS change, Shift Timing, Ignition Timing Reduction.

[AJxtcman]

OK I have some Data Logs.
We ran out of time this morning. I will get the amount of torque graphed in ft lbs. I was looking at too much data at one time and the data and the data is a little choppy. One run we did not go as fast as the others, so I ended up with 0 to 73 MPH graphs.

All three runs were made with WOT and he never backed off.
We made one more with the Traction off, but we had driven through some water before we started. On launch the tires spun and the PCM shut off some cylinder. Bert backed off the gas :bigroll: so it was not a good run. Yes it killed cylinders with the Traction off.

The fastest run was Traction Control ON



The next fastest was Traction OFF. We had a little tire spin not much



The slowest run was the Traction Defeat.
That is ok we had a ton of wheel spin and that is what I wanted!

[AJxtcman]

This is the run with Traction Control on
The start


The PCM Power output read is 6% at 0mph


The PCM does not show the Traction Control Active, but the ABS/TCS requested the PCM to reduce output by 15%. The Dark Blue line


The Max Torque output read before the 1-2 shift is 86%


On the 1-2 Shift the PCM reduced output to 50% for 2 frames


Output after the shift is completed 87%


This is the run with the Traction Control OFF

The PCM shows 66% power output @ 0 mph


Max power output before shift 81%


The PCM shows the power was reduced to 44% on the shift, but for less time.


The power output went up to 83% after the shift.


This is the run with the Traction Control Defeated

The PCM reading was 59% power output @ 0 mph
Hey we had a lot of tire spin


The Max power output before the shift was 82%


The power was reduced to 46% on the shift


After the shift the output jumped to 85% This was the last run

[SILVERGS]

Traction control will not have any effect on the operation of the vehicle until the control module detects one or both of the front wheels rotating faster than the rear wheels

What happens when there is a ABS fault? If someone has a bad wheel speed sensor does this affect the torque management? I am just wondering because it seems that on a few of the "beaters" that I have worked on in the past the mileage has been lower on these with the ABS light on.

Thanks
Mike

[97K15004WD]

Guys, let's start a new thread on these questions. This is a sticky so let's keep it on topic.....

Thanks!