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Tuning Information and Common Questions

Information on tuning, troubleshooting and tune-related questions.

Information on tuning, troubleshooting and tune-related questions.

DOD/AFM and VVT Information

Displacement on Demand/Active Fuel Management (DOD/AFM) and Variable Valve Timing (VVT)

DOD (also referred to as AFM) and VVT became options starting with Gen 4 LS motors (5.3L, 6.0L, and 6.2L). DOD/AFM disables four cylinders (1,4,6 and 7) at cruise. VVT is Variable Valve Timing. Some motors had both, some had one or the other, and some had none. This is important to know when planning your cam install, so you can have the correct parts. PCM of NC’s cams will all be three bolt, non DOD, non VVT cams unless other arrangements are made. This means any 07+ motor will need to use a 3 bolt cam gear kit with any of our cams. Check out our DOD/VVT Delete Kits here – link.

You can tell if your motor has VVT by looking at the cover. You can see the camshaft phaser actuator on the top, and also a five pin harness at the bottom. If the motor does NOT have VVT, there will be no phaser, and the harness will be three pin.

You can tell if your motor has DOD by peeking at the valley cover. If it is smooth, it does NOT have DOD. If has channels running through the top, then it does have DOD.

Idle Set Up (93 & Older)

Idle Setup (93 & Older)

No aftermarket throttle body should be expected to work out of the box. Also, if you have a large cam and/or more displacement you should pay close attention.  All GM vehicles in our focus use what is called a IAC motor.  This motor controls a air bypass in the throttle body which basically controls your idle. For example, if your idle is low and needs to be raised the motor will open a valve and give the engine more air which will allow the idle to come up.  The IAC motor has a certain range it may operate in, officially its 0 – 160 IAC counts.  If the valve is closed completely it will be at 0 counts, open is 160.

What you want to do is set your throttle body up so that you put your IAC motor in a good effective range so that it may catch any idle dips and trim high idles just like it does in a factory vehicle.   To do this open your scanner and look for IAC counts.  With a fully warmed engine at idle in P/N we recommend 30-50 counts.  The closer to 30 the better but don’t drive yourself crazy finding it, after all that is what the IAC is for anyway. If your IAC counts are not in this area adjust your throttle stop until it does.  If your IAC counts are high add throttle stop (make blades open).  If your IAC counts are too low remove throttle stop.  All aftermarket LT1/TPI throttle bodies are adjustable. Stock throttle bodies are adjustable as well after you knock out the plug. The Computer will see that the TPS voltage is increasing as you adjust up. This may lead the computer to believe that you are intentionally holding the gas open so at this point it will kick the idle up under throttle follower and throttle cracker routines.  BE SURE that your throttle position (%) is zero before noting IAC position and making a subsequent change. You can reset your throttle position % by resetting the ECM, unplug battery, pull ECM fuse, etc.

After you set your throttle stop look to see if your throttle position sensor is still within range.  We recommend about .65 volts or so. An acceptable range is .5v-.69v. If you are outside this range elongate or slot the TPS mounting holes so that you can “clock” it until you get the appropriate voltage.

Here is a snapshot of a vehicle with a improperly setup throttle body.  Red stars have been added next to important data to help  you find them.

 

Electric Fan Patches

Electric Fan Patches

Purchasing one of our LS1, C6, or SPAL electric fan kits? You will need to have your PCM patched in order to operate them. The patch can be done by anyone with HPtuners tuning software. Start by visiting our fan patch link here to download the appropriate file. Compare your file to the downloaded file, copy the fan settings, and reflash.

Don’t have access to HPtuners software? No problem! With the purchase of our electric fan kit, we will patch your ECM for free (just cover return shipping). Please enclose a note in the box with your name, contact info, and which fan kit you bought and we will patch it for you. Electric fan patches are typically turned around the same or the very next day.

Available Tuning Programs

Send In/Exchange Options and Core Refunds For Tuning

Send In Program

As the name implies, you send in your PCM to PCM of NC. The vehicle will not be drivable during this period of time. Sent-in PCMs are our first priority, and are typically shipped back out the next day. No security relearn or CASE relearn is required. NOTE: Some vehicles will also have a TCM (transmission control module). If you do not know whether you have a TCM or not, call us at 704-307-4227 to find out. If your vehicle does have a TCM, we will need both the PCM and the TCM so that we can tune the engine as well as the transmission for you.

Core Program

In the core program, we send you a tuned core PCM (and TCM if applicable). We start by using GM software to program your vehicle’s VIN & calibration, and then tune that file. Once you receive the core, you may send yours in back for the core refund, or retain both modules. If you choose to send in your stock PCM/TCM for the core refund, it must be postmarked with seven days of receiving the tuned PCM. The core program requires a CASE relearn and security relearn also.

Loaner Program

The loaner program sends you a stock PCM/TCM to borrow so that you can send in yours for programming. When we receive your PCM, we tune it and return it to you, and then you send in the loaner for the core refund. The loaner PCM will need a security relearn, but there are no CASE relearns required. NOTE: Expedited shipping on loaner programs only covers one shipment. To upgrade both shipments to express, please contact us!

 

PCM/TCMs MUST be in good shape aesthetically and not have any damage or we will not accept them for core returns. 1996 PCM’s are not eligible for core return.

 

These are the amounts we refund for core/loaner programs.

2002-2005 I6 Trailblazer – $75

2006 I6 Trailblazer, Hummer H3 – $159

2004-2006 Colorado/Canyon – $159

2007 Hummer H3, Trailblazer I6, Colorado/Canyon – $150

1997-2005 V6 3.8L – $75

2005-2006 Trailblazer SS/5.3L – $250

2007+ Trailblazer SS/5.3L – $200

2008+ Trailblazer I6/Hummer H3/Colorado/Canyon – $200 (automatic), $150 (manual)

Loaner program fees ($50) are not refundable.

 

Exchange and Send-in Programs Compared

Send-in Core Loaner
Requires Security Relearn No Yes Yes
Requires CASE Relearn No Yes No
Average Turnaround Same/Next Day 2-3 days 2-3 days
Is the tune locked? No No No
Customer can perform CASE relearn -Not Required No No
Customer can perform Security relearn -Not Required Yes Yes
Costs incurred Tune only Tune + core charge (refundable) Tune + core charge (refundable) + loaner fee
Option to keep stock/loaner PCM No Yes Yes
Able to return to stock on your own No Yes, if you keep stock PCM No

Flash Options for Tuning

Tune + HP Tuners 

With this purchase, you will receive HP Tuners software, and a tune from us. Upon receiving HP tuners, you will need to install it to a laptop, read your stock file and email it to us for tuning. We will email you back a file to flash. HP Tuners is a full tuning suite. You will be able to modify your program as often as you like, or go back to stock if you wish. HP Tuners is also capable of datalogging so that you can submit helpful data to us if needed. THERE ARE NO REFUNDS UNDER ANY CIRCUMSTANCES ON TUNING SOFTWARE OR TUNES. Also please note we do not offer support in teaching the customer to tune using HP tuners.

 

OBDII Datalogging with HP Tuners

If you need to submit an HP Tuners Datalog to us, please download our channels list here: PCM of NC HPT Channels List RIGHT CLICK, “SAVE LINK AS”!

Please see our video below detailing how to set up the log so that we may use your data. Please note, we only accept ONE log at a time for continuity purposes. Logs must be at least 15-20 minutes long and be taken while driving. It is smart to try and capture all data on one log, i.e., cold start, drive while cold, then warm, etc. If you have any driveability issues, note the time stamp and mention that in your email. If you have a tune file from us, please do not make any edits to it.

 


 

 

OBD1 Datalogging

Obtaining a Datalog Contents:

OBD1 Specific
Hardware
Software
Scanning
Rules for Submitting to PCM of NC
Simple Diagnostics
Sensor Parameters
Idle Setup

 

OBD1 Specific
Hardware
While there are many solutions on the web to scan your own car, we have grown especially fond of those sold at moates.net.  Their products have offered reliable service and the product is very well packaged and professional.  We have used Moated hardware for years here in our own shop with no major failures or problems to speak of.   Another good company to try  is OBD1.com

* For all OBD1 GM vehicles our favorite is the ALDU1 & CABL1

Software

We are a bit picky when we have datalogs sent to us.  Just like Windows users don’t like to switch to Mac and vice versa, we like to stick to TTS Datamaster for our 86-93 Car and 93-95 Truck datalogs. TTS Datamaster provides a nice reliable platform for scanning which is easy to use and easy to on the eyes.

Datamaster is available for download here: Please notice that there are many versions available so be sure to pick the correct one for your application.

 

Scanning

To initiate a datalog with TTS Datamaster

1. Open the correct version of software for your platform

86-89 TPI use version 32
90-92 TPI use version 8D
92-93 LT1 use DA
94-95 LT1 use EE

2. Click File -> Record ALDL Data

3. A new window appears, click Setup -> Com Port and choose the appropriate com port for your cable. It should be one of the selectable items in the list.

4. Click File -> Open, Navigate to a easy to find location (like your desktop) and type a new name for a log. Click Open.

5. Click Start in the lower left corner of the Serial Data Acquisition window. Drive the car for 15-20 minutes if possible.  To end the log click Stop and then File -> Save Now.  Note that Save Now might not be selectable as the software will automatically save itself periodically.

6. Send the log to us.

 

Rules for Submitting to PCM of NC

Before sending a datalog to PCM of NC please take note of these following rules.

1. Use common sense and include your full name. We cannot look up orders by email alias as easy as a full name.
2. Please use the scanning software we recommend. For most OBD1 Vehicles this is TTS Datamaster.
3. Please capture plenty of data in one single file. Multiple small files are cumbersome and inconsistent for us to work with. Typically 15 minutes worth is the minimum.  Drive it like you normally would.  Wide open throttle samples are also handy but be sure to do them in a safe place like a sanctioned track.
4. Correct issues noted by us before sending us a new log. If we noted that you have a sensor that is bad it doesn’t help us to send us another log with the same bad sensor.

OBD1 Datalog Check list

() File type correct TTS Datamaster *.uni unless prior arrangements made
() Name log file with coherent description such as  “log 10.7.2011 using tune 4”
() A SINGLE Log file no shorter than 15 minutes. Multiple files not accepted!
() TPS and IAC adjusted properly. Click HERE for idle setup help
() Wide open throttle data. You must drive through at least one gear at 100% throttle. Do not roll in the throttle, or get data in anything other than 100% throttle
() Trouble Codes present – Fix before proceeding

More often than not we receive files with incomplete, wrong, or bad data.  In this case we will send back the following with X marks noting the problem. Please take time to re-read this document if necessary and correct the issue.  Thanks!
Failed OBD1 Datalog Return list

() Incorrect file type correct TTS Datamaster *.uni unless prior arrangements made
() Name log file with coherent description such as “log 10.7.2011 using tune 4″”
() A SINGLE Log file no shorter than 15 minutes.
() Multiple files not accepted!
() TPS and IAC adjusted properly. Click HERE for idle setup help
() No wide open throttle data. You must drive through at least one gear at 100% throttle. Do not roll in the throttle, or get data in anything other than 100% throttle
() Trouble Codes present – Fix before proceeding
() Sensor problems – Fix before proceeding

 

Simple Diagnostics

It is always a good idea to see if there are any DTC’s (Diagnostic Trouble Code).  With Datamaster if you have a code there will be a red box illuminated in the top right corner of the main Datamaster window.  Double click the box.  Inside the box you’ll see a red box (or many). These indicate trouble codes.  If you click on the little red box it will tell you what the code is.


Datamaster showing DTC’s

Sensor Parameters

You do not need to be a professional technician to catch most problems.  A simple glance over your sensor perimeters will reveal most problems.  For instance, if your engine coolant temperature sensor reads -40F and you do not live at the north pole chances are the sensor is bad OR the wiring/connection to that sensor is faulty.  Remember that these computers are only as smart as the people who programmed them and they may not give you a DTC.  Here are some examples

Notice the TPS %. It is 100% nearly all the time. Obviously this is not the actual case and indicates a problem with the TPS sensor.  Also note that there are no trouble codes present.  This customer would otherwise think he may have a tuning issue if he did not have a datalog.

This one may not jump out at most of you.  This car is equipped with 2 oxygen sensors both of which are supposed to jump between 300 and 800 in a fast heart beat motion once the car is in closed loop.  This car has one dead o2 sensor and one lazy o2 sensor. You can see clearly the purple line has insufficient activity especially when compared to the opposite o2 sensor highlighted in blue.

We are here to help and with a datalog you are equipped to tell us exactly what is wrong with your car.  If you are unable to diagnose a problem yourself let one of us know and we will be glad to assist.

Idle Setup

Let me start off by saying, no aftermarket throttle body should be expected to work out of the box. Also let me say that if you have a large cam and/or more displacement you should pay close attention.  All GM vehicles in our focus use what is called a IAC motor.  This motor controls a air bypass in the throttle body which basically controls your idle. For example, if your idle is low and needs to be raised the motor will open a valve and give the engine more air which will allow the idle to come up.  The IAC motor has a certain range it may operate in, officially its 0 – 160 IAC counts.  If the valve is closed completely it will be at 0 counts, open is 160.

What you want to do is set your throttle body up so that you put your IAC motor in a good effective range so that it may catch any idle dips and trim high idles just like it does in a factory vehicle.   To do this open your scanner and look for IAC counts.  With a fully warmed engine at idle in P/N we recommend 30-50 counts.  The closer to 30 the better but don’t drive yourself crazy finding it, after all that is what the IAC is for anyway. If your IAC counts are not in this area adjust your throttle stop until it does.  If your IAC counts are high add throttle stop (make blades open).  If your IAC counts are too low remove throttle stop.  All aftermarket LT1/TPI throttle bodies are adjustable. Stock throttle bodies are adjustable as well after you knock out the plug. The Computer will see that the TPS voltage is increasing as you adjust up. This may lead the computer to believe that you are intentionally holding the gas open so at this point it will kick the idle up under throttle follower and throttle cracker routines.  BE SURE that your throttle position (%) is zero before noting IAC position and making a subsequent change. You can reset your throttle position % by resetting the ECM, unplug battery, pull ECM fuse, etc.

After you set your throttle stop look to see if your throttle position sensor is still within range.  We recommend about .65 volts or so. An acceptable range is .5v-.69v. If you are outside this range elongate or slot the TPS mounting holes so that you can “clock” it until you get the appropriate voltage.

Here is a snapshot of a vehicle with a improperly setup throttle body.  I have added red stars next to important data to help  you find them.

Notice

IAC Pos = 160  throttle stop too low, IAC valve max open trying to keep idle
TPS Volts = .65v   This value is good for the time being
TPS % = 0  Critical, be sure your at idle before making adjustments. Your foot should not be on the gas pedal
Idle RPM = 1100 Not highlighted, but important.  This is a big cam car that requires a higher idle. This value is the idle in which the car was tuned to idle at, or its desired idle.
RPM = 625 The actual idle RPM which you can see is far less than the Idle RPM or desired idle. Here in lies the problem!

From what you can see this car has the throttle stop set way too low.  The car has a desired idle of 1100 RPM which is required for a cam of this size. It is currently at 625 RPM and it wants to be 1100 RPM so the IAC valve is wide open. At this point in time the IAC is at its max adjustment and it is still not able to reach the desired RPM.  The car is not running good, it is chugging, and stalling.  A couple of turns in the throttle stop will put the IAC in a place where it can adjust and maintain the idle required for this car.

Copyright 2008 PCM of NC INC.
NOT TO BE USED WITHOUT PERMISSION

Dyno Tuning Read Me!

Looking to have your car dyno tuned or street tuned by us? Reading this may save you some time.

About Dyno Testing/Tuning

A dyno is basically a treadmill for a car.  It is an extremely handy tool for a good tuner because he can test the car under controlled conditions and measure power, torque, transmission slip, and air/fuel ratio among other things.  It keeps the test environment clean, safe and repeatable. The dyno we have is a 224XLC  which is a dyno jet that incorporates a load brake. This gives the same ability as a loading dyno such as a Mustang dyno but the repeatability of a dynojet. The dyno will test your vehicle to its full power potential.  Your engine’s power potential may overcome your vehicle’s ability to handle such power.  It is required that you know and understand this and expect that part failures may occur. All vehicles must have a waiver signed before being dropped off. 

 

What to Expect

Most bolt on cars can be dyno tuned within 2-3 hours.  The tune will consist of two parts. A driveablity tune where we drive the car, record how the tune is functioning, make changes to the tune, and then drive the car some more. We will repeat this process until we are determine the fueling, spark, and transmission settings are best for the car.  The second part will consist of the dyno tuning. Here we measure horsepower, torque, air/fuel, among other things and make changes until we get the maximum power possible safely.

Cammed cars or cars with intensive modifications will take longer. We typically require the car to be dropped off with us for a minimum of 3 days.  The first day we work out as much driveablity and idle tuning as we can.  The second morning serves as check to make sure the car drives good and idles properly.  After we are happy with the driveablity on the second day we use the dyno to find the best power possible at wide open throttle. The third day is the final check. Our test is to get in the car crank the vehicle and immediately start driving just as the car was expected to as it came from the factory. We want the car to drive as absolutely good as it could. If it fails this test we will make changes again until we are happy.  If in the case the car does not drive like we expect it should on the third day we will contact the customer and let them know it will be at least one more day.  It is not a good idea to rush the tuner as some cars take longer to tune that others. We want to give you a good running car and if that takes 4 days as opposed to 3 than so be it. Its not quite as simple as installing a part like a set of headers!

Mooresville, NC Tuning

We offer GM dyno tuning and street tuning by appointment only.  We can be reached at 704-307-4227. Generally, appointments are scheduled Monday-Friday 9-5. We are not available for tuning on Saturdays.  Please call for current dyno/street tuning rates.
 

Prerequisites For Dyno or Street Tuning at our NC Office

Having your vehicle in its best condition will help the tuning process go a lot smoother and faster. Before dropping a car off be sure to check:

  • The car has a full tank of gas
  • The car has the appropriate octane gas in it that you plan on running after the tune. Please bring the vehicle with premium if it is a car that says Premium Recommended on the fuel cap/door.  Most cars can benefit from premium fuel.
  • All appropriate sensors are installed and working correctly
  • If the vehicle has an engine swap, that all wiring is done correctly, the DLC is accessible, and all sensors are reading
  • All fluid levels have been checked
  • The vehicle is in good mechanical condition.
  • If we have requested you drop the vehicle off, be sure you have allotted a minimum of 2-3 days for us to keep the vehicle
  • Street cars must have valid license plates (n/a for race cars) and be road ready for driveability tuning
  • Must have no leaks
  • If running nitrous, bottle is full, and system is ready
  • Brakes & suspension are in good working condition, battery is strapped down, etc.
  • If heavily modified, bringing a list of modifications with you is helpful

Recommended Prerequisites

  • Premium fuel
  • Fresh oil change
  • Fresh fuel filter
  • Fresh spark plugs and general tune up items
  • Clean MAF sensor if equipped
  • Check transmission fluid
  • Bring at least a half of a tank of fuel if not more.

Security and CASE Relearns

 

If you send in your own PCM, you do not need to do a security or CASE relearn. If you install a core PCM and the vehicle does not start, you will need to do a security relearn. This occurs about 75% of the time. If you install the PCM and your vehicle does start, you do not need to worry about the security relearn. Security relearn instructions are included with your purchase. Try not to read too far into it, just do as it says. When in between steps, allow the security light to turn off before trying to start the vehicle. Also make sure you cycle through the relearn for at least four cycles or until the vehicle starts. If you cannot get through the security relearn, unplug the battery for about 10 minutes and then try it again, or perhaps have a friend try it for you.

A CASE relearn is a Crank Angle Sensor Error relearn, which realigns the position between the crankshaft position sensor and the camshaft position sensor. This relationship helps the vehicle determine advanced misfires. Anytime you install a new PCM into your vehicle that you intend to run long term, you need to have the CASE relearn done. So, this would apply to any of our core programs. The CASE Relearn can be done by anyone with a Tech 2 scan tool, advanced snap-on scanner, or also a Dashhawk or Aeroforce Scan Gauge depending on the vehicle. It is a 5 minute procedure. Cost will vary depending on where you go – you may want to call around first before deciding between the core program or loaner program. The CASE relearn will not keep the vehicle from running, however it should be done within at least two weeks of installing the new PCM. Once the CASE relearn is done, it’s done. You do not have to redo it if you switch back to your stock PCM or unplug the battery.

Security Relearn Procedure

 If the car does not start after installing the PCM, perform the security relearn procedure:

After installing the PCM, most of the time you will need to perform a Security Relearn Procedure. This can be done at your home and requires no tools. If your vehicle starts after installing the PCM, you do NOT need to do it.

  1. Attempt to start the truck by turning the key to the Start/Run position. Try to crank the vehicle.
  2. Observe that the vehicle fails to start and the security light is illuminated.
  3. Release key to the ON/RUN position (not the ACC position or OFF)
  4. Allow the vehicle to sit with key in the ON/RUN position for no less than 11 minutes. Security light will turn off after this.
  5. When the light goes off, turn key to OFF position and allow the vehicle to remain in the OFF position for no less than 30 seconds.
  6. Repeat #1-#5 for four cycles or until vehicle starts.

NOTE: Since this is a fairly long procedure (35 minutes) I would limit all electrical sources, such as shutting off headlights and AC fans to prevent discharge of battery. It is safe to wait longer than the allotted times above, but it is not safe to wait less.

 

Tune Troubleshooting

The first step is to notify us of an issue. If you do not tell us, we cannot help you fix your problem. Our mail order tuning is based off of roughly twenty years of in-house dyno tuning, which makes our tunes very close. Occasionally, some vehicles will need more adjustment than others. If you can call or email us about the issues you are having, we might be able to make adjustments. The BEST thing you can do for us is to provide a datalog. A datalog is a snapshot of what the vehicle is doing while you drive it – including sensor values, etc. If we have that (in datamaster or HPTuners format depending on the year) we can fix your issue much faster. Before calling us about an issue, verify it is not a problem with the vehicle itself. Sometimes in older vehicle sensors will go bad, harnesses will chafe, grounds will corrode, etc. Spend some time doing a quick look over to make sure the issue is not on your end. Also, make sure you are running our tunes with stock timing and fuel pressure unless told otherwise.

Reflash Policy

If you already have a tune from us and change some parts later on, we charge a $50 (plus shipping) fee to update the tune for your modifications. The first step is to call or email us to see if your changes require a reflash. Depending on what it is, it may or may not require additional computer tuning. You will need to send your PCM or chip back in for reflashing, we do not send one to you unless you make arrangements (i.e. contact us and purchase a core outright). When you send your PCM or chip back in, please include a note with your name on it, contact information, and what has changed since last time. Retunes are usually processed within 2-3 days. Reflashes are only honored for the original purchaser of the tuning.

What Does Tuning Do For My Vehicle?

While each vehicle will be different, we are always aiming for more power, more gas mileage, and the best driveability possible. Gains will depend on what kind of engine you have and what modifications are done to the vehicle. For instance, a car with headers may pick up more from a tune than a stock vehicle does. Most of our tuning descriptions will tell you what kind of gains we expect.

From the factory, GM often leaves a lot to be desired in the calibration. They are set up on the weak side because they do not know who will be using what car for what purpose. Since you know the intended use of your vehicle and the modifications you are planning to add, we can nail down a file that will work for you based off of our experience. In the tune we can change things such as timing, fueling, power enrichment, rev limiters, speed limiters, speedometers, VATS (security), shift firmness and time, torque management, and much more.

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