Frequently Asked Questions

Before our fuel injection harnesses are packaged for shipment, every single harness is plugged into a continuity board that tests every wire and circuit in the harness.  If there are any problems, they will show up on our board, and not later on your car. 

KOEO= Key On Engine Off

Tuned Port Fuel Injection- KOEO 40-47psi  KOER 30-40psi

Throttle Body Fuel Injection 9-13 psi

CMFI  60-62psi

Gen3 Truck 4.8/5.3/6.0/6.2L KOEO & KOER 55-62psi

LT1/LT4  KOEO 41-47psi  w/regulator vacuum applied 3-10psi less than KOEO

LS1/LS6  KOEO & KOER 55-60psi

LS2/LS3/LS7  KOEO & KOER 55-60psi

Ford 5.0HO KOEO 35-45psi  KOER 30-40psi

Does the PCM need a VSS signal to operate correctly?  Generally speaking the answer to this is yes.  The PCM uses the vehicle speed sensor to determine what gear to command the transmission into when an electronic shift automatic is equipped.  The VSS also lets the PCM know when the vehicle is not moving or coming to a stop.  Without this signal the engine may idle very low or even stall.  Painless Performance suggests always using a vehicle speed sensor.  We offer several screw inline type that can be easily installed onto your cable speedometer output on the transmission.  Click these part numbers #60115 & #60116  to check them out.

When a late model engine is transplanted into a project car, the PCM will sometimes need to be reprogrammed.  Listed below are some of the parameters inside the PCM that may or may not need adjustments or deletions.  Please note that TBI, TPI and early LT1 PCMs use removable chips.  These chips are what will be reprogrammed on these fuel injection systems.  With late LT1 and newer fuel injection systems the PCMs do not have removable chips. The internal flash memory is what is reprogrammed.

Vehicle Anti-Theft Systems (VATS) can be programmed out of any flash-able chip or PCM.  If you are not using one of the Painless Performance VATS delete modules, or you are using a PCM that uses serial VATS, the PCM must be re-flashed in order to delete the VATS.  If you do not defeat or delete the VATS the engine will start, run for two seconds and then die.

If you are using a PCM controlled transmission, the PCM must be flashed with the proper transmission drivers in order to control it.  For instance, if you plan on using a 4L60E transmission and an LS1 engine the PCM must be flashed for this setup.  You cannot use a PCM flashed for a T-56 six speed and run a 4L60E transmission with it.  Also, keep in mind that the up-shift and down-shift points, line pressure, torque converter lock-up points and many other parameters can be altered when the PCM is flashed.

Throttle by wire engines must have the PCM flashed to work with the corresponding TAC module and throttle pedal.  You cannot take a PCM flashed for a cable throttle engine and run a throttle by wire setup.  This is also true for the reverse.  If using a throttle by wire setup, keep in mind the programmer can eliminate the traction control strategies that are factory programmed into the PCM.  Doing this will help with throttle response.Timing, fuel, diagnostic trouble codes, emissions, electric cooling fan temps, speedometer corrections, speed limiters, and about 30 other parameters in your PCM can be modified by your programmer.  Do some research and ask around for a trust worthy programmer.  Make sure you figure out exactly what you want before you have the PCM flashed.

1997-2004 LS1-LS6 Corvettes have throttle by wire engines.  To transplant one of these engines into your project car use Painless Performance part number 60522 or 60523.  These harnesses will operate T-56 standard or 4L60E-4L65E transmissions.  Please see the harnesses instruction manual for the parts needed for this transplant.

In 2005 General Motors moved away from the LS6 and made the LS2 standard equipment for the Corvettes.  All LS2s are throttle by wire.  Painless Performance offers either the 60520 or the 60521 harness for this engine transplant.  These harnesses will operate the throttle by wire system, T-56 standard transmissions and 4L60E-4L65E transmissions. 

Note these harnesses use a 2002-03 LS6 PCM serial number 12200411, pedal and TAC module in order to operate the LS2 engine and its throttle by wire throttle body.  Engine production codes ZJA, ZJB, 5MC, YTA and 6MC work with these harnesses.  Any other LS2 engine production codes will need the crank and cam sensors and target wheels changed to be compatible with these harnesses.  Please see the harness instructions for other parts needed for the transplant.

In 2006 General Motors made another big change to their engine controllers line up.  First they moved electronic automatic transmission controls to a separate transmission controller.  Second they did away with the TAC module and moved these functions directly to the ECM.  Lastly, they changed all of their engines over to 58X crank reluctor and 4X cam reluctor.  Painless is currently designing harnesses for these late model engines.

Our Throttle Body, Tuned Port and 4,3L CMFI Fuel Injection harnesses use one O2 sensor and our LT1, LS1, LS2, Gen 3 truck and Vortec truck fuel injection harnesses use two HO2S sensors.  We do not require the use of post Catalytic Converter HO2S sensors on any of these harnesses.  Where applicable, you can purchase the optional add-on emissions harness which will include the wiring for post Catalytic Converter O2 sensors.

 Part numbers for all applicable HO2S sensors are listed within the instruction manual for all Painless fuel injections harnesses.

Painless builds stand alone harnesses.  These transplant harnesses only need simple connections to the chassis wire harness of the vehicle receiving the transplanted engine.  They do not plug into the factory bulkheads of the vehicle the engine is transplanted into.  If you plan to integrate the to harnesses we suggest you acquire a factory wire diagram of your vehicles wiring. 

Depending on the harness, you may have optional connections to your instrument cluster such as tachometer and vehicle speed outputs.  You may also have cruise control, brake switch and cooling fan relay(s) to connect.  All Painless fuel injection harnesses have electric fuel pump connections.

General Motors' V8 engines built from 1997 to the present have used three styles of fuel injectors. V8 truck engines including 4.8L, 5.3L and 6.0L built from 1999 to 2002 and 2003-2006 non Flex-Fuel engines were equipped with Delphi Multec 2 injectors.  A sample of this type of injector is pictured below. 

Fuel injectors fire when the Engine Control Module commands them to.  This command is just a ground signal.  This ground signal is only commanded when the ECM sees the engine rotating via the crank position sensor or cam position sensor.  If you are experiencing this problem with your injectors, try the following:

1. If your injectors have been sitting or your engine has not ran in a month or longer the chance that you have stuck injectors is very high.  The longer they sit, the more likely you have stuck injectors.  Have them cleaned.
2. Check to make sure your fuel rail pressure is set to what your instruction manual says it should be.
3. Make sure you bleed the air out of the fuel rail by cycling the ignition key on/off/on a few times.  Pressing in the bleeder on the fuel rail while doing this can help bleed this air.  Careful when doing this.  Use a rag and catch can and eye protection.
4. With the ignition key off, unplug one of the injectors.  Turn the ignition key to the on/run position.  Connect a volt meter or test light ground lead to a known good ground source and then gently probe the terminals on the injector connector with the positive lead.  Crank the engine.  You should see 12 Volts or the test light glow on one of the terminals for both positions of the ignition key.  If not, you don't have power to your injectors.  Check the fuse block for blown fuses.  Check to make sure the check engine light is on with the igntion key in the run and crank position.  The check engine light is commanded on by the ECM when the key is in the on and crank position and the engine is not running.
5. So you have power at the injectors and they still won't fire.  If you have access to a scanner this would be a good time to use it.  With the scanner check to make sure the engine rpm is showing when you are cranking the engine.  No rpm showing when cranking could mean you have a bad crank or cam sensor.  It could also mean you didn't plug them in during the harness install.  Double check that they are plugged in.  Most times, if you have a bad crank or cam sensor then you will also not have any spark at the spark plugs.  You can check this by unplugging one of the plug wires.  Remove one of the spark plugs from the engine.  Plug the spark plug back into the plug wire and ground the threaded portion of the plug to the engine block or head.  Crank the engine and you should see spark.

Fuel injection requires high pressure (greater than 8 psi) fuel at the injectors.  When designing your high pressure fuel system for your vehicle keep these things in mind. What fuel pressure does your engine require?  This varies according to what engine you have. What volume of fuel does your engine require?  Use one of the calculators found on the web to calculate your required fuel volume. What type of fuel does your engine require?  Make sure the components you design the fuel system with can withstand the type of fuel you plan to use. Does your engine require an external fuel regulator? Always use a fuel filter.  Fuel injectors clog fast when trying to pump dirt, sand, varnish and other contaminants through them. Route the fuel lines as far away from any heat source as possible.

All electronic fuel injection systems are operated by either an engine control module or powertrain control module.  Depending on the manufacturer the only difference between the two is whether they control the transmission in addition to the engine.  ECM is engine only and PCM is both engine and transmission.

Programming and modification of the control units calibration is done differently depending on what type of control unit you have. 

• Early (pre-1994) units had removable calibration chips.  These chips can be sent to a number of performance companies to have them reprogrammed.

• Later (1995-Up) have Electrically Erasable Programmable Read Only Memory which cannot be removed from the control unit board.  These control units can be reprogrammed through their OBD1 or OBD2 communication ports with laptop based software.

ECM/PCMs are programmed to operate with all of their related components plugged into them.  If for your application you have a factory calibrated ECM/PCM then you must plug in all of the components it orginally was calibrated for.  The Painless Performance harness that was built for your application has the bare minimum component connectors that must be plugged into their component in order for the engine and transmission to operate properly.

Calbrations can be modified to remove the need to plug all of the factory components into the ECM/PCM.  The software to do this is available to the public, just do a search for it on the web.  If you don't feel comfortable doing this yourself you can always have someone that has already purchased this software do it for you.

A few things to consider when reusing your factory instrument cluster. Factory gauges must use factory style gauge senders.  For instance, if your vehicle has an oil pressure and-or temperature gauge that you will be keeping, make sure you install the original sender onto the new fuel injected engine.

Late model transmissions have electric vehicle speed sensors.  This sensor's signal is used by the PCM to control shift points, idle and de-fuel cut off.  If you plan to change out the sensor to a mechanical speedometer gear then you must install inline with the speedometer cable a VSS sensor.

Later model  LS1,6,7, Gen3 PCMs output a 5Volt square wave for use as a tachometer source.  This signal is not strong enough to drive an early model tachometer.  Contact Dakota Digital for a signal modifier.

Depending on which harness you have purchased you may be required to connect some wires to a brake switch.  These wires for the most part are to let the PCM know when the brake is depressed.  This in turn will unlock the torque converter and cancel cruise control.  See the instruction manual for your specific application and brake switch connections.

In 2005 General Motors implemented an electrical change to their light duty automatic transmissions.  They added an input speed sensor onto the pump of the transmission.  Two more wires to the round grey transmission connector were also added. 

A 4L65E can be operated by a PCM designed for a 4L60E transmission.  No changes to calibration or harnessing is needed.  The two new pump speed sensor wires just are not used by the older PCM.

If you are experiencing overfueling when the engine is at idle here are several things that can be the cause.

1. Vacuum leaks.  Any fuel injection system to utilizes a MAP sensor will run rich if a vacuum leak is present.  The vacuum leak is seen as increased engine load the the ECM/PCM compensates for the engine load by increasing fuel delivery.
2. Bad HO2S sensor.  HO2S sensors indicate to the ECM/PCM what the oxygen content the exhaust has.  It uses this information to modify its fueling strategy in order to get as close as it can to its commanded air fuel ratio.  A bad sensor, contaminated sensor or a sensor that the heater is not working properly can cause false readings which in turn sends to the ECM/PCM and incorrect Voltage signal.  Scan tools will show codes for this issue.
3. Bad engine coolant temperature sensor.  The ECM/PCM uses the ECT sensor to command open/close loop and also modify fueling strategies according to engine temperature.  If the ECT has no signal most ECMs will command a very rich condition.  Scan tools will show codes for this issue.
4. Leaking fuel injectors.  Fuel injectors wear out, get stuck and dirty.  Any fuel injector that does not close all the way will leak fuel into the intake manifold.  This will cause a rich condition most noticeable at idle.
5. Leaking fuel regulator.  Any fuel pressure regulator that uses a vacuum biased line from the intake manifold has the potential to leak fuel back into the intake manifold.  This will usually only be noticeable at idle.  If you suspect this just unplug the vacuum line from the biased port and plug it off.  If the richness goes away, change the pressure regulator out with a new one.
6. High fuel pressure.  Higher than required fuel pressure can cause a rich engine.  Check to make sure you have the fuel pressure regulator set properly for your fuel injection system requirements.  More pressure does not = better atomization and does not increase the injector volume output enough to warrant it.  More pressure does = leaky injectors, broke injectors and shortened fuel pump life.

Transmission speed sensors are basically variable reluctance sensors.  They output a voltage directly related to output shaft speed. 

Early 200-4R & 700-R4 are 2 pulse per output shaft revolution.

Late 200-4R & 700-R4 are 4 pulse per output shaft revolution.

4L60E/4L65E/4L80E/4L85E are 40 pulse per output shaft revolution.  This signal is required by the PCM for upshift/downshift and torque converter lockup.

Throttle by wire engines and the PCMs that control them are designed with specific sensors which have very specific signals.  If you have a throttle by wire engine make sure to pay special attention to the required parts list in your harnesses manual.  TAC modules, accelerator pedals and throttle bodies are not interchangeable even if they bolt up.

The GM service #12200411 PCM was factory installed in many different makes and models of General Motors vehicles. Both V6 and V8 engines can be operated by this controller. When procuring a PCM for use with Painless harnesses be sure to specify it be from a V8 car or truck.  If you have a PCM but do not know for a fact what the calibration is in it or need the calibration modified please visit our website www.painlessperformance.com and sign up for our PCM re-flash. We will program your PCM with the correct calibration for your specific application of this harness.  V6 to V8 change requires a license fee which makes it cheaper to just get a V8 PCM instead.

The final drive ratio utilized in 1999-2002 Camaro Z-28 and Trans Am cars was 3.23:1. The rear tire on these vehicles had an overall diameter of 25 inches. Transmission shift schedule calibrations are based around this rear end gear ratio and tire diameter. Most likely your rear end gear ratio and tire diameter is different than this. If so, without a calibration change to the transmission shift schedules your vehicle may up shift late/soon and down shift late/soon. You may also experience improper torque converter lock up operation. 

These statements are true (different ring gear and tire diamter) for late model trucks and vettes also.  Send your PCM to us and we will recalibrate it to eliminate these issues.  Click here.

LS series engine cooling systems have some specific requirements. 

• First, the lower radiator hose connects to the water neck with the thermostat behind it. If looking at the front of the engine it is the water neck to the lower left of the water pump. The upper radiator hose connects to the water neck at the top of the water pump. 
• Second, the factory coolant thermostat only starts to open at 195^oF and is fully open at 210^oF. Aftermarket thermostats are available that will open at a lower temperature. 
• Third, these engines incorporate steam tubes that are plumbed into both the front and rear of each head. They are all tied together and then plumbed through the bottom of the throttle body and then to the radiator. Most people remove the throttle body from this coolant loop by connecting the steam tube outlet, which is located just the lower right of the throttle body and protruding forward from under the intake manifold, directly to the upper radiator hose or to an open coolant bung in the radiator. Do not plug off this steam tube, it must be connected to either the upper radiator hose or to the upper third of the radiator in order to bleed off any steam that accumulates in the engine heads.

Coolant temperature and oil pressure gauge senders can easily be connected to any LS series engine. In both engine heads are threaded coolant ports with Metric 12 x 1.5 threads. The coolant port on the driver side head is utilized by the coolant temperature sensor needed for the PCM. The port on the passenger head usually has a plug in it that can be removed and a temperature sender for a gauge can be inserted. Most aftermarket gauge manufacturers offer adapters to adapt their gauge sender so you can thread it into this coolant port. 

4L60E and 4L65E transmissions require external fluid coolers. The ports on the side of the transmission usually have quick-connect fittings installed. Most local auto parts suppliers will offer fittings that adapt these ports to pipe flare fittings. If you plan to bend your own hard lines this is your best bet. Or, you can also screw in 3/8” NPT fittings into these ports. Make sure to use Teflon tape on the threads for a good seal. Fittings are available from many online retailers or your local hydraulic hose shop that are male 3/8” NPT to male -6AN or whatever your application may need.

Painless Performance fuel injection harnesses require connections to the battery (+) and an ignition/crank 12 Volt source.  The battery (+) connection is where the harness draws its amperage from to operate the coils, injectors, HO2S sensors and the PCM.  The ignition/crank 12 Volt source is used to activate the relays built into the harness which in turn switch the battery (+) connection into the harness.  You must be sure the source you choose for the ignition/crank wire provides 12 Volts in both the ignition on and crank positions of the ignition switch.

A loss of 12 Volts to this wire will shut power off to the fuse block and the entire Painless Performance harness.

VIN numbers identify a specific vehicle with it's make, model, year and options.  Each PCM is programmed with a VIN number that matches the vehicle it was programmed for.

Service numbers identify the version of that type of PCM.  Different service numbers of the same PCM actually designate what vehicle it can be programmed for.  For instance, 16238212 is a 1998 Camaro Z-28 PCM service number.  This particular PCM can only accept VIN #s from 1998 Camaros.  12200411 is a 1999 Camaro Z-28 PCM service number.  This PCM can be programmed not only for this Camaro but also 2000-2002 Camaro, 1999-2003 Corvette, 1999-2002 Truck, and many V6 applications.  Both 16238212 and 1200411 PCMs use the same connectors, terminals and locks.

PCM calibrations change with the VIN number flashed to them.  For instance, a 12200411 PCM flashed for a 2000 Camaro will utilize a mechanical throttle body with an IAC and most likely a 4L60E transmission.  The same PCM flashed for a 2002 Vette Z06 will utilize an external TAC module, electronic throttle body and accelerator pedal and a manual T-56 transmission.  Just by changing the VIN flashed to the PCM the pinout changes, fuel tables, shift tables and just about anything else in the calibration changes along with it. 

So, as you can see it is very important that your PCM service number matches what your instruction manual calls for and that it is flashed with the proper VIN so that the calibration matches the engine/transmission you are using.