DIY Network

SRT-4 Engine Management System: Overview and System Components Computerized Engine-Control Module, Part 1 of 4 From "Tricked Out" episode DTRK-308

(Continued from page 1)

	Figure A
	Figure B

Making a Good Thing Better:
Tweaking Your Engine Management

Factory-installed engine-control units, like the stock PCM (power-train control module) in this SRT-4, monitor and adjust fuel levels and boost conditions to maximize performance within the parameters of the factory specs. But when you change or modify critical factory engine components--like the turbocharger, fuel injectors or exhaust--the performance capabilities of the car can become more than the factory PCM can handle.

In order to take advantage of these major improvements, you need to get reliable information about what's actually happening as a result of the modifications, process that information, and feed it back into the system. That's where this aftermarket engine-management system comes in. It begins with the main control unit, followed by all the sensors and other control units that will need to be hooked up in order for the system to do its job. These include the load sensor, the unit that handles throttle position and injector activity, MAP sensor (figure A), the boost control solenoid, the knock sensor light, and a control module for the wideband oxygen sensor (figure B).

advertisement

Mounting the System Components

Materials/tools needed for the first phase of the project:

DTEC computer
knock sensor light
wideband tuner
portable gaming system
standard shop tools
wire coat hanger
alcohol and cleaning rags
industrial strength hook-and-loop tape

Safety Alert: As a standard safety precaution, always disconnect the vehicle's negative battery cable before you begin work on any electrical or mechanical components.

Figure C

• Since all cars are set up differently, you'll have some situations that are specific to your car and will likely need to be set up at your workbench before you start wiring the system into the car. For our SRT-4 project car, the knock sensor light had to be soldered into the harness, and the throttle position sensor wire had to be wired into the green load input wire (figure C) before the system was ready to install.
  

  We chose these handy mounting locations on the SRT-4 for the knock light and control interface.

• You'll have to do a little guesswork to figure out where the mount the components in your vehicle. In the project car, the interface is positioned in front of the tachometer. You'll also want to keep a close eye on the knock light, so a good place for it is right on the steering column.

  The control units can be placed under the dash. All the other components go under the hood, so the next step is to run the engine harness wiring through the engine.

• Important: For safety, disconnect the cable from the negative battery terminal before beginning electrical or mechanical work on the engine.
  

  Figure D

• Start by removing the two screws from under the dash panel, and then remove the panel altogether for better access.

• From the engine side, slide a coat hanger through an existing grommet in the firewall, hook the sensor wires to it underneath the dash, and carefully pull them through (figure D).

• Back under the dash, run the knock light wire up along the steering column.
  

• Clean the steering column with alcohol for a good bond, and attach it with industrial strength hook-and-loop tape.

• Do the same with the interface wiring and the interface.

• Plug the interface into the wiring harness, and use more hook-and-loop tape to attach it securely to the steering column cover.

Now that the control modules have been mounted, in the next phase of this project work begins on wiring the new control unit into the existing factory ECU. A boost control solenoid is also installed.

Important: Included in this summary are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular car or truck, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of upgrade-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.

Safety Alert: Always wear eye protection and ear protection, and follow proper safety precautions, when working with power tools or pneumatic tools. Also wear eye protection any time you are working underneath a vehicle.

1 | 2

RESOURCES :

Design Engineering
www.designengineering.com

Howell Automotive
www.howellautomotive.com

AEM
www.aempower.com

LNS Motorsports
www.LNSmotorsports.com