DME Control Unit Chip Installation

Overview

This procedure guides you through installing a new chip in the DME (Digital Motor Electronics) control unit of a Porsche 944 with a 16v engine. The DME chip controls critical engine functions like fuel injection and ignition timing. Replacing it can optimize performance or address specific tuning needs. This guide is tailored for DIY enthusiasts with mechanical experience, ensuring a safe and accurate installation.

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Tools Required

• Phillips screwdriver
• Small flat-tip screwdriver
• 7mm (9/32 inch) wrench or 7mm (9/32 inch) socket and ratchet
• Grounding strap (optional, for static-sensitive environments)

Parts Required

• DME chip, compatible with Porsche 944 16v engine (verify with supplier for stock replacement or performance tune)

Required Additional Procedures

Steps in these procedures are required to complete this process:

• DME Control Unit Removal
• DME Control Unit Installation

Step-by-Step Procedure

Step 1: Remove the DME Control Unit

1. Follow the steps in the –DME Control Unit Removal– procedure to safely remove the DME control unit from your Porsche 944. Ensure the car is powered off and the battery is disconnected to avoid electrical issues.
2. Before detaching the control unit from its mounting bracket, note its orientation. Sketch or photograph how it’s mounted to ensure correct reinstallation.
3. Remove the control unit from the mounting bracket using a 7mm (9/32 inch) wrench or socket and ratchet. Place it on a clean, dry, flat surface.

Step 2: Open the DME Control Unit

4. If working in a dry or static-prone environment, attach a grounding strap to your wrist to protect the electronics from static discharge.
5. Turn the control unit so the back side faces up.
6. Use a small flat-tip screwdriver to gently pry up the casing tabs on the rear of the module.
7. Once all tabs are raised, slide the module cover off to access the internal circuit boards.

Step 3: Separate the Circuit Boards

8. Inside the unit, you’ll see two circuit boards mounted face-to-face, held together by plastic posts and connected by a ribbon cable. To replace the chip, you must separate these boards.
9. Locate the plastic posts. Each post is split in the middle and snaps together. Insert the tip of a small flat-tip screwdriver into the slit at the middle of a post and gently pry back and forth until the two halves separate. Repeat for all posts.
10. Once all posts are separated, lift the top circuit board on the side closest to the ribbon cable. Slide it toward the ribbon cable to disengage the opposite edge from the electrical connector.
11. Carefully open the circuit boards and lay them flat, keeping the ribbon cable intact.

Step 4: Replace the DME Chip

12. Locate the DME chip on the circuit board. For the Porsche 944 (16v engine, 1989–1991), it’s typically a 28-pin chip inserted into a socket, not soldered.
13. Note the chip’s orientation before removal. Look for an indent on one end of the chip and the socket. These must align when installing the new chip to avoid damage.
14. To remove the old chip, slide a small flat-tip screwdriver under one end and gently pry up. Move to the other end and pry up slightly. Alternate between ends, lifting gradually until the chip comes free. Avoid excessive force to prevent bending the pins.
15. Take the new chip and align its pins with the socket’s holes. Ensure the indent on the chip matches the indent on the socket.
16. Gently press the chip into the socket, applying even pressure on the center until it’s fully seated.

Step 5: Reassemble the DME Control Unit

17. Fold the circuit boards back together, ensuring the ribbon cable isn’t pinched.
18. Slide the top circuit board’s edge into the slot on the electrical connector.
19. Align the plastic posts on both boards and press gently to snap them together.
20. Place the module cover back on and bend the casing tabs to secure it.

Step 6: Reinstall the DME Control Unit

21. Mount the control unit back onto the bracket, matching the orientation you noted earlier. Secure it with a 7mm (9/32 inch) wrench or socket and ratchet.
22. Reattach the electrical connector to the control unit.
23. Follow the steps in the –DME Control Unit Installation– procedure to reinstall the control unit in the car.

Post Procedure Checklist

• Verify that the DME control unit is securely mounted and the electrical connector is firmly attached.
• Check that the car starts and idles smoothly, indicating the new chip is functioning correctly.
• Inspect for any warning lights on the dashboard, such as the check engine light, which could indicate an installation issue.
• Drive the car for 5 miles (8 km) to ensure the engine runs properly under normal conditions.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• YouTube