How To Advance 4G63 Timing

How To Advance 4G63 Timing


Ignition Timing is a critical piece of engine tuning, and a big hurdle when you are turning up the boost and looking for more power. Advancing or increasing ignition timing is a goal of almost every tuner when you are using piggyback computers. This question is posed to us quite a bit considering the amount of older 4G63’s out there.

Today I’ll be showing you how to advance 4G63 timing by raising the base ignition timing in a 4G63. This article and guide assumes you already know how to properly time the engine using a timing gun or timing light.


This how to advance 4G63 timing guide is meant for the 1995-1999 Mitsubishi Eclipse Turbo with the 4G63T. This model is commonly known as a 2G DSM, and part of our how to advance 4G63 timing will involve installing a cam angle sensor (CAS) from an older generation 4G63.

Things you should know before starting this tutorial :

  • This modification is not street legal – Whether you are in California or not, this modification will alter and change your emissions and how your vehicle responds. Because we are adjusting the base timing, that means every single part of your rpm range is affected.
  • Advancing your base ignition timing can be dangerous – Stating the obvious, raising your base ignition timing can be catastrophic to your engine if you aren’t careful. Because you are effectively raising the base ignition timing, your pistons could melt before you have any idea what is going on. When you raise your base ignition, you run out of safety margin when at Wide Open Throttle (WOT)

Parts you will need to perform this install and conversion :

  • 12mm wrench
  • Timing Light
  • Previous Generation Cam Angle Sensor

There are three cam angle sensors you can choose from for this particular job that you can choose from. Each one has different distinguishing ways of telling what generation or year range the cam angle sensor is.

Image Courtesy DSMPOWER

Part Number : MD121786

Vehicle it’s found in – 1989-1990 Mitsubishi Eclipse, Eagle Talon TSi, Plymouth Laser Turbo

This cam angle sensor is an optical style and comes with a long flying loom to help identify it. The lid is flat green and it uses a disc with grooves in it to help identify the intake camshaft position for the ECU.

Image Courtesy DSMPOWER

Part Number : MD148855

Vehicle it’s found in – 1991-1992 Mitsubishi Eclipse, Eagle Talon TSi, Plymouth Laser Turbo

The second cam angle sensor in our How To Advance 4G63 Timing Guide is another green cam angle sensor, this time with a plug in style connector, and a slightly raised green lid. This too uses the same optical methods and slotted disc to determine camshaft positioning.

Image Courtesy DSMPOWER

Part Number : MD184529

Vehicle it’s found in – 1993-1994 Mitsubishi Eclipse, Eagle Talon TSi, Plymouth Laser Turbo

The last cam angle sensor is the first unit to switch to a hall effect style and with the same plug in style connector. This cam angle sensor lid is black and this cam angle sensor is what you are ideally looking for.


How to Install the 1g CAS


  1. Disconnect the negative terminal battery.
  2. Rotate the engine to Top Dead Center at the #1 cylinder


Once you have the engine set to TDC, remove the 2g cam angle sensor, or the rubber metal cap located at the end of the intake camshaft. If you own a 1997-1999 Eclipse Turbo, you will need to remove the sensor itself.

Look inside the camshaft slots and note the orientation of the cam slots. The intake cam should be at the 9 oclock position, take your 1g CAS and align it before installing.

Slide in the 1g cam angle sensor and now you are ready to do the wiring, secure the sensor by using the 12mm nuts but do not tighten yet. If you don’t have a prepared flying loom

Make sure the ignition key is off and the ECU fuse is pulled. At this time make changes to your plug wires and injector wires if necessary. Connect your custom wiring harness to the 1G CAS.  Route the harness away from extreme heat possible noise generators, (spark plugs, coil’s, alternators etc.)  Behind/under the intake manifold works fine.

How To Set your Base Ignition Timing

  1. Make sure the cam angle sensor is seated properly and slightly tightened cam bolts. Start the car and connect your timing light to the battery.
  2. Connect a scan tool to read real time values on the vehicle.
  3. Warm up the vehicle to operating temperature or 212 ºF, or until the fans turn on.
  4. Point your timing light at the crank to determine base timing. Do not turn on your headlights or air conditioning, each mark past the base is 5 degrees.
  5. Loosen the camshaft position sensor bolts and turn the camshaft position sensor until the timing light timing matches the scan tool reading.
You can add base timing from this point onward, but you must use caution and increase in small increments. For pump gas purposes more than a 5 degree advance is not recommended. This timing modification is crude but very effective as you can significantly increase power output throughout the RPM band while lowering your EGT’s.
The only negative to this modification are the intermittent misfire codes that can occur, depending on your usage. For more information, check out Magnus Motorsports for their 1G CAS in a 2G misfire tips and forum discussion.
It can also cause your pistons to melt and lose seal integrity before you realize what is happening, so be aware this modification is not for the novice. Race gas or higher octane fuel is great for this modification if you are going to the track or if your vehicle is “off-road” use only.  Please be responsible when you know how to advance 4G63 timing, your motor may thank you.