Idle Speed & Ignition Timing

WARNING: This page is about a different car, the 2003 Jeep Wrangler, 2003 Jeep Liberty, and 2003 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

Ensure idle speed is set to specification. For adjustment procedures, see appropriate ON-VEHICLE ADJUSTMENTS article.

NOTE: Ignition timing is not adjustable on any engine.

On the Wrangler, the engine firing order for the 2.4L 4-cylinder is 1-3-4-2. For the 4.0L 6-cylinder, firing order is 1-5-3-6-2-4, with cylinder No. 1 being the first cylinder from the front of the vehicle in the in-line 6-cylinder engine. For the Liberty, the 2.4L is also 1-3-4-2. The 3.7L 6-cylinder has a firing order of 1-6-5-4-3-2. For the Grand Cherokee, the 4.0L firing order is 1-5-3-6-2-4 and the firing order for the 4.7L V-8 is 1-8-4-3-6-5-7-2.

All ignition timing functions are controlled by the Powertrain Control Module (PCM). Mechanical adjustments are not needed and can't be made. On the 4.0L 6-cylinder engine, do not attempt to rotate the oil pump drive to adjust timing. This adjustment is used for fuel synchronization after camshaft position sensor replacement.