Operation CHARM: Car repair manuals for everyone.
Home >> Jeep >> 1994 >> Wrangler L6-242 4.0L VIN S MFI >> Repair and Diagnosis >> Specifications >> Mechanical Specifications >> Engine >> System Specifications >> Tune-Up Specifications
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Tune-Up Specifications

The following specifications are published from the latest information available. This data should only be used in the absence of a decal affixed in the engine compartment.

Engine Liters/CID 4.0L/6-242
Spark Plug Gap 0.035

Ignition Timing deg.BTDC

Fig. B:




Firing Order [03] As Shown
Man. Trans. [04]
Auto. Trans. [04]
Mark Location Damper

Curb Idle Speed, RPM [02]
Man. Trans. [04]
Auto. Trans. [04]

Fast Idle Speed, RPM
Man. Trans. [04]
Auto. Trans. [04]

Fuel Pump Pressure, psi [01], [05]
Valve Lash Specifications [04]


BTDC -- Before Top Dead Center.

[01] -- With suitable fuel pressure gauge connected to fuel pressure test port on throttle body.
[02] -- Idle speed for man. trans. models is adjusted in Neutral. On auto. trans. models, idle speed is adjusted in Drive (D). When checking idle speed, set parking brake & block drive wheels.
[03] -- Before removing wires from distributor cap, determine location of No.1 wire in cap, as distributor position may have been altered from that shown.
[04] -- Non-adjustable.
[05] -- Pressure should be 31 psi with vacuum connected to fuel pressure regulator, rising to 39 psi with no vacuum.

pro multis · About Operation CHARM