Engine Controls - Adjustments Jaguar XJS Series 3

INTRODUCTION

Note. Introduction information not applicable.

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

Scheme 1

1. Adjust valves with engine cold. With camshaft cover removed, rotate camshafts and record clearance between heel of each cam lobe and its respective tappet.
2. Adjust valve clearance if not within specification. See the «VALVE CLEARANCE SPECIFICATIONS»(/jaguar/xjs/series-3-1990-1996/remont/adjustments/#engine-controls-adjustments) table. If adjustment is necessary, rotate engine until cylinder No. 1 is at TDC of compression stroke. Align camshaft with Timing Gauge (18G 1433). VALVE CLEARANCE SPECIFICATIONS Application In. (mm) Intake & Exhaust.012-.014 (.30-.36) CAUTION: DO NOT rotate engine while camshaft sprocket is disconnected from camshaft. Serious damage can occur to valve train components.
3. Mark distributor rotor and housing position for installation reference. Remove distributor from engine. Remove upper chain tensioner clamp bolt. (Scheme 1)
4. Remove clamp and upper chain tensioner valve. Insert a 3-mm Allen key into center of tensioner. Turn Allen key clockwise until a click is heard. Chain tension is relieved.
5. Remove chain tensioner bolt and chain tensioner. Discard "O" ring and gasket from chain tensioner. Remove camshaft sprocket bolts and lock tabs. Remove camshaft sprockets.
6. Starting from center, remove camshaft bearing caps one at a time. Install Spacer (18G 1435) to cylinder head. Tighten spacer with cylinder head bolt. Tighten cylinder head bolt to 45 ft. lbs. (61 N.m); then turn bolt an additional 90 degrees.
7. Repeat step 6) until all camshaft caps are removed and replaced with spacers. Remove camshaft. Remove each tappet that required adjustment, and note its location for reassembly in its original position. Remove adjusting pad and measure thickness.
8. Use measured pad thickness and difference between measured valve clearance and specified clearance to calculate required thickness of new adjusting pad. Adjusting pads are available in increments of.001" (.03 mm) from.085" (2.16 mm) to.108" (2.74 mm) and are marked with letters from "A" to "X" respectively.
9. Insert correct adjusting pads and install cam followers. Install camshafts and align with timing gauge. Remove spacers from cylinder head in the following order: No. 1, 4, 2, 3, 5, and 6 cylinders. After removing one spacer, immediately install camshaft bearing cap before removing another spacer. NOTE: Always use new cylinder head bolts when installing bearing caps.
10. Install camshaft bearing caps. Tighten new cylinder head bolts in sequence to 45 ft. lbs. (61 N.m); then turn bolt an additional 90 degrees. (Scheme 2) Install camshaft bearing cap bolts. Tighten camshaft bolts to 17-20 ft. lbs. (23-27 N.m).
11. Install camshaft sprocket. Tighten camshaft sprocket nuts to 17-20 ft. lbs. (23-27 N.m). Install cam timing chain, chain tensioner and camshaft covers. Tighten camshaft cover bolts to 13.3 INCH lbs. (1.5 N.m).

Scheme 2

IGNITION TIMING

Ignition timing is electronically controlled by Electronic Control Module (ECM). Ignition timing adjustment is not necessary.

IDLE SPEED & MIXTURE

Note. Mixture adjustment is NOT a part of normal tune-up procedure and should not be performed unless mixture control unit is replaced or vehicle fails emissions testing.

BASE IDLE

1. Run engine until normal operating temperature is reached. Turn ignition off. Turn ignition on and wait 5 seconds. Disconnect wire harness connector from Idle Air Control Valve (IACV). Turn ignition off. Wait 15 seconds, then reconnect IACV connector.
2. Repeat step 1) twice and on the last procedure. DO NOT reconnect IACV connector. IACV should now be fully wound in. Start engine and check idle speed. If idle speed is not 550-600 RPM, adjust idle speed air by-pass screw using a 7/32" Allen wrench. Reconnect IACV wire harness connector.

IDLE SPEED & CO LEVEL

COLD (FAST) IDLE

Fast idle speed is electronically controlled by ECM. No adjustment is necessary.

THROTTLE BODY & LINKAGE

1. Remove air intake elbow. Remove intake elbow to throttle hose. using a feeler gauge, measure clearance between butterfly valve (throttle plate) and throttle body. Clearance should be.038-.064" (.97-1.63 mm).
2. If necessary, adjust butterfly valve gap by loosening throttle cable lock at manifold bracket. Loosen throttle stop lock nut. Adjust throttle stop screw to obtain a gap of.002" (0.05 mm) between butterfly valve and each side of housing. tighten throttle stop lock nut.
3. Install and align Full Throttle Setting Adjuster (JD131) to throttle stop plate. Ensure pointer aligns with "I" (idle mark) on throttle linkage. (Scheme 3)
4. Loosen full throttle stop lock nut. Fully open throttle and adjust full throttle adjustment screw to align pointer with "M" mark on throttle linkage. Release throttle linkage and tighten full throttle stop lock nut.
5. Remove full throttle setting adjuster. Check kickdown switch adjustment. See «KICKDOWN SWITCH»(/jaguar/xjs/series-3-1990-1996/remont/adjustments/#engine-controls-adjustments__kickdown-switch). Check base idle speed and adjust if necessary. See «BASE IDLE»(/jaguar/xjs/series-3-1990-1996/remont/adjustments/#engine-controls-adjustments__base-idle).

Scheme 3

MASS AIRFLOW SENSOR

1)Ensure engine is at normal operating temperature and Malfunction Indicator (CHECK ENGINE) Light (MIL) is not on. Place transmission in Neutral and let engine idle.

2) Using a digital volt-ohmmeter, measure mass airflow sensor output voltage between terminals No. 1 (ground) and 3. (Scheme 4) Mass airflow sensor output voltage should be 1.10-1.40 volts at idle.

3) Block driving wheels and firmly apply handbrake. Apply service brakes and place transmission in "D" (Drive). Have an assistant measure full throttle output voltage. Output voltage at full throttle should be 3.0-3.3 volts.

Scheme 4

KICKDOWN SWITCH

1. Locate throttle potentiometer harness connector. Using a digital volt-ohmmeter, backprobe terminal No. 5 (Green/Blue wire) at throttle potentiometer connector.
2. Turn ignition on. With accelerator pedal released (idle position), voltmeter reading should be .58-.62 volt. With accelerator pedal fully depressed (kickdown position), voltmeter reading should be 4.4-4.6 volt.
3. If necessary, set pedal to 90 percent of its travel and adjust pedal so voltmeter reading is 3.9-4.2 volts. This position is the kickdown point.
4. With accelerator pedal held at kickdown point, adjust kickdown switch to lightly contact the underside of accelerator pedal (using a piece of paper). When paper can be withdrawn with a slight resistance, the kickdown switch setting is correct. Road test vehicle to double check kickdown switch setting.

See also:
• VALVE CLEARANCE SPECIFICATIONS
• KICKDOWN SWITCH
• BASE IDLE