Toyota Camry 1983-1996 Repair Guide

Ignition Timing

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GENERAL INFORMATION



Ignition timing is the measurement (in degrees) of crankshaft position at the instant the spark plug fires. Ignition timing is adjusted by loosening the distributor locking device and turning the distributor in the engine.

It takes a fraction of a second for the spark from the plug to completely ignite the mixture in the cylinder. Because of this, the spark plug must fire before the piston reaches TDC (top dead center, the highest point in its travel), if the mixture is to be completely ignited as the piston passes TDC. This measurement is given in degrees (of crankshaft rotation) before the piston reaches top dead center (BTDC). If the ignition timing setting for your engine is 10° BTDC, this means that the spark plug must fire at a time when the piston for that cylinder is 10° before top dead center of its compression stroke. However, this only holds true while your engine is at idle speed.

As you accelerate from idle, the speed of your engine (rpm) increases. The increase in rpm means that the pistons are now traveling up and down much faster. Because of this, the spark plugs will have to fire even sooner if the mixture is to be completely ignited as the piston passes TDC. To accomplish this, the distributor incorporates means to advance the timing of the spark as the engine speed increases.

The distributor in your Toyota has two means of advancing the ignition timing. One is called vacuum advance and is controlled by that large circular housing on the side of the distributor. This type of distributor is found on vehicles produced in the US from 1983-85 and also those produced in Canada in 1986. The other Electronic Spark Advance (ESA) and is controlled by a microcomputer in 1986-96.

In addition, some distributors have a vacuum retard mechanism which is contained in the same housing on the side of the distributor as the vacuum advance. The function of this mechanism is to retard the timing of the ignition spark under certain engine conditions. This causes more complete burning of the air/fuel mixture in the cylinder and consequently lowers exhaust emissions.

Because these mechanisms change ignition timing, it is necessary to disconnect and plug the one or two vacuum lines from the distributor when setting the basic ignition timing, if the distributor is equipped with a vacuum advancer.

If the ignition timing is set too far advanced (BTDC), the ignition and expansion of the air/fuel mixture in the cylinder will try to force the piston down while it is still traveling upward. This causes engine ping, a sound which resembles marbles being dropped into an empty tin can. If the ignition timing is too far retarded (after, or ATDC), the piston will have already started down on the power stroke when the air/fuel mixture ignites and expands. This will cause the piston to be forced down only a portion of its travel. This results in poor engine performance and lack of power.

Ignition timing adjustment is checked with a timing light. This instrument is connected to the number one (No. 1) spark plug of the engine. The timing light flashes every time an electrical current is sent from the distributor through the No. 1 spark plug wire to the spark plug. The crankshaft pulley and the front cover of the engine are marked with a timing pointer and a timing scale.

When the timing pointer is aligned with the 0 mark on the timing scale, the piston in the No. 1 cylinder is at TDC of it compression stroke. With the engine running, and the timing light aimed at the timing pointer and timing scale, the stroboscopic (periodic) flashes from the timing light will allow you to check the ignition timing setting of the engine. The timing light flashes every time the spark plug in the No. 1 cylinder of the engine fires. Since the flash from the timing light makes the crankshaft pulley seem to stand still for a moment, you will be able to read the exact position of the piston in the No. 1 cylinder on the timing scale on the front of the engine.

If you're buying a timing light, make sure the unit you select is rated for electronic or solid-state ignitions. Generally, these lights have two wires which connect to the battery with alligator clips and a third wire which connects to the No. 1 plug wire. The best lights have an inductive pick-up on the third wire; this allows you to simply clip the small box over the wire. Older lights may require the removal of the plug wire and the installation of an in-line adapter. Since the spark plugs in the twin-cam engines are in deep wells, rigging the adapter can be difficult. Buy quality the first time and the tool will give lasting results and ease of use.

INSPECTION & ADJUSTMENT



Canada and 1983-85 US Models

See Figures 1, 4 and 8

  1. Warm up the engine, apply the parking brake and block the wheels. Stop the engine when warm.
  2.  
  3. Locate the IIA service connector coming from the distributor and remove the rubber protective cap.
  4.  
  5. Attach the test probe of the tachometer to the service connector. Check the idle speed with the tachometer and make sure that it is correct. Adjust as necessary.
  6.  
  7. Attach the timing light to the engine according to the manufactures instructions. If the timing marks are not visible, use chalk or a dab of paint to mark them.
  8.  
  9. Disconnect the two vacuum lines from the vacuum advance and plug the lines.
  10.  
  11. Start the engine and run it at idle with the transaxle in Neutral on manual transaxles and Park on automatics. Make sure the parking rake is securely set and that the wheels are blocked.
  12.  
  13. Point the timing light at the timing marks. With the engine at idle, the timing mark on the crankshaft pulley should be aligned with the degree mark specified in the tune-up chart or according to the values listed on the emissions label.
  14.  
  15. If the timing is not specified, loosen the pinch bolt at the base of the distributor and move the unit to advance or retard the timing as required.
  16.  
  17. Stop the engine and tighten the pinch bolt. Start the engine and recheck the timing and the idle speed.
  18.  
  19. Stop the engine and disconnect the timing light and the tachometer. Install the rubber cap on the service connector.
  20.  
  21. Reconnect the vacuum lines to the advancer.
  22.  

1986-95 Models
EXCEPT 1MZ-FE

See Figures 1, 2, 3, 4, 5, 6, 7 and 8

This service procedure is for setting base ignition timing. Refer to underhood emission sticker for any additional service procedure steps and/or specifications.

  1. Warm the engine to normal operating temperature. Turn off all electrical accessories. Do not attempt to check timing specification or idle speed on a cold engine.
  2.  
  3. Connect a tachometer (as shown in the illustrations) and check the engine idle speed to be sure it is within the specification given in the Tune-Up Specifications chart or underhood emission sticker.
  4.  



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Fig. Fig. 1: Attach the tachometer to the battery and check connector terminals-2S-ELC and 3S-FE engines



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Fig. Fig. 2: Attach the tachometer to the battery and check connector terminals-2VZ-FE engine



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Fig. Fig. 3: Attach the tachometer to the battery and check connector terminals-3VZ-FE and 5S-FE engines

  1. Remove the cap on the diagnostic check connector. Using a small jumper wire or Special Service Tool SST 09843-18020, short terminals at T and E1 (1986-88) and TE1 and E1 together (1989-96).
  2.  



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Fig. Fig. 4: Using the SST 09843-18020 or a jumper wire, connect terminals TE1 and E1 of the DLC1-2S-ELC and 3S-FE engines



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Fig. Fig. 5: Using the SST 09843-18020 or a jumper wire, connect terminals TE1 and E1 of the DLC1-2VZ-FE engine



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Fig. Fig. 6: Using the SST 09843-18020 or a jumper wire, connect terminals TE1 and E1 of the DLC1-3VZ-FE and 5S-FE engines

  1. If the timing marks are difficult to see, shut the engine OFF and use a dab of paint or chalk to make them more visible.
  2.  
  3. Connect a timing light according to the manufacturer's instructions.
  4.  
  5. Start the engine and use the timing light to observe the timing marks. With the jumper wire in the check connector the timing should be to specifications (refer to underhood emission sticker as necessary) with the engine fully warmed up (at correct idle speed) and the transmission in correct position. If the timing is not correct, loosen the bolts at the distributor just enough so that the distributor can be turned. Turn the distributor to advance or retard the timing as required. Once the proper marks are seen to align with the timing light, timing is correct.
  6.  



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Fig. Fig. 7: Aim the timing light at the mark-1986-96 models

  1. Without changing the position of the distributor, tighten the distributor bolts and double check the timing with the light (check idle speed as necessary). Tighten the pinch bolt to 9 ft. lbs. (13 Nm) on 2S-ELC and 3S-FE engine, 14 ft. lbs. (19 Nm) on 5S-FE engines or 13 ft. lbs. (18 Nm) on the 2VZ-FE and 3VZ-FE engines.
  2.  



Click image to see an enlarged view

Fig. Fig. 8: Loosen the distributor bolt(s) and turn the unit to adjust

  1. Disconnect the jumper wire or Special Service Tool (SST) at the diagnostic check connector.
  2.  

This jumper will be used repeatedly during diagnostics in later sections. Take the time to make a proper jumper with correct terminals or probes. It's a valuable special tool for very low cost.

  1. Refer to the underhood emission sticker for timing specification and any additional service procedure steps. If necessary, repeat the timing adjustment procedure.
  2.  
  3. Shut the engine OFF and disconnect all test equipment. Roadtest the vehicle for proper operation.
  4.  

1MZ-FE ENGINE

See Figures 9, 10 and 11

This procedure only applies to the 1994 1MZ-FE engine. The timing on 1995 engines is not adjustable.

This service procedure is for setting base ignition timing. Refer to underhood emission sticker for any additional service procedure steps and/or specifications.

These engines require a tachometer hook-up to the check connector-see illustrations. NEVER allow the tachometer terminal to become grounded; severe and expensive damage can occur to the coil and/or igniter.

Some tachometers are not compatible with this ignition system, confirm the compatibility of your unit before using.

  1. Warm the engine to normal operating temperature. Turn off all electrical accessories. Do not attempt to check timing specification or idle speed on a cold engine.
  2.  
  3. Connect a tachometer (+) terminal to the terminal IG- of the data link connector.
  4.  



Click image to see an enlarged view

Fig. Fig. 9: Attach the tachometer to the battery and check connector terminals-1MZ-FE engine

  1. Connect a timing light according to the manufacturer's instructions. On the 1MZ-FE engines, using a 5mm hexagon wrench, remove the two cap nuts and valve bank cover. Attach the timing light pick-up clip on the green lead wire for the No. 4 ignition coil. The timing light will detect the primary signal.
  2.  



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Fig. Fig. 10: Attach the timing light clip to the green wire of the lead wire on the No. 4 coil-1MZ-FE engine



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Fig. Fig. 11: Timing mark at TDC-1994 1MZ-FE engine

  1. Race the engine speed at 2500 rpms for approximately 90 seconds. Check the idle speed.
  2.  
  3. Using SST 09843-18020 or its equivalent jumper wire, connect terminals TE1 and E1 of the DLC1 under the hood.
  4.  
  5. Check the ignition timing, the reading should be 8-12° BTDC at idle.
  6.  
  7. Remove the jumper wire from the DLC1.
  8.  
  9. Recheck the timing, the mark ranges from 7°-17° BTDC at idle. The timing mark will move in the range specified.
  10.  
  11. Disconnect the timing light. Install the valve bank cover and tighten the cap nuts.
  12.  
  13. Disconnect the tachometer from the engine.
  14.  
  15. Roadtest the vehicle for proper operation.
  16.  

1995 1MZ-FE and 1996 Models

The ignition timing is not adjustable on these engines.

 
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