GM Cutlass RWD 1970-1987 Repair Guide

Troubleshooting The HEI System

Print

The symptoms of a defective component within the HEI system are exactly the same as those you would encounter in a conventional system. Some of these symptoms are:



Hard or No Starting
 
Rough Idle
 
Poor Fuel Economy
 
Engine misses under load or while accelerating
 

If you suspect a problem in your ignition system, there are certain preliminary checks which you should carry out before you begin to check the electronic portions of the system. First, it is extremely important to make sure the vehicle battery is in a good state of charge. A defective or poorly charged battery will cause the various components of the ignition system to read incorrectly when they are being tested. Second, make sure all wiring connections are clean and tight, not only at the battery, but also at the distributor cap, ignition coil and at the electronic control module.

Since the only change between electronic and conventional ignition systems is in the distributor component area, it is imperative to check the secondary ignition circuit first. If the secondary circuit checks out properly, then the engine condition is probably not the fault of the ignition system. To check the secondary ignition system, perform a simple spark test. Remove one of the plug wires and insert some sort of extension in the plug socket. An old spark plug with the ground electrode removed make a good extension. Hold the wire and extension about 1 / 4 in. away from the block and crank the engine.


CAUTION
Its a good idea to wear heavy gloves at this time.

If a normal spark occurs, then the problem is most likely not in the ignition system. Check for fuel system problems, or fouled spark plugs.

If, however, their is no spark or a weak spark, then further ignition system testing will have to be done. Troubleshooting techniques fall into two categories, depending on the nature of the problem. The categories are:

  1. Engine cranks, but won't start.
  2.  
  3. Engine runs, but runs rough or cuts out.
  4.  

To begin with, let's consider the first case.

Engine Fails to Start

If the engine won't start, perform a spark test as described earlier. This will narrow the problem area down considerably. If no spark occurs, check for the presence of normal battery voltage at the battery terminal (BAT) in the distributor cap. The ignition switch must be in the on position for this test. Either a voltmeter or a test light may be used for this test. Connect the test light wire to ground and the probe end at the BAT terminal at the distributor. If the light comes on, you have voltage to the distributor. If the light fails to come on, this indicates an open circuit in the ignition primary wiring leading to the distributor. In this case, you will have to check wiring continuity back to the ignition switch using a test light. If there is battery voltage at the BAT terminal, but no spark at the plugs, then the problem lies within the distributor assembly. Go on to the distributor components test section.

Engine Runs, But Runs Rough or Cuts Out
  1. Make sure the plug wires are in good shape first. There should be no obvious cracks or breaks. You can check the plug wires with an ohmmeter, but do not pierce the wires with a probe. Check the chart for the correct plug wire resistance.
  2.  
  3. If the plug wires are OK, remove the cap assembly and check for moisture, cracks, chips or carbon tracks, or any other high voltage leaks or failures. Replace the cap if any defects are found. Make sure the timer wheel rotates when the engine is cranked. If everything is all right so far, go on to the distributor components test section.
  4.  

DISTRIBUTOR COMPONENTS TESTING



If the trouble has been narrowed down to the units within the distributor, the following tests can help pinpoint the defective component. An ohmmeter with both high and low ranges should be used. These tests are made with the cap assembly removed. and the battery wire disconnected. If a tachometer is connected to the TACH terminal, disconnect it before making these tests.

  1. Connect a ohmmeter between the TACH and BAT terminals in the distributor cap. The primary coil resistance should be less than 1 -.
  2.  
  3. To check the coil secondary resistance, connect an ohmmeter between the rotor button and the BAT terminal. Note the reading. Connect the ohmmeter between the rotor button and the TACH terminal. Note the reading. The resistance in both cases should be between 6,000 and 30,000 -. Be sure to test between the rotor button and both the BAT and TACH terminals.
  4.  
  5. Replace the coil only if the readings in Step 1 and Step 2 are infinite.
  6.  

These resistance checks will not disclose shorted coil windings. This condition can only be detected with scope analysis or a suitably designed coil tester. If these instruments are unavailable, replace the coil with a known good coil as a final coil test.

  1. To test the pick-up coil, first disconnect the white and green module leads. Set the ohmmeter on the high scale and connect it between a ground and either the white or green lead. Any resistance measurement less than infinity requires replacement of the pick-up coil.
  2.  
  3. Pick-up coil continuity is tested by connecting the ohmmeter (on low range) between the white and green leads. Normal resistance is between 650 and 850 -, or 500 and 1500 - on 1977 and later models. Move the vacuum advance arm while performing this test. This will detect any break in coil continuity. Such a condition can cause intermittent misfiring. Replace the pick-up coil if the reading is outside the specified limits.
  4.  

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Ohmmeter 1 shows the primary coil resistance connection. Ohmmeter 2 shows the secondary connection (1980 shown, most models similar)

  1. If no defects have been found at this time, and you still have a problem, then the module will have to be checked. If you do not have access to a module tester, the only possible alternative is a substitution test. If the module fails the substitution test, replace it.
  2.  

HEI SYSTEM MAINTENANCE



Except for periodic checks of the spark plug wires, and an occasional check of the distributor cap for cracks (see Steps 1 and 2 under Engine Runs, But Runs Rough or Cuts Out for details), no maintenance is required on the HEI system. No periodic lubrication is necessary; engine oil lubricates the lower bushing, and an oil-filled reservoir lubricates the upper bushing.

Component Replacement

See Figures 2, 3, 4, 5 and 6

Integral Ignition Coil

  1. Disconnect the feed and module wire terminal connectors from the distributor cap.
  2.  
  3. Remove the ignition set retainer.
  4.  
  5. Remove the 4 coil cover-to-distributor cap screws and coil cover.
  6.  
  7. Using a blunt drift, press the coil wire spade terminals up out of the distributor cap.
  8.  
  9. Lift the coil up out of the distributor cap.
  10.  
  11. Remove and clean the coil spring, rubber seal washer and coil cavity of the distributor cap.
  12.  



Click image to see an enlarged view

Fig. Fig. 2: Disconnect the feed and module wire terminal connectors from the distributor cap.



Click image to see an enlarged view

Fig. Fig. 3: Loosen the coil cap retaining screws and remove the coil cap



Click image to see an enlarged view

Fig. Fig. 4: Loosen the coil attaching screws and remove the cap

To install:
  1. Coat the rubber seal with a dielectric lubricant furnished in the replacement ignition coil package.
  2.  
  3. Install the coil spring, coil assembly and press the coil terminals into the distributor cap.
  4.  
  5. Install the coil cover and torque the attaching screws to 60 inch lbs. (6 Nm).
  6.  
  7. Position the spark plug wire and retainer over the correct cap terminals, then engage the retainer and plug wires to the cap. Attach the distributor feed wires and negative battery cable.
  8.  



Click image to see an enlarged view

Fig. Fig. 5: Coat the rubber seal with a dieletric grease



Click image to see an enlarged view

Fig. Fig. 6: Install the coil assembly and press the coil terminals into the distributor cap

Distributor Cap

See Figures 7 and 8

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner, feed and module wire terminal connectors from the distributor cap.
  4.  
  5. Remove the retainer and spark plug wires from the cap. Remember to label them first.
  6.  
  7. Depress and release the 4 distributor cap-to-housing retainers and lift off the cap assembly.
  8.  



Click image to see an enlarged view

Fig. Fig. 7: Label and disconnect the spark plug wires, remove the retainer



Click image to see an enlarged view

Fig. Fig. 8: Depress and release the 4 distributor cap-to-housing retainers and lift off the cap assembly

  1. Remove the four coil cover screws and cover.
  2.  
  3. Using a finger or a blunt drift, push the coil spade terminals up out of the distributor cap.
  4.  
  5. Remove all four coil screws and lift the coil, coil spring and rubber seal washer out of the cap coil cavity.
  6.  
  7. Using a new distributor cap, reverse the above procedures to assemble being sure to clean and lubricate the rubber seal washer with dielectric lubricant. Torque the coil cover attaching screws to 60 inch lbs. (6 Nm). Make sure the spark plug wire retainer and the four cap-to-housing retainers are fully engaged. Connect the negative battery cable.
  8.  

Rotor

See Figures 9 and 10

  1. Disconnect the negative battery cable and remove the air cleaner assembly.
  2.  
  3. Disconnect the feed and module wire connectors from the distributor.
  4.  
  5. Depress and release the 4 distributor cap-to-housing retainers and lift off the cap assembly.
  6.  
  7. Remove the two rotor attaching screws and rotor.
  8.  
  9. Install the rotor, make sure that the square shaft tab is properly engaged with the rotor and torque the retaining screws to 60 in. lbs. (6 Nm). Reinstall the cap and connect the neative battery cable.
  10.  



Click image to see an enlarged view

Fig. Fig. 9: Remove the two rotor attaching screws



Click image to see an enlarged view

Fig. Fig. 10: Remove the rotor

Vacuum Advance

  1. Disconnect the negative battery cable, and remove the air cleaner. Remove the distributor cap and rotor as previously described.
  2.  
  3. Disconnect the vacuum hose from the vacuum advance unit.
  4.  
  5. Remove the two vacuum advance retaining screws, pull the advance unit outward, rotate and disengage the operating rod from its tang.
  6.  
  7. Install the vacuum advance and engauge the operating rod, torque the screws to 60 in. lbs. (6 Nm) and in stall the distributor cap.
  8.  
  9. Install the air cleaner and connect the negative battery cable.
  10.  

Module

  1. Remove the distributor cap and rotor as previously described.
  2.  
  3. Disconnect the harness connector and pick-up coil spade connectors from the module. Be careful not to damage the wires when removing the connector.
  4.  
  5. Remove the two screws and module from the distributor housing.
  6.  
  7. Coat the bottom of the new module with electric lubricant supplied with the new module..
  8.  

The silicone lubricant supplied with new modules MUST be applied, as it serves as a heat conductor and aids in module cooling. Running the engine and ignition system without the silicone lubricant is the equivalent of running the engine without antifreeze! That is, the module will cook itself without the lubricant!

  1. Install the new module and torque the retaining screws to 48 in. lbs (5Nm)
  2.  
  3. Connect the module wiring harness and install the distributor cap.
  4.  
  5. Connect the negative battery cable and install the air cleaner.
  6.  

PICK-UP COIL



See Figures 11 and 12

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Mark the base of the distributor and the position of the rotor-to-housing. Remove the distributor-to-engine block retainer and bolt. Make sure the distributor base is marked with a scribe or grease pen for proper timing after installation.
  6.  
  7. Remove the distributor cap and disconnect the cap harnesses.
  8.  
  9. Twist and pull upward to remove the distributor assembly from the block.
  10.  
  11. Mark the distributor shaft and gear so they can be reassembled in the position.
  12.  
  13. Drive out the roll pin with a flat punch or equivalent.
  14.  



Click image to see an enlarged view

Fig. Fig. 11: Mark the base of the distributor and the position of the rotor to housing. Remove the distributor-to-engine block retainer and bolt



Click image to see an enlarged view

Fig. Fig. 12: Remove the distributor

  1. Remove the gear and pull the shaft out of the distributor housing.
  2.  
  3. Disconnect the pick-up harness.
  4.  
  5. Remove the three pick-up coil attaching screws and remove the magnetic shield, C washer, pick-up coil, magnet and pole piece.
  6.  

To install:
  1. Install the pick-up coil so wires go through the opening provided.
  2.  
  3. Install the magnet, pole piece and torque the three screws to 50 inch lbs. (5 Nm).
  4.  
  5. Clean the shaft with solvent to remove the varnish to ease installation.
  6.  
  7. Install the C washer, shaft, gear and tap in the roll pin. Make sure the marks are lined up. Connect the pick-up wiring harness.
  8.  
  9. Install the distributor into the block at the original marked position.
  10.  


WARNING
Make sure the distributor seats into the block fully. The base of the housing will stick up about1/4of an inch until the distributor gear engages the oil pump drive. Damage to the oil pump, distributor and engine may result if the distributor is forced into position by tightening the distributor retainer bolt. If the distributor will not fully seat, grab the housing and shaft, twist and wiggle until the distributor drops into the oil pump drive. If this does not work, install a socket wrench onto the large bolt on the front of the crankshaft pulley. Slowly turn the crankshaft in either direction until the distributor drops into the block fully.

  1. Install the distributor and retainer. Hand tighten the bolt at this time.
  2.  
  3. Install the distributor cap, connect the wiring harness and negative battery cable.
  4.  
  5. Plug all disconnected vacuum lines, install a inductive timing light and adjust the timing to specifications. Refer to the underhood sticker and timing procedures in this section for more information.
  6.  
  7. Install the air cleaner and connect the vacuum hoses.
  8.  

HEI SYSTEM TACHOMETER HOOKUP



See Figure 13

There is a terminal marked TACH on the distributor cap. Connect one tachometer lead to this terminal and the other lead to a ground. On some tachometers, the leads must be connected to the TACH terminal and to the battery positive terminal.


CAUTION
Never ground the TACH terminal; serious module and ignition coil damage will result. If their is any doubt as to the correct tachometer hookup, check with the tachometer manufacturer.



Click image to see an enlarged view

Fig. Fig. 13: Tachometer connection for the HEI system

TACHOMETER HOOK-UP-DIESEL ENGINE



A magnetic pickup tachometer is necessary because of the lack of an ignition system. The tachometer probe is inserted into the hole in the timing indicator.

 
label.common.footer.alt.autozoneLogo