Volvo Coupes/Sedans/Wagons 1970-1989 Repair Guide

Fuel Injected Engines

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IDLE SPEED & MIXTURE ADJUSTMENTS



K-Jetronic (Through 1975) and L-Jetronic Systems

See Figure 1

The idle mixture adjustment or CO value may be set only with the use of a CO meter. This adjustment is made by attaching a CO meter to the exhaust pipe of a vehicle with a warm (176°F/80°C) engine, and turning the adjusting screw of the Bosch control unit (beneath the passenger seat) until the correct CO value is obtained. The correct value is 1-1.5 percent for cars with manual transmissions and 0.5-1.0 percent for cars with automatic transmissions. Because this operation requires highly technical skills and expensive equipment, it is best referred to a Volvo dealer or other competent shop.

The idle speed adjustment may, on the other hand, be set with a tachometer and an average amount of experience. The check should be made with the engine idling at temperature (176°F/80°F). On 140 and 1800 series Volvos, remove the air cleaner-to-inlet duct hose. Check to see that the auxiliary air regulator is closed properly by removing the inlet duct-to-regulator hose and covering the opening with your hand. If the idle speed differs greatly, the engine is not fully warm or the regulator is faulty. Fit the hose again and adjust the idle speed to specifications with the idle adjusting screw. The idle adjusting screw is located on the inlet duct below the air cleaner hose opening on four-cylinder models, and inline in the auxiliary air pipe on six-cylinder models (see illustrations). On 140 and 1800 series Volvos, install the air cleaner hose.



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Fig. Fig. 1: Mechanical (K-Jetronic) idle speed adjuster

Bosch Continuous Fuel Injection Adjustment (Mechanical)

Special Tools Required: CO meter and CO idle mixture adjusting Allen wrench (Volvo tool No. 999 5015). For 1981 and later models, see the Constant Idle Speed (CIS) system.

1974-75 B20 F ENGINE

1974 140 series models, and all 240 and 260 series and 1980 models are equipped with the CIS system. With this system, the injectors are open all the time, and the amount of fuel injected is directly proportional to the amount of air drawn into the intake.

The idle mixture adjustment or carbon monoxide (CO) value may be set only with the use of a CO meter. Also, a special tapered setscrew tool is needed to turn the mixture adjusting screw. The adjustment is made with the engine idling at curb idle speed and at operating temperature-176°F (80°C) with the CO meter attached to the exhaust pipe. 1975 models with air injection require disconnecting and plugging the air pump output hose to prevent an erroneous CO reading. With the special setscrew tool inserted into the small hose between the fuel distributor and the bellows for the air sensor plate, engage the adjusting screw and adjust to a 1.5 percent CO value.

The idle speed adjustment is a simple matter of rotating the idle adjusting screw located in-line in the auxiliary air pipe. With the engine idling at operating temperature-176°F (80°C)-and the transmission in neutral, adjust to 800 rpm on cars with automatic transmission, and 900 rpm on cars with manual transmission.

B21F ENGINE

See Figure 2

  1. Disconnect and plug the air injection pump output hose and the EGR vacuum hose.
  2.  
  3. With the engine warmed to operating temperature-176°F (80°C)-check that the idle speed is 900 rpm (manual transmission) or 800 rpm (automatic) with the car idling in neutral. Adjust as necessary by rotating the air adjusting screw (knob) located beneath the intake air box.
  4.  
  5. With the engine at specified idle speed, check that the CO value is 2.0 percent (1.0 percent 1977-80). Adjust as necessary by inserting special tool No. 5015 into adjustment hole located between the air intake bellows and the fuel distributor. Recheck the idle speed.
  6.  


WARNING
Do not race the engine with the tool inserted.

  1. Stop the engine.
  2.  



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Fig. Fig. 2: Adjust the idle mixture as shown-B21F engines

B27F AND B28F ENGINES

See Figures 3 and 4

Special Tools Required: CO meter with two position switch capable of isolating left or right cylinder banks, CO meter plumbing and fittings to screw into exhaust pipe gas pickup points and CO idle mixture adjusting Allen wrench (Volvo tool No. 999 5102).

  1. Remove the air cleaner and housing. Disconnect the air pump output hose (large hose on rear of pump) and plug it with a large diameter screwdriver shaft. Disconnect and plug the vacuum hose at the EGR valve.
  2.  
  3. Set the idle balance screws (No. 1 and No. 2) to their basic setting by screwing them in clockwise until they bottom out, and then backing them off counterclockwise 4 full turns each.
  4.  
  5. Start the engine and allow it to reach operating temperature (176°F/80°C). Using the idle air adjusting screw (No. 3), set the idle speed to 900 rpm.
  6.  
  7. Using the CO meter, check that the carbon monoxide level is 1.4-2.0 percent (1.0 percent 1977-80) at 900 rpm. If necessary, adjust CO level by inserting the special Allen wrench (Volvo tool No. 5102) into the adjustment hose between the fuel distributor and throttle valve, and turning it clockwise to increase CO and counterclockwise to reduce CO. Before inserting the tool, remove the copper washer and plug covering the hose. Also, between adjustments, remove the tool and plug the hose to prevent a lean mixture and erroneous reading. Do not race the engine with tool inserted.
  8.  

On oxygen sensor equipped models, perform CO adjustments with sensor disconnected. When sensor is connected after adjustment, CO should drop below 1 percent.



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Fig. Fig. 3: Location of idle balance screws "1" and "2" and the air adjusting screw "3"-B27F and B28F engines

  1. The final step is to check the CO balance between the right and left cylinder banks. Both must have equal CO value; (see Step 4). Air adjusting screw No. 3 controls the total amount of air bypassing the throttle at idle, whereas screws number 1 and 2 divide this air to the two cylinder banks. Screw No. 1 is for the right (passenger) side cylinders, and screw No. 2 is for the left side. If you decrease the airflow past screw No. 2, it will increase the airflow past screw No. 1, and vice versa. More air means a leaner mixture, and less air a richer mixture. After balancing the CO value of each cylinder bank, recheck the total CO value at 900 rpm. Stop the engine.
  2.  



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Fig. Fig. 4: Make sure the idle speed adjustment screw is bottomed on its seat-1981-86 B28F engines

THROTTLE SWITCH AND BASE IDLE ADJUSTMENTS



Bosch Constant Idle Speed (CIS) System-1981 and Later

See Figure 5

This system controls the engine idle speed by regulating air flow around (bypassing) the throttle valve in the intake manifold. It is used on engines with both mechanical and LH-Jetronic electronic fuel injection systems.



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Fig. Fig. 5: CIS system idle speed adjuster location

1981 B21F ENGINE

See Figures 6 and 7

  1. Run the engine to normal operating temperature. Disconnect the throttle control rod at the lever. Make sure the cable and pulley run smoothly and do not bind in any position.
  2.  
  3. Remove the Emission Control Unit (ECU) cover panel. De-activate the ECU by disconnecting the white-red wire from terminal 12 of the blue connector plug at the ECU. Reinstall the connector plug.
  4.  

The same wire ends at the ignition coil but cannot be disconnected there.

  1. Connect a tachometer to the engine according to the manufacturer's instructions. Connect a test light across the battery positive terminal and the terminal on the throttle micro-switch with the yellow wire connected. Start the engine. The test light must NOT light up. If it does, adjust the micro-switch position by slackening the switch retaining screws. Move the switch down until the light goes out, then retighten the screws.
  2.  

This adjustment is temporary; final adjustment will follow later.

  1. Idle speed should be 850-900 rpm. If outside these limits, adjust idle speed by proceeding to Step 5. If idle speed is within these limits, continue to Step 6.
  2.  
  3. If the idle speed is outside the stated limits, use the throttle position adjustment screw to adjust the speed to 850-900 rpm. The test light must NOT light up; if it does, readjust the micro-switch position. Reconnect the white-red wire in terminal 12 of the blue connector plug at the ECU to reactivate the ECU. The idle speed should have changed to 900 rpm (850-950 rpm is permitted). Stop the engine.
  4.  
  5. Reconnect the throttle control rod at the lever, making sure the cable pulley is completely retracted. If the control rod length must be adjusted, disconnect the throttle cable and automatic transmission kickdown cable (if equipped). Loosen the locknuts on either end of the rod and adjust the rod as necessary by turning the nut on the end of the cable. Automatic transmission kickdown cable length should be checked at closed and open throttle with the engine OFF . Open throttle cable measurement should be checked with the throttle pedal in the car depressed, NOT by actuating the linkage by hand. The cable should be pulled out about 1.97 in. (50mm).
  6.  
  7. Adjust the micro-switch by moving the switch UP, with the engine not running and the throttle closed. Adjust the switch UP until the test light lights up. Set the switch position by moving the switch DOWN 0.08-0.10 in. (2.0-5.5mm). The test light must NOT light or the adjustment will have to be performed again.
  8.  
  9. Remove the test light, reinstall the ECU panel.
  10.  



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Fig. Fig. 6: Adjust the idle speed if the test light illumines at idle speed-B21F engine with CIS



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Fig. Fig. 7: Disconnect the throttle control rod at this location-B21 engines

1981 B21F-MPG; 1982-83 B21F AND B23E ENGINES

The procedures for these engine models are the same as those for the 1981 B21F above, EXCEPT that the ECU from 1982 on has two extra terminals, 7 and 10, to de-activate the ECU, ground terminal 10 with the connector in place by inserting a copper wire along the terminal wire. Also, the idle speed should be 700 rpm with the ECU de-activated, and 750 rpm (700-800 rpm permitted) with the ECU activated. On Step 2, DO NOT reinstall the connector plug.

1981-85 B21F TURBO ENGINE

See Figures 8 and 9

  1. Follow Steps 1 and 2 of the 1981 B21F procedure EXCEPT do not reinstall the connector plug. Note the procedure above for de-activating 1982 and later ECUs.
  2.  
  3. Connect the test light across the battery positive terminal and the orange wire terminal on the throttle micro-switch.The test light must NOT light up while adjusting the idle speed. (The electric circuit through the micro-switch is open.) If the test light illuminates, adjust the micro-switch position by loosening the switch retaining screws and moving the switch down until the test light goes out. Tighten the screws. This is a temporary adjustment; the final adjustment will follow later on.
  4.  
  5. Run the engine to normal operating temperature if not already done. Connect a tachometer to the engine and check idle speed; idle speed should be 850 rpm. If idle speed is outside these limits, follow the procedure below.
  6.  
  7. Using the throttle position adjustment screw, adjust throttle position until the idle speed reaches 850 rpm. The test light must NOT light up. If necessary, adjust the micro-switch position DOWN.
  8.  
  9. Activate the ECU by reconnecting the white-red wire in terminal 12 of the blue connector on 1981 models, and by disconnecting the ground wire that was inserted at terminal 10 of the blue connector on 1982 and later models.
  10.  
  11. After activating the ECU, the idle speed should change to 900 rpm on (850-950 permitted) on 1981 models, and to 900 rpm (880-920 rpm permitted) on 1982 and later models. Stop the engine and install the ECU panel.
  12.  
  13. Reconnect and adjust the throttle control rod and cable, and the automatic transmission kickdown cable (if equipped) by following Step 6 of the 1981 B21F procedure.
  14.  
  15. Adjust the B21F Turbo throttle switch by inserting a 0.12 in (0.3mm) feeler gauge between the throttle adjustment screw and the throttle control lever. Move the switch UP until the test light lights up. Set the switch by moving it DOWN until the test light just goes out. Disconnect all test instruments, install the ECU panel.
  16.  



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Fig. Fig. 8: Use a 0.3mm feeler gauge between the throttle adjustment screw and the throttle control lever-B21F turbo engine



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Fig. Fig. 9: Turn the adjuster nut to pull or loosen the automatic transmission kickdown cable-B21F turbo

IDLE ADJUSTMENT



Bosch LH-Jetronic System
1982 B21F; 1983-89 B23F AND B230F ENGINES

See Figure 10

  1. Seat the throttle butterfly valve by loosening the stop nut on the adjuster one or two turns. Set the adjuster screw by screwing it in until it just touches the lever, then screw it in an additional 1 / 4 turn. Tighten the locknut.
  2.  
  3. Disconnect the CIS connector in the firewall. This is the connector that is directly behind the engine.
  4.  



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Fig. Fig. 10: LH-Jetronic idle adjustment location

  1. Connect a test light across the battery positive terminal and the orange wire terminal in the connector. Start the engine. The test light SHOULD LIGHT up at idle speed. If it does not, readjust the adjuster screw for the throttle butterfly valve position.
  2.  
  3. Open the throttle slightly (by hand) at the throttle control lever, with the engine running. The test light should go out. If it does not, run through the procedure again and try a new throttle switch.
  4.  

1981-83 B23F ENGINE
  1. Disconnect the throttle rod at the cable pulley. Check the cable assembly, making sure the cable and pulley run smoothly and do not bind in any position. Check the throttle; make sure the throttle shaft and plate do not bind during operation.
  2.  
  3. Screw in the idle speed adjustment screw all the way until it just seats.
  4.  

This screw is used to adjust the idle speed on engines without the CIS system.

  1. Remove the access panel to the ECU module. (The ECU is located on the passenger's side kick panel on all models except the 760 GLE, on which the ECU is mounted on the driver's side kick panel).
  2.  
  3. On 1981 models, disconnect the white-red wire at terminal 12 of the blue connector plug at the ECU. On 1982 and later models, ground terminal 10 with the connector in place. This can be done by inserting a copper wire along the number 10 terminal wire.
  4.  
  5. Connect a test light across the positive battery terminal and the orange wire terminal on the throttle micro-switch. On 1981 models, the test light should light up while adjusting the micro-switch, indicating current is flowing through the switch. On 1982 and later models, the test light should NOT light up while adjusting the switch, indicating the electric circuit through the micro-switch is interrupted.
  6.  
  7. Connect a tachometer to the engine, and run the engine up to normal operating temperature.
  8.  
  9. Adjust the idle speed by adjusting the throttle position adjustment screw. DO NOT adjust the idle speed screw (it should still be screwed in on its seat).
  10.  
  11. Activate the ECU by reconnecting the white-red wire in the blue connector at the ECU. With the ECU activated, the idle speed should change to 900 rpm on 1981 and 1982 models (850-950 permitted on 1981, 880-920 permitted on 1982) and 750 rpm on 1983. Shut off the engine and install the ECU panel.
  12.  
  13. Reconnect the throttle control rod at the cable pulley. Disconnect the throttle cable and automatic transmission kickdown cable. The cable pulley should be completely retracted. Adjust the control rod length as necessary. Attach and adjust the throttle cable.
  14.  
  15. Check automatic transmission kickdown cable length at closed and open throttle with the engine off. Open throttle measurement should be checked with the throttle pedal in the car depressed, NOT by actuating the linkage by hand. Cable movement should be about 2 in. (50mm). Cable length with closed throttle should be 0.4 in. (1mm); with open throttle, 2.4 in. (51mm).
  16.  
  17. To adjust the throttle micro-switch, insert 0.12 in. (3mm) feeler gauge between the throttle position adjustment screw and the throttle stop. On 1981 models, adjust the switch by turning the adjustment screw until the test light comes on.
  18.  

1982-86 B28F ENGINE
  1. Disconnect the throttle rod at the cable pulley. Check the cable assembly, making sure the cable and pulley run smoothly and do not bind in any position. Check the throttle, make sure the throttle shaft and plate do not bind during operation.
  2.  
  3. Screw in the idle speed adjustment screw all the way until it just seats.
  4.  

This screw is used to adjust the idle speed on engines without the CIS system.

  1. Remove the access panel to the ECU module. (The ECU is located on the passenger's side kick panel on all models except the 760 GLE, on which the ECU is mounted on the driver's side kick panel).
  2.  
  3. On 1982-86 models, ground terminal 10 with the connector in place. This can be done by inserting a copper wire along the number 10 terminal wire.
  4.  
  5. Connect a test light across the positive battery terminal and the orange wire terminal on the throttle micro-switch. The test light should NOT light up while adjusting the switch, indicating the electric circuit through the micro-switch is interrupted.
  6.  
  7. Connect a tachometer to the engine, and run the engine up to normal operating temperature.
  8.  
  9. Adjust the idle speed by adjusting the throttle position adjustment screw. DO NOT adjust the idle speed screw (it should still be screwed in on its seat).
  10.  
  11. Activate the ECU. With the ECU activated, the idle speed should change to 900 rpm 1982 models (880-920 rpm permitted) and 750 rpm on 1983-86. Shut off the engine and install the ECU panel.
  12.  
  13. Reconnect the throttle control rod at the cable pulley. Disconnect the throttle cable and automatic transmission kickdown cable. The cable pulley should be completely retracted. Adjust the control rod length as necessary. Attach and adjust the throttle cable.
  14.  
  15. Check automatic transmission kickdown cable length at closed and open throttle with the engine off. Open throttle measurement should be checked with the throttle pedal in the car depressed, NOT by actuating the linkage by hand. Cable movement should be about 2 in. (50mm). Cable length with closed throttle should be about 0.04 in. (1mm); with open throttle, 1.97 in. (50mm).
  16.  
  17. To adjust the throttle micro-switch, insert 0.12 in. (3mm) feeler gauge between the throttle position adjustment screw and the throttle stop. Turn the adjustment screw until the test light lights up.
  18.  

SWITCH ADJUSTMENT



Full Throttle Enrichment Switch
1982-86 B28F ENGINE

The B28F V6 is equipped with two micro-switches actuated by throttle control. This second micro-switch closes a Lambda-Sond (the oxygen sensor) circuit at full throttle to provide richer air/fuel mixture at maximum acceleration. Vehicles sold in high-altitude areas have this switch disconnected.

  1. To adjust the switch, loosen the micro-switch retaining screws. Turn the switch sideways. The test light should come on, then go out 3 / 32 in. (2.5mm) before the pulley touches the full throttle stop. Tighten the retaining screws.
  2.  
  3. To check full throttle enrichment switch operations, disconnect the green wire at the micro-switch. Connect a test light between the micro-switch terminal and the positive battery terminal.
  4.  
  5. Turn the pulley slowly to the full throttle stop. The test light should light up 1 / 32 - 5 / 32 in. (1-4mm) before the pulley touches the stop. Adjust the switch as necessary, following the switch adjustment procedure above.
  6.  

1987-89 B280F ENGINE
  1. Ground the CIS test point. The CIS test point is the red/white wire in the two wire connector which is located in the engine compartment across from the air conditioning compressor.
  2.  
  3. The green/white wire is the test point location for the oxygen sensor test.
  4.  
  5. Grounding the red/white wire will set the air valve in the wide open position.
  6.  
  7. Adjust the basic idle speed to 700 rpm. Disconnect the ground wire from the CIS test point. The idle speed should increase to 750 rpm.
  8.  

 
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