Engine idle is affected by valve timing, spur belt tension, cold start advance, injection pump timing, accelerator cable adjustment, idle speed and maximum speed.

Therefore all of these items should be checked to assure that all factors that can cause idle problems are adjusted properly.

 

Perform injection system tests:

• Check/adjust valve timing
• Check/adjust cold start advance
• Check/adjust injection pump timing
• Check/adjust idle and maximum speed

 

Quality check

Except 1981 – 82 Rabbit/Jetta

1. Start engine, allow to warm up and observe idle quality.
   • the idle speed is correct
   • engine should idle smoothly
   • the idle speed should not vary more than 50 RPM
2. With correct tire pressure, drive car on a level road.  Accelerate to a constant speed of 35 MPH.
   • in 3rd gear (4-speed transmission)
   • in 4th gear (5-speed transmission)
3. Accelerate again to full throttle and note the acceleration quality from 35 MPH to 55 MPH.
   • engine should accelerate evenly
   • engine should not lack power or smoke
4. Maintain steady speed and observe performance quality.
   • engine should maintain adequate performance at all speeds and show no symptoms of loss of power or smoke.

1981 – 82 Rabbit/Jetta

1. Start engine, allow to warm up and observe idle quality
   • the idle speed is correct
   • engine should idle smoothly
   • the idle speed should not vary more than 50 RPM
2. With correct tire pressure, drive car on a level road.  Accelerate to a constant speed of 35 MPH.
   • in 3rd gear (4-speed transmission)
   • in 4th gear (5-speed transmission)
3. Accelerate again to full throttle and note the time it takes to reach 55 MPH.
   • should be 16.1 seconds maximum (4-speed transmission)
   • should be 18.6 seconds maximum (5-speed transmission)

If test passed, return car to customer
If test failed and if diagnosis I and II have been completed, replace injection pump.