Thread: trigger points
View Single Post
norustscott norustscott is offline
Registered User
norustscott's Avatar
Join Date: Jun 2000
Location: sykesville, MD
Posts: 912
Here is a quick in car test, although not exact, will help trouble shooting efforts. Trigger points fire alternating pairs of injectors. 1/4 and 2/3. With the ignition in the run position go to the engine bay. Operate the throttle from closed to wide open ( note: the engine is NOT running) the TPS, throttle position switch will send a signal to rapidly open close the injectors 1/4 or 2/3 according to the trigger point position. ( this is sort of an electronic accelerator pump function) With one hand operating the throttle, place the other on an injector. you can feel the "BRRRRRP"sound made by the injector when operating the throttle. You should be able to feel/ hear the BRRRP from two injectors on opposite sides of the engine. 1/4 or 2/3 Now, Turn the engine over 180 degrees. You should now be able to repeat the process with the other pair ( opposite sides of the engine). This will tell you that the trigger points are making contact and completing the require circuit. However, you may still have some sort of trigger point mechanical failure, although rare that could still be a problem during operation. I have used this trick to trace bad injectors, poor grounds, a bad wiring harness ... This test does require a good TPS ( throtle position switch) and should be tested before jumping to Trigger point conclusions...

Hope this helps...

1982 911 SC
1962 sunroof bug
1991 WE Vanagon CARAT WRX conversion
Old 01-30-2004, 06:36 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)