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    VWVortex


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    Thread: Fuel injectors

    1. 09-27-2012 12:57 PM #1
      What is the easiest way to check injectors spray? Do take the whole fuel rail and injectors out and check them all at the same time or pull the rail and plug the other 3 holes somehow? Or some other way?

    2. Member
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      09-27-2012 08:17 PM #2
      CIS injectors can be pulled and observed -- they operate based on fuel pressure. Digifant injectors are electrical -- basically they are a solenoid which opens and closes based on an electrical signal. The computer controls the length of open time. Since you mention "fuel rail" in your post you are likely talking Digifant. All of the Digifant II injectors fire at the same time.

      I test the resistance of Digifant injectors with a multimeter. Each injector if disconnected and tested individually should test between 15 and 20 Ohms. You can test off the end of the fuel rail electrical connection. Disconnect the connector and test across the fuel rail end of the connector. Four injectors connected should test at 3.7 to 5 Ohms, three injectors connected should test at 5 to 6.7 Ohms, two injectors connected should test at 7.5 to 10 Ohms and you should get the above 15-20 Ohms with only one injector connected. I also test the harness for wiring faults. If the injector is out of specification replace it.

      You can also use a 12V DC LED test light to test for injector pulse across the terminals of the wire end of the fuel rail connector. LEDs are polarized so if you do not initially get results reverse the connections. The test light should flicker when you have someone try to start the car. The flickering is fast and I generally cup the test light in my hands to see the flicker better. FR

    3. 09-27-2012 08:48 PM #3
      It is digi2. I tested the ohms to each of them already. They were all 17.x I was gonna check of they were clogged. Is that not possibly? I had also tested the ohms to the end of the fuel rail and it was 4.9.

    4. 09-27-2012 10:08 PM #4
      Is there an easy way to get the fuel rail on the injectors once it is off?
      Last edited by veedubclub91; 09-28-2012 at 09:57 AM.

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      09-28-2012 12:49 PM #5
      According to your test results all of the injectors are OK. I have never had issues with reassembling the fuel rail and injectors. I simply lube the "O" rings with gasoline and put it all back together. If the present "O" rings have any time on them at all or if you don't know when they were last replaced I'd replace them. Maybe a place that works on injectors could flow test each injector individually. They probably would want quite a bit to do that -- maybe $10-20 per injector. I also suppose you could pull the fuel rail, reinstall the injectors into it and try to observe the injectors as they fire. That might get messy. FR

    6. 09-28-2012 03:55 PM #6
      Is it easier to put the injectors in the fuel rail first and then put the whole thing in? Or injectors in head then put fuel rail in? I tried lubbing the o rings with gas and they still dont wanna go in. I remember having a hard time the last tome I put a fuel rail in but I dont remember how I ended up getting it on. It was at least 7-8 years since I've had a fuel rail off.

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      09-28-2012 09:05 PM #7
      Thought I answered this earlier but don't see my response. As I recall -- I've done it both ways in the past. But, like you, have not installed a fuel rail for a few years. I believe it would be easier to carefully seat the injectors in the fuel rail first -- then push the assembly into the head so it seats well. Then install the screws and injector clips. While I am thinking of it -- one thing I have done is remove the fuel rail, pressurized the system and observed the injectors off the engine but still connected to the fuel rail for fuel leakage. That's different from actually firing the injectors to observe spray patterns -- but I suppose, as I indicated above, that could also be done if done carefully. (I am not a big fan of spraying gas around.) When we would bench test CIS injectors for opening pressure and spray pattern we used mineral oil instead of gasoline. FR

    8. 09-30-2012 08:37 AM #8
      So I pulled all the injectors out cleaned em up a little and replaced the o rings. Lubbed em up real good with gas and they slid right on this time. Guess I didnt lube em up enough the first time. They were easiest putting the injectors in the head then putting the fuel rail on. Thanks for the help.

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