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injector test

how do you check an injector on a 85.5 944 n/a? need to test each one to find the bad ones

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Old 12-04-2003, 03:27 PM
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Check FRWilk.com


I Think......with engine on and clips on each injector loosened, pull them one at a time and see if there is any change in rpms etc. Should be a drop in rpms. If you pull one and nothing happens you should bench test it....see site above.
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Old 12-04-2003, 04:02 PM
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*WARNING: THIS PROCEDURE IS VERY DANGEROUS! GASOLINE IS VERY FLAMABLE, AND ATOMIZED FUEL IS EXPLOSIVE! USE EXTREME CARE AND DUE CAUTION!*

You can pull the fuel rail with the injectors still attached. Then either

  • Put cups under each injector and crank the motor. When you are done, check the cups and see if there is an equal or any fuel in each cup.
Or
  • unplug and connect two jumpers to a 9v batt. touch the jumpers to each post of the injector. This will open the injector. You'll have to run the pump to rebuild pressure between each test.
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Old 12-04-2003, 07:26 PM
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Two years ago I took all mine out and attached a hose filled with fuel then hooked up to an air compressor set at 50 psi. I blew them at a piece a cardboard after attaching a battery charger to them which is AC causing them to open and close. They all dumped the same pattern in the same number of seconds.

I then did it again squirting them into a test tube. Amount looked same.

This is not really scientific, but the car runs well except for puking oil out of its pan gasket which I'm on this weekend.
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Old 12-05-2003, 03:30 PM
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Checking flow and spray patterns is important. If the little flattened end is broken off of the pin you will get a stream of gas and not a fine spray. Not good.

Use the same procedure to slip a hose filled with solvent over the delivery end of the injector and use shop air to drive the solvent backwards through the injector. Don't need any 12 volts as this is force the pintel open against the return spring. Mostly flushes the filter screens on the feed side.
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Old 12-05-2003, 06:56 PM
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so far we have tested just about everything... DME, all grounds, errr.. still have the run and stall problem..... but will run on 3 cylinders if you unplug one injector.. and it doesnt matter which one
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Old 12-05-2003, 07:05 PM
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FPR

High pressure. Not enough magnetic force in the injectors to open unless you take one off line and thus increase the current to the others.
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When was the last time you changed your timing and balance belts and/or cam chain and tensioner?
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Old 12-05-2003, 07:27 PM
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i put a brand new one on.. didnt change anything.... i have replaced the fuel pump, dme relay, and fuel pressure regulator... only thing on the fuel system i havent replaced is the fuel damper.. would that cause high fuel pressure?
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Old 12-06-2003, 06:51 AM
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I think SoCal hit the nail again. If you unplug 1 and runs with all 4 plugged in won't not enough voltage to pull all 4.

Remove and clean the engine ground strap. Scrape the paint away where attaches to the firewall and clean. After re-attachind spray down with "battery terminal protectant".

Pick up a "noid" light at auto parts store for bosch injectors to monitor the pulses as well.

Check for vacuum at the fpr and fpd

Seeing as you went ahead and replaced the pump, how about the filter? should do it at the same time. It is also wise to replace the fpr and fpd as a set as well.

Rick

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Old 12-06-2003, 07:24 AM
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