QuestionQUESTION: Will pick up a voltmeter on the way home from work today, I have a 12v test light. Ready to go!
ANSWER: Go to http://mg-tri-jag.net/XJ-6Inject1.jpg for half of the diagram and change the ending on the URL to /XJ-6Inject2.jpg for the other half.
Look at the power supply and the several grounds and test the ignition signal. Test all at the ECU plug in the trunk. The ECU must see the power supply and all of the several grounds and see a ignition pulse signal to start grounding injectors. All of the other input signals are to modify the injection pulse duration to control fuel mixture. You should also purchase a "Noid Light" available at most auto parts stores. (get the one for Bosch/Lucas systems) They are not expensive. It plugs into a injector wire. Don't forget to test the injector wire for power with the key on.
Let me know.
Howard
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QUESTION: I'll recap my test results since this has stretched out a bit:
ALL TEST IN FAILED MODE
Fuel Pressure test - 32psi (flap open) 40 psi vacuum removed from regulator (pressure holds after release of flap)
spark test - orange/red spark
noid light test - good on all 6 injectors
power to ALL 6 injectors (both sides) tested with 12v light
used a 12v test light (grounded to trunk bolt) (w/key on) tested large black plug into ECU:
got light on following pins:
1 - speed signal
10 - main feed
30 - injector 2 ground
31 - injector 1 ground
14 - injector 3 ground
32 - injector 4 ground
15 - injector 6 ground
33 - injector 5 ground
Am I testing the ECU correctly?
Are there pins that should light, that are not?
I noticed that there is no light from the ECU ground pins.
How do I test ignition signal?
Thank you again for your help.
ANSWER: Adam, If the Noid light flashed on every injector wire then the injection system is operating. If it starts for a second or two on starting fluid then you have to have primary and secondary ignition. But since you have Noid light flash this also proves you have primary ignition. When you have Noid light flash it is a waste of time checking anything else because Noid light flash is the END result for the ECU. This eliminates primary ignition and injection system up to the injectors. Spray in the intake and get a second or two run eliminates secondary Ignition (Coil, cap, wires and plugs) Power to the injectors eliminates the resistor pack and power supply. While your color of your spark is not great (should be thick and blue in a garage). It fired off on starting fluid.
This only leaves injectors and engine and exhaust. While injectors can fail it is not possible for 6 to die at the same time unless something is in the fuel like water. Since water has a very hard time getting through the injector orifice. If the engine runs and dies and then runs again later and dies again this rules out injector failure as six injectors can't all die at the same time and come back to life later.
What are the circumstances that the engine runs and dies? How long does it run when it runs? Can you go to high throttle settings when it runs? How long before you can restart?
FYI-- It is no use testing the ECU if you have Noid light flash on all injector wires. However, if you ever need to test the ECU you ground the clip of the test light as you did to test the powers IN (Main feed, Start signal#4 and engine speed signal (coil)) You didn't list any of the several ECU grounds. (35,17,16 %26 5) To test a ground you need a power supply to connect your clip to. Then probe pin # 35,17,16 %26 5. It is a good idea while at the ECU plug with the clip grounded to probe the injector grounds (misnamed) and you would probably find them hot because they would be receiving power from the resistor pack. This test would at least check the wiring from the ECU to each injector and on to the resistor pack.
There is a simple fact about all gasoline engines and that is that all piston gas engines only require 3 items to run, Compression, Fire and Fuel. Compression can make an engine die but it is not likely to come back later. So Fire and Fuel is where you need to look. ALL TESTS MUST BE RUN IN THE FAILED MODE!!!! Some times it is necessary to be able to see fire and fuel at the time of failure the failed mode is too short. A timing light under a wiper with the trigger taped down will give you a visual of Fire at the moment of failure. A "T" in the fuel line and a long hose out to a fuel pressure gauge under another wiper arm will give you a visual of Fuel supply at the time of failure. All this is only necessary when the failed mode is too short to catch and test.
Tell me about the car and when it first died and how long it ran between times it dies etc.
Howard
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QUESTION: Car suddenly died while running. Would not re-start... sat 2 days, started back up with no problems. Ran for 2 weeks, then died again while running. Would not re-start. Has sat for almost 3 weeks, will not start without starting fluid sprayed into intake, will sputter and die within 2 seconds of stopping spray. It will throttle up while being sprayed, but chokes out and dies once spray is stopped.
AnswerOk, At the last time when spray makes it run and no spray makes it stop there is NO injection of fuel so you need the pressure gauge on it in a "T" connection so it can still supply fuel to the rail and you can see pressure and pull only one injector wire and put the Noid light on it so you can see injection pulse and spray starter fluid into the intake and keep it running on starter fluid long enough to look at fuel pressure and the Noid light. If it still does not run keep spinning the engine or spraying starter fluid in and put you fingers on several injectors to feel the clicking. (or use a mechanic's stethoscope if you have one)
If you have fuel pressure and the engine runs on spray and the injectors are clicking, you need to remove several injectors and maybe the whole fuel rail and empty the left over fuel in the rail and injectors into a pan or jar so you can see if there is any water in the fuel.
Howard
