One "bad" fuel injector??

[Zed Head]

7 hours ago, ramsesosirus said:

So essentially, I verified that:  1) the bad injector will not spray fuel no matter which spot on the rail it is installed to  2) the bad injector will not spray fuel no matter which electrical connector from the car it is connected to  

 6) after cranking the car with the bad injector installed, it won't spray, BUT when I push the pintle needle with a tool on the car, it WILL spray gas  7) the good and bad injectors all have (nearly) the same resistance  8)  all electrical connectors have the same voltage at the pins  

Only posting as a fan of rigor and method.  Did you actually try "all" of the other connectors? 

You've shown, according to your other posts with the 9 volt battery, that the bad injector will open electrically.  The solenoid will take current and produce a  magnetic field and the pintle will move.  But you haven't confirmed that the current available at the connector on the car is making it through the injector coil.  If it was mine, and I had your results, I'd run two jumpers from the engine electrical connector, measure voltage at each and then make sure that each pin in the injector got that voltage.  I would have done that right after it opened using the 9 volt battery.  Once you know that the current available at the car won't open the injector there's no need to swap it around.  You already know the injector "works" but won't work on your car.

[Chickenman]

^ Yes, I do believe  he did check electrical connectors and #5 connector worked with a different injector swapped in.

Quote from Post #1:

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Anyways, still no fuel from the bad injector.  Swapped injector connectors to make sure it wasn't them.  Same result.  So I know the connectors are good.  

 

 

 

[Zed Head]

The thing about electrical connectors is that we tend to assume that if the plastic fits, the metal parts are touching and electricity can flow.

All I'm saying is make sure that electricity can actually pass through the injector coil.  I have a bunch of alligator clips, and wire, and stripped solid core wire that I've crushed in to probes, so that I can be certain of things like this.  How many times have we wiggled the plastic on a connector and seen it affect the actual electrical contacts?

This is all just to know if the it's really bad.  If he has a pile of spare injectors and one works, he could just throw it in and run it.  I tend to take my broken stuff apart to know why it's broken.  When I'm done it's usually more broken.  Sometimes it ends up fixed though.

[ramsesosirus]

Good news, tried again and I got one of the spare injectors to spray on the car;

The initially bad one would only drip fuel, no spray. 

So I swapped it with one of the spares, and it sprayed, so I buttoned it all up and ran it, and the injector now passes the "screwdriver stethoscope" test, clicks just like the others.  

I think the cleaning probably helped, possibly applying 9v may have applied enough magnetic force to un-stick the spare injector.  (It was not working properly on the first try either).   

So I suppose, in summary, what I've learned is:

-9 v won't necessarily fry an injector (but it could).  I only touched the connection to make it pulse though, not a constant hook up.

-the screwdriver stethoscope is a great method to verify if the injector is or is not working

-both pins on the injector should have 12 volts (if good)

-the injector should have a resistance of about 3 ohms (if good)

-the ferrules on the injectors can be a pain to remove, to replace the hose

-if you can get the injector to spray/operate off the car, it should theoretically work on the car, given that other items are in proper working condition  (when I did the 9 volt, I wan't able to exert 36 psi of force, so I only got a stream out of the injectors.  But that is enough to verify no clogging.)  However, just because it operates off the car doesn't mean it will operate CORRECTLY on the car.  ie) fuel spray pattern, etc...

 

Also, my car seems to shake less through the chassis, so the bad cylinder may have  been contributing to this issue (maybe not engine mounts)

I will be monitoring this cylinder's plug, as well as checking the injector via the stethoscope test as I go, making sure it KEEPS working....

I do not seem to have the missing/surging issue at higher RPMs right now, likely due to getting this injector to fire as well as adjusting the TVS to only contact at idle and very close to WOT.  I may need to adjust again.  Both of the TVS that I have seem to initially touch the WOT contact way too early, and one had never been opened, which I found odd.    I do hear a change when I unplug the TVS at idle, so it is operating (enriching the idle mixture).

Thanks, hope this comes in handy for those facing similar issues.  

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[siteunseen]

When I first bought my 280 my mechanic bent those arms on the tps trying to get the stumble out. He'd twist the throttle rod and look then bend it some. Turns out it was the coolant sensor. I put a potentiometer in line and it runs great now. Fwiw