I think I have a dead injector

[thrdtryGSX]

I have searched dead injectors and nothing answered my question. I was trying to find out why I could not get my car to tune correctly. I went into misc. in the dsmlink menu and highlighted each injector individually. All of them made the car run like crap when I highlighted them except #2. I traced the wires back into the harness and replaced them with good wires and a good connector using solder. That did not help. Today I did a compression test and I have 145/140/145/145 for compression. The plug wires looked good they are only 3 months old NGK brand blue. #2 was wet and fouled so I replaced all of the sparkplugs with another set of bpr6's. I turned the engine over with the plug out to check for spark and no fuel or mist or anything. The transistor and coil pack are less than a year old so I am thinking it is fuel I read that a resistor pack goes bad. Would it be likely at 200,000 miles? Can I repair an FIC injector or do I need to replace it all together? How can I test this resistor pack? Thanks to those who help. DAN

 

[luv2rallye]

Sounds like the resistor for injector #2 is bad (or possibly the injector itself). Unplug injector #2. With key on (MPI relay activated) and engine not running, check for +12V on the black/blue wire of the connector. If not there the resistor is blown open. (You can do comparison with the black/yellow wire of injector 1 plug).

If +12V is there, you then need to measure the resistance of the resistor to see if within spec. Turn key off and disconnect one terminal of battery. You need to measure between that black/blue (black/yellow of injector 1 for comparison) and the red wire of the MPI relay. This red wire goes to many things but the easiest would probably be to use the red heater wire of the O2 sensor. The reading of injector 2 resistor should be near that of injector 1. The 2g turbo uses 5.5-6.5 ohm resistors. Couldn't find the value for the 1g but it should be similar (less than 15 ohms). At any rate it should be near injector 1's value.

If all that ok, then measure resistance of the injector itself. Should be 2-3 ohms.

 

[steve]

I go about this problem in a slightly different direction. I start at the ECU and check the injector pins with the ignition on but not running. You should see 12v at each. If you don't then work backward to the injector, resistor pack, etc until you find where the power stops.

Steve

 

[luv2rallye]

Well that works too. Just start at the other wire in the injector connector and you have Steve's way (minus the wire going to the ECU). If no +12V there then go to the ECU as Steve says to see if voltage there (to determine if problem is in the ECU or that wire). Since it's much easier to get at the injector harness than the ECU, I suggested starting at the injector first. But either way will work. Thanks Steve.

 

[thrdtryGSX]

I learned alot from you both thanks. I tracked down the prob. It was the injector itself. I am back to my 450's and running great. I took another resistor off of a talon parts car I have. Mine was cracked and very brittle. It still worked and tested 12v on all 4 terminals but it spit out the system failure code a couple days ago so I replaced it. Thank you both for the advice. DAN

 

[Talesin]

I'm tracking down a similar problem now... checked and have spark on all four, and it's blowing fuel out the back pretty badly. It'll run on two (or maybe three, not fully sure) for diagnostic purposes.

Disconnected the resistorpack (since it has a plug right there) and just checked the resistance from the white wire pin to each of the black wire pins. All of them came back between 4 and 7 ohms (my multimeter doesn't have a 1x scale, so I'm using the 10x).
All of the injectors themselves came back right around 3 ohms, though it's oddly difficult to get good contact with the injector electrical spades.
The battery's gone completely flat for some reason so I'll have to get a charger before I can test for +12V or plug in the noid light.
I did however check the resistance across the injector wires, and noted that 1-2 had a small measure of resistance, while 3-4 had infinite.

On a side note, three of the four spark plugs were fuel-fouled, but looking inside with a fiber optic light, only #2 is visibly fouled on the top of the piston.. so that's my suspected 'failing' injector, whether it's stuck open or whichever. Going to replace all the plugs, as it's really not worth even trying to clean them at this point.

 

[steve]

I'm tracking down a similar problem now.

I did however check the resistance across the injector wires, and noted that 1-2 had a small measure of resistance, while 3-4 had infinite.

This sounds suspect. From what to where were you measuring?

Steve

 

[Talesin]

Sorry, should have been clearer. Measuring from one receptacle of the injector wire to the other on the same plug (essentially putting the meter where the injector normally would be, electrically speaking), car off battery connected. The plugs for 1 and 2 showed some resistance, 3 and 4 were infinite. None of the checks listed above, just figured I had the meter right there, might as well see if there was an electrical path for sh*ts and grins.

Hopefully I'll be able to borrow a battery tomorrow and check for +12V as listed above, and start it with a noid light to make sure it's flashing correctly... if I can get things sussed before Tuesday, I can cancel my appointment with RRE, and save a few bucks.
At the very least I'll be able to point out things that it's not.

(edit: Actually, is there ANY way the MAS could be causing this? I have two, and I'd changed to my un-hacked one and reset the ECU a few days before the car started having this problem. I haven't swapped them back as it seems like a very, very remote possibility. Only reason I mention it is when something breaks, it's most likely due to the last thing you changed.)

 

[steve]

Sorry, should have been clearer. Measuring from one receptacle of the injector wire to the other on the same plug (essentially putting the meter where the injector normally would be, electrically speaking), car off battery connected. The plugs for 1 and 2 showed some resistance, 3 and 4 were infinite. None of the checks listed above, just figured I had the meter right there, might as well see if there was an electrical path for sh*ts and grins.

You didn't really measure anything interesting.
Measuring the resistance between pin 1 on the injector harness and the white wire on the resistor pack would test the wire between those two points. Between pin 2 and the same color wire at the ECU connector would test that side of the wiring.

Keep in mind that you can have intermitant problems that only happen when things are hot, as wall as, when things flex. If you not getting an injector code then it might be something else.

Steve

 

[Talesin]

As I said, was just for grins. Was just somewhat interesting to me that the two sides were matched.

It doesn't appear to be a hot versus cold type thing; the car's been sitting for a couple days now, and still starts and runs only on two cylinders. Believe me, I'd suspected that before. It almost seems random, to be honest.
Hopefully I'll get some answers today... though the test leads on my meter are just a little too short to test between the injector wire and ECU pins directly, I'll definitely be checking the end leading to the resistorpack. Here's hoping +12V shows up so it won't even really need to be tested.. otherwise I'll have to find some long-ass wires.

(edit)
Tested, and all have +12V on one wire. Looks like one of the injector plug ends was put on with the wires reversed, if that'd hurt anything. Also was registering a lower voltage on the other wire, around 8-10V. Didn't bother plugging in the noid light just yet.
It's also decided to stop exhibiting the behaviour now aside from running very rough/rich and occasionally misfiring, leaving me with a dead battery and quite confused.
Plugged in the datalogger and the MAS is reading around 5 at idle, while the O2 sensor isn't reading at all, even after the car warmed up... apparently a replacement is around $110 for a new Denso unit. I'm pretty sure that it was killed as an aftereffect of limping the car to an area with some kind of cell reception to get a tow, rather than being the cause of the failure.
While the datalogger was on, switched off a few injectors... #1 and 4 made a large difference to the idle (almost killed it) while 2 and 3 made a minimal, though noticeable change.