Injector clip only grounding once car is hot? wtf?
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Injector clip only grounding once car is hot? wtf?
So my car is being super weird. I usually can solve any problem that arises, but this one has me and everyone else I've talked to kind of stumped.
I drove the car 3 hours to the beach 2 weeks ago, everything was fine. The next afternoon I went to start it up to cruise around the beach for a bit and its only running on 3 cylinders. Cylinder 1 was not firing.
I was freaking out because I was so far from home and didn't bring any of my tools with me. I limped the car around for about 5 mins, and then, once it heated up...BAM injector starts firing and car is running strong and fine.
Everytime the car cools off and I start it up, same thing, 3 cylinders, car gets hot and then it starts running normal.
FACTS:
-I took a injector niode and tested the harness. Cylinder 1 injector is fine, however, per the niode test the clip is not sending a signal to shoot fuel in the cylinder.
-We tested the clip for power. There IS power on both sides of the clip.
-It appears it is not being grounded. However my question is then WHY THE HELL DOES IT GROUND WHEN THE CAR IS HOT?!
-Per discussion with my tuner, the ECU historically never has a problem with injector drivers.
I have not yet unloomed the wires and really started tracing them back to the rest of the harness and ECU but does anyone have any advice?
This is really freaking goofy.
I drove the car 3 hours to the beach 2 weeks ago, everything was fine. The next afternoon I went to start it up to cruise around the beach for a bit and its only running on 3 cylinders. Cylinder 1 was not firing.
I was freaking out because I was so far from home and didn't bring any of my tools with me. I limped the car around for about 5 mins, and then, once it heated up...BAM injector starts firing and car is running strong and fine.
Everytime the car cools off and I start it up, same thing, 3 cylinders, car gets hot and then it starts running normal.
FACTS:
-I took a injector niode and tested the harness. Cylinder 1 injector is fine, however, per the niode test the clip is not sending a signal to shoot fuel in the cylinder.
-We tested the clip for power. There IS power on both sides of the clip.
-It appears it is not being grounded. However my question is then WHY THE HELL DOES IT GROUND WHEN THE CAR IS HOT?!
-Per discussion with my tuner, the ECU historically never has a problem with injector drivers.
I have not yet unloomed the wires and really started tracing them back to the rest of the harness and ECU but does anyone have any advice?
This is really freaking goofy.
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Re: Injector clip only grounding once car is hot? wtf?
One side should be power. The other should be no resistance unless its being fired.. U need to find out why it has power on both side
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Re: Injector clip only grounding once car is hot? wtf?
Honestly, I'm not big on volts/amps, etc so I'm not sure what he really found. I'm a mechanical guy with very basic soldering abilities haha
What should we be seeing?
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Re: Injector clip only grounding once car is hot? wtf?
i would unwrap that wire and see if anything became loose/disconnected somewhere
could be that once the engine bay warms up enough the contacts can have good contact (kind of like how main relays go bad)
could be that once the engine bay warms up enough the contacts can have good contact (kind of like how main relays go bad)
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Re: Injector clip only grounding once car is hot? wtf?
Okay, anyone can feel free to correct me, but this is how I know honda injectors.
Injectors (in hondas and other vehicles) use NCT or Negative Controlled Transistors. The switch in the circuit is in the computer, on the negative side in order to not create a inductive kick into the circuit when it is switched on. This allows for longevity of the consumers(injectors) in that circuit as well as a way to control the voltage. So technically, if you unplug the injector connector and stick your leads into the connector, with the DMM on the Volt setting, you should receive battery voltage on the yellow and black side, and "OUCH" or "OL" on the brown wire.
The condition you are relating to sounds like a short when the car is cold, and a complete circuit when the vehicle is hot. Exactly what you are saying, the car is grounding when it is at operating temperature.
You could try doing a resistance check across the injector and match your number accordingly to the other three injectors while the vehicle is cold, and then warm. Possibly a short in the solenoid that is altered when the coil gets warm and can move the plunger in the injector.
The only other ideas I can think of right now could be either a ground being intermittent somewhere and adding some resistance to your circuit, possibly a chewed up wire under your dash from rodents or animals, and maybe the injector driver in the computer. This is an unusual condition with hondas coming from the experience I've had with them.
I'll stick around to see what you get.
Injectors (in hondas and other vehicles) use NCT or Negative Controlled Transistors. The switch in the circuit is in the computer, on the negative side in order to not create a inductive kick into the circuit when it is switched on. This allows for longevity of the consumers(injectors) in that circuit as well as a way to control the voltage. So technically, if you unplug the injector connector and stick your leads into the connector, with the DMM on the Volt setting, you should receive battery voltage on the yellow and black side, and "OUCH" or "OL" on the brown wire.
The condition you are relating to sounds like a short when the car is cold, and a complete circuit when the vehicle is hot. Exactly what you are saying, the car is grounding when it is at operating temperature.
You could try doing a resistance check across the injector and match your number accordingly to the other three injectors while the vehicle is cold, and then warm. Possibly a short in the solenoid that is altered when the coil gets warm and can move the plunger in the injector.
The only other ideas I can think of right now could be either a ground being intermittent somewhere and adding some resistance to your circuit, possibly a chewed up wire under your dash from rodents or animals, and maybe the injector driver in the computer. This is an unusual condition with hondas coming from the experience I've had with them.
I'll stick around to see what you get.
Last edited by Ramma; 07-28-2009 at 12:36 PM.
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Re: Injector clip only grounding once car is hot? wtf?
Btw, the comparing resistances is only for simplicity. You really should get the specs of whatever injectors you are using and compare your results to those.
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Re: Injector clip only grounding once car is hot? wtf?
Thanks for the thoughts guys. I'll just start unwrapping the wire and see what I find, it has to be something stupid. I doubt it would be injector driver related since the clip starts grounding once the car heats up. Sounds like something with the heat is causing metal to expand somewhere and complete the ground.
I'll report back once I've started messing around with some stuff.
I'll report back once I've started messing around with some stuff.
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Re: Injector clip only grounding once car is hot? wtf?
I'll be the one to disagree with your tuner.. I have seen and repaired many Honda ecu's with faulty injector drivers..
On a side note, a few years back, I had a customers bone stock 99 Civic Si that wouldn't start when the ambient temperature was below 40 degrees F.. After two days of troubleshooting it, I finally figured out that it was the ecu.. Put the ecu in the freezer for a few minutes, car wouldnt start. Left it in the sun for a few minutes, it would start right up, lol.. Stock P2T OBD2b Si ecu went into the trash can.
On a side note, a few years back, I had a customers bone stock 99 Civic Si that wouldn't start when the ambient temperature was below 40 degrees F.. After two days of troubleshooting it, I finally figured out that it was the ecu.. Put the ecu in the freezer for a few minutes, car wouldnt start. Left it in the sun for a few minutes, it would start right up, lol.. Stock P2T OBD2b Si ecu went into the trash can.
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Re: Injector clip only grounding once car is hot? wtf?
I'll be the one to disagree with your tuner.. I have seen and repaired many Honda ecu's with faulty injector drivers..
On a side note, a few years back, I had a customers bone stock 99 Civic Si that wouldn't start when the ambient temperature was below 40 degrees F.. After two days of troubleshooting it, I finally figured out that it was the ecu.. Put the ecu in the freezer for a few minutes, car wouldnt start. Left it in the sun for a few minutes, it would start right up, lol.. Stock P2T OBD2b Si ecu went into the trash can.
On a side note, a few years back, I had a customers bone stock 99 Civic Si that wouldn't start when the ambient temperature was below 40 degrees F.. After two days of troubleshooting it, I finally figured out that it was the ecu.. Put the ecu in the freezer for a few minutes, car wouldnt start. Left it in the sun for a few minutes, it would start right up, lol.. Stock P2T OBD2b Si ecu went into the trash can.
Yea but why would it only be 1 injector and why would is start working once the car heated up? To me it sounds like a wiring issue somewhere. The car will run for hours fine at 500+ whp once its heated up. I think if it was a driver I wouldn't be seeing those kind of events taking place...though I will admit I know very little about ECU's, wiring, and tuning, so please correct me if I'm wrong.
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