2G 420A - No power to fuel injectors... What am I missing?

[Dipwhittle]

None of my injectors are getting power, so it's obviously at a point where they all connect. I checked continuity at A-74, A-82 and A-107 for all of them. In the MFI system diagram, it looks like they're in parallel with the heated o2 sensors, spark plugs/coil, and "generator." Since my spark plugs are still getting spark, (and because I heard it) I know the ASD relay isn't the issue. I don't think there's a short drawing all of the voltage to another branch, unless it's past the spark plugs, which I'll be checking soon.

If that doesn't work out, I'll be tracing voltage, but I'm not sure if there's a constant 12V applied to the injectors or if it's only when the engine is cranking. Either way, it wasn't there. I just need to know that for when I'm tracing if anyone knows.

Anyone else got another idea that could be causing it?

The main thing I need an answer for here is whether the 12V is constant or only when cranking. That's not very clear on the diagrams. I can keep bumbling my way through the rest of the electrical.

 

[evil_eagletalon]

Post some diagrams.
Do you have voltage while crankiing?

 

[Dipwhittle]

Post some diagrams.
Do you have voltage while crankiing?

Nope, that's why I'm trying to find out which it is -- so I know how to look for it while I'm tracing voltage.

 

[Sirius1995]

Probably either your crank or cam sensor, and have you done continuity test/measure resistance for the harness?

There's a noid light what you can use to test if injectors get power when cranking, they only get power a short time to energize injector's solenoids so cheap multimeters won't even catch that

 

[evil_eagletalon]

No power at pin 13 of a-82?

 

[BLACK'98DSM]

Rule out the cam sensor. It has no effect on fuel injectors, or any part of the fuel system. It is only used for determining ignition timing.

 

[Dipwhittle]

Probably either your crank or cam sensor, and have you done continuity test/measure resistance for the harness?

There's a noid light what you can use to test if injectors get power when cranking, they only get power a short time to energize injector's solenoids so cheap multimeters won't even catch that

I have a noid light on order. It hasn’t shown up yet. Is the power or ground the one that the PCM sends the signal through? The way it is on my other car, there is a constant 12V to the power that you can just check as long as the key is on, and when you crank, the PCM flickers the ground connection. I wouldn’t see anything on a cheap multimeter if I measured across the lines, but if I use a chassis ground, I can see it. I know that some models, it’s the other way around though. That’s why I was asking if there’s a constant 12V with the PCM flickering the ground side or if the PCM flickers the power when you crank.

 

[Dipwhittle]

No power at pin 13 of a-82?

I only checked continuity. I’ll check power. Is it constant or only while cranking there?

 

[Sirius1995]

ECM grounds injectors, Just wait until you get your noid light to do further diag for it.

Injectors are only energized when rotation is detected from CPS, that also turns your fuel pump on

 

[evil_eagletalon]

According to the diagrams i found it looks like constant power and pcm grounds the injector.

 

[Sirius1995]

According to the diagrams i found it looks like constant power and pcm grounds the injector.

I'm also just looking at it, yea, it's 12V constant and PCM grounds it

Power comes from ASD relay, if power side looks good then check pin 6 from PCM and other grounds too, if ground is also good, it's either your ASD relay or PCM.

Looks like CPS only powers fuel pump.

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[evil_eagletalon]

He said he has spark so im assuming the asd relay is good. Go to joint connector a82 and check power at pin 15.

 

[jesse12345]

I went through everything you did except my fuel pump lost power it ended up being the pcm. I can't beleive how many of these actually have problems. I feel like the gel that it's coated in doesn't help it at all.

 

[BLACK'98DSM]

The gel is intended to act as a shock absorber, reducing internal damage from standard vibrations. It isn't harmful by itself. It does typically deem the boards as non-serviceable though. I hardly see a defective OE ecu, but I also mostly deal with cars that have not spent time in corrosive areas or have hacked up wiring harnesses (less risk of electrical short). The biggest killer is electrical shorts. I wish the connectors had some sort of rubber gasket as I've seen build up engine oil and water inside the connectors causing the shorts and burning the boards.

 

[jesse12345]

Yeah I live in a very nasty area so maybe corrosion runs through the connector itself. I'm no wizard in the pcm department but I can see why it's made how it is, with the pcm being under the hood as apposed to inside the car.

 

[Dipwhittle]

I'm also just looking at it, yea, it's 12V constant and PCM grounds it

Power comes from ASD relay, if power side looks good then check pin 6 from PCM and other grounds too, if ground is also good, it's either your ASD relay or PCM.

Looks like CPS only powers fuel pump.

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What website or document did you get this version of the diagrams from? My books are still on order, but I'd like a good electronic copy, and this one seems to combine the entire circuit rather than splitting it up.


Also, just an update for anyone that cares... my noid light still hasn't shipped... it says it'll be here next week though. I guess the holidays have slowed the process down pretty significantly.

 

[Sirius1995]

What website or document did you get this version of the diagrams from? My books are still on order, but I'd like a good electronic copy, and this one seems to combine the entire circuit rather than splitting it up.


Also, just an update for anyone that cares... my noid light still hasn't shipped... it says it'll be here next week though. I guess the holidays have slowed the process down pretty significantly.

Using alldata at work but you can download wiring diagrams for eclipse for free, just search in the forum for workshop manuals

 

[Dipwhittle]

Ok, got a noid light and injector rebuild kit in. I used those. Noid light was getting nothing. Reinstalled injectors after rebuild and was getting voltage to noid somehow. Traced continuity, and it turns out there was a break in the harness an inch or so away from the connector that caused intermittent connectivity/voltage. It wasn't melted or bare, so I wouldn't have noticed it if I wasn't wiggling the cable looking for it. I soldered it and... it started. It's running super sluggishly though. I just put new oil and stuff in it, so I imagine it's just burning off years of neglect. On to the other problems, . Thanks for all the help guys. I'll probably be posting again when I get stuck, which is bound to happen with this car. it's in pretty rough shape.