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Old 06-08-2011, 09:28 PM   #1
Ztrip
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Matt Zwicker
Default 1984 Crossfire - One injector not working

I recently fixed a couple of codes that the car was bringing up. Now, however, one of my injectors (drivers side) isn't spraying at all and the car just dies after a few seconds (not surprisingly). I took the electrical connector off of the injector that works and connected it to the faulty injector. That made it work. So that eliminated any mechanical problem with the throttle body and must point to a problem with the connector itself? Although I am getting around 12 volts on the connector (of the non working injector).

Does anyone have any insight in how I can track and fix the problem?

Thanks!
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Old 06-08-2011, 10:04 PM   #2
tehcarguy
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How do you know it's not working? You should test them with a noid light. The engine should still run even with one faulty injector. You need to check other things, is the fuel pressure good? Are you getting a good spark? Is the timing right?
Edit: sorry, just noticed it was an 84 that only has two injectors so nevermind...

Last edited by tehcarguy; 06-08-2011 at 10:09 PM.
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Old 06-08-2011, 11:35 PM   #3
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Does the "bad" connector work on the other injector?
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Old 06-09-2011, 09:57 AM   #4
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Yes it worked when I put the good injector connector on the bad injector. But like I said there is still voltage from the connector of the non working injector. So I'm a little confused.
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Old 06-09-2011, 10:10 AM   #5
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but did you put the connector that was not working on the injector that was working normally. It could be a problem with the connector even though it has 12v to it. The injector 12v comes from the inj1 and inj2 fuses. the other two wires go to the ecm and are grounds that get triggered from the ecm. the ground wire could be messed up. thats why I asked if you tried the "bad" connector on the other injector to make sure the connector worked properly.
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Old 06-09-2011, 10:22 AM   #6
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Oh sorry, I see what you're saying. I didn't try that, but Im certainly gonna now! (After work). Thanks.
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Old 06-09-2011, 12:44 PM   #7
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Update:

I hooked the bad connector up to the working injector and the car would not start.

Though both connectors had 0 volts on the ground wire and 12 volts on the positive one. (theoretically meaning both connectors should be good?)

One odd thing I noticed and I'm not sure if it's my multimeter or the car, but I find voltage to be surging up and down. I set my TPS to 0.54v recently and all of a sudden it would spike to 5v then down to 0v when I just check it again. Eventually I got it to read a steady 0.52v. Same thing with the battery, it would spike between around 0v and 12v, but sometimes stay steady at around 12v.

I also checked resistance of both connectors on ground wire and every now and then there would be a quick spike.

Again, could be a messed up multimeter, or the car? Any insight would be appreciated as I am certainly no electrician....or a decent mechanic. Thanks!
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Old 06-09-2011, 12:56 PM   #8
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The 'bad' connector wire has a break somewhere.

Testing it with a volt meter would show nothing or '0' volts,break or not.

Try tying the 'bad' connectors ground wire to the 'good' connectors ground and see if it works.

If so, then you need to find the break.

Those injectors are 'batch' fired. Which means they both fire at the same time so tying the grounds together to test won't hurt a thing.

BTW. I should have mentioned that the 'ground' side of the connectors is really the 'pulse' line from the ECM.


One injector goes to pin 8 and the other injector goes to pin 9 on the ECM but I think they are tied together internally.. Not certain though.

Here is a diagram showing the connections: (near the bottom of the page)

http://chevythunder.com/cross_fire_i...n_19821984.htm

Last edited by Keystring; 06-09-2011 at 01:19 PM.
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Old 06-09-2011, 05:23 PM   #9
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Quote:
Originally Posted by Keystring View Post
The 'bad' connector wire has a break somewhere.

Testing it with a volt meter would show nothing or '0' volts,break or not.

Try tying the 'bad' connectors ground wire to the 'good' connectors ground and see if it works.

If so, then you need to find the break.

Those injectors are 'batch' fired. Which means they both fire at the same time so tying the grounds together to test won't hurt a thing.

BTW. I should have mentioned that the 'ground' side of the connectors is really the 'pulse' line from the ECM.


One injector goes to pin 8 and the other injector goes to pin 9 on the ECM but I think they are tied together internally.. Not certain though.

Here is a diagram showing the connections: (near the bottom of the page)

http://chevythunder.com/cross_fire_i...n_19821984.htm
a ground spike would be the ecm triggering the injector. I would try tying the 2 injector grounds together like he said to see if that helps.
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Old 06-09-2011, 08:31 PM   #10
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Thanks for the info guys. I was able to combine the ground wires, and success....for about 20 seconds....then the car died. My battery is weak, however, from all of the electrical testing I've been doing without the engine running.

I had my other car boosting the battery as I tried starting the vette again but no luck. I then put the connectors back on normally (where one injector would usually fire up) and the car still didn't start.

There was a bit of mist in the air, so I'm not sure if that would have an effect on the combustion process or not. (Seeing as how the throttle bodies and valves are open to atmosphere.)

I will try again tomorrow, hopefully it's dry out. At least now I do know for sure that the ground is bad on one of the injectors......how fun it will be to track down the bad point.
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Old 06-09-2011, 09:22 PM   #11
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Charge your battery and try again. The important part is that your making some sort of progress. The wire just runs right behind the distributor on the passenger side and thru the firewall to the ecm.
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Old 06-13-2011, 01:25 PM   #12
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Update:

Battery is charge now and I connected the injector grounds together again. Both injectors are firing but car does not want to keep running. Should there be a difference in firing sequence? It appeared that they may have been injecting fuel at the same time.

Thanks
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Old 06-13-2011, 09:34 PM   #13
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I would go about finding out where the short in the wire is and fix that first and see what happens. You don't wanna be chasing down a "why wont it run" problem while you still haven't fixed that original non fire problem as the 2 might be the same problem
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Old 06-13-2011, 09:38 PM   #14
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Oh good point, I'm still looking for the bad spot. I suppose in the mean time I was just wondering if an altering spray pattern would be noticeable. I'll just keep trying to find the break. Hopefully I'll find it soon I want to getting this beast running well for the summer!
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Old 07-25-2011, 08:11 PM   #15
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I found out that it wasn't a break in the ground wire. It was the ECM itself. I checked for continuity between the injector and the pin at the ECM and there was nothing. So I orderd a new ECM and installed it. Both injectors are now firing, however, the car is running pretty much the same as it was before (before injector stopped working). It stumbles bad on hard acceleration, backfires a bit and the exhasut smell is very rich and sweet. I'll check my TPS voltage setting again (since I put a new ECM in)? and check for any bad vacuum lines and check the timing....other than that I'm not quite sure what else to look for. I would have done all this today but it was getting dark out.
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Old 07-25-2011, 08:11 PM
 
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