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Injector Questions

 
Old 04-09-2013, 04:00 PM
  #31  
sundog
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OK, so from the wiring diagram, it appears as if the fuel injectors are all on a separate harness. Going to a connector T31. Does anybody know the location of this connector. I can't find it in the manual. If it is all in the engine compartment, then I can take it out and repair, or build a new one.

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Old 11-23-2013, 04:13 PM
  #32  
Alex Sol
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sundog,

were you able to figure out the wiring for the injectors

i may have similar issues

i started it up and it misfires.

pulled injector 1 and 2, no change no stall
pulled injectors 4,5,and 6 and instant stall

suspect a wiring issue or some lack of communication with the ecu

frustrating!!
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Old 10-19-2017, 05:54 PM
  #33  
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Originally Posted by Alex Sol View Post
sundog,

were you able to figure out the wiring for the injectors

i may have similar issues

i started it up and it misfires.

pulled injector 1 and 2, no change no stall
pulled injectors 4,5,and 6 and instant stall

suspect a wiring issue or some lack of communication with the ecu

frustrating!!
Nope, just had to have it flat bedded home today. Flooded the motor, and wouldn't start.

- I've checked the signal with an Oscilloscope, and it matches the wave form.

- Is is possible that this could be due to a bad alternator? The battery went low too quick when trying to crank the engine to restart it.


Update!

OK, so I get home and charge the battery, car starts right up. No check engine light. A little rough idle, but likely to burn all the crap out of the cylinders.

I'm thinking that it is the alternator, or some other little electrical gremlin. I saw a post about doing things to reduce the current draw when the car is sitting. I'll go through those.

Any chance it could just be a poor ground somewhere?

Last edited by sundog; 10-19-2017 at 10:33 PM.
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Old 01-09-2018, 03:17 PM
  #34  
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I had a similar issue - albeit on a Spec Miata car.
A bad battery cell caused the killswitch to fail.
Not sure if you have one but if you do try to replace the kill switch and the battery.

My issue went away.
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Old 01-11-2018, 04:17 AM
  #35  
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This sounds to me very much like an electrical issue. The injectors are all powered via a common supply line (as shown in the section of schematic you posted earlier).
To fire an injector, the ECU will ground the other side of the injector. One of two things could be happening here.
Either (1) there is an intermittent short to ground on that injector return line back to the ECU or (2) an intermittent fault with the low side driver for that injector within the ECU.
Yo may get lucky and stumble across (1) if you carefully inspect the engine loom. (2) will require diagnostics.
In all honesty tho, you could spend a great deal of time chasing this without putting a scope on it (I don;t mean a simple voltmeter) to see what is going on with that injector->ECU ground line. (pin 35 on the ECU)
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Old 01-11-2018, 11:59 AM
  #36  
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Originally Posted by robt964 View Post
This sounds to me very much like an electrical issue. The injectors are all powered via a common supply line (as shown in the section of schematic you posted earlier).
To fire an injector, the ECU will ground the other side of the injector. One of two things could be happening here.
Either (1) there is an intermittent short to ground on that injector return line back to the ECU or (2) an intermittent fault with the low side driver for that injector within the ECU.
Yo may get lucky and stumble across (1) if you carefully inspect the engine loom. (2) will require diagnostics.
In all honesty tho, you could spend a great deal of time chasing this without putting a scope on it (I don;t mean a simple voltmeter) to see what is going on with that injector->ECU ground line. (pin 35 on the ECU)
I have put an oscilloscope on the offending injector, with the car running, and get the "correct pulse" as shown in the manual. That is what is so confusing to me. The intermittent nature of the problem is something that is very bothersome to me.

My battery drains fast, and will need to be charged after sessions at the track, so I'm wondering if it is maybe the alternator which is going bad. It's been going on for so long now, that I rarely even drive the car anymore.
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Old 01-11-2018, 02:01 PM
  #37  
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2nd time: do you have a battery kill switch?
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Old 01-11-2018, 03:20 PM
  #38  
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Originally Posted by The Italian Pursuit View Post
2nd time: do you have a battery kill switch?
No kill switch. I do manually disconnect the battery each time I park it for more than a few hours.

I'm thinking maybe it is the alternator. It has over 180,000 miles, so likely brushes and other things are dubious. I'm going to do an alternator test this weekend.

I do have a set of brand new high flow injectors, but I need a custom chip to use them. So that is probably a winter project.

And I did have a battery with a bad cell a few years ago. Can't remember if it was before or after this symptom appeared. Wonder if that did some damage to other electronics?
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Old 05-20-2018, 08:04 PM
  #39  
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Checked the alternator light. It comes on when you start the car and then goes off. So the light and system seems to be good.

I tested the alternator with the voltmeter, and with the battery fully charged 12.5V, when running the alternator shows 13.6 volts. According to Adrians book, the alternator should be putting out 13.8 - 14.4 VDC. Even if I up the RPMS, the voltage stays at 13.6 V.

And the same types of symptoms still occur. I'll drive it casually for 20 minutes, and then one injector will start to stick. If I rev it, it will most of the time correct itself. But the last time battery was dead before I got 8 miles to work.

If I take it to the track, as long as I can get it out on the track it will last the entire 20 minutes.

Very baffled. Don't know what to do. Getting so frustrated I've only driven it 3 times in the last year. Such a waste.
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Old 12-31-2018, 02:07 AM
  #40  
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At this point in time I think that I'm at a point where the problem is solved. I went ahead and replaced the alternator. After a couple of drives I have had none of the typical symptoms.

So, if you have weird gremlins in the electrical system, and can't find any culprit, replace the alternator.

Must have been just not putting out enough amps to charge the battery, even though the voltage was OK.
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