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Old 11-24-2011, 11:51 AM   #1
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Default Electrical / Charging system still having minor issues

Hello all,

So a couple weeks ago I had problems with a connection somewhere in my charging system which caused a severely bouncing voltmeter and eventually the car to stall. Back when I had originally purchased Bonnie she had this issue as well, but I have replaced a number of items and hadn't seen it since.

So I went in and reseated and cleaned all of the main connections and replaced the negative battery cable. I also replaced the 3 small ground connections beneath the ICM. It is running much better, but I notice that if I sit at idle for a few moments the charge (very slowly) starts to trickle down. For example, at start it is always 14+ V on the voltmeter. If I'm driving, it hangs around that range, maybe just 13.75 V worst case. But if I'm at a light or something, you can watch the charge slowly dwindle. It will typically not go below 13 V or so, but it never used to drop like this.

I have had the battery and alternator tested, both passed. Although the guy at Autozone did not recharge the battery before he tested it and it was only at 8 V, so I'm a bit skeptical of that test. The positive cable to alternator/starter was replaced in June. Negative cable was just replaced last week. The negative cable was a cheap crimp-me kind - seen here:

http://napaonline.com/Catalog/Catalo...RecType%3aA%29

I don't think this would affect the charging system though since the main ground is a single cable. I did notice it is a much smaller diameter than the previous cable. Could this be doing it? A number of places have this cable for my vehicle though.

Grounding bolts to block were soaked in degreaser and cleaned with a wire brush this past week. The alternator connector is a replacement, so I resoldered the connector and taped it up really well. All connections still seem nice and tight. Any suggestions besides reseating everything again?
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Old 11-24-2011, 01:52 PM   #2
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Something that comes to mind is your idle speed. If the idle gets to low the alternator will shut down and your engine is running on battery voltage. And this will drain fast if you have radio and lights on. Try shifting out of gear at the light. Idle speed is set different when out of gear. The voltage should come up a bit. You may want to clean the throttle body. You will also want to check for vacuum leaks, your PCV valve, and your EGR. How old are your spark plugs, coils and plug wires?
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Old 11-24-2011, 04:49 PM   #3
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I idle around 800-1000 RPMs. What is the RPM when the alternator cuts out? I'll try the shifting at the light.

Plugs and wires are coming up on two years / 20,000 miles. Coils are unknown.

I do still have a little voltmeter bouncing when the charge starts draining, which seems that the alternator would still be running. However, there are some other issues which may help diagnose. Starting a warm engine is very difficult. Very long crank and I have to give it some gas. I might try to resolder the ICM ground just to be certain.

The new negative cable did not have a connection for the block to frame ground as the original cable did. So I put a connector on there and grounded it on the same bolt as the ICM. I'm wondering if it wasn't a large enough connector as the cable barely fit inside it. However, all of the charging components are grounded to the block, so would this be affecting it?

Also, I have suspected there may be a leak of some kind going on. Back about a month ago when I replaced the UIM I gained a lot of power/responsiveness to the pedal. Now it'* all gone back to how it was. The first time I think it was the throttle body gasket, but it seems it may be worse after the cable replacement.

I briefly looked but couldn't locate a write up on cleaning the throttle body, does one exist?
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Old 11-24-2011, 05:02 PM   #4
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I don't have a write up on cleaning the throttle body. It'* easy. Remove it, take off sensors, and then spray with cleaner. Put it back together and your done.

I believe the alt starts to kick out around 750 or so. You may be getting very close to that, just enough that it'* switching on and off.
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Old 11-24-2011, 05:34 PM   #5
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Easy enough. I'll pick up some TB cleaner tomorrow and give it a go.

Forgot to mention in response to your original post - EGR was replaced around 2 years ago. PCV was replaced with new UIM last month. I have suspected a leak from the upper EGR hose where it meets the intake for a while, but I haven't been able to prove it. I may try replacing the O-Ring on it, but it seems to be in decent condition.
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Old 11-24-2011, 09:01 PM   #6
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You can try spraying carb cleaner around. If the idle changes, you found a vacuum leak.
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Old 11-27-2011, 10:32 PM   #7
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She'* stalling (i hope) because the new fuel filter is leaking, about to go take it off and reseat it. BUT I think I found a likely culprit of the fluctuating voltage.

One of the nuts that secures the ICM to the bracket has gone missing. This allows the ICM to shift back and forth fairly easily. I'm assuming that the ICM to bracket connection acts as a ground in addition the the one grounded on the bolt? If so, I believe this would explain it?

My TPS connector was also broken in a few spots so I put a new one in and soldered and heat shrinked the replacement connections. I also cleaned the throttle body as you suggested. Once I fix the fuel filter I'll update how it goes.
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Old 11-27-2011, 10:33 PM   #8
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I did spray carb cleaner around trying to find vacuum leaks but didn't come up with much. Is it a major change in idle? I thought I heard some very minor changes but this could have been definitely due to normal operation since I couldn't replicated it.
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Old 11-27-2011, 10:42 PM   #9
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If you had a vacuum leak you would notice a difference.
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Old 11-27-2011, 11:16 PM   #10
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What'* the best way to get rust off of the fuel filter nut without blowing myself up? Typically I would just use a wire brush, but that doesn't seem like the greatest idea...

I sprayed some penetrating oil on there and I've got it at least spinning now, but the threads are horribly filled with rust.
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