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My '86 has a slight cold start stumble. Sometimes it will hold idle other times it won't and stall. If I give it gas at start up idle is solid, but if I don't it will idle low and the battery light is on. Then once I blip the gas all is well. Warm idle extremely solid. I'm thinking it could be the AAV or a loose hose, but I have retightened all hose fittings. Could it be my alternator belt sticking or too tight? It probably needs replacement anyways. Any advice would be much appreciated.
 

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I have the exact same problem... I haven't looked into it too far, but the alt light seems to be a symptom of the extremely low idle (the blip will raise up the min idle, afterwhich the alt light will go out.) I doubt the problem is with the alt, but I'm swapping out my alt for an 85 amp one (for completely different reasons) this weekend, which should confirm that low idle is the problem.

Here's a summary of the problem as it happens with me:

1. Sit in alfa
2. start alfa for first time of the day.
3. engine will start right away, you can watch the RPM gauge go up to about 1200, but then will drop down really far (to around 400ish)
4. looking around, notice that alt light is on.
5. driver worries that the car is going to stall so blips the gas.
6. RPMs rise due to gas, then fall down to a normal idle... alt light goes out.


Anyone have any ideas??
 

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Both my Alfas occasionally do this. From watching the voltmeter I think it's just that the voltage regulator doesn't see enough juice at startup so it outputs too low a voltage. Once it sees a high enough voltage from the alternator it's able to stabilize at the correct output voltage.

As you said, just blip the throttle to get the RPMs up for a sec and the regulator will sort itself out. I don't think it's worth worrying about.
 

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My Spider has always done that. With the alt it came with I would have to blip it up to about 1500 RPM to get the light to go out. I replaced the alternator with one of those "100 AMP" upgrade remanufactured units from a seller on e-bay and now I have to blip it up to 2000 rpms to get the light to go out.

I think Gubi is right, I remember reading somewhere about the need to build up enough initial current or voltage on the stator(?) to get things up and going initially.

While I'm on the subject...the reason I bought the upgraded amperage alt was because the gauge would drop below 12 if I ran a couple things at the same time. I've got an electric fan in there instead of the engine driven one that draws around 9 amps I think. If I use the headlights and the blower fan or the wipers it would drop below 12. Forget about it if I had to use three! Well I put in the higher amp alt and it doesn't see any better :-(. In fact I'm thinking it might be a little worse. I'm debating pulling it out and having it tested to see what the actual amp output is but didn't want to have it done at a Pep boys or Autozone as they usually have no clue what the heck they are doing. I just found a local alternator place while out on a drive in the Verde this weekend so if I can only get up the energy (no pun intended) to pull it...

Kevin
 

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That doesn't bode well for the 85 amp upgrade I bought (b/c light would glow a bit if running with the headlights and radio @ night) I could watch the voltage fall with every device I turned on... I figured I'd install the upgrade, then rebuild the 55 amp one (new brushes, etc.) That way I'd have a spare. I suppose if it makes the low idle/alt light problem worse, I'll just swap them back with the old one after it's rebuilt. I'll post an update this weekend with results.

I didn't think there was a 100 amp upgrade... the biggest alt that would fit in a spider is the 85 amp alfetta alternator... right?
 

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most likely bad connections due to corosion causing the problems. both wire ends and grounds can caust the voltage to drop excessively.
cliff
 

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My mechanic (Joe at Alfa Import Center) tells me that the voltage drop is not so much a case of not enough alternator, but a case of making too much demand on the wiring and the ignition switch. I am having a relay installed (as we speak/type) to bypass the switch. I'll let you all know how it works out. He even tells me I will have a fast speed for the windshield wipers!
 

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I've already got a starter relay installed. I've got a 6(!) gauge wire running from the alt to the junction box. I haven't run a new heavier gauge wire to the fuse box yet but am considering, don't know how much work that is.

I don't think the higher amp has anything to do with the size of the alt, I think it is just higher density windings inside?

Kevin
 

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as some have found out, the connection on the starter, where the battery connects is also critical to opoeration, the battery cable goes to the starter and then a smaller cable goes to the fuse box. any corosion or bad connection there causes trouble.
cliff
 

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Cliff,

Are you saying that the connection to the fuse box is from the starter and not the junction box on the drivers side of the engine bay? I wouldn't have thought that would be the case (of course I've been surprised many a time on these Alfa's :) ).

Kevin
 

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on my 74, and others from what i've read, the wire to the junction box comes from the lug on the starter that has the battery cable on it. not the way I would have done it.
cliff
 

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Toptick said:
I am having a relay installed (as we speak/type) to bypass the switch.

<-- Would be curious as to how that is done (yes, I'm looking for a bit of magic for that system as I've done the headlights already but want more :) )
 

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So I got motivated to get my alternator checked. I called up the local shop and they said they would check it on the car. The "100A" one I bought was putting out 65A but he said that it is possible that on a bench it could be doing 100A at the perfect RPM etc... It also was a bit low on voltage, about 13v, I think it should be around 13.7.

What he did say is that the "hopped" up alts usually never are worth it. They usually don't put out as much at idle (that is what I'm seeing) and that he just doesn't do it anymore. Going with a unit that is higher rated but originally built that way by Bosch is better (like your 85A).

For some reason I was under the impression that the alternator was driving the electrics when the car was running, silly me... I asked about this and he patiently explained that the voltage drop you see on the gauge is that whatever you are doing is drawing more power than the alt is putting out (that part I already understood) but that the alt was just trying to keep the battery charged and that everything runs off the battery. Now that I think about it I give myself a big Duh! on this.

He did suggest running a 6 gauge welding(?) wire from both the pos and neg terminals of the battery to the alternator so that it will minimize the loss due the battery being in the back.

Kevin
 

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you already have a hevy wire running from the battery to the starter, a heavy wire to the alternator 8 or 6 to the battery terminal on the starter would work to reduce loss. if all the grounds are working well enough to start the car, you dont really need a large wire to the ground side of the battery. the car does that. !IF ! the grounds are good and clean.
cliff
 

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Tifosi said:
<-- Would be curious as to how that is done (yes, I'm looking for a bit of magic for that system as I've done the headlights already but want more :) )
My mechanic bypassed the ignition switch with a relay (not exactly sure how, where, and what wires yet), and it is truely amazing what a difference a half volt makes.

I'm now indicating 12+ volts with the radio, headlights and A/C all humming away at full power. Pre Relay, all that load would drop me below 12v indicated. It even looks like the wipers are running faster!

The headlights were already on a relay, but it's probably better for the ignition switch, too.
 
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