HELP! - 78 Euro w/ 4.7L euro engine

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27 Aug 2010 15:24 #764 by mrrodfitz
1. The alternator was replaced, but with all 3 new alternators, when the car got hot, it cut off, especially with accessories on. With no accessories on, it will idle for a few minutes, then quit.

2. Mechanic rebuilt last alt w/ higher amperage, but still cuts off when it gets hot with accessories on.

3. Every now & then, the voltmeter will hold at 12v for about 5-10 minutes, during which it idles fine, then it drops to between 10-11v & quits. Idles better when cool at night.

4. Replaced the air cooling hose & added a mini fan from a Mini Cooper. Throttle wire/assembly, fuel filter, & fuel distributor were replaced.

I've read the tech advice on alternators, but I'm wondering is there something we're missing? When I bought it last October, I drove it cross country, running all accessories with no idle problems.

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27 Aug 2010 15:33 #765 by srshaw3
My immediate thought, perhaps not informed enough, is that the 928 be reviewed for problem with grounds. Drains are very common in 928s due to corrosion and faulty grounds.

Perhaps it isn't the alternator that is the problem but rather the draw in the car is too high....

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27 Aug 2010 23:20 #767 by Kiln_Red
Yeah, I would definitely check my connections first if you're certain that the alternator is fine. Sounds frustrating.

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28 Aug 2010 02:32 #768 by 928mac
Also to expand on the bad connections.

A poor connection causes heat which uses more power.

I had a week charging system and so I replaced my alternator as well, But,
even though I had tested the battery and charged it many times, it was part of the problem.
I bought a deep cycle jell cell battery and have never looked back.
I still have some poor connections but my car runs strong.

Clean the ground terminal on the battery, Both ends. Take them off and use sand paper.
Do the same to the engine ground on the right rear of the engine, Both ends.
you can get anti oxidation paste from the local auto store. Tell them it is for aluminum wiring.

You can also take a bolt down to the store with you and get some of those star washers that fit but only put one between the bolt head and the cable, not between the body.

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18 Sep 2010 09:38 #1110 by N2O-928
Have you ohmed out the Battery Ground strap? Or any of the main wires supporting and connections. (you need to disconnect the battery first!)

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20 Sep 2010 09:58 #1167 by mrrodfitz
My mechanic checked all the connections before we got tech tips from you guys and the tech list, because he didn't want to pull the dash for no reason. We also found the exit wire from the fuse board was too small and replaced. Also rebuilt alternator for higher amperage.

Shouldnwe be concerned about replacing/rebuilding the voltmeter?

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20 Sep 2010 21:25 #1178 by SeanR
There are about a dozen ground points on the car. No dash removal needed. I don't have the tech sheet handy, but each of those should be gone through and cleaned.

Also, take a look at the 14 pin connector by the battery jump post. Pull it off, pop the top, ensuring you don't knock the pins out and check for corrosion. It is not uncommon that the wires from the starter to this point are bad. There is a good chance you will have to peel the insulator/harness cover from it if you find a bad spot.

I'd not keep looking at the alternator, but looking at the harness/grounds on the car.

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20 Sep 2010 21:47 #1179 by srshaw3

There are about a dozen ground points on the car. No dash removal needed. I don't have the tech sheet handy, but each of those should be gone through and cleaned.

Also, take a look at the 14 pin connector by the battery jump post. Pull it off, pop the top, ensuring you don't knock the pins out and check for corrosion. It is not uncommon that the wires from the starter to this point are bad. There is a good chance you will have to peel the insulator/harness cover from it if you find a bad spot.

I'd not keep looking at the alternator, but looking at the harness/grounds on the car.


Sean,

On my '90 GT, in the past couple of weeks my alt. gauge will go from charging fine to zero. I happen to have a Porsche Hammer on loan to me, but this won't tell me the issue, correct?

Does this sound like perhaps just a gauge issue? This is going to be my first Frenzy prevention issue.

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21 Sep 2010 07:51 #1186 by SeanR
Hammer won't tell you anything about the charging system but it is great for all sorts of things.

Can you duplicate this at idle in the garage? If not, wire up a multi-meter at either the battery or jump post, (long leads) and go for a drive. If it does looses charge on the multi-meter the same time as the guage, I'd say charging issue.

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21 Sep 2010 18:54 #1198 by adminVB
Replied by adminVB on topic HELP! - 78 Euro w/ 4.7L euro engine

Can you duplicate this at idle in the garage? If not, wire up a multi-meter at either the battery or jump post, (long leads) and go for a drive. If it does looses charge on the multi-meter the same time as the guage, I'd say charging issue.


It is intermittent, but happening more often lately. And of course as a 928 owners of many years, I do have a multi-meter, just have been lazy in using it :)

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24 Sep 2010 19:59 #1312 by srshaw3

Hammer won't tell you anything about the charging system but it is great for all sorts of things.

Can you duplicate this at idle in the garage? If not, wire up a multi-meter at either the battery or jump post, (long leads) and go for a drive. If it does looses charge on the multi-meter the same time as the gauge, I'd say charging issue.


Checked the battery before starting the car, it was @11.4v
Started the car, and the alternator gauge stayed at zero.
The battery volts jumped to @13.4v
I presume this is conclusive that it is a gauge issue, not an alternator issue, correct?

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24 Sep 2010 20:27 #1314 by 928mac

Checked the battery before starting the car, it was @11.4v
Started the car, and the alternator gauge stayed at zero.
The battery volts jumped to @13.4v
I presume this is conclusive that it is a gauge issue, not an alternator issue, correct?


Correct Stan. She is charging so now you have a good direction and can check where the charge lead comes into the car. I can't help you there but I would be tracing the schamatic. at work now

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24 Sep 2010 20:46 #1315 by srshaw3

Correct Stan. She is charging so now you have a good direction and can check where the charge lead comes into the car. I can't help you there but I would be tracing the schamatic. at work now


Well, a common problem with 928s is with grounds, and there are some behind the pod. As it happens, I had a pod recovered a while back, and now it will move up in the priority list to get done. I plan on upgrading the lighting behind the cluster as well.

I can live with it as is, and just hope the central warning system will let me know if there really becomes a charging problem.

Thanks!

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29 Sep 2010 06:36 #1415 by Mrmerlin
Stan I dont think the pod gauge is an issue it sounds more like either a bad connection to the exciter circuit or worn brushes in the alt. check the hot post connections and the 14 pin connector above it.
fit a hot post cover if you dont have one, check the fuses and clean them with a pencil eraser verify no water leakes over the Ce panel, as well as ground connections and power connections to the CE panel
clean both battery terminals and the wires going to them

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29 Sep 2010 08:02 #1418 by Kiln_Red

Stan I dont think the pod gauge is an issue it sounds more like either a bad connection to the exciter circuit or worn brushes in the alt. check the hot post connections and the 14 pin connector above it.
fit a hot post cover if you dont have one, check the fuses and clean them with a pencil eraser verify no water leakes over the Ce panel, as well as ground connections and power connections to the CE panel
clean both battery terminals and the wires going to them


I wouldn't suspect worn alternator brushes if he applied a voltmeter to the battery and it revealed a 13.4V reading if, simultaneously, the pod gauge showed no reading. I think this would conclude that the alternator's mechanical function was alright.

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29 Sep 2010 16:47 #1428 by srshaw3

Stan I dont think the pod gauge is an issue it sounds more like either a bad connection to the exciter circuit or worn brushes in the alt. check the hot post connections and the 14 pin connector above it.
fit a hot post cover if you dont have one, check the fuses and clean them with a pencil eraser verify no water leakes over the Ce panel, as well as ground connections and power connections to the CE panel
clean both battery terminals and the wires going to them


Does the exciter circuit pass through the gauge, as I recall it did in my '80 Euro?

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29 Sep 2010 17:57 #1429 by Kiln_Red

Does the exciter circuit pass through the gauge, as I recall it did in my '80 Euro?


Am I confused about something here or haven't you already concluded that the alternator IS charging?? If there were a problem with the exciter circuit, then the alternator would not charge. Correct? :confused:

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29 Sep 2010 18:19 #1430 by srshaw3

Am I confused about something here or haven't you already concluded that the alternator IS charging?? If there were a problem with the exciter circuit, then the alternator would not charge. Correct? :confused:


I definitely saw voltage at the battery change from 11.4 to 13.4 even with the gauge sitting at zero. I thought Stan understood this, so was a bit confused myself :)

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02 Oct 2010 16:39 #1481 by Mrmerlin
after rereading this post I would check the the charge rate.
if its below 13.5 then you have a bad diode in the alternator.
If the gauge isnt working then this is another issue that needs to be looked at,
you might have a bad connection at the pod or the connection at the 14 pin connector under the hood. Check the voltage with the car running at the hot post

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03 Oct 2010 10:17 #1492 by 928mac

after rereading this post I would check the the charge rate.
if its below 13.5 then you have a bad diode in the alternator.
If the gauge isnt working then this is another issue that needs to be looked at,
you might have a bad connection at the pod or the connection at the 14 pin connector under the hood. Check the voltage with the car running at the hot post


Hey Guys, do all the main wires run through that 14 pin connector?
If so that is the first place I would check for any other problems.
Low volts (voltage drop) or high resistance in the grounds.
I should check mine. (I'm so dam Lazy) don't forget to use dielectric grease after cleaning, before it goes together




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