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Re: Cutting off at idle [Re: TJP] #3088420
10/22/22 09:32 PM
10/22/22 09:32 PM
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Originally Posted by TJP
Originally Posted by Sniper
Originally Posted by TJP



The part I am having trouble with is why the battery which should be at ~ 12.4- 12.6 won't keep the car running, but will start it powering both the starter and ignition, during which time the static V will drop to 11 or so volts due to the amps drawn by the starter.
I am not disagreeing or wanting to start an peeing contest but rather understand how low alternator output at idle makes the motor die but start right back up with less available V and I from the battery than was available when it died


Ballast resistor is bypassed in start so you will have more voltage to the ECU in start than in run.

In a normally working system you have about 9v to the ECU in run, when the ballast resistor is bypassed you get full battery voltage, even if it battery voltage drops to 11v in start that is more than the ECU gets in run.


Every schematic I've seen has the ecu pin 1 getting full voltage in the run position with either a single or dual ballast ?



You are right, I meant to the coil + not the ECU. The coil will, at some point went the supply voltage drops too low, not produce enough juice to reliably spark the plugs.

Re: Cutting off at idle [Re: Sniper] #3088528
10/23/22 11:10 AM
10/23/22 11:10 AM
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Originally Posted by Sniper
Originally Posted by TJP


Every schematic I've seen has the ecu pin 1 getting full voltage in the run position with either a single or dual ballast ?



You are right, I meant to the coil + not the ECU. The coil will, at some point went the supply voltage drops too low, not produce enough juice to reliably spark the plugs.


Just wanted to clarify for others as well as make sure I wasn't losing it LOL up

I had a customer years ago with a car that would randomly not start. He had taken it to several different shops and a customer recommended bring it to me. They had wired the pin 1 to the wrong side of the ballast blush. A 12V component depending on it's mood will sometimes function on the lower voltage and other times not. Temperature and a number of other factors will cause this.
When I was in Final test at intel there were parts that would consistently pass as a bin 1 @125c and drop to a bin2 at 127c, 3 degrees F made the difference. Others would flat fail at the higher temps beer

Re: Cutting off at idle [Re: bobbyb] #3088765
10/24/22 08:05 AM
10/24/22 08:05 AM
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Originally Posted by bobbyb
I’d like to thank everybody else for their input also, thanks guys! Hope this isn’t premature but I think it’s fixed.


I am so happy for you that you found the problem. This issue had me so upset with the car all this season that I didn't even care to drive it. I lost an entire cruising season because of it. Also glad it is confirmed that this was a genuine issue and genuine fix. Ever since I tightened the belt,the car doesn't stall when warmed up. Good cruising to You. as a side note..My life-long mopar guru still shakes his head about the fix and now I can tell him there was another just like mine. Lol.

Re: Cutting off at idle [Re: terzmo] #3088796
10/24/22 10:14 AM
10/24/22 10:14 AM
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Originally Posted by terzmo
Originally Posted by bobbyb
I’d like to thank everybody else for their input also, thanks guys! Hope this isn’t premature but I think it’s fixed.


I am so happy for you that you found the problem. This issue had me so upset with the car all this season that I didn't even care to drive it. I lost an entire cruising season because of it. Also glad it is confirmed that this was a genuine issue and genuine fix. Ever since I tightened the belt, the car doesn't stall when warmed up. Good cruising to You. as a side note..My life-long mopar guru still shakes his head about the fix and now I can tell him there was another just like mine. Lol.


Tell your guru there is another dissident that agrees with him wink I will repeat my earlier comment, share it with him and I'll bet he agrees with te following statement thumbs

Quote
I am glad you found a solution wink . But electrically, it does not make sense. If the alternator output was low, the battery should have supplied adequate current/ voltage to compensate for the low alternator output. The exception being the battery is very weak which is unlikely as it starts right back up, or there is a problem elsewhere in the circuit. In that case the Alternator could back feed the circuit to mask the root cause beer


Re: Cutting off at idle [Re: TJP] #3088800
10/24/22 10:27 AM
10/24/22 10:27 AM
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Loosen the belt on your alternator after it's warmed up..see what happens

Re: Cutting off at idle [Re: terzmo] #3088868
10/24/22 02:03 PM
10/24/22 02:03 PM
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Originally Posted by terzmo
Loosen the belt on your alternator after it's warmed up..see what happens



that would be a good A-B-A test.
beer

Re: Cutting off at idle [Re: terzmo] #3088886
10/24/22 03:23 PM
10/24/22 03:23 PM
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Originally Posted by terzmo
Loosen the belt on your alternator after it's warmed up..see what happens


Loosen the belt..run it on the street until it hits temp..and just drive normal..stop and idle at lights or pull into a spot,go to reverse, back up ...those were most of the times it quit

Re: Cutting off at idle [Re: terzmo] #3088964
10/24/22 09:14 PM
10/24/22 09:14 PM
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Originally Posted by terzmo
Originally Posted by terzmo
Loosen the belt on your alternator after it's warmed up..see what happens


Loosen the belt..run it on the street until it hits temp..and just drive normal..stop and idle at lights or pull into a spot,go to reverse, back up ...those were most of the times it quit


With a good battery, the alternator field windings can be disconnected and the vehicle should still run, UNLESS there is a problem between the battery and the alternator that the alternator is back feeding. Current follows the path of least resistance. 68 years old, 30 years in engineering and 25 years owning a classic car restoration and repair business. Brush up on electronics 101A and Mopar charging ignition circuits. I'm done
beer wave

Re: Cutting off at idle [Re: TJP] #3089779
10/27/22 10:17 PM
10/27/22 10:17 PM
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I’m not seeing a loose belt solving this. Band aid.


I want my fair share
Re: Cutting off at idle [Re: SomeCarGuy] #3089887
10/28/22 11:43 AM
10/28/22 11:43 AM
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Originally Posted by SomeCarGuy
I’m not seeing a loose belt solving this. Band aid.

whistling up bow

Re: Cutting off at idle [Re: TJP] #3090127
10/29/22 07:31 AM
10/29/22 07:31 AM
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still no stalling after several cruises with it and put into described situations purposely to get it to quit and runs excellent. Believe it or not.

Re: Cutting off at idle [Re: terzmo] #3090180
10/29/22 11:26 AM
10/29/22 11:26 AM
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Originally Posted by terzmo
still no stalling after several cruises with it and put into described situations purposely to get it to quit and runs excellent. Believe it or not.

What we are trying to get across is that if the battery is in good condition and fully charged, the car should run off the battery alone (for a short time) unless there is a connection issue in the wiring between the battery and alternator.

The alternator will back feed the connection issue masking it until it can no longer do so. At that point it will either stop running altogether or caus a melted harness / fire.

Disconnect your alternator field terminal and see if the issue returns. It should as the alternator will no longer be charging.
IF so, run a 10G jumper from the Alternators battery post to the battery. this will prove what we are trying to tell you as the jumper will now back feed from the battery. beer

Re: Cutting off at idle [Re: TJP] #3091118
11/02/22 10:26 AM
11/02/22 10:26 AM
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my opinions:

-Stock alts still being new back on the days where unneficent at iddle. In most cases you disconect the batt with engine running and engine will stall. Alt don't provide enough juice at iddle.
-If you add to this a low tension on alt belt... increases the problem
-then, add to this years of sulfating, oxidation, loosen contacts, damages on wiring (and ammeter itself) between batt and the main power splice which is located between ammeter and alt.

we have the perfect storm to an ignition system failure ( along with the rest of the car electrocity ) with everything of this working together.

sure if you have an alt able to source the complete car electrical system at iddle, you barelly will notice any problem if some, between batt and main splice, because alt will be feeding the main splice without any reading on ammeter... straight to all the devices





Last edited by NachoRT74; 11/02/22 10:30 AM.

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Re: Cutting off at idle [Re: NachoRT74] #3091136
11/02/22 11:27 AM
11/02/22 11:27 AM
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Originally Posted by NachoRT74
my opinions:

-Stock alts still being new back on the days where unneficent at iddle. In most cases you disconect the batt with engine running and engine will stall. Alt don't provide enough juice at iddle.
-If you add to this a low tension on alt belt... increases the problem
-then, add to this years of sulfating, oxidation, loosen contacts, damages on wiring (and ammeter itself) between batt and the main power splice which is located between ammeter and alt.

we have the perfect storm to an ignition system failure ( along with the rest of the car electrocity ) with everything of this working together.

sure if you have an alt able to source the complete car electrical system at iddle, you barelly will notice any problem if some, between batt and main splice, because alt will be feeding the main splice without any reading on ammeter... straight to all the devices

Nacho,
I'm glad you joined in as your electrical knowledge seems superior to most, myself likely included wink
if I understand your statements correctly,
1. The charging systems back in the day were adequate but marginal by today's standards. iagree
2. If the engine stalls when the battery is disconnected the alternator is not charging enough, or the output is being lost in poor connections etc.
3. But with the battery connected, if the alternator output is low, the battery should supply the needed power to keep the engine running unless
a. the battery is weak
b. there are bad connections between the battery and loads causing voltage drops which in turn causes the ignition system to fail.
4. If "b" is the case, the real problem is the bad connections between the battery and loads.

Raising the output of the alternator will "mask" or hide these connection issues as the alternator is "backfeeding' the voltage drops.
So, I maintain the real problem is the bad connections not the alternator's output.

I have driven several 60-70's mopars home with a non-working alternator years ago. Maybe 20-30 miles at most with no other loads on the system.
To summarize:
The batteries main purpose is to start the vehicle and provide power when the alternator output is low a for a period of time. The amount time depends on the load, condition and capacity of the battery.

If the above is true, the real issue the OP is facing is bad connections somewhere between the battery and alternator.

To confirm this one could run a heavy gauge wire between the battery and alternator output stud. this would allow the battery to backfeed the bad connections.


Last edited by TJP; 11/02/22 11:53 AM.
Re: Cutting off at idle [Re: TJP] #3091249
11/02/22 07:00 PM
11/02/22 07:00 PM
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In my opinion, it was marginal still for those days standards. But is just my opinion. If you are driving around the country, you will barely keep the car at idle so the charging deficit will be marginal, but on big cities will be mostly at idle between traffic lights, loosing load from batt being discharged constantly. I guess back in the days with less heavy traffic conditions we can say that could be considered as a “standard” stage? Dunno

Yes, you are 95% correct on the interpretation of my words. As many of you know, english is not my mother language so sometimes it CAN be hard to my explain what I’m trying to say.

About the wire between alt and batt, that will VIRTUALLY bypass the amm but, also provides an extra path for the load coming/going through all the network. If some problem is present on wiring you are not fixing but hiding it.

Alternator output has been always a problem anyway, from factory.

With a damaged charging system ( damaged alt, belt or alt wire ) sure you should keep the load demand as low as posible because:
-Ignition system will need the best load and voltage rate capacity as posible.
-Ammeter will be safer, same as all the wiring between Batt and main splice.

The OP can be confronting several issues at the same time, but yes, still with an inoperative alt ( for WHATEVER reason ) the batt should supply the power to still keep running the engine. So it could be a problem between batt and main splice ( ammeter included ) down the under dash harness tape which spreads the power to everywhere.

And is not about voltage really, since voltage can still run through a hair, but amperage, which needs to get a good path to supply the requested power. Of course, a damaged path causing resistance will affect both, voltage and amperage, and both are always in a straight relationship, but a good amount of amperage being supplied, will affect less the voltage rate.

Energy is based on watts… increasing voltage or amperage on a steady resistance. Electric devices sucks amperage to provide watts based on a steady voltage rate and resistance.

Increasing voltage will require less amperes to produce watts.

Amperes are sucked in by the devices not pushed in by the source, to keep their energy/work capacity,

Resistance will produce amperes restriction and poor work capacity.

Etc…

Last edited by NachoRT74; 11/02/22 07:25 PM.

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Re: Cutting off at idle [Re: NachoRT74] #3091275
11/02/22 08:41 PM
11/02/22 08:41 PM
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Re: Cutting off at idle [Re: NachoRT74] #3091277
11/02/22 08:41 PM
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Originally Posted by NachoRT74
In my opinion, it was marginal still for those days standards. AGREED smile

About the wire between alt and batt, that will VIRTUALLY bypass the amm but, also provides an extra path for the load coming/going through all the network. If some problem is present on wiring you are not fixing but hiding it. AGREED

The OP can be confronting several issues at the same time, but yes, still with an inoperative alt ( for WHATEVER reason ) the batt should supply the power to still keep running the engine.

So it could be a problem between batt and main splice ( ammeter included ) down the under dash harness tape which spreads the power to everywhere.

thank you for responding bow bow up

My suggestion to run a jumper from the battery to Alternator was to prove the real issue was between the battery and alternator feed and that the car should stay running even with low or no output from the alternator for reasonable periods of time>

If the OP is wanting to verify,
Disconnecting the field wire(s) will shut the alternator down and should cause the vehicle to die that would prove what we are saying.
if the vehicle does stop running, running the suggested jumper from the battery would PROVE that the connection issue is being hidden by the alternator.
thank you again beer

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