Power Draw Help needed
07-16-2011, 03:25 PM
#1
Drifting
Thread Starter
Power Draw Help needed
As you might have read from my threads,
I have been working on my 90 S4. I changed the steering rack, OPG, MM, TB/WP.
The first time I started the car it idled fine but then when it got up to temperature still at idle, I got a wiff of buring plastic from the driver side engine bay by the valve cover and also noticed it inside the car.
I checked every where and could not locate anyoverheating wire or rubbing etc. The smell went away the car idled fine so I thought while I was under the car cleaning and painting there might have been some residue on the exhaust that burned off.
The car ran fine, drove it for a couple of days no problem. Then 2 days ago, I go to start it and the engine does not want to turn. Looks like low battery. Try again and it turns the engine very slowly and all the dash lights show that the car is low on battery power. Try again and this time crank slowly for some time, still the low battery with all dash lights dim but it catches. Drive it on the highway and shut it off at the gas station. Cannot get it to start. Have to call my daughter to come and give me jump/ As soon as I connect the jumpercables it starts right up.
Did not start it due to the water leak for a couple of days, but left the battery on the charger. The battery is brand new.
Today after I get the leak fixed, connect and get it to start the same thing happens, Looks like low battery.
Anyway with very slow cranking it starts up.
So at idle at the battery I got 13.83 and at the post I got 13.87
With all lights and AC running with both fans at max i get 11.36 at battery and 11.26 at post.
Now after I let the car run for a good 1.2 hour to 45 mins, I started seeing that the dash lights were changing in intesity as the engine went thru its cycle.
So I Shut the car of and went to check the Voltage at the battery and it read 11.34. As I had the meter connected it was couning down. I disconnected the battery from the car at 10.94. AFter disconnecting the reading was stationary.
So it seems that there is a short somewhere or sme wire is grounding.
Any thoughts where to start as per where I have been lately.
Also I get a taillight failure on the dashboard whenever I turn the lights on even though all the lights are functioning properly. This has een happening for a while and don't know if the two things are related.
Thanks
Bilal
I have been working on my 90 S4. I changed the steering rack, OPG, MM, TB/WP.
The first time I started the car it idled fine but then when it got up to temperature still at idle, I got a wiff of buring plastic from the driver side engine bay by the valve cover and also noticed it inside the car.
I checked every where and could not locate anyoverheating wire or rubbing etc. The smell went away the car idled fine so I thought while I was under the car cleaning and painting there might have been some residue on the exhaust that burned off.
The car ran fine, drove it for a couple of days no problem. Then 2 days ago, I go to start it and the engine does not want to turn. Looks like low battery. Try again and it turns the engine very slowly and all the dash lights show that the car is low on battery power. Try again and this time crank slowly for some time, still the low battery with all dash lights dim but it catches. Drive it on the highway and shut it off at the gas station. Cannot get it to start. Have to call my daughter to come and give me jump/ As soon as I connect the jumpercables it starts right up.
Did not start it due to the water leak for a couple of days, but left the battery on the charger. The battery is brand new.
Today after I get the leak fixed, connect and get it to start the same thing happens, Looks like low battery.
Anyway with very slow cranking it starts up.
So at idle at the battery I got 13.83 and at the post I got 13.87
With all lights and AC running with both fans at max i get 11.36 at battery and 11.26 at post.
Now after I let the car run for a good 1.2 hour to 45 mins, I started seeing that the dash lights were changing in intesity as the engine went thru its cycle.
So I Shut the car of and went to check the Voltage at the battery and it read 11.34. As I had the meter connected it was couning down. I disconnected the battery from the car at 10.94. AFter disconnecting the reading was stationary.
So it seems that there is a short somewhere or sme wire is grounding.
Any thoughts where to start as per where I have been lately.
Also I get a taillight failure on the dashboard whenever I turn the lights on even though all the lights are functioning properly. This has een happening for a while and don't know if the two things are related.
Thanks
Bilal
07-16-2011, 03:50 PM
#2
Team Owner
I would begin by disconnecting the battery and then going on a wire hunt make sure the harness that runs along the left side of the crossmember is routed correctly,
Check the starter connections for tightness and correct routing
Since you smelled burning plastic its a good bet you have done something to cause it,
next would be to remove the aircleaner and tap out the filter on a white piece of cardboard, use a magnifying glass and inspect the debris for black pieces of belt, the tubes will suck the belt debris into the air filter.
If you find black bits then open the passenger side timing cover and inspect the belt for damage, inspect the belt run as well this may entail taking the front of the engine apart again
Next would be to verify that the wires that run in front of the engine are routed correctly as well as over the PS pump belt,
also check the ABS wire for correct routing under the ABS bracket and along the top of the PS belt. Next clean the battery terminals and all of the wires going to them then check the hot post and verify that its tight and inspect the 14 pin connector. Did you at any time let the alternator hang from its wire harness?
If so then check for continuity from the 14 pin connector the blue wire with it disconnected from the back of the alternator, this wire has a habit of shearing about 4 inches up from where it goes into the red harness covering
Check the starter connections for tightness and correct routing
Since you smelled burning plastic its a good bet you have done something to cause it,
next would be to remove the aircleaner and tap out the filter on a white piece of cardboard, use a magnifying glass and inspect the debris for black pieces of belt, the tubes will suck the belt debris into the air filter.
If you find black bits then open the passenger side timing cover and inspect the belt for damage, inspect the belt run as well this may entail taking the front of the engine apart again
Next would be to verify that the wires that run in front of the engine are routed correctly as well as over the PS pump belt,
also check the ABS wire for correct routing under the ABS bracket and along the top of the PS belt. Next clean the battery terminals and all of the wires going to them then check the hot post and verify that its tight and inspect the 14 pin connector. Did you at any time let the alternator hang from its wire harness?
If so then check for continuity from the 14 pin connector the blue wire with it disconnected from the back of the alternator, this wire has a habit of shearing about 4 inches up from where it goes into the red harness covering
07-16-2011, 04:22 PM
#3
Drifting
Thread Starter
Thanks for the reponse.
I had checked the TB and it was tracking perfectly. The battery posts are totally clean. The routing in front of the engine is good and there are no wires touching the belts. The alternator was removed but not let to hang, it was placed on an upside down pail so that the wires would not stretch.
I will go under the car and see if the connections to the starter are tight and that the wiring is run properly.
I had run it correctly, but will double check and report back.
The alternator was cleaned / degraesed. The starter was also removed and cleaned.
Thanks
Bilal
I had checked the TB and it was tracking perfectly. The battery posts are totally clean. The routing in front of the engine is good and there are no wires touching the belts. The alternator was removed but not let to hang, it was placed on an upside down pail so that the wires would not stretch.
I will go under the car and see if the connections to the starter are tight and that the wiring is run properly.
I had run it correctly, but will double check and report back.
The alternator was cleaned / degraesed. The starter was also removed and cleaned.
Thanks
Bilal
07-16-2011, 05:47 PM
#4
Pro
Join Date: Apr 2010
Location: Magnolia TX, just north of Houston, Red 1984 S
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I would suspect the alternator itself, since you have already been through the grounds to some extent. As Mrmerlin suggests you do need to inspect the alternator wiring itself, both the B+ (main wire) as well as the smaller blue wire. Your burning plastic smell could be from failing diodes in the alternator itself...and you also do need to resolve why the computer thinks the taillight(s) have failed.
Alternators are a bit wierd in how they work, or don't work..... I have had 3 either outright fail or go substandard output on 2 928's in the last year. I replaced one this week. It tested good at the local parts store, but as it gets hot it's output voltage drops and drops untill iit is 10.3 vdc +/-. Cold it is over 13 vdc. First clue is it should be nearly 14 v cold and at 1800 rpm on the engine....second clue is how it drops voltage as it gets hot. The new one shows 14vdc......
Is your car an automatic? And if so have you completed the verification of endplay and release of the flex plate? A huge current draw on starting coupled with a defective alternator could give you some of the symptoms you describe...could be a starter begining to fail......and a bad alternator.....also the ground cable on the battery tends to turn gray from oxidation and fail intermittantly inside the plastic sheath, and behave like a bad battery or bad alternator.....
Alternators are a bit wierd in how they work, or don't work..... I have had 3 either outright fail or go substandard output on 2 928's in the last year. I replaced one this week. It tested good at the local parts store, but as it gets hot it's output voltage drops and drops untill iit is 10.3 vdc +/-. Cold it is over 13 vdc. First clue is it should be nearly 14 v cold and at 1800 rpm on the engine....second clue is how it drops voltage as it gets hot. The new one shows 14vdc......
Is your car an automatic? And if so have you completed the verification of endplay and release of the flex plate? A huge current draw on starting coupled with a defective alternator could give you some of the symptoms you describe...could be a starter begining to fail......and a bad alternator.....also the ground cable on the battery tends to turn gray from oxidation and fail intermittantly inside the plastic sheath, and behave like a bad battery or bad alternator.....
07-17-2011, 10:03 AM
#5
Drifting
Thread Starter
OK, started today, checked the ground on the passenger side to the block, clean and tight. Took the wires off the starter clean and tight.
Checked the main plu at the post fitted snugly. Checked the wires at the post clean and tight.
Had the battery charge over night only reached 11.83. Hooked it up and just with the interior lights on it started counting down. Unhooked it at 11.37.
The battery starts discharging very fast like every second. It looks like you are looking at a clock in reverse. After I disconnect the load/car then the voltage stays the same. Like I said it is a brand new battery.
How do you get the alternator wires off the alternator to check for continuity? But should this have any affect when the car is off and you just connect the battery?
Thanks
Bilal
Checked the main plu at the post fitted snugly. Checked the wires at the post clean and tight.
Had the battery charge over night only reached 11.83. Hooked it up and just with the interior lights on it started counting down. Unhooked it at 11.37.
The battery starts discharging very fast like every second. It looks like you are looking at a clock in reverse. After I disconnect the load/car then the voltage stays the same. Like I said it is a brand new battery.
How do you get the alternator wires off the alternator to check for continuity? But should this have any affect when the car is off and you just connect the battery?
Thanks
Bilal
07-17-2011, 10:32 AM
#6
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Join Date: Apr 2010
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Well, firstly, your battery, if good, should be charged to well over 12 vdc after charging all night. Something more like 12.4 vdc in my case. Either your new battery has a problem, i.e. defective cell, or your charger is not working well/properly.
Regards the draw when you reconnect, one of the troubleshooting methods used is to pull all fuses and reinstall them one at a time. When an uptick in current draw (or voltage drop) is noted, you then know what circuit to start checking.
By the way, my first new 928 battery, purchased from what is normally a high volumn parts house, failed in a month or so of my buying it. Turns out it was over 4 years old. Not a high sales item....
From your symptoms you may have more than 1 problem...it is difficult to ascertain remotely if the main problem is the alternator, the battery, or still something simple like the battery ground strap itself. I have had all 3 of those problems across 2 928's and they are confusing and offer similar symptoms as to what you report
It would also be helpful if you reported the year of your car... The secondary problem would seem to be the current draw with the car not running....the interior lights are often the source of partial shorts and excessive electrical current draw, so you might start on that fuse...pull it and report results.
Regards the draw when you reconnect, one of the troubleshooting methods used is to pull all fuses and reinstall them one at a time. When an uptick in current draw (or voltage drop) is noted, you then know what circuit to start checking.
By the way, my first new 928 battery, purchased from what is normally a high volumn parts house, failed in a month or so of my buying it. Turns out it was over 4 years old. Not a high sales item....
From your symptoms you may have more than 1 problem...it is difficult to ascertain remotely if the main problem is the alternator, the battery, or still something simple like the battery ground strap itself. I have had all 3 of those problems across 2 928's and they are confusing and offer similar symptoms as to what you report
It would also be helpful if you reported the year of your car... The secondary problem would seem to be the current draw with the car not running....the interior lights are often the source of partial shorts and excessive electrical current draw, so you might start on that fuse...pull it and report results.
07-17-2011, 10:47 AM
#7
Team Owner
Jim the car is a 1990 S4 ,
did you find anything in the aircleaner?
to test the charging system,
put a volt meter on the hot post and run the engine at 1500 RPM see what you get,
if its over 13.5 then the charging system is working as it should.
The battery should hold a charge of 12.4 disconnected,
if it wont go to this then the battery or the charger is defective.
to see if the interior lights are shutting off ,
open one of the windows and look inside the door with the door open,
you should be able to see the rear edge light illuminated, by looking down the inside of the door
close the door and wait for a minute see if the light delay switches off.
All in all I think that there is an issue with the belt run if your smelling any kind of the burning plastic and one of the timing covers should be pulled off to investigate
did you find anything in the aircleaner?
to test the charging system,
put a volt meter on the hot post and run the engine at 1500 RPM see what you get,
if its over 13.5 then the charging system is working as it should.
The battery should hold a charge of 12.4 disconnected,
if it wont go to this then the battery or the charger is defective.
to see if the interior lights are shutting off ,
open one of the windows and look inside the door with the door open,
you should be able to see the rear edge light illuminated, by looking down the inside of the door
close the door and wait for a minute see if the light delay switches off.
All in all I think that there is an issue with the belt run if your smelling any kind of the burning plastic and one of the timing covers should be pulled off to investigate
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07-17-2011, 11:09 AM
#8
Drifting
Thread Starter
I had put the car in my original post. It is a 1990 S4 automatic. It has 117K miles on it and was/is my daily driver. I did the original TB/WP when I had bought it in 1999 with 85K. It has been working flawlessly with out any issue. It has never left me stranded.
OK. since this morning I had put it on at a higher charge rate. The charger was putting out 14.5. I took it off the charger and it started at 12.5 reading and quickly dropped to 11.35 without any load. Will take it back to the shop and see what they say about the battery. It is an autozone battery and usually they have not given me any trouble.
OK. since this morning I had put it on at a higher charge rate. The charger was putting out 14.5. I took it off the charger and it started at 12.5 reading and quickly dropped to 11.35 without any load. Will take it back to the shop and see what they say about the battery. It is an autozone battery and usually they have not given me any trouble.
07-17-2011, 12:41 PM
#9
Race Car
I had put the car in my original post. It is a 1990 S4 automatic. It has 117K miles on it and was/is my daily driver. I did the original TB/WP when I had bought it in 1999 with 85K. It has been working flawlessly with out any issue. It has never left me stranded.
OK. since this morning I had put it on at a higher charge rate. The charger was putting out 14.5. I took it off the charger and it started at 12.5 reading and quickly dropped to 11.35 without any load. Will take it back to the shop and see what they say about the battery. It is an autozone battery and usually they have not given me any trouble.
OK. since this morning I had put it on at a higher charge rate. The charger was putting out 14.5. I took it off the charger and it started at 12.5 reading and quickly dropped to 11.35 without any load. Will take it back to the shop and see what they say about the battery. It is an autozone battery and usually they have not given me any trouble.
If it is like any Autozone they will replace it. Check the manufacture date (per thread above) and make sure to find one that has a newer date if they replace it at the store.
07-17-2011, 12:49 PM
#10
Team Owner
Bilial what did you find in the air cleaner?
Have you removed any of the belt covers to investigate the burning smell?
Have you removed any of the belt covers to investigate the burning smell?
07-18-2011, 12:01 AM
#11
Drifting
Thread Starter
Sorry, did not get a chance to work on the car due to family activities.
Did take the battery back to Autozone, they checked it and said bad battery and gave me a replacement new one.
Put the battery in the car and checked with voltmeter it started at 12.66 and just like the other one started counting down with just the hatch open and interior lights. I believe there is a short somewhere.
Checked the air filter and just sand etc no rubber chunks from the belt.
Checked the fuse panel visually and did not see anything melted.
To reiterate:
Did all the work, started the car and it ran fine. When the car came up to temp got a plastic burning smell from the passenger side front engine area but was also present inside when I sat in the car. The car ran fine for a couple of days, short trips. Also checked the belt and it was tracking fine on both sides from the veny holes.
Now if I put the battery in it starts discharging rapidly. and then kills the battery. The last battery only lsated for a couple of days.
The wiring harness seems fine in the front no contacts with the accessory belts, the routing of the wiring harness to the starter is also fine and not rubbing on anything.
Its a 90 S4 any help would be appreciated.
Bilal
Did take the battery back to Autozone, they checked it and said bad battery and gave me a replacement new one.
Put the battery in the car and checked with voltmeter it started at 12.66 and just like the other one started counting down with just the hatch open and interior lights. I believe there is a short somewhere.
Checked the air filter and just sand etc no rubber chunks from the belt.
Checked the fuse panel visually and did not see anything melted.
To reiterate:
Did all the work, started the car and it ran fine. When the car came up to temp got a plastic burning smell from the passenger side front engine area but was also present inside when I sat in the car. The car ran fine for a couple of days, short trips. Also checked the belt and it was tracking fine on both sides from the veny holes.
Now if I put the battery in it starts discharging rapidly. and then kills the battery. The last battery only lsated for a couple of days.
The wiring harness seems fine in the front no contacts with the accessory belts, the routing of the wiring harness to the starter is also fine and not rubbing on anything.
Its a 90 S4 any help would be appreciated.
Bilal
07-18-2011, 02:41 AM
#12
Rennlist Member
Sorry, did not get a chance to work on the car due to family activities.
Did take the battery back to Autozone, they checked it and said bad battery and gave me a replacement new one.
Put the battery in the car and checked with voltmeter it started at 12.66 and just like the other one started counting down with just the hatch open and interior lights. I believe there is a short somewhere.
Checked the air filter and just sand etc no rubber chunks from the belt.
Checked the fuse panel visually and did not see anything melted.
To reiterate:
Did all the work, started the car and it ran fine. When the car came up to temp got a plastic burning smell from the passenger side front engine area but was also present inside when I sat in the car. The car ran fine for a couple of days, short trips. Also checked the belt and it was tracking fine on both sides from the veny holes.
Now if I put the battery in it starts discharging rapidly. and then kills the battery. The last battery only lsated for a couple of days.
The wiring harness seems fine in the front no contacts with the accessory belts, the routing of the wiring harness to the starter is also fine and not rubbing on anything.
Its a 90 S4 any help would be appreciated.
Bilal
Did take the battery back to Autozone, they checked it and said bad battery and gave me a replacement new one.
Put the battery in the car and checked with voltmeter it started at 12.66 and just like the other one started counting down with just the hatch open and interior lights. I believe there is a short somewhere.
Checked the air filter and just sand etc no rubber chunks from the belt.
Checked the fuse panel visually and did not see anything melted.
To reiterate:
Did all the work, started the car and it ran fine. When the car came up to temp got a plastic burning smell from the passenger side front engine area but was also present inside when I sat in the car. The car ran fine for a couple of days, short trips. Also checked the belt and it was tracking fine on both sides from the veny holes.
Now if I put the battery in it starts discharging rapidly. and then kills the battery. The last battery only lsated for a couple of days.
The wiring harness seems fine in the front no contacts with the accessory belts, the routing of the wiring harness to the starter is also fine and not rubbing on anything.
Its a 90 S4 any help would be appreciated.
Bilal
If the battery voltage starts "counting down" when you connect the battery, then you have a short somewhere, for sure. And whatever it is, it will be getting hot (amps times volts). That is also what probably killed the previous battery.
The main battery cable runs under car on the driver's side, just inside the frame rail to the starter. From there, a smaller wire goes (through sleeving) to the alternator, and from there around the front of the engine (through the timing belt) to the jump-post on the passenger side. There is also a branch to the ABS pump on the driver's side. And from the jump-post there are two or three fat red wires which continue to the CE panel on the passenger side.
Connect the battery and then check every inch of all of those cables, running your finders over the cable and each terminal, feeling for something warm and looking for anything melted or burned, or that smells funny. Seriously, every inch.
Good hunting!
07-18-2011, 08:28 AM
#13
Drifting
Thread Starter
The battery count down does not give me enough time to check any wiring or any part to get hot. It basically loses .01V every second. So if I leave it on for too long the battery dies.
07-18-2011, 10:32 AM
#15
Rennlist Member
Rennlist Site Sponsor
Try splitting the possibilities.
Disconnect the smaller wires on the positive battery terminal and the wires at the jump start terminal. This will eliminate everything inside the car. Connect the battery momentarily, and see if the voltage drops. If it does drop, the problem is between the battery and the jump start terminal.
If the voltage does not drop, reconnect the smaller wires on the positive battery terminal one at a time. If it still does not drop, disconnect the main power wires at the top of the Central Electric Panel, then reconnect the wires at the jump start terminal.
Eventually, you will begin to close in on the problem.
Disconnect the smaller wires on the positive battery terminal and the wires at the jump start terminal. This will eliminate everything inside the car. Connect the battery momentarily, and see if the voltage drops. If it does drop, the problem is between the battery and the jump start terminal.
If the voltage does not drop, reconnect the smaller wires on the positive battery terminal one at a time. If it still does not drop, disconnect the main power wires at the top of the Central Electric Panel, then reconnect the wires at the jump start terminal.
Eventually, you will begin to close in on the problem.