Alterantor Or Trailing Coil?
03-26-2004, 04:13 PM
#1
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Join Date: Jan 2004
Posts: 44
ok....i start my car, sometimes the tach works somtimes it doesnt....as long as the rpms are up while driving it seems ok but a little jerky.....when i go back down to idle it dies....
when the tach does work at around 3k rpm (cruising) the volts are between 12-13 volts,,,,, but at idle if it doesnt die it will sit a around 11-12 volts.....if my headlights are on when i rev my car they will brighten with higher rpm and then dim when rpms are below 1k.....
my car once warmed up is a real bitch to start too....it will just crank over for at least a minute and sputter...you can hear the battery loosing power.....eventually starting but dies if i dont keep my foot on the gas....
my knowlege tells me that the alternator is going bad...also maybe the trailing coil is bad too thus the reason for no signal to the tach....
but i have read somewhere that if the charging system and battery are going bad that the car will disable the trailing coils to save power...
help me guys.....i need to get my car up and running again
trevor
when the tach does work at around 3k rpm (cruising) the volts are between 12-13 volts,,,,, but at idle if it doesnt die it will sit a around 11-12 volts.....if my headlights are on when i rev my car they will brighten with higher rpm and then dim when rpms are below 1k.....
my car once warmed up is a real bitch to start too....it will just crank over for at least a minute and sputter...you can hear the battery loosing power.....eventually starting but dies if i dont keep my foot on the gas....
my knowlege tells me that the alternator is going bad...also maybe the trailing coil is bad too thus the reason for no signal to the tach....
but i have read somewhere that if the charging system and battery are going bad that the car will disable the trailing coils to save power...
help me guys.....i need to get my car up and running again
trevor
03-26-2004, 05:18 PM
#2
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Join Date: Jun 2003
Location: Chicago
Posts: 226
Well, the tach not working is a definate sign the trailing coil isn't firing. Could be an issue with the alternator as well. To be honest I really don't know what would cause that. Try grounding it in a bunch of spots and see if that helps.
03-28-2004, 07:06 PM
#6
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Join Date: Jan 2004
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well i had my alternator checked....its good.....
i fixed my idle by adjusting the throttle cable....
my tach still isnt working....i need a trailing coil ithink
and my battery is dead.......not sure why that is if my alternator is good
i fixed my idle by adjusting the throttle cable....
my tach still isnt working....i need a trailing coil ithink
and my battery is dead.......not sure why that is if my alternator is good
03-29-2004, 12:21 AM
#7
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Join Date: Oct 2003
Location: Canada
Posts: 3,502
Don't drive around with a dead battery.. Your alternator assumes all the load to keep the voltage up and you will burn it out as well.
I don't know where you read about the trailing coils being disabled on low voltage.. ? If the voltage was low your battery light would come on.. The stock gauge isn't 100% accurate either.. Mine reads a tad low when idling.
If you still have a bad tach signal then your trailing coil is probably in need of replacement. Try cleaning the coil mount (which is it's ground) and see if it makes a difference. If not, time for a new coil then.
I suggest getting a beefier battery. But don't drive around with the dead battery and good alternator or else you will burn the alternator out.
I don't know where you read about the trailing coils being disabled on low voltage.. ? If the voltage was low your battery light would come on.. The stock gauge isn't 100% accurate either.. Mine reads a tad low when idling.
If you still have a bad tach signal then your trailing coil is probably in need of replacement. Try cleaning the coil mount (which is it's ground) and see if it makes a difference. If not, time for a new coil then.
I suggest getting a beefier battery. But don't drive around with the dead battery and good alternator or else you will burn the alternator out.
03-29-2004, 02:55 AM
#8
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Join Date: Dec 2001
Location: Louisville KY 40299
Posts: 344
Well the good ( and I guess kinda bad ) news is that coils almost NEVER go bad. Under regular operating conditions, Ive never seen, or heard, one fail.
Also, if youre only getting 11-12 volts at idle, you need a new alternator. It has to be above 12.5 ( I think...Maybe 12.6 or so... ) to even charge the battery. I dont know who tested your alternator but I think they didnt know what theyre doing or their machine was bad.
Never heard about the energy saving thing with cutting the trailing spark, but you never know. I do know that if youre tach isnt working, 99.9% of the time it means your trailing plugs arent firing.
Hope this helps some.
Also, if youre only getting 11-12 volts at idle, you need a new alternator. It has to be above 12.5 ( I think...Maybe 12.6 or so... ) to even charge the battery. I dont know who tested your alternator but I think they didnt know what theyre doing or their machine was bad.
Never heard about the energy saving thing with cutting the trailing spark, but you never know. I do know that if youre tach isnt working, 99.9% of the time it means your trailing plugs arent firing.
Hope this helps some.
03-29-2004, 09:45 AM
#9
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Join Date: Mar 2004
Posts: 172
Miscellaneous ramblings from the FNG . . . . . .
- If you’ve drained a several year old battery while cranking the starter, the battery is probably toast.
- In looking at almost any automotive wiring schematic, without a good battery, all bets on electrically dependant systems are off.
- Any voltage measurement is dependant on a working battery, and dead batteries don’t work.
- Costco sells brand new batteries for $35 where I live.
- You can burn up a perfectly good alternator with a defective battery.
- For 100 points: Does the ECU operate properly on substandard voltage? For 50 bonus points, does the ECU control the trailing coils? (Aside from not operating properly, it’s possible to fry an ECU using low voltage, but that’s not your problem . . . . . . yet . . . . . . . we hope . . . . . .)
I would start by replacing the battery.
- If you’ve drained a several year old battery while cranking the starter, the battery is probably toast.
- In looking at almost any automotive wiring schematic, without a good battery, all bets on electrically dependant systems are off.
- Any voltage measurement is dependant on a working battery, and dead batteries don’t work.
- Costco sells brand new batteries for $35 where I live.
- You can burn up a perfectly good alternator with a defective battery.
- For 100 points: Does the ECU operate properly on substandard voltage? For 50 bonus points, does the ECU control the trailing coils? (Aside from not operating properly, it’s possible to fry an ECU using low voltage, but that’s not your problem . . . . . . yet . . . . . . . we hope . . . . . .)
I would start by replacing the battery.
03-29-2004, 09:56 AM
#10
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Join Date: Oct 2003
Location: Canada
Posts: 3,502
Originally Posted by adamlewis' date='Mar 29 2004, 12:55 AM
Also, if youre only getting 11-12 volts at idle, you need a new alternator. It has to be above 12.5 ( I think...Maybe 12.6 or so... ) to even charge the battery. I dont know who tested your alternator but I think they didnt know what theyre doing or their machine was bad.
I was testing my battery and alternator output with a DMM back when I had the stock FC alternator. It was charging about 12.7, 12.8 at low idle, and a hare above 13 when I blipped the throttle.
However in the same manner, but reading from the stock gauge, I was looking at similar output to what he described.
The alternator probably is fine, but the battery isn't holding a change anymore or something. But who knows how long the alternator will be good for when you drive the car with a dead battery like that..