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What is this little capacitor looking thing?


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24 replies to this topic

#1 Dinky26

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Posted 15 February 2013 - 05:18 PM

Okay, so anybody know what this little do hicky is or does? :confused:

 

This is on my 86 Brat with an EA81 engine.

 

It is on a bracket that slips under the coil hanger. 

 

Attached File  try2.JPG   45.4K   142 downloads

 

 

New format giving me issues posting pics :banghead:



#2 MilesFox

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Posted 15 February 2013 - 05:41 PM

IT is a noise suppressor to keep alternator whine out of the radio



#3 Dinky26

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Posted 15 February 2013 - 05:47 PM

Oh, so being the wire on the one end looks like it is going to break off, could cause the radio to cut in and out?? maybe??

#4 ShawnW

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Posted 15 February 2013 - 05:51 PM

Don't worry about it until your radio makes funny noises.  I see them all the time missing that piece and no complaints of the radio.  



#5 Cougar

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Posted 16 February 2013 - 10:26 PM

It's a capacitor alright and it helps filter the ignition pulses getting into the power supply.



#6 scoobiedubie

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Posted 16 February 2013 - 11:13 PM

Better replace it ASAP.  It is so critical that I run 2 in parallel.  If that wire breaks, your engine won't start.  The static on your radio will get real bad right before it goes out.  Then you will need a tow, if you don't have a replacement. 



#7 Turbone

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Posted 17 February 2013 - 02:23 AM

Better replace it ASAP.  It is so critical that I run 2 in parallel.  If that wire breaks, your engine won't start.  The static on your radio will get real bad right before it goes out.  Then you will need a tow, if you don't have a replacement. 

 

You cant be serious?

The main purpose of this capacitor is to reduce the amount of signal noise to the radio.

Thats it, nothing else.



#8 scoobiedubie

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Posted 17 February 2013 - 12:36 PM

You cant be serious?

The main purpose of this capacitor is to reduce the amount of signal noise to the radio.

Thats it, nothing else.

 From personal experience, the engine would not start with a defective capacitor.  Laugh all you want.  Once I replaced it, then I could get it running. 



#9 mikaleda

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Posted 17 February 2013 - 12:47 PM

I've never seen one of these cause any problems with the engine performance including Chevys, dodges, subarus they are just to keep eltrical noises out of the radio
I usually take them off in fact lol

Edited by mikaleda, 17 February 2013 - 12:48 PM.


#10 Dinky26

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Posted 17 February 2013 - 01:03 PM

I've never seen one of these cause any problems with the engine performance including Chevys, dodges, subarus they are just to keep eltrical noises out of the radio
I usually take them off in fact lol

And upon doing this you don't get a bunch of noise through the radio??



#11 mikaleda

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Posted 17 February 2013 - 01:05 PM

I don't listen to the radio much on the cars I did it to :) I never noticed though

#12 Dinky26

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Posted 17 February 2013 - 01:17 PM

 From personal experience, the engine would not start with a defective capacitor.  Laugh all you want.  Once I replaced it, then I could get it running. 

Wierd that it would do that. :confused: ....at least from what everybody else is saying.

 

The stereo does seem to make intermitent poping sounds, at first I thought it was just the CD skipping, then I plugged in my USB drive and it still does it on occasion too.  But I am not sure about actual radio responses since I don't listen to that part of stereo much. 



#13 capn_r

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Posted 17 February 2013 - 02:40 PM

 From personal experience, the engine would not start with a defective capacitor.  Laugh all you want.  Once I replaced it, then I could get it running. 

Possibly yours failed by shorting the capacitor to ground when it would be more common to fail open which would act the same as not having one. Just a thought.



#14 Turbone

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Posted 17 February 2013 - 11:50 PM

 From personal experience, the engine would not start with a defective capacitor.  Laugh all you want.  Once I replaced it, then I could get it running. 

 

You have it wired in wrong then. The RFI cap has nothing to do with the running of the car.

And I'm not laughing. If you want to volunteer info, please be sure its legit.

 

Heres something I pulled off a Marine Engineer's site...

 

Gas Engine Ignition Systems

The most troublesome source o f interference on small gas driven vessels is the engine ignition system. The release of energy across the electrodes of a spark plug involves very sudden changes of voltage, and current in the ignition wiring. This causes a popping noise at low speeds, and a loud buzz as the speed increases.

Most of the radiated noise originates from the high voltage leads to the spark plugs. Resistance in the high voltage circuit considerably reduces the high frequency interference generated. The best place to put the resistance is as close as possible to the spark plug. Resistor spark plugs must be used as a first step in reducing ignition interference. In addition, resistance type high voltage wiring will further reduce the 
interference. The use of both resistor type plugs and resistive spark plug wire will suppress the noise more effectively without producing detrimental effects on engine performance or spark plug life providing the proper spark plug heat range is selected.

Any deterioration in the ignition system can completely defeat the advantages of resistor plugs and wiring. The ignition system must be periodically checked for such things as: loose connections between wiring, plugs and distributor; excessive wear on the distributor rotor; dirt or cracks in the distributor cap; dirty or fouled plugs.

In addition to the high voltage secondary circuit, the low voltage primary circuit can add to the noise problems. The main offender in the primary circuit is the breaker points. Noise generated at the points can be conducted and radiated by the ignition primary lead. As this lead generally goes through the vessel to the key switch on the dashboard, the noise must be eliminated from this wire. The most effective way is 
to install a 0.5 microfarad coaxial condenser as close as possible to the ignition coil primary terminal. 

Besides the ignition lead going to the ignition switch, there is often a tachometer lead from the ignition system. As many tachometers depend on pulses from the engine for there operation, it is not practical to filter the pulses from this line. 

Where an ignition operated tachometer is used, the wiring to the tach must be shielded. This can be done by replacing the existing wire with shielded wire or 
pulling a copper braid over the existing wire. The braid should be securely grounded at the engine. 

The above techniques will considerably reduce ignition interference. If a further reduction is required, the ignition system must be shielded to prevent radiation of the remaining noise. This can best be accomplished by using a shielding kit on the entire ignition system. These kits are available for most engines and consist of shields for the plugs, shield braid for the high voltage leads, and metal shields for the coil and distributor. Ignition shielding kits can reduce the high voltage available at the spark plugs. In this instance it may be necessary to install a higher voltage coil.

While the shielding kit may provide good suppression when installed, the performance will deteriorate with age. When we shield and connections become corroded, there are many points where radiation may occur. The effective life of a shielding is probably no more than two years. This plus the cost of the kit ($150 -$200) makes them useable only in the most extreme cases.

Another effective method of shielding is to enclose the entire engine compartment in a metal screen cage. The screen must completely surround the engine and all leads into the engine compartment must be filtered with capacitors.

 

 

http://www.dieselduc...nterference.htm

 

I've had many old gen Subaru's that were missing caps or were disconnected. They all ran fine.



#15 scoobiedubie

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Posted 18 February 2013 - 10:54 AM

You have it wired in wrong then. The RFI cap has nothing to do with the running of the car.

And I'm not laughing. If you want to volunteer info, please be sure its legit.

 

Heres something I pulled off a Marine Engineer's site...

 

 

http://www.dieselduc...nterference.htm

 

I've had many old gen Subaru's that were missing caps or were disconnected. They all ran fine.

And my subaru dealer also told me that defective capacitors can cause the engine to not function.  Not only that, but entire cars were being taken to the junk yard, because the mechanic could not find the cause of the engine not starting, which the subaru dealer believed was due to that capacitor.  The capacitor may have shorted internally, which would be a different scenario from the wire breaking.  Subaru even made a completely different style to replace that little can like capacitor.  The new style was a fully encased electronic board.



#16 Dinky26

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Posted 18 February 2013 - 12:42 PM

Well, I guess that if my BRAT quits running I will check this wire first.

#17 NorthWet

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Posted 18 February 2013 - 02:13 PM

Could it be we are confusing apples with oranges?  As in:

 

Electronic distributor, non-required RFI suppression.

 

Mechanical/Points distributor, needed points-arc suppression.



#18 Turbone

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Posted 18 February 2013 - 05:59 PM

And my subaru dealer also told me that defective capacitors can cause the engine to not function.  Not only that, but entire cars were being taken to the junk yard, because the mechanic could not find the cause of the engine not starting, which the subaru dealer believed was due to that capacitor.  The capacitor may have shorted internally, which would be a different scenario from the wire breaking.  Subaru even made a completely different style to replace that little can like capacitor.  The new style was a fully encased electronic board.

 

Screw it, I dont need to prove anything here.



#19 MilesFox

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Posted 18 February 2013 - 07:24 PM

don't feed the troll



#20 l75eya

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Posted 18 February 2013 - 09:50 PM

I was curious why there were so many responses to such a simple question. Should have known though.



#21 scoobiedubie

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Posted 19 February 2013 - 12:29 PM

Could it be we are confusing apples with oranges?  As in:

 

Electronic distributor, non-required RFI suppression.

 

Mechanical/Points distributor, needed points-arc suppression.

The 85 & 86's are the mechanical/points distributors.  87 & beyond are the electronic.



#22 mikaleda

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Posted 19 February 2013 - 12:32 PM

1980 was the first year of electronic ignition I know I have an 80 and a shop Manuel for it

#23 mikaleda

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Posted 19 February 2013 - 12:46 PM

05782F69-639B-47A8-B844-14AFACDAF109-997
1980-1987 chiltons shop Manuel

Edited by mikaleda, 19 February 2013 - 12:47 PM.


#24 NorthWet

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Posted 19 February 2013 - 01:29 PM

1980 was the first year of electronic ignition I know I have an 80 and a shop Manuel for it

Thanks for anchoring this with a fact.  So, the OP's ignition is electronic.  Conclusion: The capacitor is for non-critical RFI/EMI suppression. 

 

The only way that I can see this capacitor causing problems is if it shorts to ground.  Removing it completely would eliminate this fault.

 

(Perhaps, the dissenter might be referring to experience in some vehicle that had points-style ignition,  Or the mechanic is less than honest/reliable/well/informed) 



#25 Dinky26

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Posted 19 February 2013 - 02:39 PM

Thanks Guys, for clearing that up, good to know the intermittent popping I am hearing is just prolly from that.




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