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Look at my cap! WTF?! High Res Macro Photos

R

RickyN29

NAXJA Forum User
Location
San Jose, California
Okay, wow. I installed this cap and rotor about 10,000 miles ago, and from day one I had a bad idle.

I opened it up and I am confused. I have never seen such colors!!!

Any ideas?

Btw, replacing the cap and rotor didn't fix my idle, so I am confused.

What is this?!?

IMG_9511Small.jpg



IMG_9496-zoomSmall.jpg



IMG_9499expSmall.jpg



IMG_9499exp-zoomSmall.jpg
 
Wow that is weird
And the top inside looks all white like powder or something. Am I right?
And the green looks bubbly.
 
Looks like either the cap was too big or the rotor was too small or the voltage was too low at the coil...really strange. I'm more used to a wear mark. I'd pop the new cap on a regular basis and see if this is gradual. Is it a daily driver ? or does it get parked for days and not used ?
 
Question.....Do you ever drive along the beach at the edge of the surf? It reminds me of what saltwater does to copper. Could it be saltwater found its way into the cap?
 
Last edited:
thats definately menthol.

when I changed my distributor cap last, I didn't realize that I had accidentally set it on ever-so-slightly krooked, but both screws still fully threaded easily without damage to the threads. When I fired her up, the idle was pitiful. I quickley realized the error of my install, and paid a bit more attention to the simple task at hand. (sometimes its easy to overlook the most basic maintenance procedures...)

Perhaps a similar situation happened to you 10,000 miles ago>?

as far as the green goes.. ...i'm still sticking to my menthol idea.. ; )
 
it is caused by moisture in the cap. if you clean the posts it will be fine. be certain to clean the connector on the rotor button also.
 
RichP said:
Looks like either the cap was too big or the rotor was too small or the voltage was too low at the coil...really strange. I'm more used to a wear mark. I'd pop the new cap on a regular basis and see if this is gradual. Is it a daily driver ? or does it get parked for days and not used ?
Click to expand...
Hum, very interesting point.

That time (when the idle got terrible) and this replacement cap are the first time I bought them from Kragen.

They have two part numbers listed for my 90 XJ Laredo. We looked at both, the only difference I could see was one cap was black and the other gray. I wonder if I have the wrong cap which is causing too large of a gap so excessive arch and bad idle.

Also, I should check the coil I suppose.

Anyone know the correct P/N for a Niehoff cap?

EDIT: When the idle issue started, i installed a AL72E (Niehoff), and just replaced it with the same one. According to the Kragen's (CSK Auto) catalog. However, I just went to the Niehoff website and it indicates a FF76A (which was the gray one that looked identicle). Think I should try that one?
 
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In my limited chemical knowledge -- copper(brass) and chlorine make green.

The cap 'looks' like the correct size.
 
You sealed the cap....you may have answered your own ques. Does that cap have a little vent in the top, if not you have trapped in a ton of moisture, could be causing all that arcing thats happening inside that cap.
PS-Great pics.
 
I just sealed the bottom, the top vent is still functional.

I went ahead and replaced it with the other part number. No difference at all. I instead just turned up the idle screw on the throttle body (not the butterfly stopper) and readjusted my TPS. Everything seems fine now. They say it is not the right way, but all sensors are new, everything adjusted right, and that screw is there for a reason dammit!
 
I wouldn't seal the bottom. I'm sure that is moisture in the cap. Sometimes parts houses list the wrong part. They go by what it says in the computer. Sometimes there is a difference in parts by what month it is built in. WD40 should help get rid of moisture also like was said before. I've seen something similar with a cap that sat to long without running and collected moisture. Glad to hear it is running well now. Perhaps idle just was to low??
 
Been there, Done that ........

Definitely caused by moisture trapped in the cap in my case, and it looked exactly like that within 5000 miles, so I would guess yours is the same.
 
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