# White Deposits Distributor Cap



## felesae (Feb 6, 2005)

Help- any ideas what causes white deposits inside the distributor cap? Got a check engine light and slightly rough idle. Plugs and wires recently replced and look good. Checked the old cap and white deposits found on the pins. Replaced cap and button - light went away and she ran smooth for a week. Now Light is back on and checked the new cap an white layer is back! Looked all through Haynes manual and no luck. Any leads appreciated. Thanks..

(1999 Nissan Frontier 4 cyl)

-felesae


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## rogoman (Dec 16, 2004)

Excessive white deposits are generally caused by insufficient ventilation of the inside of the cap. The distributor has vent holes that may be plugged up with dirt.


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## azrocketman (Oct 5, 2005)

1) You need to read the code to see what problem is indicated. Some auto parts stores, e.g. Checker, will read the code for free.

2) Are the white deposits on the contacts? Does the cap have aluminum inserts? I've seen white deposits deposits in other vehicles in the past which are corrosion of the aluminum. I'd look for a cap which is not black (the carbon black in black caps can carbon track)and has brass inserts.

3) How many miles?

Steve L.


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## felesae (Feb 6, 2005)

I've seen the code before. 1148 closed loop control fault right bank. I think this is odd since I have a straight 4 - usually you see banks with engines with sides. And it went away on its own when I replaced the cap, then came back 100 miles later. She's got about 86K altogether on her.

It looks like a fine white flat spray paint and is on the blade tip of the rotor and just the facing flat metal faces of the contacts pins inside the cap. The old cap was on for the last 86K, the new one only 100 miles and it has just as much build up in a week as the old. They do look like aluminum but so was the original. Man and she ran so good there for a bit. 

I've got one lead to check the ignition resistor and coil but the Haynes manual refers to no spark problems. I get spark and she runs- just a little rough.

Thanks. Have a good night. -felesae


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## azrocketman (Oct 5, 2005)

Just a thought based on some other threads. Did you install original equipment plugs or Bosch? I've had no problems with Bosch but the general consensus is that the 4 cylinder engine does not like them. If you did not install original equipment plugs you might want to. Did the onset of the problem match up with the plug change?

Steve


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## felesae (Feb 6, 2005)

Nope special order iridium just like original and nothing really odd on the old plugs to indicate misfire. Wires from the dealer. I'm gonna check them again this weekend and maybe get more of that diaelectric goo to put in all the sockets. Thanks for thinking about it though. 

Man I remember my old 8 cy buick with a quadrajet.. plugs were like 78 cents and you had enough room to all but stand in the engine well to work on it. 

Thanks- felesae


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## azrocketman (Oct 5, 2005)

Rebuilding a Q-jet was not fun and you had to do something about the well plugs in the carb body so they would not leak. Q-jets were fun to play with though, by swapping metering rods and jets.

I'd clear the code with a reader if you have one and see if it repeats. There is some info on the web that suggests the oxygen sensor might be a culprit but I'm not ready to agree with that.

Steve


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