Blackened spark plugs. Charred like chicken

[cuzinyung]

I hope html works here.That's all 4 plugs in order from front of car to back of car.

I got my car used in march. It's a '90 KA24E, no mods, just been trying to get this thing running smoothly. Right after getting the car I replaced the spark plugs & wires, fuel filter and air filter. It stumbles at idle and lower RPMS (not too bad, but noticeable) and my mileage stinks. Something like 12-18 mpg. Aside from that, the car is dependable and runs fine.

I just got financial aid money finally, and I want it fixed. Are the charred plugs from injector leak, or FPR? Or both, maybe? It worries me that I found all 4 plugs lookin like that. Guesses please.

I <3 NICO. Ronnie

Modified by cuzinyung at 8:30 AM 9/30/2005

Modified by cuzinyung at 8:31 AM 9/30/2005
Modified by cuzinyung at 10:22 AM 9/30/2005

[anyotherone]

I don't have a definative answer, but you might try looking at this:

http://www.pdm-racing.com/features/plugs.html

and this:

http://www.4secondsflat.com/Sp....html

Cheers!

[navysnail]

they just look like old plugs to me.

[dfw240_EE]

Except they aren't old. He said he got the car in March and replaced the plugs. That would be only 6 months. I don't think the plugs should be looking like that this quick.

Try this link:zer...58975

[ricebike]

well, comparing to the pdm site link,

#1 seems normal

#2-4 looks like they're overheating <unless the white pocelain are from a flash from your camera>

Quote »Electrodes have a glazed appearance, core nose is very white with few deposits. Check plug heat range, ignition timing, fuel octane rating (too low) and fuel mixture (too weak). Discard plugs and cure fault immediately.[/quote]

[cuzinyung]

Fuel octane? eh? I'm ok with 87, right? I took the pics w/o flash. Could be the overheating thing... ugh, so many things to check.

Thanks for the links. LOTS of info - I'm reading up, and I'll do some more checks before I fork out any cash.

I just know that I'm losing gas somewhere, cuz my mileage is horrible. I'm sure the carbon all over the spark plug ends is my biggest clue of that.... but I just need to figure out where to go from here. I feel like my fuel regulating system is all messed up... I need to figure out how to get in there and check it all.

Now if you'll excuse me, I'm going to go sniff some car exhaust.

[ricebike]

well 87 ocatane should be the going rate for these sohc, or u just have gobs of carbon buildup--search seafoam to get rid of it, lowering your octane need back to factory specs. i'd clean/gap those old spark plugs, do the seafoam procedure, let it cool down, then change plugs.

u check the trouble codes to make sure there's no problem that the car's pc has stored?

compression test would tell if your engine's still healthy...

http://www.240sx.org FAQs to check on how u can retrieve the codes...

car's pc also has a mode to check how fast your o2 sensor is fluctuating/ or u may just change it.

goto nissan online mechanic forums & read the "stickies" lotsa info there to play around w/...

lotsa other stuff, BUT

if it ain't broke--- 12-18 mpg is city driving? or mebbe we in that climate change for gas formulations to be altered for the winter months, which i heard will temp see a drop in mpg

[cuzinyung]

I haven't done the trouble code thingy - I've been wanting to. I'll check that out.

Yeah, I've had bad mileage ever since I got the car, really - independent of seasons. It just irks me more and more, seeing the gas prices rise!!! Hence my car's name: "Moneysponge"

I've heard of the seafoam thing, I just need to make sure to do it right. I've heard mostly good stories, but here and there I hear some weird ones.. and people say to do it at night, cuz it smokes up the whole block???

But thanks for all the tips, and if I find more solutions/questions as I'm working on the car I'll post 'em here.