Reasons For Fouling Spark Plugs?

[10secdream]

Well guys I can't figure out why I keep carbon fouling my spark plugs. I know many of you will say I am running too rich but I really beg to differ unless my wideband is very inaccurate.

I am running the stock twins with 3 inch catless exhaust, hks downpipe, hks intake, hks intercooler, jdm 440 cc injectors all tuned with stinger ems and bosch wideband.

My AFR at idle is around 16 and my lean cruise is around 15.5
Under wide open throttle I am only going to factory boost of 12 psi and my AFR is right around 11.8

My current set of spark plugs are champion plugs in the stock heat range gapped at .30 and I am not missing or breaking up at all.

This is my 4th set of plugs and I have no clue why they keep fouling overnight. The car drives and runs like a dream and I just can't figure it out. Any advice?

 

[IJ.]

Stem seals

 

[10secdream]

How much work is involved to replace the seals?

 

[IJ.]

Quite a bit.

Is it at all smokey on closed throttle overrun?

ie: Accelerating after a big downhill off the gas does it puff smoke when you get back on it?

 

[10secdream]

Quite a bit.

Is it at all smokey on closed throttle overrun?

ie: Accelerating after a big downhill off the gas does it puff smoke when you get back on it?

It is funny you mention that because last summer whenever I would stop at a light and idle there would be a huge puff of black smoke and it would fill the intersection in seconds. Now that I have put the stinger in the smoke has disappeared completely. :aigo:

 

[IJ.]

Blue Smoke not black

 

[CyFi6]

Any pics of the plugs?

 

[10secdream]

Any pics of the plugs?

Sure I will get a picture for you tomorrow but imagine this. A spark plug just covered in carbon with no trace of the white insulator to be seen. There is no oil on the plugs just carbon buildup.

 

[10secdream]

Blue Smoke not black

Well the smoke I had last summer was not black but more of a white color.

 

[IJ.]

Go for a drive find a big hill throttle off and engine brake going down.

watch the rear view mirror as you put your foot back on the gas

if it's stem seals you'll see what I mean.

The amount of deposits that you describe doesn't sound like fuel.

 

[10secdream]

Go for a drive find a big hill throttle off and engine brake going down.

watch the rear view mirror as you put your foot back on the gas

if it's stem seals you'll see what I mean.

The amount of deposits that you describe doesn't sound like fuel.

I will try my best to find a hill where I live. It is all prairies and nothing but boring flat roads.:icon_bigg

I have a feeling that my spark plug issues are not fuel related as well. I have honestly gone through 3 sets of spark plugs in a matter of 300kms:nono:

 

[IJ.]

Anywhere nearby you can get it to 100 without being arrested and violated anally?

If so same test replace Hill with speed
(keep in mind I said safely)

 

[10secdream]

Anywhere nearby you can get it to 100 without being arrested and violated anally?

If so same test replace Hill with speed
(keep in mind I said safely)

Well if she starts tomorrow I will take her for a spin. The spark plugs only last a day so it is getting expensive to run the car.

 

[IJ.]

Never considered cleaning them?

 

[10secdream]

Never considered cleaning them?

You bet I got 3 sets to clean now so I can just start the rotation going. I am becoming very good at changing plugs btw.

 

[IJ.]

I beadblast mine.

I can swap them out in 15 minutes.

 

[grimreaper]

Basically, soft, sooty carbon deposits, as shown below, have a dry, black appearance. If only one or two plugs in a set are fouled, it is a good practice to check for sticking valves, a cracked distributor cap, or bad secondary ignition wires. Fouling of the entire set might result from an incorrect heat range spark plug or an over-rich air/fuel mixture caused by a clogged air cleaner filter element, a sticking heat riser valve, or a faulty choke. Fuel injectors that malfunction can also lead to this condition.

Other causes include weak ignition system voltage or an inoperative pre-heating system (carburetor intake air) or poor cylinder compression.


^^ pulled it of google, at least its a place to start besides the plugs! just double checking on this, but is your wbo2 calibrated?

 

[10secdream]

It is my understanding that the Bosch O2 sensor does not need to be calibrated.

I am going to try IJ's highway run this weekend and do a compression test to see what is going on with my 1JZ. Also what are signs of a weak ignition system?

 

[figgie]

It is my understanding that the Bosch O2 sensor does not need to be calibrated.

I am going to try IJ's highway run this weekend and do a compression test to see what is going on with my 1JZ. Also what are signs of a weak ignition system?

it is an electrical part.

It needs to be free air calibrated to make sure that the resistance value has not changed or if it has, to compensate for it.

 

[10secdream]

Well here is a quick update. I tried the highway test and everything seemed normal. I would decelerate off throttle and then put my food on the gas and there was NOT a big cloud of smoke trailing behind me.

I drove the car for appoximately 3 days and it started up everyday but it was missing under boost. I changed the spark plugs to NGK 6097's and the previous spark plugs (Stock heat range plugs) were really carbonized. I ran the NGK 6097's for about a day and the car ran awesome. The idle was very good with no miss and it pulled hard and never missed during boost.

Finally the 1JZ seemed to be running right for a change. I go to start the car last night and what do you know the car is only running on a couple of cylinders and is bucking hard. I pulled a plug and what do you know it has carbon on it.

Anyways here is some information that I hope will help solve this mystery. When I am on the throttle the car WILL pull normally on all 6 cylinders. When I happen to let off the throttle the car will only run a couple cylinders. When I stop at a light the car will completely die unless I give it gas.

So here are my thoughts. I am thinking it is probably a weak ignition system and during no/low throttle conditions the plugs are not getting enough juice to completely ignite the air/fuel mixture and thus fouling spark plugs. My question is why does the car run normally under load/WOT conditions? I am going to try a friends ignitor for the week and see if this will solve the issue.