2G Yellow Tip Spark Plugs?

[TuRBoTaLooN]

I just went to swap out my plugs for new ones today. I took out the old plugs and they were all yellow??? (see pictures below). I searched the forum and found one thread about it (YellowPlugs) but I cannot post there, so I posted a new thread here for some more insight.

BTW: the old (yellow) plugs were NGK 7's and the new ones are NGK 7's as well.

My mods are in my profile, but quickly I have a 16g w/ 18g compressor wheel, FMIC, 550s, SAFC II and chipped for 550s. I never tuned it with the SAFC II. It was tuned by the previous owner a month or so ago. The only mod I've done since I bought it was the FMIC/greddy type s bov. It previously had a Dejon Super SMIC. Car seems to run ok, but I have no way of logging yet. I'm going to pick up a wideband this week to give it a fresh tune. Is this a sign of running too lean at WOT??

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[steve]

Have you put any sort of octane booster?
The various additives can cause different color deposits.

Steve

 

[TuRBoTaLooN]

I've never used any octane booster, but I can't say for the previous owner. I will check the new plugs tomorrow after driving around and report back.

 

[Locke]

Looks like it's glazed. High EGT's at high engine speeds. Try a colder plug. Or get it tuned.

 

[steve]

What do your new plugs show?

Steve

 

[TuRBoTaLooN]

What do you new plugs show?

Steve

I've driven the car a total of maybe 8 miles with the new plugs so far and no WOT pulls. Pulled them out today and they look fine. Little black. I don't really want to get on it until I can get a wideband.

 

[dsm-onster]

Looks like it's glazed. High EGT's at high engine speeds. Try a colder plug. Or get it tuned.

Yes, those are clasical pics of glazed plugs. I'm glad you posted them so that others can see. . .

Yellow glazed plugs suggest that normal plugs deposits have melted rapidly. Sometimes these melted deposits are slightly conductive and cause misfiring at high rpms.

I've driven the car a total of maybe 8 miles with the new plugs so far and no WOT pulls. Pulled them out today and they look fine. Little black. I don't really want to get on it until I can get a wideband.

Glazing usually occurs when you do a series of highspeed/highrpm pulls. It indicates that combustion chamber temps have suddenly risen during hard accel. NGK 7s are fine for any hp level 550s will allow. It is likely your timing is significantly advanced and/or you're running quite lean.

It seams like your fmic is doing its job and preventing detonation/preignition as your plugs were not white.

If the plugs are a little black now (w/ no wot pulls), then there is some deposit build up from possibly running a "little rich" in closed loop. then running really lean at WOT will likely glaze those deposits.

What does your logger show WRT timing spikes and IDC? Waht are your fuel trims telling?

 

[TuRBoTaLooN]

dsm-onster thanks for that post. very informative.

I do not have a logger right now, nor a wideband. The car was tuned via SAFC before I purchased it. The only difference since I bought it was the FMIC. I plan on buying a widband o2 sensor immediately and do some tuning of my own. If the problem still persists, I will get a logger to log some more information.

In case it helps any, the car seems to pull very hard from like 3k to 4800rpm range, then seems to fall off at the top end. Perhaps that is the issue with timing being incorrect?

 

[dsm-onster]

dsm-onster thanks for that post. very informative.

I do not have a logger right now, nor a wideband. The car was tuned via SAFC before I purchased it. The only difference since I bought it was the FMIC. I plan on buying a widband o2 sensor immediately and do some tuning of my own. If the problem still persists, I will get a logger to log some more information.

I wouldn't run any aftermarket setup w/ out a logger, especially one w/ an 18G and the other supporting mods you have listed. I'd get the logger first. They can be had for cheaper than a good wideband (scanmaster=200, tunerstein=freesoftware+cable+palm(or laptop). Visualizing just your air/fuel ratio is not enough here. A LM-1can log it but to log it over the rev range you need to have the rpm converter and spen 450 total. I'll bet you can solve your problem w/ just a logger.

In case it helps any, the car seems to pull very hard from like 3k to 4800rpm range, then seems to fall off at the top end. Perhaps that is the issue with timing being incorrect?

Have you verified your timing w/ a light? I know you cannot adjust timing on a 2G, but your intake cam timing may be off a tooth and sending base timing through the roof.

Do you have a lopey idle? Your discussion of your power range suggest that you have significant overlap. More overlap yields great spool and midrange torque, but falls on it's face up top w/ stock cams. . . Increased overlap will occur if your intake cam timing is advanced. Since your cas runs off of your intake cam timing, advancing the intake cam, even only one tooth, will advance your ignition timing WAY too much.

 

[TuRBoTaLooN]

The idle seems a LITTLE lopey (if that's the word you want to use) but I thought nothing of it. But yea, the car seems to die at the top end. Again, I will report back after some more diagnosis. Need to find a friend with a timing light.

But can the intake cam just skip a tooth? Or would it have to be installed incorrectly??

 

[blcknspo0ln]

It can be either/or. That's known as "skipping timing". If you're off by a tooth, however, it's general due to install error.

 

[TuRBoTaLooN]

Here's some follow up based on recent diagnosis:

Drove the car some more with some WOT pulls, partial throttle pulls, etc. Plugs look 100% fine (didn't get a chance to post pictures yet.)

Car still runs like poop. However upon a PROPER boost leak test, found that I leak in a few places at 8psi!! Going to order some new t-bolt clamps and a new bov because mine is leaking. Perhaps some new gaskets as well.

Also, installed an NGK Powerdex wideband. At idle, A/F reads 16.00. Using the SAFC, I tried to adjust this. If I go +20% or -20% the A/F will adjust accordingly for a few seconds, and then it will go right back to 16.00??? Partial throttle and WOT under boost A/F ranges in the high 11's, low 12's. Also, the A/F seems to vary quite a bit even while cruising. Any ideas?

BTW: ECU is chipped for the 550's I am running.

 

[snox135]

It seams like your fmic is doing its job and preventing detonation/preignition as your plugs were not white.

Impossiable to tell from those pictures. You need to look at the base of the porcelain for wot (boost) conditions.

 

[steve]

Also, installed an NGK Powerdex wideband. At idle, A/F reads 16.00. Using the SAFC, I tried to adjust this. If I go +20% or -20% the A/F will adjust accordingly for a few seconds, and then it will go right back to 16.00??? Partial throttle and WOT under boost A/F ranges in the high 11's, low 12's. Also, the A/F seems to vary quite a bit even while cruising. Any ideas?

BTW: ECU is chipped for the 550's I am running.

At idle and crusing the system is in closed loop where the AFR is controled by the feedback from the front O2 sensor. Assuming you calibrated the wideband, located it according to the manual and don't have any exhaust leaks then it would seem that your front sensor has problems. Since the AFR is regulated by the sensor any changes you make with the SAFC will be counteracted by the ECU and accounted for in your fuel trims until you go outside the range the ECU can correct for.

Any time the front O2 sensor voltage is cycling the ECU is in close loop mode. What most people call tuning is adjusting the AFR while the ECU is in open loop.

Steve

 

[TuRBoTaLooN]

At idle and crusing the system is in closed loop where the AFR is controled by the feedback from the front O2 sensor. Assuming you calibrated the wideband, located it according to the manual and don't have any exhaust leaks then it would seem that your front sensor has problems. Since the AFR is regulated by the sensor any changes you make with the SAFC will be counteracted by the ECU and accounted for in your fuel trims until you go outside the range the ECU can correct for.

Any time the front O2 sensor voltage is cycling the ECU is in close loop mode. What most people call tuning is adjusting the AFR while the ECU is in open loop.

Steve

I calibrated the wideband according to the manual. It is located far enough away, but before where the cat would be and mounted facing down. Cruising at 2500-3000rpm range, AFR ranges from like 14.4-14.8. Idle at 800-1000rpm, AFR is constant 16.00 (which means it may be higher since that is the highest this wideband reads).

 

[dsm-onster]

So the 1:1 a/f ratio you're mentioning is only at idle?

Many wideband o2 sensors "load up" w/out sufficient flow across them. My lm-1 w bosch sensor does this. I will read a very lean idle until I rev up enough to blow the deposits off of it. . .

What is your narrowband STOCK o2 doing at idle. Is it cycling?

Don't adust the SAFC base settings (injector compensation and anything under 1500 rpms) using a wideband. Adjust it using the fuel trims as a reference. Another reason you need a logger. . . Adjsut WOT and open loop SAFC settings w/a wb o2, if you have one. . .

 

[TuRBoTaLooN]

Thanks for all the help. But in the interest of staying on topic here, the new spark plugs look fine after hard driving. I'll just say it was something the old owner did that I will not do. I will post back up if the new plugs turn yellow.