sechott

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I replaced these plugs 10,000 or less miles ago. I rubbed the white off the ones that are black. They are from a 3vze 5sp I think they are too lean, no codes from CEL replaced fuel filter at the same time of SP change. I am thinking O2 sensor. Timing is correct 10-12 btdc I am getting 21+ mpg with mixed driving.

myyota

It looks like your running a little lean. The plugs should be a light tan color. If your 02 sensor is original or has over 50 thousand miles on it, it should be replaced.

scope103

You can test the O2 sensor. http://www.ncttora.com/fsm/1990-1995...e/heatedox.pdf

Replacing an O2 sensor "on the blind" at 50,000 probably isn't a complete waste of money, but in general replacing parts without a clear reason is a good way to use up a lot of time.

The plugs look fine to me, but to each his own.

wyoming9

iTrader: (1)

It is sometimes hard to read plugs from a picture on line .

I think they don`t look bad:wabbit2:

vital22re

iTrader: (2)

are those the platinum? or uranium special $12 each plug? May be best to just run the standard denso or ngk plugs. When was the last time you had the injectors cleaned?

sechott

Thanks for your replies, I never had the injectors cleaned and the plugs are platinum about $4 a piece. I was concerned about running too lean might damage valves and we know about the 3vze valves. Wouldn't all the injectors be dirty if the white is that even on each plug. I would think if it were a fuel problem most likely it has low pressure, right?
From reading other forums of different vehicles pictures of plugs in the same condition are normal, and some say way too lean. I will do as Scope suggests and check the O2 sensor. Again thanks, I am trying to stay ahead of the engine trouble game.

MudHippy

I'm saying too lean. Assuming they're the correct temperature range plugs. Which they look to be, PK16TT right? And I must say I'm shocked that it would even be questionable. As in, if that's not what too lean looks like...then what does it look like?

DEFINITELY a problem somewhere. And other than insufficient fuelling(pressure and/or volume), it could also be an unmetered air/vacuum leak. Or a combination of things. These engines generally run too rich, though some don't. But I've never seen plugs come out of a 3VZ-E looking too lean like that. Mine were always looking too rich, until I started fiddling with things trying to make it run leaner. Which obviously worked because now they come out looking pretty much perfect/normal.

sechott

Mudhippy is correct on the #, I will check fuel pressure and ohm check the O2 sensor, it maybe in need of at least a cleaning. If it were a bad sensor I would get a code, it may just be sending a wrong signal. I looked for a week to find vacuum leaks, no luck I sprayed carb cleaner on every hose, connection and gasket. The engine holds 19" of vacuum at 800 RPMS almost 21" at 1100_1300. Maybe a clogged pressure regulator or fuel pump,

sechott

BTW I found a can of starting fluid behind the seat after I bought the truck last year, and a hole drilled out under the filter box for spray access. Could starting fluid hurt the MAF? Causing lean condition.

sechott

I adjusted the VAFM to give a richer mixture. I feel that I just masked a symptom instead of fixing right, but at least my plugs are showing light tan after a few 100 miles. I took propane all over the engine, sprayed MAF cleaner all over every hose hose connection and couldn't find a vacuum leak. Could the brake booster leak at certain times while driving? And not at idle. I guess I still need to do a fuel pressure check.

abecedarian

I would say (left to right):
1 has a good fuel mixture but slight oil burn
2 has a good fuel mixture and some more oil burn
3 has a good fuel mixture and minimal oil burn
4 has a lean fuel mixture and minimal to moderate oil burn
5 has a good fuel mixture and little oil burn
6 has a lean fuel mixture and moderate oil burn

Overall, #3 and #5 is how they should all look. Black is bad, blisters are bad. #6 ground electrode looks bend all crooked.

Overall, you're not lean, contrary to the expert opinions. You have some oil burn and maybe a bit lean on a couple cylinders.

Burning oil will throw the O2 sensor off and lean the mixture a tad, but I'd say overall you're not as bad as the "experts" suggest.

Pat8942

This might help

Dirt Driver

+1.

Emission-controlled EFI engines burning modern gasoline are not as straightforward to do plug readings on as the carbureted engines that were often tuned by doing just that. Light tan to gray to white is not uncommon in modern engines that have no problems. What does this plug say to anyone? More importantly, what doesn't it say?



Besides that, the plug color is most indicative of the fuel mixture used most often and most recently. Old-fashioned plug readings are done by installing new plugs, doing at least one long pull at the target throttle opening, shutting off the engine immediately upon throttle chop, then you look at the color.