4af white spark plugs - Toyota Nation Forum : Toyota Car and Truck Forums

toyota4x4$ · 06-10-2009, 12:15 AM

i got a 89 corolla sr5 4af motor. i changed every fluid and filter on the car and changed the spark plugs. when i changed the spark plugs i noticed that they were white. so i changed them again 3 months later and they were white again. i changed them again to a lower heat range plug and it still didnt do anything. i changed the timing to 5 degrees btdc. i cheked the codes the other day and it read no stored codes. the car runs not bad, but i feel its running lean by the way the plugs look. any help is appreciated. iain

kcwa · 06-10-2009, 07:39 AM

Could be that you are running lean or the timing is advanced...but what I am thinking is that the plugs you are running might be too hot and you need to use cooler plugs. What plugs are you running? Could be a combination of all three...

Flashmn · 06-10-2009, 08:38 AM

Unleaded fuel makes plugs whitish. BCPR527Y should be the correct plug, no need to go to a different heat range, hell, I run 5's on a turbo corolla :P

toyota4x4$ · 06-15-2009, 06:50 PM

i did change the plugs to a cooler heat range and i changed the timing to 5 degrees btdc (stock). and it still didnt do anything. im takin it to a auto shop tomorrow and gettin them to diagnose it., so i can fix it at home.

toyota4x4$ · 06-22-2009, 08:09 PM

turns out the plugs were fine according to the mechanic, he said that the car was suppostu run a little lean for added horsepower?? he said that they were not that bad and i had nothing to worry about.

kcwa · 06-22-2009, 08:51 PM

That is good to hear... at least I was kinda correct about running a little lean. Sounds like you are good to go!

Flashmn · 06-23-2009, 02:11 AM

Quote:

turns out the plugs were fine according to the mechanic, he said that the car was suppostu run a little lean for added horsepower??

wait what... a little lean eh? no way man, horsepower is made slightly rich, but its normal for the plugs to be white when using unleaded.

enginemount · 07-07-2009, 12:56 AM

Maybe there just a little vacuum leak, in carb engine case, vacuum leak cause the venturi flow down and less fuel atomization.the normal vacuum should be more then 20 in/hg (mine is 23in/hg) , you may check the hoses or devices about the intake manifold & carb.