stanz

iTrader: (1)

Ok, so after months of headaches and endless weekends of wrenching my 1986 4Runner is finally getting to a point that I can knit pick the little things...

Here's something that the average driver probably wouldn't even pick up on but it bothering me...

-Idles strong, accelerates strong
-No misfires at idle or under load

However, while that idle is going strong up front, I get a very random subtle hiccup in the exhaust accompanied by some water droplets. There's not pattern to the hiccup, it can go a few minutes without it and then hiccup once or a few times in a row. The whole time the motor up front does not skip even the slightest.

A friend was thinking perhaps the catalytic converter is clogged.

-Exhaust manifold is new, exhaust behind the cat is new
-No exhaust leaks
-No vacuum leaks

Thoughts?

myyota

The things I would do is pull the throttle body off and give it a good cleaning, check all vacuum lines. Has the 02 senser ever been replaced ?, if its original or has over 50 thousand miles on it then is need to be replaced. Use a Denso 02 sensor, DO NOT use a Bosch 02 sensor they don`t work in toyotas. When was the last time the fuel filter was replaced ?.

The water in the exhaust is probably just condensation. Take your 4Runner out on the highway and let everything heat up and it should stop

stanz

iTrader: (1)

Thanks for your note. In the past three months I have already done everything you suggested and more... throttle body removed, cleaned, calibrated, new fuel filter, new PVC, new denso o2 sensor, every vacuum line replaced, cap, rotor, plugs, valve adjustment.

The motor doesn't miss at all. I only hear it in the exhaust.

Motox711

I am curious as i have a similar issue where it slightly hiccups. done all the same stuff. but i recall that all fuel has more ethanol now and wondering if that would affect our older rigs in these minor hiccups etc.

combatcarl

Hey stanz, mine has done it too, for years. My dad never noticed it because the motor doesn't make any movement while idling, and I've tried to point out the little random hiccup I hear, and nobody else ever catches it. It's done it with a fresh motor and tune up, so I don't worry about it. Just another Toyota tic.