ArgenEnd21

Welp, I wish my first post on YT would have been more positive, but such is life sometimes.

Background info- 1997 4runner 3.4 V6 4x4 (auto) with 167,000 miles

Bought the Truck a year ago and have replaced the cooling system in that time (rad, thermostat, water pump) All done at dealer. Ive also changed the plugs (with correct dual-electrode NGK plugs gaped to spec) and cleaned the MAF and throttle body as well.

Truck has been running fine and not using any oil between changes with the coolant staying clean and not disappearing. Engine is quiet and gets oil changes every 3-4k miles.

HOWEVER, the last few days the engine has been running rough at start up, most often warm-starts (within an hour of being driven ). While the engine is misfiring, I can see a large cloud of an unidentified gas exit the tail pipe. I've only experienced the smoke at night so I am unsure of the exact color of it, but i can testify that it smells petroleum based and stung my eyes/nose as I walked through it. It appeared whitish, but again I just saw it at night.

It only does this for a few seconds and once the engine smooths out there is no smoke. The car doesn't smoke when being driven normally, just during these 'fits'. Revving the engine during the misfire produces more smoke, but once its all smoothed out I can drive without any noticeable loss in power. The engine never stalls during the fits. If i re-start the engine immediately after it smooths out it will start fine with no smoke.

There is no smoke at all on cold starts and the coolant gauge never rises past half-staff while driving.

If it matters, I'm located in Southern California. It pains me to see the old gal like this since she hasn't a lick of rust nor a door ding and I just did the tundra brake upgrade and replaced the master cylinder a month ago

I hope it's as easy as a bad IAC or fuel injector, but I appreciate any advice. Sorry for the novel, but thanks for the help!

I think I'm going to change the oil tomorrow and check for coolant and take a look at the plugs.



tl;dr- 4runner with 3.4 V6 with 167k has recently begun misfiring and smoking when started warm. After the misfire and driving she runs like a champ and breathes clean. Should I go to the dealer and buy some parts with beer money, or should I look to sell a kidney? *I also searched but could not find anything that matched my exact symptoms*

-Scott

redhawk427

well im probably no help but i thought id give an idea for something to research. try looking for knock sensor troubleshooting?? or possible throttle position sensor?? just wild guesses

kball

That doesn't sound like a head gasket to me. It should smell musky sweet like a sweaty locker room mixed with cologne. If it smells like fuel I'd bet it's a leaking injector. After you shut it down it dribbles into the cylinder and then you fire it up and you have a bunch of fuel that's not getting burned. After it sits for a while the injector stops leaking and the fuel seeps past the piston rings and into the crankcase. So then it starts fine. Of course I could be completely wrong... Check your coolant level and see if it's low.

mt_goat

I'd send an oil sample off to Blackstone for UOA ASAP, probably taking a cold sample would be best in this case.

swampfox

the leaking injector suggestion is a good start, also i had a chevy that that acted similarly and it was a bad temp sensor for the ecu. the ecu didn't know what the engine temp was so it over fueled on hot starts.

ArgenEnd21

Well, after driving the truck today I could tell the smoke is in fact white and dissipates rather than lingers. I can also smell coolant inside the cabin so this is making me suspect the head gasket even more..

After changing the oil I saw no coolant with the motor oil, however, i could see/feel a greasy red fluid dripping out of my existing exhaust leak right before the cat that smelled like burnt coolant

My coolant overflow tank doesn't seem low, but this problem has arisen within the last few days.

Smelling the coolant has my suspicions high so I'll be dropping the runner off at the dealer for them to properly diagnose the problem.

So I suppose what i should be asking now is, what is a fair price for a head gasket replacement from a Toyota dealership?

Being a gear-head, I'd love to tear apart the engine and do the work myself, but being a shade-tree mechanic who can't be without a vehicle, I think i should let the guys with the certificates and fancy tools tackle this one.

*edit* I feel I should also mention that when I originally bought the truck a year ago (20k miles) it had an overheating problem due to a clogged radiator.