Well i went to smog my 1991 toyota 4 runner with a v6 and it didn't pass. Check engine light came on with code 25 and the guy doing the smog said gas was coming from the exhaust. Dont know anything about the v6s so i dont know where to start. Anyone have any ideas.?

 

umm...
Code 25- Air/Fuel mix Lean ...
... and ...
gas coming out of the exhaust?

Either the smog tech doesn't know his fuel from his condensate or the O2 sensor, ECU and the rest of the engine is fubar'd.

 

the paper work said The HC (PPM) measured at 482 at 15mph and 233 at 25 miles per hour

 

still.... those numbers suggest a rich condition and the code says you're lean.

what does the whole report say? HC, CO, O2, CO2, NOx, etc.?

 

at 15mph co2 at 13.6, o2 at 1.3, co at .53, and NO PPM at 300

at 25mph co2 at 13.3, o2 at 1.7, co at .55 and NO PPM at 114

 

where are you located and / or what are the pass / fail specs for your locale?

 

i live in california

HC ppm max is 121 at 15 mph and 101 at 25mph.

 

What a coincidence: I live in Cali too.

So the code says you're running lean, yet are running rich and failing your emissions.
I'd say the air-injection is working fine since HC is dropping at higher speeds.
I'd lean towards a converter issue, or probable O2 sensor problem myself.

Only thing bugging me is the O2 reading. It should be near zero. Another reason I think the air injection is working and it's a converter or O2 sensor issue.

 

Is an 02 sensor for a 22re the same as the v6? The electrical connector is the same. I have an oem one from a 22re that is new.

 

Well it was misfireing so i pulled some plugs and when i pulled one of the wires on a cylinder it didn't do anything, did a compression check and cylinder had 15 psi. Did a leak down test and it sounded like it was leaking into the exhaust manifold but not sure yet gunna have to pull the valve cover and check em.

 

I would start with the o2 sensors but it is very likely that u have an exaust leak comin from the manifold its a 3.0 v6 right?
and also i have had problems with coils going bad and they are not too expensive as far as the miss fire i would say let it idle while u take plug wires off till u hear the one that doesnt change the idle and then replace that one
between and exaust leak and a bad coil u will lack power and hear some added racket but as far as the coil goes that will make u fail the smogg test and run rich because one of your pistons is not buning that fuel even though it still makes it to the exaust valve so hope that helps good luck

 

well ended up replaceing a head on one side of it because of burnt valve. Got it all back together and went to smog it and it failed for high HC again. This time was 475 at 15 mph and 176 at 25 mph. Anyone have any ideas on whats next?

 

any ideas

 

just pulled wires off and the one furthest back in driver side didnt affect the idle when i removed it, and there are new wires plugs cap and rotor..

 

just swapped out coil and didnt affect it

 

pulled number 6 plug out and was black, but not oily nor did it smell like gas...

 

ever figure anything else out on this one? I'm getting a code 25 myself. I just replaced the left exhaust gasket, the old one was burnt up, and replaced the o2 sensor. Will bad plugs or plug wires cause the engine to run lean?