olympic42

Hey everybody,

I have a 95 4runner with the 3.0 in it, and I am having some problems.If I start the truck up and the truck is cold, it idles just fine. As soon as it gets warm the idle drops way down and is really rough and lopey like a tractor. If I let it continue the engine will stall, if i give it gas it is fine until I let off. About 5 months ago i replaced the o2 sensor because the check engine light came on and it was spitting a code for a bad o2 sensor (it also had the same symptoms now as it did then). During the replacement I also cleaned a bunch of stuff and put some new things in. I cleaned the throttle body, the maf, new k & n air filter, did the intake silencer mod removal checked for vaccum leaks, new cap and rotor, and new spark plug wires. It seemed like the problem went away for the most part but every once in awhile it would come and go. Now my check engine light is back on with the same thing bad o2 sensor and running too lean. What are some other areas I should be looking at to fix this problem? Thanks for looking and helping.

rworegon

What brand O2 sensor did you put in? These engines do not tend to like Bosch, etc. and OEM Denso is the only way to go, IMO.

ksti

X2 to Rworegon, Just picked up mine from dealer this morning (had to special order) only way to avoid brain aches.

oestreich84

I am having same issues. Did a new O2 sensor take care of it?

TNRabbit

Perhaps the wiring leading to the O2 sensor is bad. It's not uncommon for it to get draped across the exhaust & burn through....

I agree with the above posts; what brand O2 sensor did you use?

scope103

What code did you get that said the O2 sensor is "bad"?

http://www.ncttora.com/fsm/1990-1995...e/diagnosi.pdf

Codes 25 and 26 do not indicate a bad O2 sensor (usually). Code 21 is just an open in the heater circuit. It could be a bad O2 sensor, or it could be bad wiring. But so far as I know, the claimed problems with the non-OEM sensors have nothing to do with the heater circuit.

If you have a code 21, that could cause your problem (when the truck idles, the exhaust temp isn't high enough to keep the O2 sensor in the operating range, so the heater helps out. It adds nothing at running speeds.) But checking the heater on an O2 sensor with a multimeter is trivial; you don't even remove the sensor from the exhaust line.

oestreich84

Figured my problem out this morning. The vane in the airflow meter was sticking partially open. If I push it all the way closed it idles great. As soon as I increase the rpm's the vane opens and won't return to the fully closed position causing it to run very rich. Anyone have an extra one laying around?

TNRabbit

They aren't cheap.

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