My '94 4x4 truck (3VZ-E, A340H) generally runs OK, but it idles just a bit rough, and the mileage has gotten even worse than usual (~13, instead of the usual 15-16. I'm the orig owner). A couple of times the I've gotten a code for rich mixture. It starts fine, and out on the freeway does OK on gas (~19, OK, I know, but it is a 3.0). One possible clue is that if I'm accelerating slowly from a stop, at about 2500-2800 RPM the power noticeably increases, as though the mixture is correct above that RPM.

The oxygen sensors were recently changed.

Any ideas? Thanks in advance.

 

try the o2 sensor mine did the same thing reoplaced o2 and mileage was back up and idle snmoothed out i also did the seafoam at the same time

 

he changed the O2 sensors...

Is the code for a knock sensor flashing as well? The KS wiring harness never last more than 150k on the 3vze... try also using premium, and some Lucas on your next oil change... new plugs might help as well

 

also check your passenger side plug wirs and look at the mounting point for the rear most wire and make sure it did not ground out and burn thru. Thats a common thing if your plug wires were changed and that wire was not tied up if the original wire mount was broken during the wire change.