Just got a trade in today and thinking about buying it on monday. It's a 94 auto, 3vze, sr5, sunroof, roof racks, trailer hitch and about 203k kms. Good tires, well maintained and it drives nice. It's basically the same as my current 4runner, except it does not have a bent frame.
I have about $1500 worth of fresh parts into my current ride. So I figure I buy this one, drive it and use my old one for parts.

Here's my question.

The only thing wrong I can find so far is a hesitation on start up with a slight misfire that sticks around but smooths out when driving it.
We got a ty off make scan tool at work and I can't get any data display out of this 4runner. I pulled the flash codes and I got 25 and 26. I'm thinking it's just an O2 sensor or possible a misfire through a plug wire or something.

On monday my boss wants to send it off to the wholesalers asap. The truck's gonna be in my bay monday morning and I've got 2 hours to do a full inspection to see if I wanna buy it. I can do a basic mechanical in under a half hour, but I figure these codes will take me a bit longer.

Just looking for some suggestions on a game plan to figure these codes out. The only thing I'm thinking right now is scope that O2.

Thanks for any help guys. In my garage at home I gotta get this motor out of a subaru I've been working on and I'm just bogged with work right now.

 

25 and 26.... fuel ratio too lean and fuel ratio too rich? Yeah, maybe an O2 failing, but those codes are usually 'deferred' codes, where it takes some time before they are thrown as the ECU learns things.

well, given you have a fuel mix issue, and you have the means, you should throw the tailpipe sniffer in there and warm the engine up and see what happens. maybe it's going too lean as it warms up, and going too rich once warm (damn them heated O2 sensors ).

 

Honestly it could take a Toyota tech all day to pinpoint that one.On the other hand I drove one for 10 years with the same codes with no ill effects.Same MPG and power as any other.Thank goodness for OBDII.
Bigblock

 

too bad the OP's truck isn't OBDII.
and an OBDII tech would be scratchin' his or her head about having both a lean and rich O2 code thrown.... and would probably do what I suggested.

 

That wont get you too far when it says the same damn thing.
Bigblock

 

ya I wish, haven't had access to a gas anylizer since I moved up here (no aircare/smog eh).

 

Check compression, change plugs, change wires. Check the timing and injector plugs as well. Other than that, you will need to drive it around 50mi to get the computer to throw another code if it will. If you can do that in two hours and see nothing, then go for it. Not likely in two hours though.

 

No man you gotta try one of those gas anylizers to believe it. Different situations produce different results. It's not like it's aggressively jumping all the time to produce those codes, they ussually stay predominantly rich or lean depending on load, temp etc.

 

Some one must have run that truck a long time rich and then fixed something a run it a long time lean.Right?Not mine ;it would produce both codes shortly after resetting them.I'm not saying they are all the same symptoms but Toyotas are dependable at working and screwing up.
Bigblock

 

nope.
given a heated O2, it's very possible the fuel mix went from rich to lean over one cycle to cause both codes. All it means is that the ECU had to adjust its fuel trim full rich, then full lean (or vice-versa), and the O2 is the reference causing the fuel trim to be adjusted in accordance to.
Let's just say the coolant temp sensor was foobared and thought the engine was warm when it actually wasn't... the heated O2 could register the 'lean' condition required to compensate for the 'warm' situation presented by the coolant temp switch... but then the coolant temp thought the engine was warmer than it was and the O2 registered that and leaned the mix out to compensate.
hmm... rich and lean codes all in one, caused by the coolant temp switch malfunctioning. It only takes one 'cycle' full rich and one full lean to trip a code.
just 'cause you don't find it logical, doesn't make it implausible.

 

Or the MAF,burnt valve,vac leak,plugged converter,cold start switch/valve,plug,wire,cap,rotor,egr,anything that puts O2 in the exhaust.
Bigblock

 

never seen a 95 or earlier 3vze with a maf, without an aftermarket conversion.
(yes, I'm being argumentative, or rather 'clarifying'.)

 

VAFM
Bigblock

 

Same thing diff way of doing it.
Bigblock

 

you forgot exhaust leaks and a faulty PAIR system (the most likely way of getting O2 into the exhaust)

 

That is not the most likely way to get O2 in the exhaust.
Bigblock

 

actually, exhaust leaks and the PAIR system are the MOST likely way for O2 to enter the exhaust ... considering an exhaust leak is a likely culprit since a leaky exhaust will draw air into the system by way of the 'bernoulli effect' and the PAIR system exists solely to add O2 to the exhaust in order to aid the catalytic converter.
... and ... you were saying?

 

I'd drop it there eh......I got into this once before

Abe's one of those intelligent ones......the kind that knows too much sometimes lol

 

awesome........but for now I think I'll keep it simple and put that ECT on the list

I'm gonna brainstorm some more and see what I get into, but right now it stands as (in order)

ECT/O2
exhaust leaks
plugs wires

I figure that's 1.5 maybe closer to 2 hours. I'll probably add compression check if I got time.
Thanks eh, too much car stuff and it's hard to focus sometimes

 

I'm trying to piece this together and I remember under the hood the only thing that stuck out was it had a brand new rad. We're talking shiny, like maybe 2 months max. Also everything else looked original like plug wires and diz cap. The heads were pretty shiny too, I should grab the VIN....I gotta go to bed
But he also drove a good 5 hours to get to us, he arrived at just after 9 o'clock so it must of been somewhat smooth cruising.
That might be something to think about.
What do you think, ECT malfunction cause an overheating issue? Overly rich mixture or not realistic?