3vz code 25 engine lean
06-26-2017, 12:52 PM
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3vz code 25 engine lean
I just got my 4runner back on the road and the CEL is on. I jumped the terminals and the code given was 25. The light goes off sometimes when I drive it in 4wd. Any ideas on what this might be.
06-26-2017, 02:21 PM
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There are (no kidding!) lots of causes of a Lean malfunction. You could have a loose ground, a loose injector (electrical) connection, and so on. But probably the easiest one to get is from a leak in the induction plumbing. This admits unmetered air, and the systems tries to dilute it out with more fuel but can't make it.
06-26-2017, 04:00 PM
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what I've done
New dist. Cap, new fuel filter and fuel pump, new plugs and wires. it had a clog in the fuel line that needed to be blower out. The maf is used and instill have the original but it's ruined. I have sprayed my vacuum lines with wd40 trying to find a leak still nothing. I really feel like it's the o2 sensor. How can I test the sensor.
06-26-2017, 04:24 PM
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well, wd is not the thing to use to spray your vac lines, for starters. use ether. more volatile/ignites better and evaporates not leaving a mess behind
what makes you feel it's the sensor? and, how'd you develop a clog in the fuel line? it's probable since there was a clog in the line the injectors could be clogged, too. so, maybe it's not the sensor. but, to test it, run a forum search or find the appropriate manual in the links stickied on the front page of this forum. or, run a google. heck....youtube probably even has a video. i forget too many of the details at the moment to explain the procedure
what makes you feel it's the sensor? and, how'd you develop a clog in the fuel line? it's probable since there was a clog in the line the injectors could be clogged, too. so, maybe it's not the sensor. but, to test it, run a forum search or find the appropriate manual in the links stickied on the front page of this forum. or, run a google. heck....youtube probably even has a video. i forget too many of the details at the moment to explain the procedure
06-26-2017, 04:25 PM
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The O2 sensor, when warmed up and running, should fluctuate back and forth between about 0.25 volts and 0.85 volts about 8 times in 10 seconds. (you may need to run the truck at about 2500 rpm to keep the sensor temperature high enough, but mine will fluctuate correctly at idle). If it is just sitting at 0.45 volts, most likely the sensor is dead.
To diagnose your O2 sensor you go to .... under the truck? No! You go to the diagnosis box attached to the fuse box. There is a connector labeled Ox1 which goes right to the sensor. You'll need a voltmeter with one of the lcd bars that imitates a needle (you're looking for up/down 8 times in 10 seconds; too fast to watch digits). Start it up, give it 30 seconds to warm up, then hold it at 2500 rpm (thereabouts). Look for up/down 0.25 to 0.85.
If it reads zero or 13.1 you've got a connection problem. If it sits at 0.45 I'd suspect a dead sensor. What about sitting at 0.25 or 0.85v? Then the O2 sensor is probably working, but you're running too rich (mileage problems) or too lean (knocking?). To track that down you need to lean out the mixture (create an air leak) or enrich it (propane?) That may be the "micky mouse" you're talking about.
Do you have a connector labelled Ox2? Welcome to California! That's the second O2 sensor downstream of the catalytic convertor. If that one switching back and forth at the same rate as your upstream sensor, your cat's dead.
Toyota recommends replacing the o2sensor at 80,000 miles. But you can buy 4 good voltmeters for the price of an O2 sensor. Do the test.
To diagnose your O2 sensor you go to .... under the truck? No! You go to the diagnosis box attached to the fuse box. There is a connector labeled Ox1 which goes right to the sensor. You'll need a voltmeter with one of the lcd bars that imitates a needle (you're looking for up/down 8 times in 10 seconds; too fast to watch digits). Start it up, give it 30 seconds to warm up, then hold it at 2500 rpm (thereabouts). Look for up/down 0.25 to 0.85.
If it reads zero or 13.1 you've got a connection problem. If it sits at 0.45 I'd suspect a dead sensor. What about sitting at 0.25 or 0.85v? Then the O2 sensor is probably working, but you're running too rich (mileage problems) or too lean (knocking?). To track that down you need to lean out the mixture (create an air leak) or enrich it (propane?) That may be the "micky mouse" you're talking about.
Do you have a connector labelled Ox2? Welcome to California! That's the second O2 sensor downstream of the catalytic convertor. If that one switching back and forth at the same rate as your upstream sensor, your cat's dead.
Toyota recommends replacing the o2sensor at 80,000 miles. But you can buy 4 good voltmeters for the price of an O2 sensor. Do the test.
06-27-2017, 07:30 AM
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O2 sensor test
Thanks for the quote. I have plenty of multimeters not plenty of oxygen sensors. The train I believe it is the sensor is simply from process of elimination. My Haynes manual says it could be 9 different things for trouble code 25 engine lean. The fuel pipe from the pressure regulator had busted after it sat for a year and was replaced with a hose from around the guys shop I noticed a kink and replaced it with OEM fuel pipe that can right off another 3vz. The MAF had been replaced with a guarantee used one with matching numbers I remember him telling me something had to match up on those. I am still in touch with this guy so I can probably exchange it if it were to be my problem. My Haynes manual says: Injector Circuit, Injector, Fuel Line Pressure, Ignition System, Oxygen Sensor Circuit, Oxygen Sensor, Air Flow Meter, Water Temperature Sensor, and ECU. All of which I can get fairly cheap if needed. Any advice given is greatly appreciated.
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06-27-2017, 09:38 AM
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reply to thook
The engine idles around 1,000 1100 when it's warm. when it's cold it idles at 1500 and slowly drops back down and you can hear the change. It has done this since I purchased it a couple years ago. The power has like a surge feel like it takes a second and kicks in. It drives better now than it used to but i feel like it's still hesitating a bit. The check engine went off whenever i drove it in 4wd during some flash flooding here any ideas on why that is? Under the hood it says idle rpms 800 also. The truck has 231,000 mi with a fresh oil change and filter.
Last edited by Jbhenson521; 06-27-2017 at 09:52 AM.
06-27-2017, 09:08 PM
#10
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1000-1100 rpm is too high. as the sticker says, it should be 800 or so when at operating temp. as suggested, you might go ahead and check the air induction tubing for any cracks or loose connections. again, use the starting fluid. or simply pull it off and visually inspect really well
as for the CEL disappearing when in 4wd, i'm sure it's coincidental. the CEL is only supposed to illuminate for a short time, anyhow. enough to let you know there's a problem. i had a lean code plague me for a few years up until recently when i found it was bad exhaust gaskets. the CEL would only come on it seemed under certain conditions and disappear for a while only to reappear when i'd hoped the problem had resolved itself. haha...wishful thinking. it did, however, seem to come on less when the weather was cold.
as for the CEL disappearing when in 4wd, i'm sure it's coincidental. the CEL is only supposed to illuminate for a short time, anyhow. enough to let you know there's a problem. i had a lean code plague me for a few years up until recently when i found it was bad exhaust gaskets. the CEL would only come on it seemed under certain conditions and disappear for a while only to reappear when i'd hoped the problem had resolved itself. haha...wishful thinking. it did, however, seem to come on less when the weather was cold.
06-28-2017, 05:41 AM
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Reply to thook.
Ok so instill go pick up some starting fluid and try it out. Every mechanic I talked to told me it would probably be a vacuum leak or the MAF. The idle speed did go down to 800 for a split second the last time we looked at the throttle body to check for carbon build ups and to see if it was stuck open. I drove it down the hill from my neighbors house and it went back up. We check it for leaks and couldn't find any. I had to replace the air intake hose that is attached to the throttle body because it was dry rotted. The air filter was new but had some grass in it where it sat I cleaned that out. I'll go check everything again would it help to hit it with more throttle body cleaner although it looks fairly clean?
Last edited by Jbhenson521; 06-28-2017 at 05:49 AM.
06-28-2017, 07:53 AM
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Progress
I cleaned throttle body quite a lot of carbon on the top of it. Cleaned all of that out. Disassembled all my hoses and reassembled them to ensure no leaks. No change in idle this time. Still idling high and then dropping back to 1000 1100. I have some gaskets for the truck all of them matter of fact but a couple are a little bent just a tad and I was told I can't use them. But not all of them are that way. My exhaust gaskets look to be in good shape I wonder if this is my problem aswell.
Last edited by Jbhenson521; 06-28-2017 at 07:56 AM.
06-28-2017, 08:00 AM
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O2 sensors
In reply to the post about the oxygen sensors. I do have terminals labeled ox1 and ox2 in my diagnostics box, so it is Cali. I still have yet to find a volmeter here with the LCD needle that i need but I'm sure I have one somewhere. I had been wondering if I had one or two that made it so much easier to tell. Thanks alot
06-29-2017, 09:08 AM
#14
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exhaust leaking wouldn't cause a high idle. that would be more of a choppy/low'ish idle situation. if it's a vacuum leak causing a high idle it would be a relatively small one. for example, the cold idle air valve allows a small amount of air passed the closed throttle plate...just enough to raise the idle to accelerate the warm up process until the engine coolant is warm and shuts off the valve. or, like the a/c switching valve. it allows a small amount of unmetered air in when the a/c is turned on...just enough to raise the idle to compensate for the extra load on the engine thereby keeping the idle at the normal rpm when the compressor is running.
do you have manual locking hubs or automatic?
do you have manual locking hubs or automatic?
07-01-2017, 07:28 AM
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reply to thook
I have automatic locking hubs. there is no a/c but I cleaned the throttle plate off and now it's getting hung up at like 1600 whenever I shift into neutral when I'm driving it and I have to blip the throttle to get it back down to the usual 1000. It runs really rough when it idles like that sounds like something is missing. I'm no expert though, after I blip the throttle it sounds like normal.
07-01-2017, 06:53 PM
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well, the reason i mentioned the type of hubs is that the auto hubs are vacuum actuated. (as well as an electrical pulse, but not pertinent here). so, i was thinking possibly...just possibly...one or more of your vacuum lines to the auto hub system could be leaking. however, after further consideration, a leak there would have to be fairly close to the intake to have any real effect. but, then it would probably also affect the ability for the hub system to even work properly. so, ignore that for now. 
anyway.....man, you've got something going on that's honestly hard to pinpoint on the web. i mean, yeah....poor fuel line pressure/a congested fuel system could cause it to have all the symptoms you're describing, but doesn't account for the high idle/throttle issue. that could be poorly adjusted throttle cable, sticky throttle linkage, or even a bad or maladjusted throttle sensor. then there's the dashpot and throttle body adjustments. i hope you've never messed with any of the adjustments because it would simplify things if you haven't. but, do check the function of the dashpot..... wouldn't hurt. and, of course, check the throttle sensor. if all of that checks okay, start looking more into the vacuum possibility. with the exhaust, hook up a shop vac to the tailpipe, seal it with some duct tape, turn it on, and spray soapy water around all exhaust piping and manifold connections. any leaks will be evident, of course, by bubbles.
so, narrow that stuff down and report back. if you haven't found any leakage in vacuum or intake hosing, maybe start looking if there's a bad gasket on the intake somewhere. i'm thinking you might be able to test for that using the shop vac method hooked to the intake tubing as an alternative approach to the ether. i've had mixed results with the ether before seeing as how the motor running tends to blow the concentration of spray around in certain areas.
anyway.....man, you've got something going on that's honestly hard to pinpoint on the web. i mean, yeah....poor fuel line pressure/a congested fuel system could cause it to have all the symptoms you're describing, but doesn't account for the high idle/throttle issue. that could be poorly adjusted throttle cable, sticky throttle linkage, or even a bad or maladjusted throttle sensor. then there's the dashpot and throttle body adjustments. i hope you've never messed with any of the adjustments because it would simplify things if you haven't. but, do check the function of the dashpot..... wouldn't hurt. and, of course, check the throttle sensor. if all of that checks okay, start looking more into the vacuum possibility. with the exhaust, hook up a shop vac to the tailpipe, seal it with some duct tape, turn it on, and spray soapy water around all exhaust piping and manifold connections. any leaks will be evident, of course, by bubbles.
so, narrow that stuff down and report back. if you haven't found any leakage in vacuum or intake hosing, maybe start looking if there's a bad gasket on the intake somewhere. i'm thinking you might be able to test for that using the shop vac method hooked to the intake tubing as an alternative approach to the ether. i've had mixed results with the ether before seeing as how the motor running tends to blow the concentration of spray around in certain areas.
