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Like it says in the title, throwing a few codes on an ’05 Tacoma 2.7.
P0300- Random miss
P0171- System Too Lean (Bank 1)
P0172- System Too Rich (Bank 1)
P0125- Insufficient Coolant Temp. for closed loop fuel controlThe only driveability problem I’ve felt is the misfire. I am also assuming that my P0125 is causing everything else. If the ECU doesn’t see the temp it needs to, it will cut/add fuel, thus causing the three other codes. I have access to a scantool and the truck runs at 176 degrees, which ALLDATA considers to be normal, although it is at the lower range of normal. I’m also part of a tacoma forum and one of the peeps gave me this bit of info:
“Interesting thing! I just went into Mitchell1 service information and actually looked up the Toyota diagnostics for what the failure conditions are, and what can cause this code to set. According to Toyota, the P0125:
‘DTC is set when sensor (Oxygen sensor) does not output a rich condition once engine is at normal operating temperature, engine speed of 1500 RPM or more, and vehicle speed is 25-62 MPH for at least 2 minutes.’
According to Toyota, the most probably cause for this code is a faulty oxygen sensor (the one in the front of the cat)
I admit this is very different from the diagnostics of other manufacturers, but this is direct from Toyota.”I will check my fuel trims and post them up in a little bit.
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I raised my RPM to 2100+, let go of the pedal, and it went into open loop for a split second. Here’s the vid, along with other pids. The vehicle is also at operating temp.
http://www.youtube.com/watch?v=2fo_JqbV7eg&feature=youtu.beFirst I would check the thermostat and make sure that the temperature is correct.
I would venture to guess that the STFT and LTFT are both at about their maximum (mine were both at 24.8 ). After you get the temperature correct check the O2 sensors and in they are not changing rapidly between 0.10 and 0.90 volts replace them and reset the codes and reset adaptive fuel to it’s original settings so it can relearn the fuel trim.
When you remove the O2 sensors you will probably find them covered in black soot. clean it off and do a propane test to check for the proper voltage changes. If thier not to specs replace.
The misfire code will probably not come back after the temperature and fuel trim problems are fixed.Hope this is helpful to you.
John
I to would look at the t-stat.it seems to be taking to long
to come up to temp. next is the random misfires its either fuel
or spark related.check spark first.check out some of this trouble
shooting in these links.read about the afr sensor.http://www.justanswer.com/toyota/13h4i-several-codes-toyota-tacoma-truck-p0125.html
After watching the video the highest I see the temperature at is 187 which seems low to me. I think it went down to 185 is the cooling fan coming on at all? I would guess it’s not because it never gets up to temp. Fuel trim numbers look fine. Had you reset anything before you took the video?
[quote=”johnbkobb” post=39180]First I would check the thermostat and make sure that the temperature is correct.
I would venture to guess that the STFT and LTFT are both at about their maximum (mine were both at 24.8 ). After you get the temperature correct check the O2 sensors and in they are not changing rapidly between 0.10 and 0.90 volts replace them and reset the codes and reset adaptive fuel to it’s original settings so it can relearn the fuel trim.
When you remove the O2 sensors you will probably find them covered in black soot. clean it off and do a propane test to check for the proper voltage changes. If thier not to specs replace.
The misfire code will probably not come back after the temperature and fuel trim problems are fixed.Hope this is helpful to you.
John[/quote]
So, I should remove the T-Stat and drop it in a hot cup of water, then drop in a thermometer, and see if it opens at the sepcific temp? Or should I get an infrared thermom. and check the thermostat housing?Actually no. With the problem you are having it would be that the thermostat is always open and not allowing the engine to build up heat. Take it out and if it is open and allowing coolant to pass it is bad. If it wasn’t opening there would probably be an overheat problem. It definitely isn’t that though.
The codes are actually readiness codes, so I don’t have a check engine light on, but they are stored. I’ve had these codes for almost 2 years now and finally have time to take care of it haha. I have the ALLDATA procedures to check the ECT, so I’ll do that too. I replaced the T-stat a few months ago and decided to erase the codes back then, and here they are again. ALLDATA and Mitchell1 both have very diff ways to diagnose the P0125 lol. Kinda confusing, but I checked the heater circuit on the AFR sensor and it’s within specs. However, I know this doesn’t mean it’s not bad. Could be lazy too.
The vid I posted is after the truck had warmed up. I just let it idle until it got up to operating temp. I’ll take a pic of what the temp is after I get back from a drive. Thanks guys!
in case you do need a new t-stat
I drove it around for a little bit and the temp only went up to about 190. I will remove the t-stat when temp drops and let you guys know what I find. Stuck open thermostat makes sense though.
Also, I forgot to answer ur question john, but the cooling fan is belt driven, so it’s always running anyway. I’ll test the clutch too.
[quote=”hondaguy453″ post=39195]I drove it around for a little bit and the temp only went up to about 190. I will remove the t-stat when temp drops and let you guys know what I find. Stuck open thermostat makes sense though.
Also, I forgot to answer ur question john, but the cooling fan is belt driven, so it’s always running anyway. I’ll test the clutch too.[/quote]
according to the stant website. That engine wants a 180F thermostat.
If you do replace the t-stat.use a quality t-stat. stant or OEEvery time I get up to work on the truck, something comes up and I gotta use it haha. It’s been running all day, so I’d rather not try to pull the thermostat right now.
Here’s the T-stat that I replaced the OEM one with. Autozone says it’s rated at 180 too.http://www.autozone.com/autozone/parts/Duralast-Thermostat/2005-Toyota-Tacoma-2WD/_/N-jnilpZ8gctr?itemIdentifier=701272_0_1632_93207
I know I haven’t checked the thermostat yet, but I thought I’d bring up a concern of mine first. Since my tacoma has a thermal fan clutch, the fan should not be spinning during open loop, cold start, right? My fan spins continuously no matter what temp.
First I’m not a fan of duralast/autozone parts.I
prefer advance auto.That said.what climate temp
are you in and whats the ambient temp? even if
the fan clutch is engaged all the time.The job
of the t-stat is to keep the engine temp at design.
which in your case is 180F so if the fan is spinning
and your temp is 190f we can rule out the fan.unless
the fan clutch is disengaging.you may have a fan clutch issue.
two things to determine.proper fan clutch operation and proper
t-stat operation.
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