Random Miss and Surging, 2012 Camry SE, 4 cyl. FINALLY DEFEATED!!!!! Yes!
 

2012 Camry SE 4 cyl. 178K miles on it.
Well maintained, all oils and trans services done.
Here is the problem: When cruising, engine either cold (just started) or at operating temp, if you let the car get into a high gear quick (5th or 6th) and backoff and kind of lug the car, it will do this weird surging/ chugging thing.
It will also do it cruising above 75 as you start up a grade on the hi-way. Down shifting via the paddles to 4th. seems to make it go away. But who wants to cruise at 4000 RPM?

The problem is not quite horrible, but's bad enuf that I know something is going wrong, and it finally made the CEL light come on!

I have done all the usual things, new Iridium Plugs, cleaned the A/F, MAF and theThrottle Body, BTW what a PITA!!! I thought maybe the fuel filter might be a perfect place to try next. According to Toyota, this Camry has no fuel filter other than a sock on the inside tank fuel pump. Toyota recommends having the fuel injectors cleaned at 60K! Wow. I added some good fuel injector cleaner in the tank, but it is still doing the surging.

I just pulled the codes again (I did this last week before swapping the plugs out,etc.) Here's what I got:

Under OBD II there was nothing.

Next under Enhanced tests, ABS Comes up with C1201

1.Brake Booster Sensor Circuit Range / Performance (Huh?)

2.Engine Control System (Probably a General "thing" that comes up under any CEL.)

Under Enhanced OBD II, I pulled:

1.P0300 Random Mis-Fire

2.P0125 Insufficient Coolant Temp. for Closed Loop Fuel Control

I've read that a bad up-stream O2 sensor can throw the P0125 code.....why? Who knows.
I have also read that any engine code will dis-able the ABS and throw that code--------it's a "safety thing" via Toyota.......Ok.
And I've read that is could be a faulty coolant temp sensor.......or worse a bad ECU!

I hate just buying parts and installing them until it's fixed........that's not how a real repair is done.

So I'm hoping someone on this board has maybe had the same or a similar event happen and will share the secret of this thing.

Heck, the cheapest O2 sensor I found here locally was $165 for a Bosch direct replacement at AutoBone.

I know this is long winded, but does anyone have any suggestions or ideas as to correcting this?

Thanks in Advance!

The codes are not always exact! They are supposed to be a guide. The Toyota dealer and repair shop has tools to check areas for proper real time function. Yet even they get stumped at times.

A home mechanic can obtain real time info and store it with the proper reader.

For some makes/models of cars, a given code popping up could be totally unrelated to the actual problem. There could be long list of codes appearing along with the one for that might actually be the problem. Then upon the next code output, another list of codes.

The codes are all software driven. It is best not to chase codes.

Ignore C1201, brake booster, etc. When the engine check light comes on, other non-engine systems are programmed to turn off. With this there could be a dash light or code indicating the systems have turned off.

P0125
Cooling system, ECT sensor, thermostat. Yes, P0125 could be totally unrelated to these listed issues. However you can check the ECT sensor resistance, connection to it, coolant level, engine temp.

P0300 is general code.
Open/short in engine wire harness. Can check this.
Electrical connectors. Ditto.

Vacuum hose leaks. Check any hose that go to engine intake or valve cover. Leaks make the engine run lean.

Ignition system. Ign coils, etc. If a problem, the ECU should throw a specific code related to a specific coil, cylinder.

Injector. Seldom plug up. The dealer sells cleaning as it makes them a good profit. You can add a cleaner to the fuel tank.

Fuel pressure. It is possible to check fuel pressure with an attached gauge. 50K is not much for a pump though.

MAF meter. Seldom fails and you clean it, plus run tests.
ECT sensor. This does cause issues.

Compression. Should not be a problem.
Valve clearance. Ditto.

Valve timing. Ditto.
PCV valve/hoses. Can cause issues.

Air induction system. Check for leaks.
ECM. Seldom fails.

A/F sensor do start to degrade over time. If having the right code reader and watch the voltage.

For parts try online sites such as Rockauto, PartsGeek, etc. Much cheaper. Suggest Denso brand not Bosch for Toyota and a sensor that is a direct fit, not one called universal.

Regarding P0125, understand that A/F sensor isn't heating up fast enough, resulting in Toyota's version of P0125.
Could be sensor or circuit problem.
Best replace sensor with what came from factory. Rockauto.com has Denso sensors.

Can you post freeze frame for P0125 and P0300?

Thanks, I appreciate the help!
cj1, whet you say the A/F sensor are you talking about the upstream O2 sensor?
Thanks again!

A/F sensor = precat/upstream sensor.
O2 sensor = after cat/downstream sensors
A/F sensor is an improved version of the O2 sensor.
Different characteristics, can't be interchanged.

Good to know, thanks!

Success!!!! Finally!!!!!!
I have been messing with this problem off and on for months.
Now I have to fix it, the car's registration is due and it needs to have a Smog to get it......CRAP!
I decided to clean the A/F sensor.
I used this guy's method to clean the A/F sensor and it really worked.
It uses Lemons!!! Watch the Vid and you'll understand.
4 bucks worth of lemons instead of 275 bucks for a new Denso A/F sensor!
Here's a link: Now that the A/F errors were cleared I went on to the 2 Transmission errors; both pointing to the 4th gear clutch servo and a overdrive servo being stuck randomly.
Back at 100K I had the local Toyota Stealership do a Trans Service....for only $450.00!!!! What a joke!
After the service I always felt that the fluid was "Low".
At the first start of the day, if the car sat more than a day, it would move forward really slowly for the first 20 feet or so. The engine would rev but the car barely moved. Then it would "catch up" and seem ok for the rest of that drive.
In "the old days" that was a symptom of fluid being low.
Toyota makes it seem that a guy at home cannot do the transmission service on this unit. Bull****! Toyota says that you have to have all the special tools, testers, etc...More BS!
This guy has a great video showing how to do your own flush on the Camry trans,
Here's a link: I did it using Valvoline MaxLife ATF; 3 quarts.
So far I have gotten rid of the weird surging and missing issues.
My Scantool shows no codes or Pending codes.
I think I have finally WON this one.
I hope my long ass rant helps someone else!


Later.....I'm having me a Beer! :D

Wow!!!!!!
Mileage has gone up.......my wife can get 34 MPG outta a car the Camry, with all of it's miles on it; all the time, meanwhile I get 32-31. :mad:
All that weird surging, missing crap is GONE!!!!!
I know these were kinda different ways to fix stuff, especially the AF/O2 Sensor fix using lemons.......
BUT IT WORKED!!!!!!
So very cool. :D:D