My car has been having power problems for a couple of months ie lack of power above 3k RPM. My gas mileage has also been suffering ( I used to get 25, now I get below 20). I have been using carb and choke cleaner regularly to fix the problem but its only a temporary fix. I had heard that cleaning the Mass Air Flow sensor and the O2 sensor might solve my problem so I cleaned them both and replaced them. My O2 sensor was as black as night so I let it sit in alcohol for a couple of minutes and then thuroughly scrubbed it with a toothbrush. Upon starting my car, however, I quickly noticed that something was wrong. My car was idling horribly and then quickly died.

I tried testing the mass air flow sensor but couldn't get any definite results. So, I pulled codes for my engine and got this:

512 - short term fuel mixture too rich
121 - Mass Airflow Sensor absent or faulty
223 - Idle air control valve absent or faulty
113 - short term fuel mixture too weak

Ive been told that a bad O2 sensor will make the engine run rich and that it will junk up alot of stuff. Im currently trying to get the Idle Air Control Valve off but I can't quite figure out how. I want to clean it and see if it solves anything becuase I dont really feel like buying a new MAS, IACV, or an O2 sensor.

Anyone have any suggestions to what might be going on?

 

Hi m8 first thing is being very cautious what ya cleaning some of these sensors are obviously electrical and cleaning them with strong agents burn them out MAF sensor is sensitive. Anyway it sounds you may have an air leak check all vacuum pipes I would focus at the MAF sensor ,if you've purchased a new 1 make sure its a branded part same as your ECM eg: Bosch etc.volvo's don’t like any cheapo sensors the ecu has trouble mapping unknown chips.The o2 sensor (Lamda) would make your mixture bonkers it will send incorrect information to ECU but i dont think it would cause a sudden problem with idling.You said you have replaced o2 sensor and MAF well put the old ones back in and see if there is any changes to engine management

 

fuel mixture to rich and to week. just reading that its kinda funny.

but in all seriousness, it sounds as though its a maf issue. i would first check all air connections like he said above. and also all wire connections and connectors (make sure they are clean)

 

What I meant by "replacing it" was that I put the part back in. Sorry for sounding so misleading, I was quite frustrated this afternoon :P.

When I cleaned the MAF and O2 and IAC sensors I only used alcohol and electrical cleaners with a Q-tip so Im pretty that I didnt mess anything up. Ive done this on several other sensors on other cars and it fixed many a problem for me .

I found a new Bosch O2 sensor online for $78 and new Bosch MAF for $150 which is much cheaper than I though they were going to be. I'm still trying to avoid buying a part and seeing is something is just dirty but as more and more time passes, Im thinking that at least one of the sensors I mentioned above is bad.

I still can't quite figure out how the car can run rich and have a weak fuel mixture... :/

 

What makes you think it has a rich mixture but running weak !never heard of that 1 before plug it back into diagnostic and see how many times the sensor (s) have sent a error signal .Do you have ya engine management light on cause if any of these sensors were down as bad as this they surely would have sent a fault code

 

I just ordered a new Bosch MAF and O2 sensor and that should fix the problem. If not, hey, I have a new MAF and O2 sensor so Ill get better MPG!

I have still yet to test the IAC with the 12v that will probably happen tonight before I go to bed...hopefully :P

 

^^ i would almost just wait till you get the other stuff in and everything. allthough it never hurts to clean all that up good.

 

Got the MAF and the O2 sensor and put them both in and my car works again!
No more lack of power and MPG is significantly increased.

I had a bit of fun when I removed the old O2 sensor and drove around the block with no sensor at all hehehe lots of fun.

Thanks for all the help guys!

 

haha, glad everything worked out well.

 

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