Trouble codes: P0300, P0171, P0174

Getting all three and engine is idling/running rough. P0300 is misfire on cylinders and the other two are engine is lean. Any ideas? Thanks.

 

Could be faulty mass air flow sensor or maybe a tear or massive air leak in the intake housing

 

0300 is multiple-cyl misfires right? I might be thinking clogged fuel filter.

 

First, can you remove and clean your mass airflow sensor? If you clean your MAF then you may resolve for free. After that, check lines after the MAF for leaks. P0300 is random misfire, whereas p0301 would be cylinder 1. Also, check your air filter, I have seen mouse nests and have seen mice earth through the filter to have debris hit and damage the MAF. let us know how this resolves!

 

i would check the MAF sensor, but first i would check for a vacuum leak. The fact that you have both P0171 (Bank 1) & P0174 (Bank 2) tells me there is most likey a pretty big vacuum leak somewhere near the intake. Thats the first thing i would check, then the MAF sensor, but thats just me, let us know what you find.

 

O2 sensors or maf sensor

 

I pulled/cleaned the MAF and there were no obvious deposits on it or anywhere in the intake. Still throwing the same codes after the cleaning and resetting.

It is the P0300 code which is for random cylinder misfire.

Both banks showing a lean condition (P0171/P0174), to me, would eliminate the 02 sensors....can't see them both going south at the same time.

I'll check for leaks and report back. Is there any way to 'test' the MAF sensor to see if it's faulty? Would a faulty MAF cause cylinder misfires or is this a seaparate issue?

Thanks for all the help/advice, much appreciated!

 

Havent seen multiple O2 sensors fail at same time before, again, without being there, the first thing i would be checking for is a pretty big vacuum leak, if it is setting a lean code on both banks at the same time, as a tech, the first thing i would do is pop the hood and make sure all vacuum lines are connected and there are no other obvious leaks.

 

How's it running if it's spitting an sputtering like it's choking out its a bad maf more then likely and I'd say about 90% sure

 

Another way would b just unplug the maf and see if it changes any with and with out the sensor

 

injector seal

 

Unplugged MAF sensor= Engine no run!

Just to make sure, i ran outside to my truck and tried it, when you unplug a MAF sensor on a toyota, the engine will die instantly.

 

It was the TRD intake flange...the one closest to the TB was rotted and completely severed. Not good. Been running the truck like this for porbably 5K miles. Hopefully I didn't do much damage.

Thanks for all the help/suggestions.

 

Score for Toyota Tech................

 

thanks for letting us know, glad to see i wasnt crazy, too many people too stuck on replacing MAF sensors, i would have done the same thing about 4 years ago before it sank in what would be wrong.

Thanks Mike!

 

Hey wood, or anyone else. I know this is an old thread, but I googled my codes and Toyota world and this came up. I have exact same codes and issues, but I was wondering what is a trd intake flange? Anyone have a pic of this? Sorry and thanks!