P0172 and P0175

Hello all,
I have a 2005 Tundra Doublecab 4.7l that has given me quite a headache. I was hoping someone on here might have a solution for me. It started probably a year ago truck was running fine and when I got off the interstate and came to a stop light it was misfiring pretty bad. I got it home and checked codes and it was saying rich B1S1. I got it to a reputable garage and they said I had some melted wiring to Airflow sensor ( I had this issue prior and had been repaired but truck still ran fine) so after paying them $800 to trace wiring and replace alternator( they said it was shorted) truck ran better but still had engine codes and random misfiring. I took it back and they cleaned #1 injector and misfiring stopped. Truck still running rich I started throwing parts at it. New parts-injectors(Denso)MAF sensor(Denso)Spark plugs, Airflow sensor(Denso). I also cleaned the throttle body. Still getting rich codes and truck having lots of hesitation when accelerating. Took it to a Toyota Certified garage they kept it for 2 weeks retracing wiring and testing different parts. Everything they tested was good they wouldn’t charge me because they couldn’t find the problem and the only suggestion was possibly the ECU but it wasn’t showing symptoms for it. Anyways I ordered a remanufactured ECU and replaced it as well as the thermostat and coolant temperature sensor and changed the oil. Same codes p0172 and p0175 show up at the same time as soon as truck warms up but it seems to be running ok. I only drove it maybe 5 miles in town. I haven’t been driving it due to it running rich but I really need to get it going. Also several years ago I added the secondary air injection bypass from Hewitt technology. When I was replacing MAF I pulled wires out of connection so I just put a new one of those on also.Any help would be greatly appreciated

thanks Jeff

 

Were all these parts bought via reputable places....Toyota dealer, Rock Auto etc or Amazon/Ebay ?
How is your air filter and is it the paper kind ?

FYI....Hewitt Tech has made comments in numerous threads concerning these codes that can be related to not installing the block off plates, so, did you install the plates ?

I would consider undoing battery to clear codes or other means you may have, OBDII scanner....etc. Then unplug the bypass kit and see if the codes re-appear.
Having a code reader that can report your Fuel Trims would be ideal.

fairly recent thread....

Air injection pump bypass kits: Hewett vs. Rutech | Toyota Tundra Forum (tundras.com)

 

Thanks for your reply Bubba. I got all the parts from Amazon with the exception of the injectors I ordered them from eBay. Air filter was clean but I replaced it as well. It is the paper oem. The bolts broke off while trying to install the bypass plates so I took it to a muffler shop and they welded the holes in the manifolds up. I hadn’t thought of the possibility of the welds cracking. That was probably 10 years ago. I have reset with reader multiple times while checking different parts. For live data short term fuel trims are -20 and -21. The long terms are -42 and -44

 

Rule # 1, never buy sensors, plugs, injectors, O2 sensors....etc off of ebay/Amazon. We've seen way too many issues come thru here concerning knockoff and/or counterfeit parts.

Don't want to assume wrongly but have you unplugged the Hewitt kit to see if codes disappear. The SAIS only runs a little after startup and is not needed after warm up.

Since you can read those items, for shits and giggles, since you said you bought a Denso MAF instead of Hitachi, what are your MAF readings ?

 

scAmazon is notorious for counterfeits. So is fleaBay. They have no reason or interest to check parts for authenticity at their warehouses, even on items they're fulfilling. You should never assume parts you buy there are authentic. Myself and plenty of others here have gotten very real-looking but bogus parts from them both.

My first thought was "man, sounds like this person's shop is ripping them off", but you've done a lot.

I'd swap back in the original coils and other electronics since you really have no way to know if you got authentic parts from your sources. I've also be hunting for a leak on the intake side, somehow the ECU either things it's getting more air than it really is, or it's reading incorrectly after ignition (upstream O2s)

This is an interesting avenue, I like this thought process.

 

It's late for this ole fart so I don't know about the thought process but it's a simple way to determine if it's indeed something with the Hewitt kit or more correctly, installation of kit. Downside will be the SAIS code P2445 popping it's head up !

 

It may not provide direct answer to the issue, but it should have an expected result as you say, so something other than the expected result is useful info.

 

I should have known better than ordering parts from Amazon/EBay. The MAF reading is .01 lb/s. I cleaned my original and reinstalled and am getting the same reading. I plan on cleaning the original injectors and reinstalling them when I get a chance. Nothing I have replaced has changed the codes. I did warm up the engine then cleared codes disconnected the bypass kit and plug harness back in. It gave the same codes.