V8 rough idling issues, anyone help? - P0300, P0303, P0305

[Rannd]

Hey everyone, I’ve spent so much money and have had so many headaches fixing the exhaust on my 4Runner. So much money spent for parts and labor. Was getting codes for not having cats and all of a sudden my air pumps started turning on at startup. So I bought the URD rear sensor simulator and a air pump delete kit for a local shop to install. They installed them and it ran great but then I got P2241 and P2A00 codes which I believe are 02 sensor codes. Do I just need to replace all the 02 sensors or do I not need to? One thing I immediately regret is going catless. It smells so bad... cars I’ve owned in the past that went catless never smelled this bad.


Mods:
Doug Thorley long tube headers (no cats)
URD off road Y pipe
URD muffler
URD rear sensor simulator

 

[Rannd]

Anyone help at all?

 

[Zero0575]

Anyone help at all?

You didn't happen to install spacers on the front O2 sensors did you? Those codes are for low voltage on bank 1 sensor 1 and bank 2 sensor 1, both of the pre-cat / AF sensors. If you install spacers, they're supposed to go on the post cat sensors.

Aside from that, just make sure the pre-cat sensors are plugged in. Doesn't make sense that they would both just randomly go bad at the same time.

 

[Rannd]

So I took it back into the shop, they were able to clear the codes and drove it three times and didn't see codes.

They told me they contacted URD and they had to adjust settings on the URD Rear Sensor Simulator.

Here are the shop notes:

Multiple miss fire codes present. Voltage issues in system for PCM/ ECM / 02 Sensor values not in spec. Customer has aftermarket exhaust , 02 sensor foulers, trick box to prevent issue. Worked with exhaust manufacturer to verify specs. Original specs from install of value box needed to be raised slightly. Told to move slightly increase as light arrives. Testing procedure is drive vehicle at temp to 75 mph and quickly let off gas pedal. This engages testing procedure. Last test drive technician did this test 3 times with no light returning.

I drove the 4Runner 2 times after I got it back and now I'm getting codes P0300, P0303, P0305. Still runs like crap when it idles... drives fine when on the highway.

 

[importman]

So I took it back into the shop, they were able to clear the codes and drove it three times and didn't see codes.

They told me they contacted URD and they had to adjust settings on the URD Rear Sensor Simulator.

Here are the shop notes:

Multiple miss fire codes present. Voltage issues in system for PCM/ ECM / 02 Sensor values not in spec. Customer has aftermarket exhaust , 02 sensor foulers, trick box to prevent issue. Worked with exhaust manufacturer to verify specs. Original specs from install of value box needed to be raised slightly. Told to move slightly increase as light arrives. Testing procedure is drive vehicle at temp to 75 mph and quickly let off gas pedal. This engages testing procedure. Last test drive technician did this test 3 times with no light returning.

I drove the 4Runner 2 times after I got it back and now I'm getting codes P0300, P0303, P0305. Still runs like crap when it idles... drives fine when on the highway.

With the fact that you have misfire codes on adjacent cylinders and it only runs poorly at idle I'd want to look for a vacuum leak in that area. I'm not familiar with that air pump bypass but I wonder if they left a hose unhooked or something.

 

[Rannd]

Had the shop remove the cat delete spacers, drove down to Florida and back with no codes and engine idling fine, woohoo!