Exhaust/fuel fumes when air injection pump is on

I had a P1604 misfire code and I read it was normal for Tacoma to misfire on cold start ups from time to time. I took it to the dealer and they reset the code and said they didn't see any code.

I had installed a new LCE header on my truck it's 2014 2.7L 2TR-FE motor. I thought I had an exhaust leak, but it would happen only when cold. I thought thermal expansion would seal the tiny leak, but yesterday I did more checking and it was when the air injection pump turns on when the engine is cold...I smell quite a bit of exhaust and fuel fumes when the AIP is turned on and makes a large noise...I'm assuming the vacuum motor sound is normal...but what is not normal is the exhaust fumes.

I mentioned about the P1604 since I think it's related. With the new header, LCE thinks with more air flow, the ECU is pushing even more exhaust air and fuel...but why into the engine bay? Do I have a stuck valve somewhere? I don't get any other trouble codes.

Anyone else with this issue of exhaust fumes when air injection pump is running. From cold engine, pop the hood and start the motor...go back to the passenger side and see if you smell any fumes from the AIP area.

I'm not sure if dealer will try to fix this with the header installed. I'm curious to know if air injection pump get blocked that it would push exhaust fumes into the engine bay.

Appreciate any help on this. Thanks!

P.s. I made a paint can smoker to check for exhaust leak and didn't see any smoke in the engine bay area....so I don't think I have any exhaust leak from the header install.

 

no one else has this issue?

 

NV Mind

 

The P1604 Code is not a misfire code. It is a code for a startability issue and may be a false indication. read this thread for good information:

https://www.tacomaworld.com/threads/code-p1604-strangest-code-ever.350182/

Looks like nothing to worry about if you don't have other symptoms or another CEL Code.

A Misfire Code would be these:

P0300 - Random / Multiple Cylinder Misfire Detected

P0301 - Cylinder 1

P0302 - Cylinder 2

P0303 - Cylinder 3

P0304 - Cylinder 4

 

I've noticed that with mine. Both before and after installing LCE headers.

 

Thxs both for replying. I didn't notice when I had stock headers with the AIP making more fumes... Just wondering if this is normal and I never realized it or AIP started to fail and have to spend more time figuring it out.

Yeah Jimmy so far no other DTC, but I still get that misfire pop on start up when cold from time to time...had a little bit tonight, but seems this is a common thing for a lot of Tacos.