Still twin- Should I keep the air pump?
 

I have a fairly heavy modified, still twin 3KAI's setup, with extensive heat management modifications and all the necessary upgrades including WMI to boost to 17-18 psi. My engine lost compression in the front rotor several years ago following PowerFC testing to research acceleration enrichment settings (I messed up and caused a lean episode). I have a currently non-functional air pump in place (de-vaned and unplugged) but have functional air pump solenoids, ACV and piping, still in place. I don't want to have a totally functional system, since I don't need to pass any emissions, and don't want the air injection into the exhaust port to mess with my O2 sensor. The three reasons to consider keeping the pump is that I then don't have to install an idler, I use special fan belts that only come in stock sizes (cannot be used with the idler), and most of all, I want to use the air injection into my exhaust pipes to help with the reducing hydrocarbons and the foul smell many of us deal with in my garage. I don't have the stock catalytic converters (don't need to worry about clogging), but have a high flow, high heat, 300 cell metal Vibrant aftermarket cat.

From what I have read researching the subject on the forum, I believe I can simply defeat both the relief 1 and switching solenoids (unplugging and/or capping or removing vacuum lines) and that would permanently send the air pump flow to the exhaust pipe prior to the cat. Does any know if that would work? Also, I may put a switch in the car to defeat the air pump clutch when the car is out in open air and use the air pump only when starting up in the garage and when returning to the garage.

Any thoughts?

Mike

I think you are pissing in the wind trying to manage exhaust fumes with an air pump with an aftermarket catalyst and likely not running at lambda 1, even with the system hot at shut down after getting home.

I will try to leave mine in even with a single if I can to pass engineering and due to belt layout but I don't expect it to run and smell like a modern DI engine with modern euro soec emissions.

I understand that the benefit would be marginal at best due to the factors you mention but is it possible is the question I still have. Does defeating the relief 1 and switching solenoids cause the air pump to go to the exhaust pipe all the time? From what I have researched in the forum and going over the FSM, in theory it should work. Does it is actually work in practice is the open question?
Mike

yep, its not as good as the "Port Air" to the exhaust ports, but it does work.

-mike

i found a copy of the HKS T04Z instructions and it came with a different bracket for the air pump. i think it would need to be longer. so i think you can swing the air pump UP more and give more room for turbos
it also came with different pipes for the air pump, and a belt, pity they don't say what size. they don't really show it though, which is kind of a bummer

i realize i'm getting a little carried away, its possible

https://cimg1.ibsrv.net/gimg/www.rx7...e453fa0c9c.jpg
https://cimg3.ibsrv.net/gimg/www.rx7...018a90f369.jpg

What ECU are you running, OEM, PowerFC or any other aftermarket rig? Whatever it is, if you're using a wideband O2 sensor to either monitor AFRs or do closed loop lambda corrections with an aftermarket ECU, sending fresh air pump air to the exhaust will cause your WBO2 sensor to read lean, similar to what would happen if you had an exhaust leak that allows fresh air to get into the exhaust. More O2 coming from anyplace other than the combustion chambers = leaner readings than reality.

Now if you're just using a narrow band O2 sensor, which can only tell you if you're leaner or richer than stoich, but has no idea by how much, this might not be a big deal.

OP, this thread may be helpful on setting up the airpump to run only to the cat:

https://www.rx7club.com/3rd-generati...-days-1090642/


This is probably true of the ACV’s port air function, but the split air pipe runs right to the cat, and is introducing air downstream of where the wideband is taking readings.

Thanks. I missed this thread when doing my research. This helps a lot. It confirms what I thought would work.
Mike