Air pump/Emissions removal.

I've seen 100 threads about this, all of which have helpful information. Although helpful, they do clash a little bit. One person says one thing in a given thread, and then a totally different thing in another. If I've missed the answer to my question I apologize in advance.

I think I've weeded out all of the crap information and found what I need, but i'd like to confirm to see if I'm right or not.

So.. from what i've read..

*Sometimes* when removing the air pump via greddy pulley kit or whatever, people have had issues with rough idle (When cold for the most part) and a very rich condition at idle. From what I've read, having something like a PowerFC can remedy this idle/rich situation. Am I correct in assuming this? I've got a greddy pulley kit just sitting here but if this idle/rich thing is true, i'll just wait till I get a PowerFC and have it tuned to install the kit.

Secondly!
Block off plates.. obviously meant for the rest of the emission system to be removed. Also obviously you're not going to pass a sniff test. (Not an issue for me) What my question is.. having these plates + the greddy kit, is it going to make the idle/rich situation even worse without having a tuned ECU?

Lastly. (If that's a word, lol)
If I were to install the greddy kit right now (And remove the air pump), what's the best way to deal with the hose that is connected to the pump? Basically stick a cork in it? (Not literally) Because from my understanding, that hose is connected to something else. (Pretty sure that problem would be covered with a block off plate set)

Anyways, lots of rambling I know.. thanks in advance for the help.

Edit: Totally forgot to mention earlier.. what is *actually* going to happen with my cat? There's no downpipe involved in this situation. I've heard quite a few different things, would just like to be clear about this.. maybe i've read too much at once because I seem to be confused a little, lol. :P

 

i have never heard of it making your car run rich? all i have been told is there is a slight lack of tension with the greddy belt. also many do not recommend removing the airpump if you are still running the main stock cat.

all the info you need is in the link:

http://www.rx7.org/Robinette/air_pump.htm

link for the block off plate:

http://www.2751engineering.com/fd_block_off_plates.htm

 

Well and this is where contradictory information comes in.

Some People (Not Certain Why or Who) experience a rich condition, which the ecu detects and tries to lean out, by way of the idle dropping below what it is set for.

The Reason is, when at Idle, and the airpump is working you're getting Extra Air into the combustion process, via all the EGR valves, and into the cat, via the Fitting Hose on the side of the cat. The Idea being that the cat below a certain RPM (2000 comes to mind), is not hot enough to burn all the exhaust fumes cleanly, and it leaves deposits of carbon on the cat, which gives it a premature death sentence, not immediate, but significantly less by 1/2 it's lifespan or less.

More air(Oxygen) in the CAT = Higher Cat Temps because you've got what amounts to a small fire (glowing metal) and if you blow on it it get hotter.

The EGR also recycles burnt exhaust back into the combustion chamber, to give it another try to burn the rest of the exhaust, and what remains of the fuel that didn't completely combust the first time.

So with the EGR Feeding Burnt Exhaust + Air back into the combustion, if that air is no longer present, the car starts running rich, and idle drops, ecu compensates, idle rises, ecu goes back to thinking everything is fine, and goes rich again... hence lumpy or irregular idle.

For some people (Possible Newer ECU) the ecu knows that the airpump is no longer a factor and leans the fuel out by a bit...

This is to the best of my knowledge. I tried learning as much as I could, due to Living in California, and trying to get around some of the nutty laws that exist here. But am by no means an expert.

 

The ecu cannot "detect" a lean or rich condition at idle. It does not even consult the o2 sensor until in a cruise situation. It runs off it's pre determined base maps in the meantime, with only the temp sensors and map sensor to change the fuel injection volume. If there is a change in idle it is due to a change in manifold pressure detected by the map sensor.

Removing the air pump WILL make the car run a bit rich at idle and stumble, because the ecu was tuned with the airpump air injection going into the engine intake manifold at idle. Take that air input away and the map shifts rich all the sudden because you still have the same table for fuel but now you have less air at idle.

It is not like the car shakes and the exhaust belches smoke, though. It simply stumbles a bit, like a good size streetport. It is nothing to worry about, but if you want to keep the idle as smooth as possible then you'll want to leave the airpump on.

Air from the airpump also went to the main cat. You can leave the ACV and other hoses in place with no air pump, but you will get some odd sounds from the hoses, so most people would cap them with something. You may also cause damage to the cat with no airpump air going to it.

Most of this is still a moot point in my eyes. Do people actually still run stock ecu's and stock cats on these cars? Unless you live in Cali or NoVa and have to pass tests, I see no reason to have these items in place. a PFC is pretty much the first mod that should be done with an FD, and it seems like everyone has them.

 

When I went non-seq I pulled all the emissions stuff plus the air pump. I'm on the stock ECU with the original main cat. The car does run rich at idle (I can smell it if I sit too long in one place). My idle when the car is warmed up however is rock solid at 750 rpm, with no bouncing what so ever. It's even better than before I pulled everything since the LIM gasket was blown and air was sneakin' in past the throttle body. My only idle problem now is at startup when the car is ice cold (45 degrees or below), but this is most likely because my car also lacks the fast idle cam. From my experience I'd say go for it, but do consider two things.

1) Try unplugging the air pump first and running without it. If it gives you issues then don't pull it.

2) I would not pull the air pump if I didn't already have plans in place for replacing the ECU. Running like I am now, I know I'm killing the cats life and it would suck to end up with a clogged cat in short order. I'm only ok with that because I'm going PFC and midpipe quite soon.

 

Jeremey,

In the least, you can increase the idle up to around 1000 rpms. On a stock based ECU, that will keep it from feeling like it's going to stall.

 

Ok, here is a question for you guys.



How to completly remove emissions AND keep sequential set up.




=Ben

 

Wow, lots of great information guys. Thanks much for the replies.. i've done a few mods to the car already and i'm definetly thinking it's time for some sort of ECU modification.

The common consensus that i've gathered from everyones post in this thread is that an ECU modificatoin will result in a better idle and more reasonable A/F condition.

My only other question is.. block off plates. Having the plates and removing all of the emissions stuff.. will I be able to smooth out my idle and not run *too* rich with ECU modification? (Pretty sure I know the answer to this question, just wanna make sure.. a smooth idle is important to me)

 

With a programmable ECU, you can "fix" the idle pretty much any way you like without doing any "hacks". If the ECU is not programmable, you'll have to do more or less "hacks" to make things stable (like increasing the idle as I mentioned above).

I run a remapped stock based ECU. In my case, I increased the idle up to 1100 rpms to keep things smoothed out.

 

Thanks Mahjik!

I find that your posts answer my questions before I even ask them in most cases.

 

i dont think its really seq or no-seq related. here are a few how-to's i saved, that you could use:

egr: http://www.rx7.org/Robinette/egr.htm

airpump: http://www.rx7.org/Robinette/air_pump.htm