Hello.
New to the car/these forums. I installed a catless mid pipe on the car, and so I need to do the air pump delete before taking it to get a tune. I have looked everywhere for videos or directions, but none of them are really answering my questions. Hopefully someone here can help me out.

(The car is completely stock, except for the turbo back exhaust, EDIT:: Also Supra TT fuel pump, and upgraded fuel pump wiring)

1. What should be done with the hoses/electricals that are going to the air pump? Plug them with bolts? Just leave them open? Electrical tape the connector?

2. There is a line that runs down to the midpipe cat (which is now gone), what should be done with that line? Remove it? Plug it? Currently it's secured but open.

3. I've seen people talk about block off plates, is removing the air pump going to leave a hole that needs to be blocked off? Or is that an unrelated modification?

4. I've seen people say that removing the air control valve is also something that should be done when removing the air pump. Is that required? Are there any draw backs to leaving it in place? I know there is a block off plate for this. So I'm assuming its related to my previous question, but I am unsure.

5. I know the pineapple racing kit seems to be popular, bonzai-racing now only sells the FFE kit. Are there pros and cons to either?

I would like to do it the right way, the best way, the first time. So I'm just trying to get as much information before I start buying parts and tearing apart something that might be over my head.

 

Stop before you destroy your engine.

Put a cat on the car. Bonez high flow is a great choice. Without an exhaust restriction you are going to overwhelm the wastegate and boost way over what the stock fuel system can handle.

On top of that you can't do an air pump / emissions delete with the stock ECU.

If you do get a PFC or something... along with the air pump you will need to remove the ACV and related tubes, then use the Banzai block off kit. Be warned the car will stink even with a well tuned idle. The air pump and cat should be retained if at all possible. Makes the car a lot more practical/enjoyable.

Edit - I'm not sure what kind of tuning you think can be done on a completely stock FD, but it can't be done. If someone has offered to tune your stock ECU they are full of it. My suggestion - you should put the stock parts back on and enjoy the stock car for a while as you do more research on how to mod FDs.

 

Sorry. I should have mentioned that I have a PowerFC already. I have no intention of driving the car until it has been tuned with the PowerFC. I am just trying to get as much done on the car myself, before the tuner takes over, to try and save a little bit on labor.

I really don't care about the smell. I find it rather ridiculous, that out of all the research I did on midpipes, not a single one mentioned anything about needing to delete the air pump or blocking off the ACV. But I guess they wouldn't sell as many mid pipes if they did... /shrug.

The only other mod to the car is I put in a Supra TT Denso pump, and I upgraded the fuel pump wiring so that it's always getting full power (it was getting 7-8volts under load).

So even with a better pump, and a PFC, you are saying the car will be undrivable?

 

I did this recently, so here's the rundown:
First step is get and aftermarket ECU. I'm not sure how anyone would tune your car without one anyway, and the stock ECU will throw a fit if you keep using it with no air pump. Like many owners, I have an Apexi PowerFC. It's an inexpensive but proven and very well supported ECU, and you can use its base tune without an air pump with no issues. I also recommend installing a boost gauge and wideband air/fuel ratio gauge if you haven't already.

1. In addition to the air pump, there's a component called the air control valve (ACV) which you'll want to delete. The hoses that connect to the air pump lead to the ACV, which regulates how much air feeds into the exhaust. Removing it and any hoses associated with it will expose two openings that need to be blocked off. There's multiple options for block off plates; Banzai Racing, IR Performance, RX7.com, and others all offer their own kits. The catch is, to remove the ACV, you'll have to take off the upper intake manifold (UIM). It's not the worst thing in the world, but not something you want to have to do often. I recommend researching what else you can get done while you have the UIM off so that you can knock it out all at the same time. Owners commonly replace vacuum lines and or do fuel rail work since they already have the access they need. You could even take it a step further and simplify your turbo control system while you're there, but that's up to you. Removing the ACV is a bit tough, but straightforward. Just pull out everything that connects to it and install the two block off plates. I can post some pictures and give you more detailed instructions if you'd like.

2. That line should be removed, and the opening that it mates to should be blocked off ("split air tube")

4. Pineapple's idler pulley is pretty much NLA unless you buy a used one. I went ahead and bought the FFE one through Banzai and have been very happy with it. There's two vent hoses for the PCV system and oil metering pump which will probably need to be pulled out of the way with zipties, but you should have no fitment issues.

In short, remove the air pump, everything connected to it, the ACV, everything connected to it (there's 2 solenoids that can be deleted), and install an idler pulley in place of the air pump as well as a block off plate for the split air tube and 2 block off plates for the ACV.

 

The assumption is that you are stripping emissions if you are removing the cats. Not really their responsibility to tell you what supporting mods are necessary.

I didn't say the car will be un-driveable. I said you can't control your boost (your boost will creep higher than you set it) with no cats and an un-ported wastegate. That has a good chance of blowing your engine with the stock injectors.

The take-away here is that a mid pipe and straight thru exhaust is not a good first mod.

If you are feeling esqecially stubborn you could make a restrictor plate to put in the exhaust flow to control limit creep. And tear out all your emissions. It's been done before. It's just a lot of work to get to the same end result that a high flow cat would get you.

FYI here is an excellent thread from a respected forum vendor with pretty common, well thought out, safe upgrade path and dyno results for each mod... it's a great recipe to follow:
https://www.rx7club.com/3rd-generati...added-1104322/

 

Agree with everything Alex mentioned above. Especially reinstalling the cat. Even WITH a programmable ECU you risk boost creep on the stock twins using a midpipe. Boost creep is an over-boost situation that can't been tuned for, so it leads to a lean condition. And on a rotary that can cost you an engine...and turbos. And no, a boost controller will NOT protect you from creep. There's only two ways to do that...maintain some restriction/backpressure in the exhaust or remove the turbos and port the wastegate. The latter is ALOT LESS fun than the former. In addition to the car not stinking, I think it sounds a lot better with a cat.

Removing the airpump will not release any noticeable power. It's only advantage is space and some weight loss. Space is always good. The weight on a street-driven car is practically meaningless. Instead consider putting the money and effort into reliability and cooling mods. A bigger SMIC, hi-flow cat, efini 'Y' pipe, an all-metal radiator, an all-metal AST or properly deleting it ....even a simple WI system.
Like your downpipe but UNLIKE the AP, some of those are both reliability AND performance modifications.

If your emissions regulations allow, a lot more than just the AP can be removed on the PFC. ALL emissions related can go. .EGR, accelerated warm-up, double throttle etc. That usually requires removal of the associated solenoids and vacuum hoses, which is usually accompanied by replacing the remaining rubber vacuum hoses with silicone or viton versions. And NONE of that is easy a walk in the park with the engine in the car. But yes, wires will have to be left unless or until the engine is out and they can be properly deleted from the engine harness. I would NOT recommend just cutting the connectors off.
There's a lot to think about and research before removing things.

 

I appreciate all of your responses. Thanks for all of the new information/knowledge.
I'll see if I can't find this Bonez catted midpipe, and swap it out for the rx7store midpipe that I put on the car.

I should have guessed this car was going to be a special snowflake. Even something as stupid as changing the exhaust is a cluster ****. So far my experience with the car is to park it, and don't look at it for too long, because just looking at it requires a supporting mod. lol

 

You can be stupid and start yanking parts off ‘just because’ and then bolting on a catalogue of others without any rhyme or reason. It’s performance and looks already meets or exceeds most just as it is. My experience is that it’s not the car that’s a cluster-****.

 

For what it's worth, I spoke to the guys over at rx7store.net, and they claim that with their resonated midpipe flows close enough to a high flow cat, that it should limit boost creep to as little as 1-2psi over stock, and that with the Supra TT pump I have installed, and the fact that I still have stock intakes, the car should be more than fine, and as long as I can get it on a dyno to verify everything looks OK, I shouldn't need to go through the massive undertaking of removing all of the emissions components.

I'm going to install the PowerFC tonight, and monitor the commander to see what boost levels hit. It's really cold outside, so if it's going to have boost creep, this is the weather to find out. If it does start hitting 14psi or higher, I'll pull the midpipe, and go with a high flow cat. I've already run the car with the rx7store midpipe, so I can't return it, and the high flow cat they sell is another $320 dollars. I'd rather not spend it if I don't have to. I'm not tracking the car, or even driving it hard, so if this solution works, with the little amount of money I've spent. I'll be happy. I still have an appointment for the dyno. So the final answer will come when they get their hands on it. Whatever the tuner decides, is what I will go with. He's been racing and building RX7s for 25 some odd years, so I'm sure he'll slap some common sense into me. hahaha

Hell, the only reason I'm even doing all of this is because the stock exhaust was rusted through. lol. What a PITA. Oh well. I'll reply to this thread with what happens, and if my car blows up, so that people in the future, who don't know WTF they are doing like me, can learn something.

@Sgtblue I'm not doing this "just because". I'm doing it because it was a rusted out **** heap and I'm trying to make it not awful. /shrug... If anything I'm trying to keep the car at stock power levels, and increase reliability. I don't WANT to remove the air pump or anything else... But it seemed like a chain reaction of things need to happen when you change out the midpipe...

Anyway, I appreciate the suggestions reliability. The car has an upgraded metal radiator, and an AST delete. I was thinking about doing the upgraded all metal AST, but not sure if it is really necessary once the system has been removed. Also, I was thinking about upgraded to the factory R1 dual oil coolers since this car is a touring model. Not sure if I should go with stock oil coolers, or say the pettit racing dual cooler kit.

 

If you don't want to remove the air pump and ACV, you can just take out the line that used to connect to your main cat and block off the opening. The air pump will still function because the ACV also sends air directly into the exhaust manifold. With a wideband A/F gauge, you can see the effects of the air pump engaging and disengaging based on engine load or RPM (its clutch lets go at ~2700 RPM). When the air pump is on, your A/F ratio will appear very lean. The stock ECU tries to maintain a ratio of 14.5 or so with the air pump running, but of course, that's with the wimpy factory style O2 sensor.

 

My ‘snowflake’ has never left me on the side of the road in nearly 2 decades of ownership and well into 6 figures of mileage. If you decipher my signature it lists my engine mods. Car makes about 300 whp. That’s not going to give me any bragging rights at the fast-food parking lot. But it’s all usable and the car easily outperforms this old man. I don’t abuse it, but I don’t baby it either.

This forum is an absolute treasure chest of knowledge and experience using the search function and some effort. Combined with the FSM it saves a lot of cars, a lot of money and a lot of frustration.

 

Negative, ghost rider. Cold weather is not the time to over boost. Cold air is much denser and requires a lot more fuel. You will run out of injector on a cold day much sooner than a hot day.

You're afraid to spend $320 on a brand new cat, but are fine risking your engine by making what is a known bad decision?

You could also sell your midpipe and buy a used cat.

Here's hoping your tuner has more sense than you and/or you come to your senses. Good luck.

 

Dude. You act like I'm just going to take the car out and run it to red line. There are ways to shake down a car other than bouncing it off the Rev limiter on the highway. And I already said I was going to put a cat on it if there was any issue, and that the tuners word was final regardless. No need to post just to try and make a quick jab.

 

OK, let’s start over. Looking at your profile you’re maybe a little older than some of the other posters. By now you should understand there’s always unintended consequences to the changes you make. And the more away from ‘stock’ you get, the less help the FSM will be. I usually tell new FD owners not to install ANY performance mods the first year of ownership. Instead, get a good baseline for maintenance...Change ALL fluids, belts, hoses and other consumables like plugs. Every time you spot something you can’t identify, look it up in the the FSM. Spend some evenings reading through ALL the FAQ stickys...with special attention to reliability mods and do those (sounds like you’ve already made a start researching dual oil coolers).
Doing that will give you time to prioritize goals for the car and save you tons of money and frustration getting there.

 

I used your own words. You were the one talking about a tuner slapping some common sense into you.

As for the rest - it's advice. And judging by your attitude so far I'm regretting that I took the time to give it. We care about these cars on this forum because we have been working on them for decades and they keep putting smiles on our faces. Yours (by your own description) might be a rust bucket that you don't care about blowing up. Still, it is frustrating when someone chooses to ignore 25 years of precedent and insists on repeating the mistakes of the past.

I do hope you do some more research and make good decisions. It's your car. Do what you want. Again, good luck.

 

I'm going to straight pipe it on the stock ECU. but I'm going to taper down to a .5" pipe because I want all that sick *** back pressure.. Maybe put some hotter plugs in. Possibly an 80LPH fuel pump. Mix it with some really nice 83 octane. Then just bounce it off the rev limiter and see what happens. I bet I can do some sick *** burnouts bro-ham.

You need to realize that not everyone is 12. Your experiences aren't necessarily going to be mine. And that this is a place to learn and share information. And most importantly, you can do all of those things without looking down your nose at people and getting upset when they decide to take that knowledge and explore the car on their own.

In summary. I reget you taking the time to answer me as well, and I regret even coming to this forum even more so. I do very much appreciate the information shared to me, but I most certainly will never make that mistake again.

 

I think the older members have seen all too often kids that have grown up on fast and furious with some money in their pocket destroy a perfectly good FD with stupid mods, so that POV is where the comments were coming from. A straight mid-pipe is probably the single largest contributor to boost creep with stock twins and stock ECU. You may be able to mitigate to some degree with a PFC by tuning extra fuel for the extra boost, but there's only so much boost the factory wastegate can manage without porting. You may be right about a resonated mid-pipe vs a high flow cat, but if you haven't purchased it, you may be better protected by the cat (with less smell as a bonus). As for the air pump, if you leave it, you won't have to pay for an idler arm which is definitely required if you delete the air pump.

FWIW, i'm running a Bonez HF cat with the air pump and a ported WG on stock twins. I find even this rather stinky at times.