Hello,

Apologies in advanced if this has been answered before but I can't seem to find an answer to this specific question that I have.

So currently my car is running the following:
Apexi Power Intakes
Apexi Intercooler
HKS down-pipe
New OEM catalytic converter
HKS Hi-Power catback

Apexi Power FC

Stock engine + Stock sequential twin-turbos (original 108k miles going strong)

So my question is:

I bought the car with an Apexi Power FC unit with a tune. (not accurate to the current state of the car.)

Do I really need the Apexi Power FC or can I just run the car "safely" with the OEM ECU?

I am not looking to push more power; my goal is to just have a solid daily driver.

My problem with Apexi Power FC:

When smogging, the CEL does not come on and possibly the AC system does not come on as well because of the Power FC?

I was troubleshooting my AC and my mechanic told me that the AC only turns on with the stock ECU (not sure of this.)

and the CEL turns on only with the stock ECU which I will have to keep swapping over every time I have to smog the car. (just an annoying thing.)

Any advise is appreciated!

Thanks!
Ken

 

I have a power PFC and my AC system works perfectly. But I do remember in the past (many years ago) people claiming the AC didn't work with the PFC so I am not sure if its version dependent (something to look into).

As far as needing a PFC: If you are still on stock twins and are boosting stock levels i.e. 10 psi no creep nor spikes, then the stock ECU is sufficient.

 

The AC part I did not completely believe, I just think that something else in my AC system is broken but I just felt like mentioning it.

Do you think I will be missing out or hurting the engine/turbos in anyway by having bolt-ons running on OEM ecu?

Thank you!
Ken

 

My AC works perfectly fine with my PFC. My PFC is the latest version if that helps.

 

Problems withthe PFC and AC have been covered alot LOL , normally it ends up being a ground issue . since I haven't had an issue with my AC . either I dont know But if you look it up you can find out you can Connect the stock ECU for smogging . and use the Power FC for regular use . but the Power FC can be of help smogging as well if you have issues passing with the stock ecu .

 

The STOCK ECU is perfectly fine as long as you stay at 10 psi. As it runs rich enough to support boltons at stock boost levels. It is when the boost is elevated that the danger occurs. That is why I stated No Boost creep, nor boost spikes. The boost must be kept in check at 10 psi if you want to keep the stock ECU. IMO since you still have a cat, you should not have much of an issue with boost control. Just make sure that you have a boost gauge to monitor. Given that you have an aftermarket intake and IC, it is very likely that you have elevated boost due to lower pressure drop of the mods

For years these were my mods: mild streetport, CAI, Peter Ferrel SMIC, DP, midpipe on the stock ECU. I kept my boost level and boost spikes in check with a boost controller- I didn't have boost creep issues because I still had my stock muffler. Never had an issue and I always WOT'ed. After a few years I got a PFC (got it tuned) and upped my hi boost to 12 psi (low boost setting was 10 psi). It was until I purchased a RB catback that I experienced creep on 4th gear to 12 psi. Never bothered to fix it because I was tuned for 12 psi anyway. My rebuilt engine with mods lasted 50K hard driven miles and only blew because my wastegate line came off and I over boosted to 23 psi. In other words, nothing to do with my mods.

 

The car will run 10 times smoother with a Power FC. No reason to go back to the stock ecu. You should be fine on the base map but can always benefit from a proper tune. The AC issue is usually a matter of the Power FC not seeing the ground when the a/c is activated. Lots of info here https://www.rx7club.com/power-fc-for...-435420/page5/

 

You will still need to swap out ECU's for smog so the CEL works. But it's pretty quick, way easier than even changing spark plugs! And AC does work with the Power FC, perhaps a mechanic with more expertise in the Power FC can help.

More interesting: What it the Power FC tuned for? It really should be tuned for the current state of the car.

 

I would argue that with stock 10 psi boost, I would prefer to run the stock ECU than a PFC that is mismatched (not correctly tuned for) the current state of your car.

If the PFC was tuned for your particular situation, then it would be fine to run. But sounds like it isn't.

 

For sure, I have been just swapping issues every time its due for smog.

I am thinking of getting the Power FC tuned but there aren't any that knows how to do it here in SF bay area or I am just not aware.

--Ken

 

California requires smog checks on 20 yr old cars, unbelievable.

 

california requires smog checks for any vehicle post 1975

 

I'm running that exact mod list with a PowerFC on base map. It runs beautifully, much better than the stock ECU. 10psi of course.

I would punch down to base map and fix the A/C rather than put up with the cruddy stock response.

 

I'm not a huge fan of the PFC, since there are now other plug and play options. However, for what you're trying to do, there are ways to get the CEL to come on when needed, and the AC problem can be fixed with a diode and a little soldering. If you search for PFC AC and diode you'll get the info that you need.

 

The CEL function for the power FC is your exhaust overheat light in the center console. If you want to keep the Power FC in for smog, then you have to tap a light into that and run a bulb up to the CEL in the dash. But considering how quick and easy it is to pop the ECUs out it is far simpler to just swap it to the oem ecu for smog then drop in the power fc afterwards. If you are running a different map other than the basemap in the power fc you'll need to save it with a datalogit so that it can be uploaded if it is lost in the process. If you are worried about the OEM ECU during daily driving, then just drive it safely with it in for the smog and stay off of boost.

Comparatively, I run the Apexi intakes, Apexi cat-back, DP, High flow cat, and stock intercooler. I'm still using the stock restrictor pills to regulate boost and I regularly see creep up to 11 psi and a few times 12. I use the Power FC and I would not want to risk running my set-up regularly on the stock ecu, but when I need to get my car smogged again shortly I will be putting the stock ECU back in. I'll just make sure I don't really get on it.

 

For the check engine light, find my writeup on making the CEL functional with the PFC. It's a simple matter of some minor wiring down by the ECU. With that done, the CEL will come on for a few seconds and go off when starting the car.

The heat hazard light does NOT work on a US car for warning. JDM cars had that light in the instrument cluster and it was wired differently.

The advantages you'll get are -

- No 3000 RPM hesitation, totally GONE.

- You can run with no airpump and have the car drive properly

- Headroom to do whatever you want mod-wise

- Tons of support in the community

- Super easy install

As one poster stated, yes there are other options out there now, but IMHO for a car with twins and bolt-ons, that's just money wasted. PFC is the way to go.

Dale

 

I have a 94 with CAI, downpipe, and cat back on a stock motor with about 90K and she runs great. I've been thinking what to do next and wondering if the Power FC is a good idea. Question will the car run any better/smoother? will the turbos come on sooner? will I notice any difference for the $1299?

Any suggestions appriciated.

 

Unless you intend to remove emissions and/or plan on more performance mods, the value isn't there IMO. As mentioned above, it would get rid of the 3k hesitation and has a few other advantages. But it won't make the turbos more responsive. A PFC...any standalone, isn't a power-adder by itself.
Personally, with only those mods on a street driven car, I wouldn't mess with a PFC.

 

You can make a turbo more responsive through tuning.

I was playing around in the vacuum cells with super lean (MPG) tuning of 15AFR's.....if you tune to a 12 AFR vrs. a 15AFR in those vacuum cells and go from cruising to full on throttle, the response of the turbo is actually a pretty big difference from these two AFR states.

I did a map that only the light throttle cells are 15's AFR and ramps down to 13.0 AFR right before boost for better turbo response.

 

A PFC is worth it alone to turn the fans on high sooner. My car runs 40* cooler now vs a stock ECU.

Jason

 

Tuning the PFC, even on a stockish car is very much a power adder, the stock ECU is very rich. The turbos can be tuned to be more responsive by adjusting the duty cycle, not to mention the PFC is capable of controlling the boost level on stock twins, with two boost settings.

The PFC is not $1299 on our site