Hey guys,


I just installed a 3" SS Downpipe(that I bought from Huy Tran[htranh@yahoo.com] for $225--Thanks Huy it fits perfectly!) Anyway, prior to installing it I was having all kinds of low boost problems. I was getting 10-8-8 psi or just 8 psi.

Now that I got the dp installed I am getting WAY too much boost! The boost guage comes up nicely, but when I floor it, it spikes up to 14-15 psi!!! I know this bad so I've been taking it easy on the car. I don't want to detonate the engine.

Here's what i've got on the car(93 Touring Package w/31k on the new motor & turbos):

RE Amemiya Intake
HKS Cat-Back Exhaust
3" SS Downpipe

So my question is: What mod do I need next to make my car reliable and power ful??? I know I need more fuel and I need to control the boost, But what EMS should I buy? Do I need a new fuel pump/injectors? I'd like to spend as little as possible. I'd like a No-Brainer EMS where I don't need to be a brain surgeon to install an d configure it.

What would the next set of mods would you guys recommend? And at what cost?


Thanks,

~ John

 

next step would be an ECU. the easiest and cheapest route would be a reprogrammed ECU such as a g-force, M2, pettit, etc. You can get them use for around $500-$550. Just plug in and drive.

The problem with that is that it limits you later on if you want to do some major mods like a single turbo.

You also should get a boost controller to turn down the boost.

 

Thanks ZoomSpeed,

Do you mean I need a Boost controller and an ECU? Is there an all in one EMS out there or will I always need a separate boost contrller?

John

 

Depends on how much money you have (doesn't everything?! )
It goes without saying that you need some type of ECU upgrade to
supplement extra fuel for the boost you're running.

If you're low on $$$$ right now, I would highly suggest changing out
your pills for some larger ones to keep the boost under control for
now....otherwise....boommmm. A friend of mine had a similar
problem with overboosting. We changed his pills out and it kept the
overboost/spiking under control, however, you will need to upgrade
your ECU.

Good Luck!

Cheers!
GEB

 

If you put larger pills in you can lower your boost back to stock. You can also make a bost controler for around $50.00 or spend 400 to 500 on a Greddy boost controler.....or better yet get a Power FC and this will take care of all it....boost and ECU. You've already gotten to the limit on mods without ECU and a new motor is in your future if you don't make the necessary improvements to keep up with your improvements.

 

Yeah the pfc is an easy install and it will control boost up to ~14PSI. Its also more flexible. It can control larger injectors, single turbo, etc. If you get the commander with it you can also monitor boost, water temp, injector duty, etc. The downside is that new it costs $1200. I've rarely seen a used one for sale.

If you get a reprogrammed ECU you'll need an aftermarket boost controller.

The manual boost controller, like the dawes device and the home made ones, work pretty well for what they cost, but it get annoying whne you have to constantly adjust when the temp changes to get the same amount of boost. and to get the right amount of boost you jsut have to start small, watch your boost gauge and slowly adjust until you get to what you want.

 

The PFC can control 1.4kg/cm2 or 19.91PSI. The Apexi & Greddy gauges use kg/cm2 which people call bar. Bar is 14.5 per 1.0, but the two main import gauges that people considered bar arent. They are kg/cm2 which is 14.223342577737328 per kg/cm2 reading on the gauge.(i.e. 0.8 X 14.223342577737328=11.38PSI)

From what I've read, the PFC uses kg/cm2. So at the max setting it can propagate 19.91PSI at 1.4kg/cm2 or 20.3PSI. If Apexi gauges are in kgf/cm2 then I'm sure the PFC is too.

 

the cheapest thing you can do is to make a restrictor plate!

 

Thanks guys,

I have one more question. I want to buy a EMS that I won't have to turn around and sell when/if I decide to continue upgrading my car.

We all know that modifiying these cars is just like crack or heroine, it just keeps you 'jonesing' for more...

I what I gather from reeading posts here is that the Power FC is probably a good choice for me, since it's programmable, right?

What about the AEM? Is it comparable? Whick one would you guys go with if you had a chance to buy your first upgraded EMS all over again???

~ John

 

sorry, My mistake

I thik the AEM is suppost to have more things you can tune, I think, It also has data logging. The PFC dosn't have that.

 

PFC now has datalogging with the new datalogit add-on

-Kib

 

I just spoke to Brett at M2 in Concord, CA. He said that they are charging $699 to reprogram my ECU.

It is me, or does that sound like a lot? Would it be better for me just to buy a PFC or AEM?

~ John

 

you can nromally find them used for 350-550. just do a search for "ecu" in the parts for sale section or on the parts trader.

PFC is nice if you don't mind spending 1200, AEM isn't out yet. At least I don't think it is.

What you should probably do is set a gola for your 7. Ask your self if you plan on doing a single turbo in the future, or are you just interested in some bolt ons. If you plan on doing injector or single turbo mods on the future you should probably go with the AEM, when it comes out, or a PFC.

 

The best thing for you to do is get an ECU. The Power FC is an awesome ECU and the Commander has so many functions that you can view while driving your car. It eliminates the need to buy other types of gauges; you can easily monitor everything on the Commander.

You can't compare the Power FC with the AEM, because it is not out yet. It would suck to see a few dozen RX-7s popping their motor, because the AEM might suck. Hopefully, this doesn't happen.

 

I had a hard time with controlling spiking after mods and an upgraded ecu until I installed a profec
B.This is one mod along with the short shifter I wish I tended to a long time ago........

 

PM Wade, I have the same psi boost you get, ranges from 12-13 but Im still on a stock ECU and have a mid pipe instead of your intake system. But he'll go into a little in depth. From what i got is FD's run a little rich, my car runs like brand new, but in the future I will get a PFC from Apexi.

 

I am not sure that i am overboosting but sometimes i get a whoo noise (like a swooshing noise) anyone know what that noise is.This happens when i get on it it doesn't hit twin turbo it lags. thanks alot

 

Real fix: To get rid of the spikes you need a ported waste gate, which means rebuilding the turbos...but you still will have overboost, so you need to turn it down and/or upgrade/replace the ECU.

McGyver fix: If you have self control, which will be hard with an RX-7, you can get a manual boost controler like a home depot deal and turn down the boost back to 10lbs.

After you replace the ECU, then you can set it to 12lbs so when it spikes to 14 or 15 it's no problem because your fuel pump max's at 15lbs of boost and no fuel cut.

12lbs is also recomended for pump gas (91)unless you are in Texas or Florida which have 93 & 95 octane.

 

Thanks to all of you guys for the great (and immediate) advice!!! I just bought and picked up a reprogrammed XS ECU for $400 today, from Justin(on the RX7 Forum-Thanks!). How's that for immediate gratification? I am going to plug it in tomorrow AM and see how it works! I hope that solves all my issues.

This Forum Rocks!

Thanks Again Everybody...

~ John

 

Update:

I just installed an XS remapped ECU and the my car's check engine light stayed on. I was also still spiking up to 14-15lbs. When I reinstalled my stock ECU the check engine light when off. Justin, the guy that sold it too me even reinstalled the XS ECU in his car and every thing was fine, no Check Engine light.

Justin was cool and just bought it back from me. What could be causing this? Any ideas?

~ John