Can I use a stock ECU for these mods?
 

Hi all,
I recently purchased a stock 93 FD with 23K miles and in mint condition. I am in the process of adding the following mods: GReddy FMIC, GReddy Airinx Dual intake, Koyo radiator, aluminum AST, HKS Downpipe, Tanabe Super Medallion Hyper Spec Cat-Back exhaust, silcone hose replacement. Question 1. I need to get an A/F meter. Does anyone have any recommendation on one and where I can buy one? Question 2. I'm concerned about running to lean with these mods. I spoke to Tri-point Engineering who says yes, and are pushing the AEM computer. Intense Motorsports on the other hand, is saying these mods are fine with the stock ECU as long as I don't add a midpipe. Anyone know who's right? Or should I just hook up the A/F meter and see what's happening?
The car will be used mainly used as a daily driver for long highway commutes and I am concerned with longevity of the engine/turbos. Any thoughts? Thanks.
Tony

I'm not a tuning expert, but I do have very similar mods to yours. My car also has 23k miles. I'm on the stock ecu, and I haven't had any problems. I did add a boost controller after the downpipe. If you keep the boost at 10psi, I'd guess that you'll be fine. Any higher than that and you're taking risks.

Re: Can I use a stock ECU for these mods?
 

If you want to keep the stock ECU, buy a boost controller and keep it at 10 psi. You should be fine. Don't worry about the A/F meter as most are inaccurate and will tell you very little in reality. As long as you keep you boost at stock levels, you wont be running lean. If you have the money for an ECU, go with the PFC. There's lots of support for it and everyboby has good experiences with it.

Thanks for the info guys. Could you recommend a specfic boost controller?

There's an HKS one that comes with some nice extra goodies.

Most people use the profec B. The Profec B Spec II is what I use, although I've read that some people are having problems with it, so you might want to get the Spec I version. If you don't want to spend $300, you can always make a "home depot boost controller" (do a search if you don't know what I'm talking about - there's loads of info). In either case, you need to make sure you have a boost gage (you didn't mention whether you had one).

Good luck.

I DO have a boost gauge being installed as well, forgot to mention that. Also, I'll order the Profec B Spec II. It appears that the Spec I is discontinued.

I think you're crazy running FMIC, intake & exhaust on the stock ECU!

-pete

It's been dyno-proven by many (including myself) that you can run several mods on the stock ecu, as long as you maintain 10 psi of boost. My A/F ratios under full boost were still barely over 10:1 with intake, exhaust, downpipe, and SMIC on the stock ecu.

Wow the US ECU's must run pretty rich! I suspect it's due to your cat durability laws. Was that 10:1 measured before or after the cat?

-pete

Is it worth it to run stock boost levels with FMIC?

Yes the air will be cooler but how much more performance can be gained at 10 psi? Seriously asking. I see it as buying a ferrari to deliver mail. That is, you have all of this power potential but it dosen't matter because you are stopping at the next house.

I would just get the computer and boost controller and set the boost at 12 psi.

There's a big difference. I wiped around 25degrees from my intake temps @ full load. It also greatly reduces the heatsoak feel you get with the SMIC.

-pete

Oh and I think a lot of people do it because spending the $ for FMIC, boost controller and ECU (plus tune) can be pretty nasty in one hit. So they stagger it. I did exhaust first on my last FD but it was already running too lean at 10psi (JDM FD) so I went stand-alone soon after. Then rad then FMIC all in steps. So it never really felt like I was spening anything.

-pete

I am in agreement here. I ran my car for a year and a half with a streetport, dp,intake and catback at ten psi. the car will run fine. however, it wont perform to its potential until it is tuned properly.

there is no substitute for tuning. if i had to do it over again I would have had it tuned sooner. I ended up with a gforce ecu (similar to the m2 or pettit unit) and the car really woke up. tuning is everything.


j