FD Mods? When Fuel upgrades??
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Joined: Dec 2001
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From: Oak Harbor, WA
I have an FD pretty stock and just tossed on a Jasma Catback ...a 99 spec downpipe and a K&N Filter. How many more engine mods can I do before I need to upgrade my fuel and ECU. The next mod I want to toss on in a good intercooler.
You need fuel mods when your Air/Fuel ratio becomes too lean. The higher the boost, more you need to compensate in richening up the fuel for the A/F ratio. How much? Well, that's where you get a wideband O2 and jump on a dyno. 
There really is no magical mod # to get to and say "I need to upgrade my fuel system".

There really is no magical mod # to get to and say "I need to upgrade my fuel system".
Thread Starter
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Joined: Dec 2001
Posts: 155
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From: Oak Harbor, WA
About the ECU upgrades.... could I just toss in a 99 ECU from Japan for cheap to richen the mixture some....or is it not worth the money??? Also what is the best way to go on ECU upgrades....there seems to be a lot of opinion on the purple box.
Your mods are ok, but...it works like this:
All of your mods will increase airflow, which improves power (more air) but makes the combustion leaner (didn't increase fuel). As you should know, lean conditions can and will blow a rotary engine, so we're talking seriously. Experienced tuners have suggested the guideline of 3 'flow' mods before the fuel gets too lean and risks toasting the engine. So you're ok. Usually a computer upgrade over the stock fuel system works fine around this point, but if you add more mods you'll need to upgrade that too.
But your a/f mixture is probably a little off and it would be extremely wise to get the computer upgrade now, even if you don't add other mods.
Dave
All of your mods will increase airflow, which improves power (more air) but makes the combustion leaner (didn't increase fuel). As you should know, lean conditions can and will blow a rotary engine, so we're talking seriously. Experienced tuners have suggested the guideline of 3 'flow' mods before the fuel gets too lean and risks toasting the engine. So you're ok. Usually a computer upgrade over the stock fuel system works fine around this point, but if you add more mods you'll need to upgrade that too.
But your a/f mixture is probably a little off and it would be extremely wise to get the computer upgrade now, even if you don't add other mods.
Dave
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I have been running a downpipe, cat-back, intake, and larger SMIC for a while now at 10 psi on the stock ecu. No problems, but that is the limit for my comfort level. I will be purchasing a Power FC next month after smog test.
There is a difference between upgrading the fuel system and upgrading the ecu.
You should be able to run 12 psi all day long on the stock fuel system (with the stock twins). Anything over that and you should look into larger injectors and higher flowing fuel pump.
There is a difference between upgrading the fuel system and upgrading the ecu.
You should be able to run 12 psi all day long on the stock fuel system (with the stock twins). Anything over that and you should look into larger injectors and higher flowing fuel pump.
You can also buy a used re-chipped ECU $400-500 if you don't want to spend $1000+ for a Power FC and have to mess with having to get it tuned on a dyno...
You can always sell the re-chipped ecu later for what you paid for it when you ar ready to "graduate" up to the Power FC. That's what I'm doing.
You can always sell the re-chipped ecu later for what you paid for it when you ar ready to "graduate" up to the Power FC. That's what I'm doing.
Originally posted by jpandes
You can also buy a used re-chipped ECU $400-500 if you don't want to spend $1000+ for a Power FC and have to mess with having to get it tuned on a dyno...
You can always sell the re-chipped ecu later for what you paid for it when you ar ready to "graduate" up to the Power FC. That's what I'm doing.
You can also buy a used re-chipped ECU $400-500 if you don't want to spend $1000+ for a Power FC and have to mess with having to get it tuned on a dyno...
You can always sell the re-chipped ecu later for what you paid for it when you ar ready to "graduate" up to the Power FC. That's what I'm doing.
a couple of points of interest -
* "Jasma Catback" - unless you are referring to a US brand I have never heard of, jasma is an association, not a brand (you'll find 'jasma' stamped on the underside of most japanese brand mufflers)
* "could I just toss in a 99 ECU from Japan for cheap to richen the mixture some" - I'm not sure what advantage you would gain by doing this. If anything, the JDM ecu would be expecting a higher octane fuel (guessing here) - possibly not a good thing.
* "Jasma Catback" - unless you are referring to a US brand I have never heard of, jasma is an association, not a brand (you'll find 'jasma' stamped on the underside of most japanese brand mufflers)
* "could I just toss in a 99 ECU from Japan for cheap to richen the mixture some" - I'm not sure what advantage you would gain by doing this. If anything, the JDM ecu would be expecting a higher octane fuel (guessing here) - possibly not a good thing.
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