jdmhatchback

i have my car for about a month already and ive got the basic reliability mods and i got a few mods already such as downpipe exhaust and hard pipes but my question was whats the rule of thumb on what mods you have before you'll need fuel upgrades?? or a new ecu?? i couldnt find anything on the search but mayb i was looking in the wrong places. thanks in advance

TwinTriangles

Its the "3 mod rule", Intake, dp, cb= new ECU, Intake, intercooler, DP=New ECU, Intercooler, dp, cb=New ECU... And so on, as far as I know, But ive been told if you upgrade the cooling system well you really wont need to upgrade as much because Mazda made the factory car run so rich to acommodate for the crappy, crappy stock cooling system...

FormerPorscheGuy

This is correct. Three mods is the rule of thumb for an ecu upgrade. You will also need to look into some type of boost controller.

This is completely false. Upgradeing your coolant system will not prevent you from leaning out. It will only help prevent your car from over heating and help stave off coolant seal failure.

DCrosby

Yeah, well 3Mod rule has to do with generalizations, and they work 0% of the time... It's like saying all blondes are stupid...
If you take that rule and put on A Down Pipe and Mid Pipe 2Mods... and you do nothing to controll boost... Bang...
So it has more to do with what mods you do that affect the way the engine flows Air and Gas, through it, and if you change one (Air) you need to change the other 2 Gas and Sparc, so DP and MP changes how well air / exhaust can get through to the back end... and consequently how much gas you'll need not to lean out... Radiator, AST, Cross Drilled Rotors, Strut Tower bar, are all mods, yet affect nothing on how well the engine burns Air and Gas... so you might want to rephrase on, this is what I've done, and here is where I'm going.... or want to go...

EdwardNorth

Now, one thing I've never quite understood is this --> Under this "3 mod rule", do you upgrade your ECU ON the 3rd mod, or before doing mods #4 and above? Like as in an Intake, DP, and CB are safe with the stock ECU?

(NOTE: After the DP goes on this weekend, that will be my last "power mod" before I get a PFC, so that will leave me only with a DP and CB. I'm just curious...)


And as far as boost control goes, the Apex'i PFC controls boost on its own, doesn't it?

Thanks!

BLACK ROCKET

People seem to forget that one of the most important MODS after HP/speed increase is to upgrade your break system to accommodate appropriately.

It is sad to hear people only talk about speed and HP and very rarely hear break system modifications.

r0t0r-rooter

The general rule of thumb is to keep boost @ 10 psi; any changes in cfm using the stock twins can be compensated by the ecu....

widebody2

"People seem to forget that one of the most important MODS after HP/speed increase is to upgrade your break system to accommodate appropriately.
It is sad to hear people only talk about speed and HP and very rarely hear break system modifications."

I'm all for safety, but before I tore my car appart it was making quite a bit of power and my only brake mod was cross-drilled and slotted rotors with good pads. I've never seen another car stop as fast as mine. I'm pretty inpressed with the stock brakes.

rotoryspeeddreamz

From what I've read on the forum the three mod rule is popular to prevent the car from leaning out. Once you've made the third mod to air flow you should have your ecu already remapped. Of course exceptions to this rule include midpipe and turning up the boost as those mods are extreme to air flow and require immediate remapping of the ecu.

FYI: Your car may react strangely if you mod air flow. For example back when I was running intake and cb my check engine light came on all the time. Ran the code and it said I needed a new O2 sensor. When I replaced the sensor the light still came on and flashed the same code. My mechanic said it was probably just the car responding to the mild increase in air flow.

P.S. my mechanic is a rotory mechanic so he knows what he's talking about.

FormerPorscheGuy

If you read everything on this forum you will also hear a lot of people telling you that you can have ALL the bolt-ons and be safe as long as you keep it at or below 10psi.

clayne

FD3S sensors use MAP not AFM.

KevinK2

3 mod rule ...

stock ecu/fueling ok at stock boost levels with any upgrades added except:

big IC (M2s, or fmics) (esp in cold weather)
porting
mp

Mitch529

So your saying that I can Install an Intake, DP, and CB with a boost controller and all the Saftey Mods (radiator, etc..) and be totally safe from running into lean conditions etc..?

KevinK2

I have that + greddy smic. No problem. Search on mod rule and Wade for his wide band TEST data.

But, mods can increase the 3k hesitation problems, and make u wish u had a PFC ecu.

overrev

i have greddy smic, dp, performance mp, apex intake, fluidyne rad, and cb, i put down like 12, to 13.5 pounds of boost with no ecu, boost con. and have not had any probs. and i get on my car hard. dont really know how it does it, guess it a special 7.

KevinK2

just go easy in very cold/freezing weather. stock ecu air temp tables don't correct enough for denser cold air, and tend to lean out as u get colder.

Rx is now Gt

Yes, this is an old thread, but bear with me. Can I do a MP, DP, and CB and be ok? orrrrr is the MP a No-No?

rynberg

There are at least 5-6 threads this month already that would answer that question, not to mention the HUNDREDS of times it has been discussed before. Please learn to use the Search function.

Larz

Get a ported waste gate to prevent boost spike and creep with your current mods. I wouldn't go any further without proffesional tuning.