Running higher cc injectors on stock ecu

Charade4efte

Member +
Hi, I've recently rebuild my 4efte. I am asking if will it experience knock or detonation if I run it @.9 bar of boost with 395cc injectors without tune and only using stock ecu
My 4efte build is:
ct12 (bolt on to the stock manifold)
395cc injectors
JAM fuel cut defender
Tomei Fuel pressure regulator
Walbro 340lph fuel pump
Oversized 75mm 1NZ pistons (OEM)
Lightened flywheel (3.8kg)
Stage 1 clutch
 
my advice will always be to go and get a proper tune, by this i mean fuel, iginition, boost, etc...afr readings and det cans or other knock detection devices would be required...it will save you trouble/expense in the long run

however, some things to consider:
- if you run 395cc injectors on the stock fuel pressure and stock ecu, your car may run excessively rich and you may have issues with your oil getting contaminated with fuel...this can lead to severe bottom end problems
- you need to take account of your fuel quality (octane rating), 1 bar of boost with even the stock ct9 turbo may lead to knock
 

Charade4efte

Member +
my advice will always be to go and get a proper tune, by this i mean fuel, iginition, boost, etc...afr readings and det cans or other knock detection devices would be required...it will save you trouble/expense in the long run

however, some things to consider:
- if you run 395cc injectors on the stock fuel pressure and stock ecu, your car may run excessively rich and you may have issues with your oil getting contaminated with fuel...this can lead to severe bottom end problems
- you need to take account of your fuel quality (octane rating), 1 bar of boost with even the stock ct9 turbo may lead to knock
Im running .8 bar at peak and I use 15w-40 mineral oil. my fpr is adjustable set to 3 bar and I have walbro fuel pump. will it cause detonation or knock under load?
 
Im running .8 bar at peak and I use 15w-40 mineral oil. my fpr is adjustable set to 3 bar and I have walbro fuel pump. will it cause detonation or knock under load?
congratulations on attempting to destroy your ( not presumably ) well cared for engine, you will be happy to know that running any modifications on a stock ecu will result in the ecu learning, as most do, they can tolerate a certain amount of, lets call it F**kery, however, like any machine, messing with its base variables by swapping in something it does not understand very well, ie injectors that are not stock, but can still use, will result in dangerous variations in fuel economy. this can also result in knock, especially since the ecu cannot accurately pull fuel properly.
 

Charade4efte

Member +
congratulations on attempting to destroy your ( not presumably ) well cared for engine, you will be happy to know that running any modifications on a stock ecu will result in the ecu learning, as most do, they can tolerate a certain amount of, lets call it F**kery, however, like any machine, messing with its base variables by swapping in something it does not understand very well, ie injectors that are not stock, but can still use, will result in dangerous variations in fuel economy. this can also result in knock, especially since the ecu cannot accurately pull fuel properly.
I thought running rich will safeguard from knock. And also my engine is cold even when under load running at 79 degrees celcius based on the water temp gauge
 
I thought running rich will safeguard from knock. And also my engine is cold even when under load running at 79 degrees celcius based on the water temp gauge
normally that would probably be the case, but in your setup, the ecu cannot understand the size of said injectors, and thus even if it did try, the attempt at correcting fuel trim will not succeed as correctly as, say my car would.

a starlet is considered in my case to be at operating temp at 75c, warm and ready to go. reaches 99 when Sending the life out of it. your temp is not normal but i am unsure as you dont live here, check your thermostat.
 

Charade4efte

Member +
normally that would probably be the case, but in your setup, the ecu cannot understand the size of said injectors, and thus even if it did try, the attempt at correcting fuel trim will not succeed as correctly as, say my car would.

a starlet is considered in my case to be at operating temp at 75c, warm and ready to go. reaches 99 when Sending the life out of it. your temp is not normal but i am unsure as you dont live here, check your thermostat.
Japanese starlet gt manual states 86-90 degrees celcius normal operating temp and thermostat opens at 92
 
Japanese starlet gt manual states 86-90 degrees celcius normal operating temp and thermostat opens at 92
well in my case, the car is extremely modified, even the thermostat isnt stock, and i really wish it was
i would bet alot of people dont actually run a stock thermostat either, although standards of care for cars in australia are, terrible.


( apoligies if this all sounds sarcastic, it is not )
 
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