Fuel injectors/Fuel pumps

This is just some quick advise, not in-depth.

First thing to check if your replacing injectors: Resistance
If there low or high. If there’s low resistance and you install high resistance, basically the car will not start. Usually you can remove a resistor block and your up and running.
If there High resistance and you install low resistance you will damage your ECU and more.

Most stock ECU’s that can be re-tuned can handle up to 1000cc injectors (Not all).
Most modern aftermarket ECU’s will handle very large injectors like 2200cc.
The issue is not under power but at idle with big injectors.
There are a old Bosch injector (Indy blue 1600cc) that had such poor response time that even with a good ECU, at idle fuel ratio was around 10-1 AFR(0.7 Lambda) on a 3.0L six cylinder at 1500rpm, They were used allot on Rotaries. (But not recommended)

Modern injectors come with injector data, This data in a modern ECU improves tuning time and end result. AFR/Lambda are able to be setup and controlled with flex fuel (E85) and trim table’s like fuel pressure drop.

I have a favorite injector price vs control vs injector data, it’s the Bosch motorsport 1000cc. They come with injector data, this is a must for better tuning and E85

There is one other injector I also rate very highly and it’s the Bosch motorsport 1650cc It’s a lot more expensive but if you need it, you need it. They come with injector data, this is a must for better tuning and E85

Fuel injector sizing. I don’t like to run an injector over 85% duty cycle.
So working out what size you need is quite easy at injector dynamics and you also can order the injectors direct from them as well. Lambda usually is between 0.80-0.85 under full throttle and 1.0 at idle, Ethanol “0” petrol or 85 for E85.

Fuel Flow Calculator

Fuel pumps are a big problem when it come’s to tuning, there are so many non genuine pumps being sold, It’s costing customers a fortune in dyno time.
What i recommend is an in-tank pump or external bosch 044’s for most street/strip and track day cars (Race/drift cars need completely different fuel systems)

walbro 455lph E85 Safe, in tank fuel pump supports up to 700hp, Recommended to be used with an aftermarket fuel pressure regulator. I usually have one in stock but if I’ve run out then it’s an over night courier

There are a lot of non genuine fuel pump getting sold out there and this is one of the biggest issue’s i’m having when it come’s to tuning on our dyno.

bosch 044 motorsport external efi fuel pump


Fuel pressure regulator is always recommended when upgrading the injectors and fuel pump. A well known brand is recommended. Turbosmart or tial, Aeromotive



Don’t over look wiring to the fuel pump, voltage drop results in fuel pressure drop.

12-14 volt feed, if you do not check this under load you shouldn’t have even bothered checking, my trick is:

Connect the multi meters earth to a good earth, start the engine hold the rpm at 2000, adjust the fuel pressure regulator to (base pressure + expected boost pressure + 10psi) so lets work through that 42psi + 30psi + 10psi = 82PSI. (This will soon show any weak point in the fuel line, I also back the main fuel of the ECU if i can)

Now check the voltage as close to the fuel pump as you can and at the battery. in a perfect world this voltage drop would be less than one volt.

Earths catch people out more often than not, check for a voltage drop from as close to the fuel pump as possible to the chassis or battery if possible, Zero voltage should be found.

After testing remember to reset base fuel pressure and the ECU main fuel

Latest wiring issue, this slowed the tuning process down. I had ordered a new fuel pump, but when i went to fit it i found the real fault