Honda Prelude Forum banner

Fuel system

241 Views 2 Replies 2 Participants Last post by  Toki90
I’m upgrading the fuel system with a Aem fuel rail, Fuel regulator, and fuel pump. Am I going to need a tune after changing these parts or is it only after I upgrade the fuel injectors
1 - 3 of 3 Posts
The fuel rail won't significantly affect fuel pressure/flow, no tune would be necessary.

The fuel regulator depends on whether the rated pressure of that unit deviates from stock. Fuel system pressures are extremely important. The ECM in the Prelude has no way of directly measuring fuel pressure; as such, the computer depends on the fuel regulator to keep the fuel pressure within expected parameters. Deviation from expected fuel pressure would result in the fuel injection calculations being inaccurate. So, assuming the pressure rating of the regulator is the same as the stock rating, you'll be good to install it. However, any deviation from standard pressure (even small deviations) will necessitate tuning the ECM to account for the change.

The fuel pump depends on the rating of the unit. Adding a higher-flow fuel pump is only necessary when the fuel supply demands of the system are not met by the stock pump. Adding a high-flow fuel pump is unnecessary unless you use forced induction and require additional fuel.

If the fuel injectors are of a higher flow rate than stock, the ECM has no way of knowing about the change in flow through the injectors. Thereby, in a scenario where a higher flow injector and a lower flow injector are subjected to the same fuel supply and injector pulse width, the higher flow injector will flow more fuel. Without tuning, adding higher flow injectors will cause an excessively rich condition.

Besides all that above, the only reason to upgrade a fuel system would be because of nitrous or forced induction. Higher flow injectors would require shorter injector pulse width in a naturally aspirated stock Prelude. Shorter pulse width means less injector precision at low RPMs and unused capability at higher RPMs (unless you use forced induction or nitrous). Additionally, the fuel pressure regulator and fuel pump are unnecessary in a stock prelude.
See less See more
so the mods I got on it rn are as follow
Apexi exhaust system
70mm skunk 2 intake manifold and throttle body
Short ram intake
Now I installed only the rail and the regulator so now I just need some headers but I can’t find anywhere to get them. Once I get them I’m going to finally be able to tune
1 - 3 of 3 Posts