Quote:
Originally Posted by Madact
Thanks Nigel_S, ever_green.
Unfortunately I don't have a lot of tuning options available to me - the ECUs supplied with Australian 6th gen Civics are either too primitive to update maps on, or just too small a market for tuning companies to make chips / add-on modules for. Whichever it is, as far as I can find out from internet forums and tuning kit manufacturer websites, the stock ECU is a black box as far as that's concerned. Now, one thing which I do have planned is a head swap using a D15Z7 head and ECU - same applies, it's an OBD2a ECU with no flashable memory, and I want to keep the stock ECU to correctly handle the 3-stage VTEC.
What I was planning there, given an ECU from a 1.5L engine on a 1.6L, was to carefully compare injector flow specs, and use an aftermarket adjustable fuel pressure regulator to increase the pressure 5-10% to keep the ECU within its parameters (especially in open loop mode) and keep the engine happy. On a side note, I went and spent money on parts before checking that theory  - am I on the right track there?
Do you think the same would work (i.e. with no ECU tuning per se) in terms of tuning open-loop fuel flow for a non-stock header (assuming the ECU can handle closed-loop conditions correctly in my case)? I presume doing this properly would require use of a dyno and appropriate exhaust gas measurement? It works in my head, just not sure how it will go in practice  |
A 5% increase in fuel pressure gives a very small increase in flow, not a 5% increase - look up the theory or an online calculator. If you need more than a few % extra fuel then consider swapping the injectors for higher flow ones. Adjusting fuel pressure is good for fine tuning if you can't change the map.
The ECU will have limits on its closed loop self tuning. If it is not using much self tuning from base to start with then your manifold will probably still have it within its limits but if there is something else it is having to adjust for then it could go beyond them. Some extra fuel pressure or higher flow injectors will bring it back towards the centre of its range allowing it to keep things perfect in closed loop.
To adjust it properly will require a session on a dyno but you can get close just by timing the acceleration from 1000rpm to 6000rpm in 3rd gear and adjusting the fuel pressure until you get the best time, then back it off a little since best economy comes with less fuel than best power and keep a watch on the tail pipe - if it collects carbon then it's got too much fuel pressure. If you are spending most time in closed loop rather than on a race track then that's probably close enough and you can't get exact anyway since the manifold will have different amounts of effect at different revs and to get that perfect needs a map change.