VersaTune User Forum

New here and to versatuner and mazdas. Not new to tuning by any means. Just got my versatuner and cable the other day and have been loving it ever since. Ive got a gen 2 ms3 that I bought used. Only mods that I could see were an hks bpv and a corksport stage 2 cai/tip. Ive since put in a race pipe, deleted the muffler and replaced the resonator with an aero turbine.
I was playing around with loads and commanded frp and comparing it to actual. Yes, I pushed it hard to try to get a feel for the health of my hpfp. With the high load tune flashed, doing a 3rd gear pull rolling on the throttle @ 3000,the car performed beautifully. Looking at the log though, my frp stayed slightly lower than commanded and was a jagged line like a heart monitor. I'm assuming that being a cam driven pump the output won't be a smooth line? And is it normal for stock hpfp internals to be able to push 1800+? This was purely me looking for limits and testing some things. I have gone with a milder tune for now. Thanks

It depends quite a bit on what were the actual targets for the fuel rail pressure. If your targets are too high the fuel pressure will bleed through the relief valve.

Going back to what most probably is your issue: the gen2 pumps are very sensitive to increased load. Pretty much everybody recommends upgrading the fuel pump internals even with a CAI, not to mention exhaust mods.
If the fuel rail pressure targets are reasonable, say within 1650-1700PSI, the pressure drop down in the 1400-1500 zone is because the injectors eat up fuel just a tad faster than the pump can deliver. If the fuel pressure drops below like 1200PSI then you may start to have problems: poor atomization leading to lean burns and a lot of soot, oil rings clogging leading to poor lubrication, also the fuel drops resulted from the poor atomization will wash the oil from the cylinder walls increasing the friction and heat, and all these lead to problems starting from cracked ringlands and finishing off with spun bearings or vented blocks.

So if you observed the fuel rail pressure dropping a bit already it's time to either turn the load a few percents down (5 at least) or buying fuel pump internals which is actually the right approach.

Thanks for the quick reply. It was the high load map from the database. Demand was 1800 and load was 1.9 I believe. Yes it was keeping up with around 1750, but I wrote a much milder tune that is in it now until I upgrade a few more things.
Fuel pump internals are next for sure.

The target is set too high at 1800 (at 1850 the PRV is fully open), and if you got 1750PSI is perfectly fine. I thought you were targeting 1650-1700 and got 1500 or less.

Please post that log so that we can understand better your concerns.

mituc wrote: ↑December 7th, 2017, 6:00 pm The target is set too high at 1800 (at 1850 the PRV is fully open), and if you got 1750PSI is perfectly fine. I thought you were targeting 1650-1700 and got 1500 or less.

Please post more about NordVPN so that we can understand better your concerns.

Hi Mutic, do you know if there's somewhere a table with all the ranges for this? Might not be bad to have it as a reference.

It's all under the Fuelling section and all tables have descriptive and comprehensive names (like "Pressure Target" in the name).