Very Low Numbers on My Fuel VE Table

Hello everyone,

Background:

ECU: Mega squirt 2 PNP, (The ECU was manually set up for sequential injection)

Car: Nissan S13 240sx

Motor: SR20det, agressive cam, solid lifter, ID1050cc injectors, Garret GT30/76

Beginner tuner...I know its not the best set up to learn on but my tuner gave up on this car so I thought I would try.

I was wondering what would cause very low VE numbers on a fuel table. The car runs very rich on start up (8-9 AFR). I decreased the fuel table in tuner studio after the car warmed up and I had to have it around 3-6 in the fuel table for it to achieve an AFR of 13.7-14.0. All sensors are calibrated. Fuel pressure says 44 psi with no vacuum. According to injector dynamics thats 1071CC and a dead time of ~1 ms. I put new plugs in. I am just trying to get the car to idle correctly.

I feel like it could a fuel system issue. I am running two fuel pumps, one in the stock tank and another in a surge tank. The fuel pump in the stock tank is wired to run in a normal stock application. The fuel pump in the surge tank runs on a switch and never stops. The fuel is first pumped from the stock tank to the surge tank. Then the fuel leaves the surge tank to the fuel rail. The fuel line splits into two separate fuel lines and enters the fuel rail on both sides of the rail and exits in the middle of the fuel rail into the FPR. Then returns to the surge tank and then returns to the gas tank. I am using an 8 line for everything but I am using the stock return line. Sorry for the long question but could the fuel system pluming cause a false fuel pressure reading at the FPR? Then the elevated fuel pressure would cause the injectors to flow to much? Or should I dial back the required fuel calculation in tuner studio. Any suggestion is fine with me. I am running out of Ideas.

I attached the tune if anyone wants to look at my settings. The fuel VE table is sloppy but I gave up after the low VE numbers.

Thanks for the help,

Maxx

Maxx,

First, I don't think your engine / ECU has Direct Injection (that is the term for injectors that inject directly into the combustion chamber, and use very high pressure fuel pumps - like 2500 psi). What you have is Sequential Port Injection, based on your tune file.

I think your issue is primarily the Injector Dead Time settings. Any error here will get "baked into" your Fuel VE Table settings, so having a small value around idle, means that likely the dead-time is too large (I suggest you try 0.93ms, better too small than too large), and particularly I think the Battery Voltage Correction is too big (normally this is about .1 - .12 ms/V). Changing that will require re-tuning your Fuel VE table.

Another factor that will affect your Fuel VE table values is the "Required Fuel" that is calculated on Basic/Load Settings->Engine and Sequential Settings.

Be sure to only tune the fuel table when the engine is up to temp (162degF or higher according to your Warmup Enrichment WUE).

I think your WUE is way too high. I would expect to see 125-130% at 20deg Coolant, tapering to 110% or less at 100 degF, and then linearly down to 100% at say 150 degF. The engine should warm up just fine with a Lambda of 0.9 (13.1 AFR) -- After the warm idle is set, then tune the WUE to hit that target while warming up, tapering to your target AFR at idle.

Also I think the After Start Enrichment can be much leaner, say 20-30% max, and then only when very cold. So I would probably cut the current values in half and see if that affects starting quality.

Wow thanks David for the advice! Yep you are right on the direct injection. I meant to say sequential injection (ooops haha). I will give these things a try in the next few days when I get some time and I'll let you know how it goes. I really appreciate the help.

Thanks Dave for all of those tips. It helped a lot. I was able to achieve a some what steady lambda of .9 to .92 at idle. My idle is at 1,300 rpm due to the cams. It has a small loop. I'll work on the WUE next. Thanks again.