E-Manage + 3S + unknown issue = WTF!?

[David15151]

Basically me and my friend are e-manage newbs.

Running a 3000GT VR4.
Fuel mods = 450cc injectors (stock is 360cc), Denso 320 LPH fuel pump.
Full exhuast, Full intake, Stage 3 Heads
Plus other drivetrain upgrades.

We have emange with all optional harnesses hooked up (I think)

So, we have 3 maps

Airflow Correction, Additional Injection, and Timing Adjustment

Setting all maps to 0 correction .. we can pull 3rd gear all the way to redline with no problem. Knock = 0, o2 voltage = 0.89, (using logger). Trying to pull in 1st or 2nd gear the car stutters BAD at around 2750-3500 and we stop the run... again Knock = 0 , o2 Volts = 0.89

We tried messing with the settings and we still get the stutter even when running richer at like .092 o2 volts

We are using the Airflow correction to tune.. tried injection but didnt seem to help.

So we think it may have something to do with timing?

Timing at idle is at 26 degrees stated by the logger. In a pull it goes to 40 degees at the start and lowers to about 26-24 degrees when we start stuttering and backfiring bad.

We have no idea what dto do or what the problem is. We tried running richer tried leaner tried a lot of different set ups.. still the same problem over and over. Anyone have an idea?

 

[suicidal2af]

Overrunning the mas, maybe?

That's the only possibility I can think of :/

 

[David15151]

Would that be consistant with being able to do a 3rd gear pull .. and stutter with a 2nd gear pull?

 

[antero]

You should go on 3si.org for better Stealth/3000 GT help.

If you're still running the factory fuel pump relay switch that goes from low voltage to high voltage -- then that may be your problem. The ECU provides full voltage to the fuel pump when boost is approximately 0psi. The ECU reads airflow on when to activate the crossover. With the larger injectors, you've now delayed this operation with the smaller airflow signal being reported.

There's a couple ways to fix this problem. You could use a pressure switch to activate the full voltage to the fuel pump. Or you could remove the relay and run full voltage to your fuel pump (don't confuse this relay with the MFI relay) at all loads. This latter mod may cause you to run rich at idle. And in the case, you'll need an adjustable FPR.

 

[David15151]

thought i would add also that the problem is worse when the car is cold

 

[TurboJunky]

my car was doing this when I was running too much boost and simply overrunning the MAS. try dialing back a little boost and see if your problems start to fade. I was running 17psi on the stock sidemount (or should I say, the PO was running that, I hadn't adjusted it yet) but I dialed it back to 14.5 and voila, my hesitation/fuel cut/etc. issues disappeared.

 

[antero]

0.92 volts isn't necessarily rich on the 3S platform. It's more like 0.98V and above. Tune for 0.96 volts minimum. Generally anything below 0.96 volts is lean on my car ( confirmed with a PLX wideband). Chances are, you're not getting enough fuel delivered with the head reworked.

 

[David15151]

ok we figured out the problem... it was so dumb

one of the spark plug wire boots was on the coil pack but the actual pin wasnt in the hole... .

we put it in and now it runs perfect at 10 psi

we will tune it on 15 psi today for 0.96