20G injector sizing, fuel cut and fuel pressure question?

[Turbo442]

90 AWD 5spd, 20G w/35mm Tial, stock 2G mas, SAFC, 3" downpipe & TP, 2.5" catback, 8.5:1 pistons, 550's, FMIC with 2.5", 3000 VR4 pump re-wired, Stock 90 turbo ECU. Currently burning 100 octane for safety. 18 psi boost.

no boost leaks (car will hold 20 psi for 30 sec), timing stock 5 deg, fuel pressure 40 psi, fuel pressure gauge in cockpit to monitor fuel pressure, also installed new fuel filter.

Outside air temp in foggy Oregon tonight is around 35 deg.

SAFC is reporting 2000 + hz over 6000 rpm and then fuel cutting with + 8 across hi settings.

EGT is quickly sweeping from 1400 to 1550+ if I dont let off.

I am assuming I am way lean and that I need much bigger injectors if I want to run 18 to 20 psi safely? I beleive I saw around 60 psi fuel pressure when I glanced at the fuel pressure gauge quickly while at WOT.

Should I consider 780cc injectors and a modified ECU code to compensate for the 2G mas and larger injectors? Or have I surpassed the limits of the unhacked 2G mas and need to move on to another air metering device? This would of course still require the larger injectors and higher flowing air meter.

 

[BigBADGSX]

Bigger injectors would be the key, i really dont think the 2g mas is gonna be to pissy right now. Especialy with it being colder out, your tune will have to change somewhat. Try bigger injectors and see what happens.

goodluck

 

[Tort9320g]

It sounds like you're way rich. I'm running 103 unleaded on 550s with the 20g, 36psi fuel pressure, 24-26psi boost, EGTs around 900c and no problems on a stock 7 bolt. Are you on stock cams? If so, you've got plenty of injector, especially for 18psi on 100 octane. Try lowering your fuel pressure a bit.

 

[turbolarry]

I've read on these boards that an unhacked 2g MAS is good for 400hp.
Bigger injectors will address the fuel cut and lower those EGT's. 680's are as big as you can go on an AFC. 780's will require something else.
Turbo442 do you have a logger?

 

[Turbo442]

First a quick question. Should I not be concerned with the frequency output of the MAS as long as its reporting a linear increase to the datalogger all the way to WOT? The ECU will not use air flow values over a 1600 hz correct or incorrect?

Tort9320g, I am running stock cams. Everything I read says go to bigger injectors especially with a 2g mas. It makes me feel better that your 1G doesnt need crazy fuel pressure to run on 550's and race gas. My EGT's seem to drop when I lean with the AFC which probably means fuel is burning in the exhaust manifold and I am indeed too rich. My O2 volts are anywhere from .82 to .78 which seems crazy low, even with a 15000 mile o2 sensor. I do have a 90 1G which seems to report lower values than 91-94 1g's.
I will ignore the stock O2 sensor for WOT tuning.
I will drop my fuel pressure to 36 psi at idle.
I will zero out the AFC and see where I am at.
I will monitor my EGT's and see if they drop

If I were to take a datalog what values would be useful.
rpm, mas airflow, dutycycle, knock?

 

[Turbo442]

Here are the results of my lunch time changes.

18 psi boost
Dropped the fuel pressure to 37 psi (factory)
SAFC is now +2 Lo across the board
SAFC is now +1 Hi across the board

Car pulls much harder through the RPM range and EGT's are not climbing past 1400 any longer. It amazes me how much of a change 2-3 psi of fuel pressure makes. Just set the car to its factory settings and everything will be fine...

So basically I thought I was to lean but actually I was way rich.

 

[Turbo442]

Tort9320g you were correct, I was rich. Now that i corrected my fuel pressure and SAFC settings the car is running awesome! I was just getting confused and thinking it was too lean which made my problem even worse! Now my EGT's are staying down and my exhaust manifold is not getting overly hot at all. This was all at 18 psi. That being said I turned up the boost to 23 psi. Now I think the rest of you are correct, I am running out of fuel. Check out the log.

Here are some logs tonight after the changes. This is at 23 psi just to see how it would react with the 550's.

Outside air temp 40 deg
Humidity: 97%
Pressure: 30.45 inches and steady
108 leaded race gas
23 psi boost
37 psi base fuel pressure
5 deg base timing

TIME TIMA MAFS RPM KNCK INJP INJD GEAR
1:56:16 24° 207.6Hz 1688 0 5.12ms 9 1
1:56:16 24° 226.4Hz 1875 0 5.38ms 10 1
1:56:16 27° 270.5Hz 2125 0 5.12ms 11 1
1:56:16 28° 283.1Hz 2250 0 5.38ms 12 1
1:56:16 28° 314.5Hz 2469 0 5.63ms 14 1
1:56:16 29° 352.2Hz 2688 0 5.89ms 16 1
1:56:16 30° 390.0Hz 2906 0 5.89ms 18 1
1:56:16 31° 427.7Hz 3156 0 5.89ms 19 1
1:56:17 31° 484.3Hz 3375 0 6.40ms 23 1
1:56:17 29° 534.7Hz 3719 0 7.68ms 30 1
1:56:17 28° 629.0Hz 3938 0 8.70ms 36 1
1:56:17 27° 761.1Hz 4281 0 10.24ms 46 1
1:56:17 27° 924.6Hz 4563 0 12.29ms 59 1
1:56:17 23° 1125.9Hz 5094 224 64.51ms 47 1
1:56:18 45° 886.9Hz 6750 0 2.05ms 14 1
1:56:18 45° 138.4Hz 6469 0 1.54ms 10 2
1:56:18 45° 207.6Hz 6000 0 2.05ms 13 2
1:56:18 45° 239.0Hz 5750 0 2.05ms 12 2
1:56:18 45° 226.4Hz 5594 0 1.79ms 10 2
1:56:19 45° 188.7Hz 5094 0 4.35ms 23 2
1:56:19 33° 616.4Hz 3750 0 8.45ms 33 2
1:56:19 27° 761.1Hz 4219 0 9.98ms 45 2
1:56:19 25° 842.9Hz 4281 0 12.03ms 55 2
1:56:19 23° 1031.6Hz 4250 0 14.59ms 66 2
1:56:19 20° 1302.0Hz 4469 0 17.41ms 83 2
1:56:19 19° 1604.0Hz 4875 0 20.22ms 105 2
1:56:20 18° 1604.0Hz 5031 0 21.25ms 114 2
1:56:20 19° 1604.0Hz 5250 1 20.99ms 117 2
1:56:20 20° 1604.0Hz 5344 1 20.74ms 118 2
1:56:20 21° 1604.0Hz 5781 0 19.71ms 121 2
1:56:20 22° 1604.0Hz 6000 10 18.94ms 121 2
1:56:20 17° 1604.0Hz 6125 10 18.94ms 123 2
1:56:20 18° 1604.0Hz 6188 10 17.66ms 116 2
1:56:20 17° 1604.0Hz 6375 10 17.41ms 118 2
1:56:20 16° 1604.0Hz 6531 9 16.64ms 116 2
1:56:21 14° 1604.0Hz 6875 9 16.13ms 118 2
1:56:21 0° 1604.0Hz 6875 9 16.38ms 120 2
1:56:21 0° 1604.0Hz 7094 9 15.62ms 118 2
1:56:21 0° 1604.0Hz 7094 8 5.89ms 44 2
1:56:21 0° 603.8Hz 6781 4 1.28ms 9 2
1:56:21 0° 151.0Hz 6500 0 1.79ms 12 2
1:56:21 0° 188.7Hz 6219 0 2.05ms 13 2
1:56:21 0° 245.3Hz 5781 0 1.79ms 11 2
1:56:22 0° 226.4Hz 5625 0 2.05ms 12 2
1:56:22 0° 207.6Hz 5438 0 1.54ms 8 2
1:56:22 0° 207.6Hz 5281 0 8.19ms 46 2
1:56:22 0° 767.4Hz 4531 0 10.50ms 50 3
1:56:22 0° 943.5Hz 4750 0 12.03ms 61 3
1:56:22 0° 1113.3Hz 4813 0 14.08ms 72 3
1:56:22 0° 1276.9Hz 4781 0 16.64ms 85 3
1:56:22 0° 1497.0Hz 4844 0 18.69ms 96 3
1:56:22 0° 1604.0Hz 5000 0 20.22ms 108 3
1:56:23 0° 1604.0Hz 5094 0 20.99ms 114 3
1:56:23 0° 1604.0Hz 5281 0 20.99ms 118 3
1:56:23 0° 1604.0Hz 5188 0 20.99ms 116 3
1:56:23 0° 1604.0Hz 5438 3 20.74ms 120 3
1:56:23 0° 1604.0Hz 5469 2 20.48ms 119 3
1:56:23 0° 1604.0Hz 5375 2 20.48ms 117 3
1:56:23 0° 1604.0Hz 5469 2 20.48ms 119 3
1:56:23 0° 1604.0Hz 5531 2 20.22ms 119 3
1:56:23 0° 1604.0Hz 5813 9 19.46ms 120 3
1:56:23 0° 1604.0Hz 5688 9 19.46ms 118 3
1:56:23 0° 1604.0Hz 5875 9 18.94ms 118 3
1:56:24 0° 1604.0Hz 5906 8 18.94ms 119 3
1:56:24 0° 1604.0Hz 5969 8 18.69ms 119 3
1:56:24 0° 1604.0Hz 6000 8 19.20ms 123 3
1:56:24 0° 1604.0Hz 6188 8 18.18ms 120 3
1:56:24 0° 1604.0Hz 6250 8 18.69ms 124 3
1:56:24 0° 1604.0Hz 6281 8 17.66ms 118 3
1:56:24 0° 1604.0Hz 6219 8 17.92ms 119 3
1:56:24 0° 1604.0Hz 6406 7 17.41ms 119 3
1:56:24 0° 1604.0Hz 6375 7 17.15ms 116 3
1:56:24 0° 1604.0Hz 6406 7 16.90ms 115 3
1:56:24 0° 1604.0Hz 6406 7 17.15ms 117 3
1:56:25 0° 1604.0Hz 6500 7 17.41ms 120 3
1:56:25 0° 1604.0Hz 6625 7 17.15ms 121 3
1:56:25 0° 1604.0Hz 6625 7 16.38ms 115 3
1:56:25 0° 1604.0Hz 6906 6 16.38ms 120 3
1:56:25 0° 1604.0Hz 6906 6 16.38ms 120 3
1:56:25 0° 1604.0Hz 6781 6 13.82ms 100 3
1:56:25 0° 1352.4Hz 6594 6 1.28ms 9 3
1:56:25 0° 220.2Hz 6469 0 1.28ms 8 3
1:56:25 0° 31.5Hz 6188 0 1.54ms 10 3
1:56:25 0° 239.0Hz 5938 0 2.30ms 14 3
1:56:26 0° 245.3Hz 5781 0 2.05ms 12 3
1:56:26 0° 220.2Hz 5188 0 1.28ms 7 3
1:56:26 0° 176.1Hz 4781 0 1.54ms 7 3