Stg3 EPROM, 3gMAS, 780cc = less power?!

[eclipsh]

After installing all of that and getting my Cyclone intake finally working, my boost levels just aren't going up the way they used to and I'm getting knock at lower boost levels than I used to.

I was boosting 14-6 psi before now I'm lucky if I can squeak past 13 psi.

Any idea what happened? Unfortunately I don't have a wideband to check my a/f ratio and haven't got a S-AFC either so I'm fairly limited on tuning ability.

 

[GVR4592]

Datalog? Did you do a boost leak test and check your base timing?

 

[eclipsh]

Base timing hasn't changed (unless the chip did something very weird) and the car ran great before.

Here's an old log from before the recent mods. The airflow numbers are double what they really were (sorry, progam was set to double Hz).

Time, RPM, Knock, Timing, Airflow, Air Temp, TPS, Fuel Trim High, Fuel Trim Mid, Fuel Trim Low
00:00.20, 3500.0, 13.0, 14.0, 2294.0, 35.0, 61.0, 101.0, 98.0, 101.0
00:00.42, 3906.0, 16.0, 12.0, 3164.0, 35.0, 58.0, 101.0, 98.0, 101.0
00:00.65, 4531.0, 16.0, 13.0, 3214.0, 35.0, 50.0, 101.0, 98.0, 101.0
00:00.84, 5094.0, 16.0, 15.0, 3214.0, 35.0, 49.0, 101.0, 98.0, 101.0
00:01.00, 5531.0, 15.0, 18.0, 3214.0, 35.0, 40.0, 101.0, 98.0, 101.0
00:01.25, 5844.0, 15.0, 29.0, 1412.0, 35.0, 24.0, 101.0, 98.0, 101.0
00:01.47, 5875.0, 3.0, 44.0, 416.0, 36.0, 10.0, 101.0, 98.0, 101.0
00:01.68, 5469.0, 0.0, 45.0, 277.0, 35.0, 10.0, 101.0, 98.0, 101.0
00:01.89, 5031.0, 0.0, 45.0, 214.0, 35.0, 10.0, 101.0, 98.0, 101.0
00:02.11, 4625.0, 0.0, 44.0, 252.0, 35.0, 32.0, 101.0, 98.0, 101.0
00:02.32, 3594.0, 0.0, 28.0, 1298.0, 35.0, 55.0, 101.0, 98.0, 101.0
00:02.53, 3469.0, 0.0, 25.0, 1588.0, 35.0, 65.0, 101.0, 98.0, 101.0
00:02.75, 3625.0, 0.0, 22.0, 1991.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:02.98, 3781.0, 0.0, 19.0, 2634.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:03.21, 3969.0, 0.0, 18.0, 3101.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:03.40, 4219.0, 1.0, 19.0, 3038.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:03.65, 4438.0, 0.0, 19.0, 3214.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:03.86, 4750.0, 0.0, 20.0, 3038.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:04.09, 4938.0, 0.0, 22.0, 2912.0, 35.0, 67.0, 101.0, 98.0, 101.0
00:04.28, 5188.0, 0.0, 23.0, 2861.0, 35.0, 66.0, 101.0, 98.0, 101.0
00:04.51, 5344.0, 0.0, 28.0, 2571.0, 35.0, 66.0, 101.0, 98.0, 101.0
00:04.71, 5563.0, 0.0, 27.0, 3113.0, 34.0, 66.0, 101.0, 98.0, 101.0
00:04.90, 5750.0, 0.0, 27.0, 2634.0, 34.0, 65.0, 101.0, 98.0, 101.0
00:05.11, 5875.0, 0.0, 33.0, 2445.0, 34.0, 65.0, 101.0, 98.0, 101.0
00:05.34, 5969.0, 0.0, 31.0, 1323.0, 34.0, 10.0, 101.0, 98.0, 101.0
00:05.55, 5875.0, 0.0, 45.0, 265.0, 34.0, 10.0, 101.0, 98.0, 101.0
00:05.77, 5375.0, 0.0, 45.0, 277.0, 34.0, 10.0, 101.0, 98.0, 101.0
00:05.98, 4969.0, 0.0, 45.0, 176.0, 34.0, 34.0, 101.0, 98.0, 101.0
00:06.21, 3938.0, 0.0, 28.0, 1613.0, 34.0, 67.0, 101.0, 98.0, 101.0
00:06.42, 4094.0, 1.0, 21.0, 2256.0, 34.0, 70.0, 101.0, 98.0, 101.0
00:06.67, 4125.0, 1.0, 16.0, 3138.0, 34.0, 67.0, 101.0, 98.0, 101.0
00:06.90, 4250.0, 0.0, 18.0, 3214.0, 34.0, 48.0, 101.0, 98.0, 101.0
00:07.13, 4281.0, 0.0, 20.0, 2508.0, 34.0, 36.0, 101.0, 98.0, 101.0
00:07.34, 4344.0, 0.0, 33.0, 744.0, 34.0, 10.0, 101.0, 98.0, 101.0
00:07.53, 4281.0, 0.0, 42.0, 277.0, 34.0, 10.0, 101.0, 98.0, 101.0

 

[eclipsh]

Here's a new log with the mods. Not a great log though. I was getting some really ugly knock late that I'd had well under control before (I got knock spikes at very low rpms before, I don't know why).


Time, RPM, Knock, Timing, Airflow
00:00.13, 3219.0, 1.0, 31.0, 328.0
00:00.27, 3188.0, 1.0, 28.0, 302.0
00:00.41, 2313.0, 0.0, 25.0, 227.0
00:00.54, 1625.0, 0.0, 21.0, 164.0
00:00.68, 1156.0, 0.0, 14.0, 126.0
00:00.82, 1000.0, 0.0, 19.0, 151.0
00:00.96, 1344.0, 0.0, 23.0, 151.0
00:01.05, 1313.0, 0.0, 23.0, 164.0
00:01.21, 1406.0, 0.0, 24.0, 189.0
00:01.34, 1594.0, 0.0, 23.0, 214.0
00:01.48, 1656.0, 0.0, 19.0, 239.0
00:01.61, 1813.0, 0.0, 22.0, 252.0
00:01.77, 1969.0, 0.0, 24.0, 252.0
00:01.89, 2094.0, 0.0, 25.0, 265.0
00:02.02, 2250.0, 0.0, 26.0, 290.0
00:02.17, 2344.0, 0.0, 28.0, 315.0
00:02.28, 2531.0, 0.0, 28.0, 328.0
00:02.42, 2656.0, 0.0, 28.0, 353.0
00:02.54, 2781.0, 1.0, 28.0, 391.0
00:02.68, 2969.0, 1.0, 28.0, 429.0
00:02.81, 3156.0, 0.0, 27.0, 466.0
00:02.95, 3250.0, 0.0, 26.0, 529.0
00:03.07, 3438.0, 0.0, 26.0, 643.0
00:03.23, 3813.0, 0.0, 24.0, 756.0
00:03.36, 3969.0, 0.0, 21.0, 933.0
00:03.51, 4344.0, 0.0, 18.0, 1122.0
00:03.65, 4781.0, 0.0, 17.0, 1260.0
00:03.79, 5281.0, 0.0, 17.0, 1399.0
00:03.96, 5781.0, 0.0, 19.0, 1462.0
00:04.11, 6094.0, 0.0, 19.0, 1538.0
00:04.26, 6438.0, 1.0, 20.0, 1550.0
00:04.42, 6656.0, 1.0, 21.0, 1525.0
00:04.53, 6656.0, 0.0, 45.0, 139.0
00:04.67, 6375.0, 0.0, 45.0, 113.0
00:04.82, 6063.0, 0.0, 45.0, 101.0
00:04.94, 5781.0, 0.0, 45.0, 88.0
00:05.07, 5438.0, 0.0, 45.0, 265.0
00:05.21, 5156.0, 0.0, 45.0, 189.0
00:05.34, 4938.0, 0.0, 45.0, 126.0
00:05.48, 4688.0, 0.0, 43.0, 189.0
00:05.61, 4531.0, 0.0, 42.0, 366.0
00:05.77, 4281.0, 0.0, 29.0, 492.0
00:05.90, 3750.0, 0.0, 28.0, 492.0
00:06.00, 3750.0, 0.0, 27.0, 542.0
00:06.13, 3656.0, 0.0, 26.0, 618.0
00:06.28, 3844.0, 0.0, 25.0, 681.0
00:06.40, 3844.0, 0.0, 23.0, 769.0
00:06.53, 3906.0, 4.0, 18.0, 882.0
00:06.67, 4063.0, 4.0, 16.0, 971.0
00:06.82, 4125.0, 4.0, 15.0, 1021.0
00:06.97, 4281.0, 3.0, 17.0, 1021.0
00:07.09, 4375.0, 3.0, 17.0, 1046.0
00:07.23, 4500.0, 3.0, 17.0, 1084.0
00:07.38, 4625.0, 3.0, 17.0, 1097.0
00:07.52, 4813.0, 2.0, 16.0, 1160.0
00:07.69, 4844.0, 8.0, 15.0, 1197.0
00:07.80, 5000.0, 8.0, 15.0, 1235.0
00:07.96, 5125.0, 8.0, 15.0, 1260.0
00:08.10, 5313.0, 7.0, 15.0, 1311.0
00:08.25, 5375.0, 7.0, 15.0, 1336.0
00:08.39, 5531.0, 7.0, 15.0, 1361.0
00:08.53, 5656.0, 7.0, 15.0, 1386.0
00:08.69, 5750.0, 6.0, 17.0, 1412.0
00:08.84, 5875.0, 6.0, 17.0, 1437.0
00:08.97, 5938.0, 6.0, 17.0, 1462.0
00:09.13, 6063.0, 6.0, 30.0, 315.0
00:09.27, 5938.0, 0.0, 45.0, 101.0
00:09.40, 5969.0, 0.0, 45.0, 101.0
00:09.52, 5656.0, 0.0, 45.0, 126.0
00:09.67, 5406.0, 0.0, 34.0, 668.0
00:09.81, 5125.0, 0.0, 27.0, 731.0
00:09.94, 4188.0, 0.0, 25.0, 756.0
00:10.09, 4219.0, 0.0, 23.0, 832.0
00:10.22, 4188.0, 3.0, 19.0, 920.0
00:10.34, 4188.0, 2.0, 18.0, 945.0
00:10.47, 4250.0, 9.0, 16.0, 945.0
00:10.57, 4250.0, 9.0, 17.0, 971.0
00:10.72, 4281.0, 9.0, 17.0, 971.0
00:10.85, 4313.0, 9.0, 17.0, 983.0
00:10.98, 4469.0, 8.0, 17.0, 996.0
00:11.10, 4469.0, 8.0, 17.0, 983.0
00:11.23, 4563.0, 8.0, 17.0, 996.0
00:11.38, 4500.0, 8.0, 17.0, 1021.0
00:11.52, 4594.0, 7.0, 17.0, 1034.0
00:11.65, 4625.0, 7.0, 17.0, 1046.0
00:11.77, 4625.0, 12.0, 15.0, 1059.0
00:11.93, 4594.0, 12.0, 16.0, 1084.0
00:12.06, 4750.0, 12.0, 15.0, 1122.0
00:12.22, 4813.0, 11.0, 15.0, 1134.0
00:12.35, 4844.0, 11.0, 15.0, 1134.0
00:12.47, 4906.0, 11.0, 15.0, 1172.0
00:12.57, 4906.0, 11.0, 15.0, 1172.0
00:12.72, 4969.0, 10.0, 15.0, 1147.0
00:12.86, 5000.0, 10.0, 17.0, 1134.0
00:12.97, 5000.0, 10.0, 17.0, 1122.0
00:13.11, 5094.0, 10.0, 17.0, 1134.0
00:13.27, 5125.0, 10.0, 18.0, 1134.0
00:13.39, 5156.0, 9.0, 25.0, 529.0
00:13.53, 5125.0, 7.0, 44.0, 113.0
00:13.69, 5188.0, 0.0, 45.0, 113.0
00:13.81, 5000.0, 0.0, 45.0, 139.0
00:13.94, 4750.0, 0.0, 44.0, 126.0
00:14.09, 4625.0, 0.0, 43.0, 227.0
00:14.22, 4281.0, 0.0, 32.0, 441.0
00:14.36, 3844.0, 0.0, 29.0, 492.0

 

[eclipsh]

So I'm now boosting around 15 psi but getting outrageous knock, to the tune of 10 counts at 10 psi.

 

[jott5555]

why are people useing 3g mas's lately?

 

[eclipsh]

More flow than 2gMAS's and still a round exit like a 1gMAS for attaching intakes.

 

[jott5555]

do you have any cfm proof for the 3g unit outflowing the 2g unit..

 

[GVR4592]

If you modify the airhorn or use the Evo 8 airhorn then you can get roughly 30%-40% more flow than a 2g mas.

 

[eclipsh]

It turns out my problem was likely a miss-matched set of injectors. I bought a full set of FIC 780's and will install those when they arrive. I should have another update in a week or so.

 

[a73_4g67]

If you modify the airhorn or use the Evo 8 airhorn then you can get roughly 30%-40% more flow than a 2g mas.

Yes, thats true. I've already seen the data. The source is very reliable.
The good thing is its range, its good for 60+lbs/min. You wont overrun it until 600+HP.