Mods are in profile, but important ones are 550cc Injectors, 2g MAF, 255lph and Big 16g.

I purchased this car a few months ago, felt it ran really strong. I haven't touched anything with it, just got a logger for x-mas. Gets 23mpg city / 30+ hwy.

Here's a log at 20psi:

RPM Timing Knock TPS 02V Airflow INJD
2500 23° 0 87.8% 0.84V 440.3Hz
2594 23° 0 92.5% 0.84V 471.8Hz
2688 21° 0 93.7% 0.82V 509.5Hz
2719 20° 0 94.1% 0.84V 559.8Hz
2813 18° 0 93.7% 0.84V 616.4Hz
2906 15° 0 92.9% 0.86V 704.5Hz
3000 15° 0 90.6% 0.86V 798.8Hz
3125 14° 3 87.1% 0.86V 905.8Hz
3250 13° 7 85.5% 0.86V 981.2Hz
3375 13° 6 81.6% 0.84V 993.8Hz
3500 13° 6 80.0% 0.84V 1031.6Hz
3656 13° 5 80.0% 0.84V 1075.6Hz
3750 14° 5 80.4% 0.84V 1119.6Hz
3844 15° 5 80.4% 0.84V 1157.4Hz
4000 16° 11 80.8% 0.84V 1232.8Hz
4125 14° 11 80.8% 0.84V 1276.9Hz
4250 14° 11 80.8% 0.84V 1320.9Hz
4375 14° 10 81.2% 0.84V 1377.5Hz
4469 13° 13 86.7% 0.84V 1465.6Hz
4594 13° 13 87.1% 0.84V 1484.4Hz 78.10%
4688 13° 12 90.2% 0.84V 1528.5Hz
4750 14° 12 96.1% 0.84V 1559.9Hz
4875 15° 12 97.3% 0.84V 1572.5Hz
4938 15° 12 97.3% 0.84V 1604.0Hz
5000 15° 11 96.5% 0.84V 1604.0Hz
5094 15° 11 94.5% 0.84V 1604.0Hz 87.50%
5188 16° 11 92.5% 0.84V 1604.0Hz
5313 16° 10 91.8% 0.84V 1604.0Hz
5438 17° 10 90.6% 0.84V 1604.0Hz
5531 17° 10 90.2% 0.84V 1604.0Hz
5656 18° 14 89.8% 0.82V 1604.0Hz
5688 17° 13 90.2% 0.82V 1604.0Hz
5719 18° 13 90.2% 0.82V 1604.0Hz
5781 18° 13 90.2% 0.82V 1604.0Hz 100.00%
5813 18° 13 89.8% 0.82V 1604.0Hz
5938 20° 12 89.8% 0.82V 1604.0Hz 103.00%
5969 20° 12 89.8% 0.82V 1604.0Hz 101.00%
5906 20° 8 11.0% 0.88V 748.5Hz
5813 44° 0 10.2% 0.78V 188.7Hz

Here's a log with the boost lowered to 17-18psi:

RPM Timing Knock 02V TPS Airflow INJD
3063 25° 0 0.82V 63.9% 559.8Hz
3156 23° 0 0.86V 60.0% 673.0Hz
3250 19° 0 0.86V 57.3% 811.4Hz
3375 15° 0 0.86V 57.3% 912.1Hz
3500 15° 0 0.86V 57.3% 930.9Hz
3563 15° 0 0.86V 57.3% 949.8Hz
3719 16° 0 0.86V 57.3% 987.5Hz
3844 17° 0 0.86V 57.3% 1031.6Hz
3938 17° 1 0.86V 57.3% 1075.6Hz
4094 17° 1 0.86V 57.3% 1119.6Hz
4188 17° 0 0.86V 57.3% 1151.1Hz
4375 18° 0 0.86V 57.3% 1195.1Hz
4469 18° 6 0.86V 57.3% 1226.6Hz
4500 16° 5 0.86V 57.3% 1276.9Hz 68.7%
4656 16° 5 0.86V 57.3% 1314.6Hz
4688 16° 9 0.86V 65.1% 1402.7Hz
4813 16° 8 0.86V 70.6% 1478.2Hz
4938 16° 12 0.86V 76.9% 1528.5Hz
5031 15° 12 0.84V 91.4% 1591.4Hz 87.5%
5156 15° 11 0.84V 92.5% 1604.0Hz
5156 16° 11 0.84V 92.9% 1604.0Hz
5313 17° 11 0.84V 92.2% 1604.0Hz
5406 17° 10 0.84V 88.2% 1604.0Hz
5500 18° 11 0.84V 75.3% 1604.0Hz 96.8%
5594 18° 11 0.84V 68.6% 1604.0Hz
5594 19° 11 0.84V 54.1% 1604.0Hz
5719 21° 19 0.86V 60.8% 1497.0Hz 96.0%
5781 16° 19 0.84V 70.2% 1604.0Hz
5781 16° 19 0.84V 75.3% 1604.0Hz 100.0%
5906 16° 18 0.84V 75.7% 1604.0Hz 103.0%
5969 17° 18 0.84V 75.7% 1604.0Hz

Here's a part of a log where I have knock at low throttle but under boost:

RPM Timing Knock TPS 02V Airflow
1063 12° 0 12.9% 0.12V 44.0Hz
938 14° 0 17.6% 0.12V 56.6Hz
1031 12° 0 18.0% 0.04V 81.8Hz
1063 18° 5 18.4% 0.00V 94.4Hz
1250 17° 18 20.0% 0.00V 113.2Hz
1313 17° 26 20.0% 0.00V 119.5Hz
1438 17° 32 20.4% 0.00V 132.1Hz
1563 17° 32 20.4% 0.00V 138.4Hz
1688 17° 32 25.5% 0.00V 157.3Hz
1844 16° 31 27.8% 0.00V 207.6Hz
2000 16° 31 28.2% 0.00V 226.4Hz
2125 17° 31 28.2% 0.00V 239.0Hz
2344 17° 30 28.6% 0.00V 257.9Hz
2500 19° 30 29.0% 0.00V 276.8Hz
2688 20° 30 29.0% 0.04V 295.6Hz
2875 22° 29 29.0% 0.12V 314.5Hz
3094 23° 29 26.7% 0.14V 320.8Hz
3000 28° 10 10.2% 0.18V 113.2Hz
2688 37° 0 10.2% 0.18V 94.4Hz
2406 38° 0 10.2% 0.14V 88.1Hz
1875 37° 0 31.4% 0.16V 188.7Hz

Here are the SAFC settings for reference:
TH - Low 16, High 72

Hi Throttle
1k +4
2k +5
3k +7
4k +9
5k +11
6k +14
7k +14
7.5k +14


Low Throttle
1k +8
2k-7.5k +15

Looks like I need to start over with the tune.

Jebus man, you're flooding your motor! I would change TH settings to 25/75 and then RESET all of your settings and start back at ZERO. If you have larger injectors than stock, you need to REMOVE fuel when tuning. 550's are about 18% larger than 450's so I would adjust my low trims first (you'll probably end up in -10 to -20 region, depending on car) and then start your HI trim settings at -5% across the board. Keep doing pulls and leaning out the car until you get knock. Most 550 cars end up around the -15% region across the HI, but your car will vary. So definitely monitor with your logger.

blcknspo0ln said:

Jebus man, you're flooding your motor! I would change TH settings to 25/75 and then RESET all of your settings and start back at ZERO. If you have larger injectors than stock, you need to REMOVE fuel when tuning. 550's are about 18% larger than 450's so I would adjust my low trims first (you'll probably end up in -10 to -20 region, depending on car) and then start your HI trim settings at -5% across the board. Keep doing pulls and leaning out the car until you get knock. Most 550 cars end up around the -15% region across the HI, but your car will vary. So definitely monitor with your logger.

Click to expand...

He's running a 2G MAS on a 1G car which is supposed to roughly cancel out the 550's.

hm, never knew that. If that's the case, start at zero across the board and lean tune for knock

I would start by adding fuel where you see knock above 5 counts. If it doesn't go away then try and take fuel away.


Your first issue is the rewired 255 without an adjustable regulator. I tried this as well and believe me tuning got alot easier with the apfr. Your base fp is through the roof without one.

I'm also assuming your on the stock i/c so you are probly heatsoaking it by the looks of your second log at 17-18psi cause you have more knock than your 20psi run.

Those hi settings look almost like mine but i have a mkiv i/c and an afpr on top of what you have.

I have done alot of reading on 550's and the 2g maf and most people that used a datalogger have to add fuel to make the trims 100% so they definatly don't cancel each other out. They might be close in some cases but i wouldn't run that combo without a safc and datalogger.

Lastly you need to fix your throttle cable it should read 100% when your at wot and i see yours is only reading in the low 90's

Yes I needed about 8-12% added fuel for the low trims to level out and about 16% at the higher rpms. Im running the same setup as you.

I then went and set the hi to +16% accross the board since that was the last highest settings I used for the low which I read you should do. I have been adding fuel and I still get about 4-12 counts of knock and thats with about +24% in the high rpms. This is all at 9psi. Im really confused. I dont have a fuel pump at the moment so maybe thats why it needs the more fuel.

JayRolla said:

Yes I needed about 8-12% added fuel for the low trims to level out and about 16% at the higher rpms. Im running the same setup as you.

I then went and set the hi to +16% accross the board since that was the last highest settings I used for the low which I read you should do. I have been adding fuel and I still get about 4-12 counts of knock and thats with about +24% in the high rpms. This is all at 9psi. Im really confused. I dont have a fuel pump at the moment so maybe thats why it needs the more fuel.

Click to expand...

Are you too running the stock i/c?? You should check for boost leaks. You can also create knock by running too rich.

Yes I have a stock intercooler and fuel pump. Im just trying to get no knock at 9psi before I turn it up at all. Here is a log

Rpm Knock Timing INJD
2200 0 30 6.2
2400 3 27 12.5
2600 3 26 16.4
2800 1 27 19.5
3000 0 24 23.4
3200 0 24 31.2
3400 0 23 35.9
3600 1 22 37.5
3800 1 21 39.0
4000 0 23 43.7
4200 0 23 43.7
4400 7 20 45.3
4600 11 20 50.0
4800 9 18 56.2
5000 9 18 57.8
5200 8 20 60.9
5400 8 21 64.0
5600 7 24 70.3
5800 6 26 71.8
6000 5 26 76.5
6200 15 16 84.3
6400 14 18 82.0

SAFC hi throttle settings are, these are all postive numbers on safc.
1000-15
1600-15
2200-15
3000-15
3600-17
4200-18
4800-19
5400-20
6000-20
6600-20
7200-20

Before I changed anything I would hit knock at 1psi. About 35 counts by redline. I then tuned the lo throttle to 100% on logger. The last setting I had was +15% so I put that accross the high throttle.

That dropped knock to about 20 counts. I looked at the log and added fuel and got it down to about 12 counts. Then added a little more and knock got worse. I added about 22% and knock went up a little or didnt change much. Im not sure if im lean or rich. Should I start at maybe +10% fuel accross the board and try that. I know the 2g maf sees 33% more air and the injectors add 18% fuel. Thats making me run lean and makes sense I needed so much fuel at idle and low throttle. Which would make sense I needed +15% on the high for starting spot.

I need help!!!!!!!!!!!!!!!!!!Can a boost leak cause this problem????????

Also didnt mean to steal your thread I thought this was in the newbie section.

Have you checked/replaced your knock sensor lately? How about your fuel filter? You should have plenty of fuel with the 550's especially at only 9psi.

xhaust50, you need to determine why your TPS is jumping around like that. Once at WOT, you should be seeing a steady 95%+ for that value. Your TPS is bouncing around from 75-96%, which is going to make getting a good tune almost impossible.

Yea thats wierd the first log the TPS almost stayed right and the second is real messed up. What would cause that??

I plan on lowering the boost and starting all over. I think the TPS was caused by the good old floormat being behind the pedal as I realizes it records at its peak on the SAFC, I might not have had the pedal all the way down. I plan on getting an AFPR and water injection and starting over. I just want to make sure my 02 sensor is working so I will post that in another thread. Thanks for all the help.