Ok so here we go. I bought a 90 GSX back in September that needed a motor. I had Buschur build me one of his stageIII shortblocks for it and we put it in. There is absolutely nothing else done to the car yet as I have been a little shy on moneys since having the block built and christmas and all. I did however buy a palm a few weeks ago and started logging. I found out that I was getting 10-15 counts of knock above 5K on a regular basis. I spoke with Tym at Buschur and he told me that this can be expected running pump gas and stock maps. So I bought an AFC and installed it this week and I have been playing with it a little bit. The logger was telling me that all three of my fuel trims were at 118.7. Following the AFC tuning thread in the tech archives, with throttle points set at 30 and 80, I managed to get my lows back to around 100. This required me to add 33% across the board. I transfered the 33% over to the hi throttle side and made a few pulls. Here is a breakdown of those logs. They were made in 2nd gear as I live in city limits and cant go ripping 90mph down city streets and I just wanted to get an idea of where this put me with the knock issue. Here is what I got:
RPM KNK TIMA O2
2625 0 22 .85
2750 0 18 .91
2937 0 18 .91
3062 0 18 .91
3281 0 17 .91
3500 0 16 .91
3781 0 17 .89
4062 4 18 .87
4406 4 16 .87
4625 4 17 .87
4906 8 17 .85
5187 12 15 .85
5375 12 15 .85
5531 11 17 .87
5812 13 17 .87
6000 13 17 .85
6062 12 17 .85
6250 18 17 .85
After this pull I added a bit in the rough spots and got this one:
RPM KNK TIMA O2
2750 0 20 .85
2875 0 20 .87
3031 0 19 .87
3187 0 18 .87
3343 0 17 .87
3625 0 17 .87
3843 4 17 .85
4156 10 16 .83
4406 9 14 .83
4656 9 16 .83
4968 9 16 .83
5156 8 15 .83
5375 12 16 .83
5531 11 16 .83
5687 11 17 .83
5781 11 18 .83
6000 15 16 .83
6218 16 16 .83
6281 16 15 .83
6468 23 12 .83
6625 22 11 .82
The two pulls were made a little close together so I am going to make the conclusion that heat soak was to blame for the slightly higher knock counts on the second pull. Here is where it gets a bit goofy. I drove around for quite awhile to make sure that the low fuel trims were going to stay where they needed to be and they did. After these two pulls messing with the hi throttle settings I was pulling back into the house and I noticed that the low trims were now at around 80% and the car smelled rich? I'm not a professional tuner, but I'm not a complete novice either. This is my first DSM and heavily built motor though. Am I living a pipe dream thinking that this car will run with stock components until I can afford to start upgrading everything else or am I doing something wrong? I have a few ideas already and I am looking for some more. Here is what I have come up with so far. O2 sensor may be going bad. Thats an easy fix and I will probably wind up getting one soon anyway. Should I be running colder plugs in the car due to the higher static compression? I know that the intercooler and small 14b is causing extra heat. Could fuel pressure be the culprit? I am planning to change the fuel filter soon as I dont know the last time it was done if ever but I've been working quite a bit and havent had much time. Lastly, the lifters make no noise. Any ideas you guys could throw my way would be appreciated.
RPM KNK TIMA O2
2625 0 22 .85
2750 0 18 .91
2937 0 18 .91
3062 0 18 .91
3281 0 17 .91
3500 0 16 .91
3781 0 17 .89
4062 4 18 .87
4406 4 16 .87
4625 4 17 .87
4906 8 17 .85
5187 12 15 .85
5375 12 15 .85
5531 11 17 .87
5812 13 17 .87
6000 13 17 .85
6062 12 17 .85
6250 18 17 .85
After this pull I added a bit in the rough spots and got this one:
RPM KNK TIMA O2
2750 0 20 .85
2875 0 20 .87
3031 0 19 .87
3187 0 18 .87
3343 0 17 .87
3625 0 17 .87
3843 4 17 .85
4156 10 16 .83
4406 9 14 .83
4656 9 16 .83
4968 9 16 .83
5156 8 15 .83
5375 12 16 .83
5531 11 16 .83
5687 11 17 .83
5781 11 18 .83
6000 15 16 .83
6218 16 16 .83
6281 16 15 .83
6468 23 12 .83
6625 22 11 .82
The two pulls were made a little close together so I am going to make the conclusion that heat soak was to blame for the slightly higher knock counts on the second pull. Here is where it gets a bit goofy. I drove around for quite awhile to make sure that the low fuel trims were going to stay where they needed to be and they did. After these two pulls messing with the hi throttle settings I was pulling back into the house and I noticed that the low trims were now at around 80% and the car smelled rich? I'm not a professional tuner, but I'm not a complete novice either. This is my first DSM and heavily built motor though. Am I living a pipe dream thinking that this car will run with stock components until I can afford to start upgrading everything else or am I doing something wrong? I have a few ideas already and I am looking for some more. Here is what I have come up with so far. O2 sensor may be going bad. Thats an easy fix and I will probably wind up getting one soon anyway. Should I be running colder plugs in the car due to the higher static compression? I know that the intercooler and small 14b is causing extra heat. Could fuel pressure be the culprit? I am planning to change the fuel filter soon as I dont know the last time it was done if ever but I've been working quite a bit and havent had much time. Lastly, the lifters make no noise. Any ideas you guys could throw my way would be appreciated.
