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View Full Version : can someone look at my tune backfiring on idle



pdasterly
September 22nd, 2009, 08:14 AM
new forged motor, bosch green top 42 injectors, comp cams 224/224, long tubes, dual breathers one on each valve cover. The car wont idle and backfires, the backfiring is probably from the low idle.

SSpdDmon
September 22nd, 2009, 09:18 AM
Post tune too pls. ;)

gmperformancecentre
September 22nd, 2009, 08:28 PM
try putting the idle around 900 rpm instead of 550 rpm a cam that size needs more 550 rpm

pdasterly
September 23rd, 2009, 02:01 PM
missed that table, i change all idle related tables to 1200, car wont idle, like it has major exhaust leak. the motor is new from the machine shop. I checked for leak and found none. I run two driver side valve covers with no fresh air ports or pcv. I have a breather in each oil fill hole

odd boy
September 23rd, 2009, 04:59 PM
what is the AFR at idle? It might be too lean or too rich.

Your log isn't good! Since u r tuning idle, u need to log more parameters:

1. Fuel Status
2. Commanded air fuel
3. O2, STFT ...etc

Check the Spark Pulgs, if they r blackish replace them.

Use the following values (with a wide band installed, because it will be lean at idle):

{B4003} Minimum Injector Pulse Width (Milliseconds)

RPM Value
0.00 0.197568
400. 0.197568
800. 0.197568
1200 0.197568
1600 0.197568
2000 0.197568
2400 0.197568
2800 0.197568
3200 0.197568
3600 0.197568
4000 0.197568
4400 0.197568
4800 0.197568
5200 0.197568
5600 0.197568
6000 0.197568
6400 0.197568
6800 0.197568
7200 0.197568
7600 0.197568
8000 0.197568


{B4004} Default Minimum Pulse Width (Milliseconds)

RPM Value
0.00 0.516715
400. 0.516715
800. 0.516715
1200 0.516715
1600 0.516715
2000 0.516715
2400 0.516715
2800 0.516715
3200 0.516715
3600 0.516715
4000 0.516715
4400 0.516715
4800 0.516715
5200 0.516715
5600 0.516715
6000 0.516715
6400 0.516715
6800 0.516715
7200 0.516715
7600 0.516715
8000 0.516715


{B4005} Small Pulse Adjust (Milliseconds)


M.S.. Value
0.000 0.258358
0.061 0.288753
0.122 0.258358
0.182 0.243160
0.243 0.212765
0.304 0.197568
0.365 0.167173
0.426 0.151975
0.486 0.182370
0.547 0.151975
0.608 0.151975
0.669 0.136778
0.729 0.106383
0.790 0.106383
0.851 0.091185
0.912 0.091185
0.973 0.075988
1.033 0.075988
1.094 0.060790
1.155 0.060790
1.216 0.060790
1.277 0.060790
1.337 0.060790
1.398 0.060790
1.459 0.045593
1.520 0.045593
1.581 0.045593
1.641 0.045593
1.702 0.045593
1.763 0.045593
1.824 0.045593
1.884 0.030395
1.945 0.030395
2.006 0.030395
2.067 0.030395
2.128 0.030395
2.188 0.030395
2.249 0.030395
2.310 0.015198
2.371 0.015198
2.432 0.015198
2.492 0.015198
2.553 0.015198
2.614 0.015198
2.675 0.015198
2.736 0.015198
2.796 0.015198
2.857 0.015198
2.918 0.015198
2.979 0.015198
3.040 0.015198
3.100 0.015198
3.161 0.015198
3.222 0.015198
3.283 0.015198
3.343 0.015198
3.404 0.015198
3.465 0.015198
3.526 0.015198
3.587 0.015198
3.647 0.015198
3.708 0.015198
3.769 0.015198
3.830 0.015198
3.891 0.015198
3.951 0.000000
4.012 0.000000