[HoustonHemi]

I am trying to get through some very odd tuning issues with my truck and want to ask some help from yall. If a bunch of you guys can do this experiment and post results it might help me. Here's the procedure:


1. Start truck and get up to temp.
2. Idle in Park
3. Record AFR and RPM. If you have a scangauge record MAP press.
4. Pump brake fast 10-15 times.
5. Record AFR and RPM (and MAP if available), note any changes in other parameters.
6. Come on here and reply with your AFR-1, RPM-1, AFR-2 and RPM-2 along with any other observations.

Should be real quick and easy to do. I really appreciate anybody who can do this. Thanks dudes.

 

[adamsredlines]

From 10-15 I am pumping the brakes...I dont have a scan gauge so all I got is AF for ya....

Time RPM AFR W R
0.000 677 14.8 0 0
0.100 678 14.7 0 0
0.200 678 14.7 0 0
0.300 680 14.7 0 0
0.400 680 14.7 0 0
0.500 682 14.7 0 0
0.600 682 14.7 0 0
0.701 682 14.7 0 0
0.801 682 14.7 0 0
0.901 682 14.7 0 0
1.001 682 14.8 0 0
1.101 682 14.8 0 0
1.201 682 14.8 0 0
1.301 682 14.8 0 0
1.402 682 14.8 0 0
1.502 683 14.8 0 0
1.602 683 14.8 0 0
1.702 682 14.8 0 0
1.802 682 14.8 0 0
1.902 682 14.8 0 0
2.002 682 14.8 0 0
2.103 682 14.8 0 0
2.203 682 14.8 0 0
2.303 682 14.8 0 0
2.403 683 14.7 0 0
2.503 683 14.8 0 0
2.603 681 14.8 0 0
2.703 682 14.8 0 0
2.804 682 14.8 0 0
2.904 681 14.8 0 0
3.004 681 14.8 0 0
3.104 680 14.8 0 0
3.204 680 14.8 0 0
3.304 681 14.8 0 0
3.404 682 14.8 0 0
3.505 682 14.8 0 0
3.605 682 14.8 0 0
3.705 682 14.8 0 0
3.805 683 14.8 0 0
3.905 683 14.8 0 0
4.005 684 14.8 0 0
4.105 685 14.7 0 0
4.206 685 14.7 0 0
4.306 686 14.7 0 0
4.406 686 14.7 0 0
4.506 686 14.7 0 0
4.606 686 14.7 0 0
4.706 687 14.7 0 0
4.806 686 14.7 0 0
4.907 686 14.8 0 0
5.007 685 14.8 0 0
5.107 685 14.8 0 0
5.207 684 14.8 0 0
5.307 684 14.8 0 0
5.407 683 14.8 0 0
5.507 682 14.8 0 0
5.608 682 14.8 0 0
5.708 682 14.8 0 0
5.808 682 14.8 0 0
5.908 683 14.8 0 0
6.008 683 14.7 0 0
6.108 681 14.7 0 0
6.209 680 14.7 0 0
6.309 680 14.7 0 0
6.409 680 14.7 0 0
6.509 680 14.7 0 0
6.609 680 14.7 0 0
6.709 680 14.8 0 0
6.809 680 14.8 0 0
6.910 680 14.8 0 0
7.010 679 14.8 0 0
7.110 678 14.9 0 0
7.210 678 14.9 0 0
7.310 680 14.9 0 0
7.410 680 14.9 0 0
7.510 680 14.9 0 0
7.611 680 14.8 0 0
7.711 681 14.8 0 0
7.811 682 14.8 0 0
7.911 682 14.8 0 0
8.011 681 14.7 0 0
8.111 681 14.7 0 0
8.211 680 14.7 0 0
8.312 680 14.7 0 0
8.412 680 14.7 0 0
8.512 680 14.7 0 0
8.612 680 14.7 0 0
8.712 679 14.7 0 0
8.812 679 14.8 0 0
8.912 679 14.8 0 0
9.013 679 14.8 0 0
9.113 677 14.8 0 0
9.213 677 14.8 0 0
9.313 677 14.8 0 0
9.413 679 14.8 0 0
9.513 679 14.8 0 0
9.613 680 14.8 0 0
9.714 680 14.8 0 0
9.814 680 14.8 0 0
9.914 681 14.8 0 0
10.014 681 14.7 0 0
10.114 682 14.8 0 0
10.214 682 14.7 0 0
10.314 682 14.8 0 0
10.415 682 14.8 0 0
10.515 684 14.8 0 0
10.615 685 14.8 0 0
10.715 685 14.8 0 0
10.815 685 14.8 0 0
10.915 685 14.8 0 0
11.015 688 14.9 0 0
11.116 688 14.9 0 0
11.216 692 14.9 0 0
11.316 695 14.9 0 0
11.416 695 14.9 0 0
11.516 699 14.9 0 0
11.616 699 14.9 0 0
11.716 704 14.9 0 0
11.817 708 14.8 0 0
11.917 708 14.8 0 0
12.017 712 14.8 0 0
12.117 712 14.8 0 0
12.217 718 14.8 0 0
12.317 722 14.8 0 0
12.417 722 14.8 0 0
12.518 726 14.8 0 0
12.618 729 14.8 0 0
12.718 729 14.8 0 0
12.818 732 14.8 0 0
12.918 732 14.8 0 0
13.018 735 14.8 0 0
13.118 738 14.8 0 0
13.219 738 14.8 0 0
13.319 742 14.8 0 0
13.419 743 14.8 0 0
13.519 743 14.8 0 0
13.619 745 14.8 0 0
13.719 745 14.8 0 0
13.819 745 14.8 0 0
13.920 747 14.8 0 0
14.020 747 14.8 0 0
14.120 748 14.8 0 0
14.220 748 14.8 0 0
14.320 748 14.8 0 0
14.420 748 14.8 0 0
14.520 748 14.8 0 0
14.621 746 14.8 0 0
14.721 746 14.8 0 0
14.821 746 14.7 0 0
14.921 745 14.7 0 0
15.021 745 14.7 0 0
15.121 745 14.7 0 0
15.221 744 14.8 0 0
15.322 744 14.8 0 0
15.422 745 14.8 0 0
15.522 744 14.8 0 0
15.622 744 14.8 0 0
15.722 743 14.8 0 0
15.822 743 14.8 0 0
15.922 743 14.8 0 0
16.023 743 14.8 0 0
16.123 743 14.8 0 0
16.223 743 14.7 0 0
16.323 742 14.7 0 0
16.423 742 14.7 0 0
16.523 740 14.8 0 0
16.623 740 14.8 0 0
16.724 738 14.8 0 0
16.824 736 14.8 0 0
16.924 736 14.8 0 0
17.024 734 14.8 0 0
17.124 734 14.8 0 0
17.224 730 14.8 0 0
17.324 723 14.8 0 0
17.425 723 14.7 0 0
17.525 718 14.6 0 0
17.625 718 14.5 0 0
17.725 713 14.5 0 0
17.825 713 14.5 0 0
17.925 708 14.4 0 0
18.025 704 14.4 0 0
18.126 704 14.4 0 0
18.226 700 14.4 0 0
18.326 700 14.4 0 0
18.426 696 14.5 0 0
18.526 696 14.5 0 0
18.626 692 14.5 0 0
18.727 690 14.5 0 0
18.827 690 14.6 0 0
18.927 687 14.6 0 0
19.037 687 14.6 0 0
19.137 684 14.6 0 0
19.237 684 14.7 0 0
19.337 682 14.7 0 0
19.438 680 14.7 0 0
19.538 680 14.8 0 0
19.638 678 14.8 0 0
19.738 678 14.8 0 0
19.838 676 14.8 0 0
19.938 676 14.8 0 0
20.038 674 14.9 0 0

 

[HoustonHemi]

Great, thanks bro. Anyone else?

 

[adamsredlines]

Thats interesting, looking at it the RPM goes up when you start pumping the brakes but the AF basically stays the same....
What kind of issue are you having if you dont mind me asking?

 

[darell_n]

Pretty sure my truck leans out when I pump the brakes quickly and the idle gets weak, but I don't remember a RPM change. I think I can remember every vac boosted vehicle I've owned do this. My '06 Chev work truck will kick your foot off the pedal if you do this.

 

[HoustonHemi]

Mine goes insanely rich; from whatever AFR it is at to about 10 AFR - at times accompanied by an idle surge up to 1100 or so. Then calm down again and go back t0 where it was.

Trying to figure out if there is a brake booster leak or some other thing wrong. I've been experience a fairly violent cycling idle surge also, but almost only in park, not when in gear. It will do it in gear at times but really almost never.

 

[spedly]

14.6 right about 750rpms
14.7 right about 900 rpms

Every now and then my truck will hunt for an idle for 5-10sec when I start it . Its not a big deal it goes between 600 and 1300rpms then calms right down. It does that maybe once every other month.

 

[dayton hemi]

what is your brake fluid level because if you have a problem with the booster you will have a problem there

 

[HoustonHemi]

Brake fluid level is good.