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dyno results and A/F ratio

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  • #76
    It is possible to have different things affecting each bank. You may have a suspect injector on one bank and an exhaust leak on the other. That's why the systematic approach. Fix the exhaust leaks so they don't leak at idle and WOT. Go one step at a time.

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    • #77
      The exhaust leaks are now fixed. Apparently I fixed it pretty well yesterday. The shop said there are no leaks now. So we did a scan and now shows idle BLMs at 129/117. The driver's side BLMs are generally around 128-133 now.
      Cell 18, it's 130/115.
      Cell 10 132/130.
      Cell 6 129/124.
      Cell 2 126/121
      Cell 1 124/118
      Cell 17 128/128
      Cell 9 128/128
      Cell 11 132/130.

      And I am experience KR at a certain RPM. It may be due to the header flange barely vibrating on the K-member at a certain RPM. Could that be a cause for KR?
      94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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      • #78
        Originally posted by Craig 94 TA GT

        And I am experience KR at a certain RPM. It may be due to the header flange barely vibrating on the K-member at a certain RPM. Could that be a cause for KR?
        Could be. You might have to clearance the K member so that there is no contact. Did you reset the computer after fixing the leaks and prior to the scan?

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        • #79
          Yes, the PCM was reset. The weird thing is that before I went to the shop, the idle BLMs were at 139/121. We got to the shop, and they verified no more leaks, so I didn't reset the PCM again. We started it up, and now idle BLMs are at 129/121.

          The slight vibration from the header to k-member (I'm assuming) comes at 1500-1800 RPM, and is RPM dependent, not speed dependent. So it's coming from the motor. The only way to prevent the contact, as I can see, is to change the motor mounts, grind the k-member, grind the header flange, or pad the k-member with a firesleeve (at the point of contact).

          Maybe I'll scan a WOT run to see what it scans
          94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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          • #80
            Originally posted by Craig 94 TA GT
            Yes, the PCM was reset. The weird thing is that before I went to the shop, the idle BLMs were at 139/121. We got to the shop, and they verified no more leaks, so I didn't reset the PCM again. We started it up, and now idle BLMs are at 129/121.

            The slight vibration from the header to k-member (I'm assuming) comes at 1500-1800 RPM, and is RPM dependent, not speed dependent. So it's coming from the motor. The only way to prevent the contact, as I can see, is to change the motor mounts, grind the k-member, grind the header flange, or pad the k-member with a firesleeve (at the point of contact).

            Maybe I'll scan a WOT run to see what it scans
            If the driver's side header flange is rubbing on the crossmember toward the center of the car like mine does, you can loosen outside flange bolt almost all the way out and tighten the other bolt which is closest to side that rubs to the approximate depth it needs to be (like when the flange is tight), so with one screw tightened and the other loose (the flange can still turn at this point), then turn the flange so that the tightened screw is out of the way of the crossmember up higher than it would go before when you still had to get to it (remember you won't be able to reach it to tighten it any more, but that's OK) then you just tighten the other screw (the one on the outside) to draw up the flange. If you do it right, it will be evenly tight on the donut gasket and out of the way of the crossmember.

            No applause! Just throw money!

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            • #81
              Thanks a bunch for all your guys' help.
              Kevin, I will try to do as you said with the flange. The only thing I'm scared of is that it's leak free right now. I'll bet, as soon as I change it, it'll leak again mainly due to the off center inner donut gasket ring. And the tighter I tighten those bolts (the ones that came with the installation kit), the more they strip. They're just that much junk. I'll try it though, because unnecessary KR is really annoying.

              I won't be able to work on the car for 2 weeks, as a family issue came up...where I will be out of town. I won't have any updates until after, so you guys don't have to waste your time with my problem for a bit
              94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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              • #82
                I finally was able to clear up some business and tried to work on the car with an illness, and this is what I did so far.

                I moved the header flanges so they're as far away from the k-member as possible. There's about 1/2" to 5/8" clearance all the way around, but I still get a vibration around 1700-1800. I really don't know what it is. Maybe the motor mounts are sagging that much at that RPM and allowing the header and/or flanges to hit something
                In doing this, though, I may have created another exhaust leak in the driver's side. And I tried to switch the AIR check valves, but that didn't do anything.
                My latest BLM scan shows:
                Cell Left Right
                18 140 122
                17 128 128
                16 138 121
                11 128 128
                10 136 130
                9 128 128
                6 133 129
                5 130 128
                2 126 127
                1 121 116

                And I'm still trying to figure out why my injector pWs are at 4/3 at idle, which seems way high.
                94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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                • #83
                  Here's another update. I was able to swap the injectors from side to side to see what happens. Well, as I removed them, #5 and #7 injectors were horribly dirty where the fuel rail meets the injector. The injector hole was literally 1/3 blocked with some kind of deposit. #3 also had a tiny bit, and #1 was clean. All of the passenger's side injectors were perfectly clean.
                  Well, the results of switching them made the BLM split even worse Now the passenger's side is adding less fuel than normal a lot under some conditions.
                  Cell Left Right
                  18 142 114
                  17 129 115
                  16 138 118
                  15 132 128
                  11 132 127
                  10 138 126
                  9 129 128
                  6 130 121
                  5 131 123
                  2 130 121
                  1 126 113

                  One thing got me thinking though...is it possible to have partially clogged fuel rails with build-up at some point in them? #6 and #8 had tons of build-up, which is right before the regulator. I would attribute this problem to something else (i.e. exhaust leak, etc.), but swapping out the injectors did something. Although not in the right direction, it showed to make a difference in most cells. I'm just not sure why or how.

                  I forgot to add, the car is still getting around 11 mpg with all city driving, not driving it hard at all.
                  94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

                  Comment


                  • #84
                    Originally posted by Craig 94 TA GT
                    ....One thing got me thinking though...is it possible to have partially clogged fuel rails with build-up at some point in them? #6 and #8 had tons of build-up, which is right before the regulator....
                    The regulator is at the end of the driver's side rail = #7 ????

                    You had two dirty injectors on the left side, and you have high pulse widths and high BLM's on that side..... seems like a fairly direct connection????
                    Fred

                    381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

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                    • #85
                      Really sorry Fred, my mind was elsewhere. #5 and #7 should be replaced with #6 and #8 above.

                      Yes, I had high pulse widths, high BLMs and dirty injectors on the driver's side. However, I cleaned them up and switched them to the passenger's side (which was previously close to 128 on most readings). So now the good, clean passenger's side injectors are now on the driver's side. But the BLMs are still high, even worse in some cells on that side.

                      On the passenger's side (which now has the driver's side injectors), the BLMs are lower than ever. Which is why this doesn't make sense...the injector swapping has obviously somewhat affected the BLMs, but not in any way that I can understand.
                      94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

                      Comment


                      • #86
                        How long did you drive it? Did you cover a wide range of rpm and engine load? Did you clear it before you drove it?
                        Fred

                        381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

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                        • #87
                          I reset the PCM after I did the injector swap. The scan was after about 20 minutes of driving, maybe not enough? I believe I got several different engine load readings, and up to 4k RPM but maybe it's still "learning"? But as time progressed, the passenger's side seemed to pull more and more fuel out. For example, initially in all cells, it would never go below 127. But as time progressed, the driver's side went slightly up, and the passenger's went down. Maybe I'll drive it around some more to see if anything changes.

                          EDIT
                          I posted the csv file of the latest scan 20 minutes after the injector swap. http://s94938520.onlinehome.us/inj2.csv Thanks.
                          94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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                          • #88
                            One thing I also forgot to mention was that...if I step on the throttle more than 1/3 (or so), I can hear some kind of "whooshing" noise. However, less than 1/3 on the throttle, it will never make this noise. I always thought it was related to having less backpressure because it never did this before the headers/y-pipe/carsound. I assume this is normal for a full exhaust?
                            94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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                            • #89
                              Fred, I have a few questions, if you don't mind. What are the requirements for getting into cells 17 and 18 in closed loop? < .3 MAP and low RPM?

                              Also, I scanned the PCM after several days of running after the injector swap. I noticed something in cells 1 and 2: after a few minutes running in closed loop, the BLMs are around 120-125 for the right, and 122-117 for the left. However, as time progresses (maybe 10-15 minutes later), the BLMs drop: 116-127 for the right, and 114-109 for the left. Is this indicative of a fuel injector leak? Or indicative of something else? In cells 5, 6, 7, 10, they all show roughly 140/128.

                              Lastly, would it be worth something to unplug the MAF and see the BLMs in speed density mode?
                              Thanks in advance.
                              94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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                              • #90
                                Just a thought................

                                If all external componants end up being good, you may be faced with internal issues. Maybe a little blowby, in certain cylinders, valve issues, etc..... it *might* be a good idea to do a compression/leakdown test, check valve lift, etc......Hope noting mechanical is the issue.

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