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Thread: Falling flat on WOT/bucking

  1. #1
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    Falling flat on WOT/bucking

    Hi, I'm new to the forced induction world. I installed a d1sc procharger on my 2001 camaro (cam/pistons/rods) over this winter.
    After finding a boost leak, fixing the bypass value, and busting a in tank fuel line, I am now actually making boost.
    The problem is the car falls flat on its face.
    It's hard to get to WOT on the street so I went to the track this past Friday and the car usually runs 11.5's non-procharged, the best run I had was 12.1 and the logs show it was very lean and inj. duty was above 100%.
    I have a walbro 450 intank, and bosch 60lb injectors, boost ref'd racetronix regulator, this setup *should* handle the power I'm making.
    I suspect the issue is entirely tune related, though theres some kind of rattling noise that I think is coming from procharger unit or the idler.

    1.hpl1.hpt2.hpl2.hpt3.hpl3.hpt4.hpl4.hpt5.hpl5.hpt

  2. #2
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    Quote Originally Posted by hindsightis2001 View Post
    Hi, I'm new
    i tried to open 2 of your datalogs and theyre a few secodns wiht a blip of the throttle.

    If you want help, post a real log, like either a full run down the track, or go drive 15 miles.

    But, im not going to look through each file to figure out what youre doing.

    help us help you.

  3. #3
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    Your timing is dropping so much you may be making less power under boost than you did N/A. The IAT table only looks to be responsible for 1 or 2 degrees of this, and the (probably false) knock retard you are showing in some spots is not going to account for the rest of the time when it is not showing knock retard. I would suspect it may be burst knock, but there is no way to know from the logs I looked at. Your main tables show far more spark than you are actually logging, so once that is figured out it may wake up. I did not go through the entire logs or tunes, so this is just from a cursory glance at things.

  4. #4
    Senior Tuner edcmat-l1's Avatar
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    Timing is pretty low for the boost level. Injectors are 90% @ 5300. That's gonna be a problem. Injectors are too small and/or fuel pressure is too low/dropping.

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  5. #5
    Tuning Addict blindsquirrel's Avatar
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    How do you have a problem like "Falling flat on WOT/bucking" and not very first thing put a fuel pressure gauge on it that you can see from the driver's seat while making it do the thing that needs fixed? I don't care what it 'should' be according to the label on the boxes the fuel system parts came out of, it has to be checked, and I would think that if fuel pressure under load had been checked and found to be OK that it would have been mentioned somewhere in the description.
    GM Gen4 Injectors v2.1.xls
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  6. #6
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    Sorry, logs 1,2, 4, 5 are all 1/4 miles runs at the track. When it started hesitating, I let off the throttle. Log 3 was a drive to the gas station, but I didn't get on it.

  7. #7
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    I have a analog fuel pressure gauge under the hood, I guess I'll have to run an electronic one to the dash.
    Is is safe to assume I need bigger injectors, or should I log fuel pressure before spending any money?

  8. #8
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    Check fuel pressure first. Those injectors should not be done on the boost you are running. Not on gas, anyway. E85 would be a different story.
    edit-- I worded that poorly. I mean that those injectors should not yet be maxed out.
    Last edited by gametech; 07-21-2024 at 05:45 PM.

  9. #9
    Tuning Addict blindsquirrel's Avatar
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    Why does everyone jump straight to the most complicated, most expensive solution first, instead of just using a fuel pressure gauge as a test instrument like it's designed for? It's no different than a tire pressure gauge - you don't permanently screw gauges onto your valve stems and drive around like that all the time.

    Get a fuel pressure gauge with a long enough hose that you can snake it up under the rear of the hood and stick it on the outside of the windshield so you can see it on a test drive. Once you confirm it holds good pressure, you can remove it and put it away until something changes and it needs to be checked again. A gauge that you can't see on a test drive is just a decoration to make your engine look all fancy. People who don't know any better will think you're cool.
    GM Gen4 Injectors v2.1.xls
    Snow Crash was meant to be a warning, not a roadmap, you smooth-brained morons.

  10. #10
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    In every log of yours I opened it was off the chart rich on your wideband and backed up with your narrowband readings.

    If you got the fueling correct you'd have more room on your injectors. Being too rich will definitely cause it to nose over.
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  11. #11
    Senior Tuner mbray01's Avatar
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    sounds to me like its entirely too rich and under timed
    Michael Bray
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  12. #12
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    Thank you. I was able to get some time to look at the car yesterday (but not test drive it as it was raining)
    Fuel pressure was way too high, I must have been in a rush last time I adjusted it.
    I took the fuel pump out because it seemed like it went lean when the tank was low, and well the wiring was on its last leg (lesson learned about heat shrink).
    And finally I pulled some plugs to make sure I didn't damage the engine, I thought I had installed br7's in back in January, however there were TR-6's in there. I even went back and confirmed that in November I ordered tr-6's. Some were white, some were black.
    The plugs definitely need to be a bit colder, so I'm waiting for rockauto to ship some br7's so I can safely tune again.

    I've been making some big mistakes that even astonish myself.
    I don't even know why the timing is so low in the WOT area. I 'swear' I set it up exactly as ChopperDoc instructed in his youtube video on boosted cars.
    I dunno, maybe I'm schizophrenic or something

  13. #13
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    I hate to revive a dead thread, but I was able to figure out my issue.
    #1 I needed to flatter IFR since Im using a boost referenced regulator. this made tuning way easier
    #2 I was running absolutely pig rich - 0.69 is the lowest lambda my AEM gauge would read. In reality the AFR was much lower. Every time I made a change, it looked like it didn't change anything, and it was making me think in the wrong directions
    #3 I found a nice section of highway, very close to where I store the vehicle, I was able to blast off some full throttle runs back to back, this made high rpm tuning way easier.

    PS I also installed a fp gauge sender [fuel pressure is fine], went to jegs rails to accommodate the extra port and also because i didn't trust using the stock rails fp test port as a return. I also killed a couple pumps in the past month or so. all dude to installation sloppyness.

  14. #14
    Advanced Tuner abc's Avatar
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    It's not reviving a dead thread if you have a resolution but you have not been clear on your resolution. During a WOT hit, it's clear it was running out of fuel based on the duty cycle, NBO2's, WBO2, VE table and so on. Making multiple hits with this scenario will burn one down, consider yourself lucky you didn't hurt it.

    If you ever become clear with a resolution feel free to share it here.