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Thread: Poping sound at idle, help..

  1. #41
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    Quote Originally Posted by SiriusC1024 View Post
    Any updates?
    yeah, sorry I took so long for a follow up.. I went with a PCM from eBay FlashMasters, found a 97 Manual VIN and had them programmed it.
    I have 2 Major problem with the car now.. Car seems kinda lazy on the throttle, it won't even rev match properly because it's so lazy/delayed..
    my next issue is, when I'm coming to a stop with clutch in, the car dips in power as if the engine slowed all the way down and the alternator just falls flat on it's face, not sure what's up with that.. I still have that #2 misfire but I think it as something to do with the fuel, and the delivery to the injector... I have a gauge on the Shrader valve and it's just bouncing all over the place once the car is hot.. not sure what could be causing that.

    it idles fine for the most part, you don't hear the popping anymore, but I can tell it's still there.. it's that #2 that's causing it..
    and spark is just as low from when I had put that Original PCM back in as a test. turns out it wasn't -4 degree it was just 4 degree

    Original.97.Tune.Manual.7.10.2024.hpt

    24-07-10 21-17-49.hpl

    https://youtube.com/shorts/FslLebz6Ddw when engine is hot
    https://youtube.com/shorts/pOC0pVxEpOY when engine is cold

    P.S Vacuum line is disconnected, it's running a Delphi FP10016 FPR - KEMSO 340LPH Fuel Pump, Fuel Filter is 4 years old.
    Last edited by LuminousX; 4 Days Ago at 09:36 AM.

  2. #42
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    Car seems to run quite a bit hotter since the new PCM installed, before I could maintain 185 degree in traffic (180 thermostat installed) with the fan on (fan on switch) but now it creeps up to 205+ guess it's time for that 3 inch aluminum radiator upgrade.

  3. #43
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    Wait the vacuum line to the FPR is disconnected? The data isn't setup for that. You should reconnect then get a good log. Get a new reg while you're at it if the pressure is all over the place. See if we can figure anything out.

  4. #44
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    I just watched the vids you posted. There shouldn't be that much variation in pressure with the line disconnected. Are you sure the factory regulator can bypass enough to regulate that fuel pump, or is it acting like a restriction and raising pressure? An aftermarket FPR may be in order. Same for the return line size.

    That jitter in the needle is from the injectors firing. Usually on a vacuum-referenced system the FPR will damp that. On returnless there's a damper on the rails.

    If this remains with the new FPR then one of these will fix it. I have one and it certainly made a difference. Problem is they require aftermarket rails.
    https://www.radiumauto.com/Fuel-Pulse-Damper-Direct-Mount-Kits-P759.aspx
    Last edited by SiriusC1024; 3 Days Ago at 08:55 PM.

  5. #45
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    Quote Originally Posted by SiriusC1024 View Post
    I just watched the vids you posted. There shouldn't be that much variation in pressure with the line disconnected. Are you sure the factory regulator can bypass enough to regulate that fuel pump, or is it acting like a restriction and raising pressure? An aftermarket FPR may be in order. Same for the return line size.

    That jitter in the needle is from the injectors firing. Usually on a vacuum-referenced system the FPR will damp that. On returnless there's a damper on the rails.

    If this remains with the new FPR then one of these will fix it. I have one and it certainly made a difference. Problem is they require aftermarket rails.
    https://www.radiumauto.com/Fuel-Pulse-Damper-Direct-Mount-Kits-P759.aspx
    Well it's normal for the most part. looses pressure and fluctuate a lot when hot, doesn't sound like a FPR issue... that thing is only 3 years old.. it does it with the vacuum and without..I might start with the power going to the fuel pump.. if that checks out then fpr it is.. I thought the data you gave me was supposed to work on a 4 bar rail.. didn't know it made a difference if referenced or not.. if I attach the line then I'm at to 43 psi cold and around 39 hot.. do you have any changes for that or just do a log?

  6. #46
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    That's the way it's supposed to work with the vacuum-referenced reg. Set a pressure with the vacuum line disconnected. When it's reconnected the regulator will maintain that pressure across the injector. Manifold vacuum pulls fuel through the injector (in the case of boost the force is reversed) just as pressure in the rails pushes. That's why all the fuel injector data in the tune has the same values for every column of kPa.

    In your case it's really a 3.8bar (55psi or 380kPa) vacuum-referenced reg. Line unplugged that's what should show on a gauge measuring rail pressure. Plug it back in. Start the car. Manifold vacuum is 37kPa in the last log. That's also vacuum to the reg. 380kPa-37kPa = 343kPa = 49.74psi.

    The regulator is not regulating to the correct pressure. That or the fpr on those cars is 3.3bar (48psi) to get 43psi idle? Like I said earlier in Post #7, I figured those were regulated lower.

    Anyway, that data is converted over from GM data that was valid for 4bar. Going to 3.8bar won't make much of a difference. Going anywhere near 3bar is going to. Looking at RockAuto, GM uses another type for some 3800's. Fortunately, you can switch to it and get the 3.8bar reg. That's what I recommend doing.

    1995-2002 Chevrolet Camaro:
    https://www.rockauto.com/en/catalog/...regulator,6124

    1997-2003 Pontiac Grand Prix GTP (3.8bar):
    https://www.rockauto.com/en/catalog/...regulator,6124

    updated fpr.png
    Last edited by SiriusC1024; 2 Days Ago at 10:35 PM.