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Thread: 347 w/ Paxton Blower Settings Help!

  1. #11

    Default 347 w/ Paxton Blower Settings Help!

    alfalfa426 wrote:

    I believe it is the opposite. The blow-thru setup like yours should have air box pressure connected to the reference port on the fuel pressure regulator. In order to maintain a constant pressure drop across the injector orifice, the fuel pressure should rise at a 1:1 ratio with manifold pressure.



    As you noted already, the blow-off valve and vacuum / boost gauge should be connected to the throttle body base plate using one of the "unported" taps (i.e. one that taps into manifold pressure below the throttle blades).

    I agree that the pressure regulator should be connected to the pressure box. I have read that fuel pressure should be 5-7psi above boost pressure. His fuel pressure is 66-68psi right now so it probably isn't a issue but could be wrong.

  2. #12

    Default 347 w/ Paxton Blower Settings Help!

    A general IAC POS target of 10 - 20 for a manual transmission is a good starting point.

    It is ok to be more or less, jus as long as the system is able to maintain a good idle and does not stall under a sudden load change.

    When the IAC counts are too high the system will not be able to save itself from stalling.




  3. #13

    Default 347 w/ Paxton Blower Settings Help!

    I have almost same setup as you 347 with Paxton supercharger but automatic trans and these are the settings I use. runs great



    Camshaft Type: Mild

    Fuel Pump Type: Non PWM with regulator

    Idle RPM Target: 950

    Rev Limit: 6100



    Ignition Timing

    Idle RPM: 850

    Total RPM: 3000

    Idle Advance: 15.0

    Total Advance: 34.0

    Vacuum Advance: 10.0

    Vacuum type:

    Nitrous Retard: Off

    Boost Retard: 1.0



    A/F Targets

    Idle: 14.0

    Cruise: 14.0

    WOT: 11.0

    Boost: 11.5

    Pump Squirt: 38%

    Power Valve Enrich: 5% I left my pump squirt and power valve enrichment at default settings.

    4 degrees boost retard is to much; use 1 degree

    connect your blow off valve to manifold vacuum use a port on the manifold or the port at the lower rear of your box. connect manifold vacuum to fuel pressure regulator.

    set the fuel pressure to 45 to 50 psi. I use PWM and that's were mine stays at.

  4. #14

    Default 347 w/ Paxton Blower Settings Help!

    Thanks for all the replies. I have fixed the charging issues. I connected the Aeromotive fuel regulator directly to the Paxton manifold, so the pressure will increase 1:1 as boost comes and it will not see any vacuum. I connected the Bosch bypass valve directly to the vacuum port on the MSD Atomic EFI unit. It now vents as it should while idling.



    I have reset the Atomic completely and updated my settings as follows;

    Camshaft Type: Mild
    Fuel Pump Type: Non PWM with regulator
    Idle RPM Target: 950
    Rev Limit: 6100

    Ignition Timing
    Idle RPM: 1050
    Total RPM: 2500
    Idle Advance: 13.5
    Total Advance: 34.0
    Vacuum Advance: 0
    Vacuum type:
    Nitrous Retard: Off
    Boost Retard: 1.0

    A/F Targets
    Idle: 14.0
    Cruise: 13.8
    WOT: 11.0
    Boost: 11.5
    Pump Squirt: 38%
    Power Valve Enrich: 5%

    I made another video: https://youtu.be/9TDLwSbAe5w after the car was warmed up to 160 degrees.

    Stats from video:

    Tach: ~965rpm - 1024rpm
    ECT: 157F
    IAT:59F
    TPS: 0
    Map: 13.7" HG
    Fuel Press: 51 psi
    Bat Volts: 14.0v
    A/F Ratio: 13.6-14.2 AFR
    Inj Duty: 5%
    IGN Timing: 12.5-13.5 Deg
    IAC Pos: 0





    The car backfires as soon as it sees boost. Hesitation under partial boost is still the same. Basically the car is super smooth and drivable up to about 2500rpms. As soon as it sees any load it bogs/hesitates and backfires.



    Watching the AFR is doesn't seem to be too lean, maybe too rich and igniting the

    excess fuel? Is my Pump Squirt too high? Vacuum leak? Timing?





    I can't find the firing order for the Anderson Racing B31 cam online, going to call them tomorrow morning. The shop set it up as 1-3-7-2-6-5-4-8 and also order a timing light to see if that may be an issue.





    The car idles smooth, no stutter or erratic rpm or timing changes. Car is pretty easy to start, sometimes just have to ever so slightly press on the gas peddle but it fires up easily.





    Edit: made a video of me driving and applying some light throttle, you can hear the hesitation/bogging at 2:05, 4:02, 8:24 and 9:10 ; https://youtu.be/cIudCytvZx8



    Attached files


  5. #15

    Default 347 w/ Paxton Blower Settings Help!

    My first thought is that the Cruise, WOT and Boost A/F ratios are way too rich. The spark plug is also indicating an overly rich condition. 11.8 is typically about the richest WOT (under boost) A/F you'd ever need - and even that is way too rich for your setup. Since you are not running a lot of boost, I would try something in the 12.4-12.5 range for both WOT and Boost A/F Ratio. Set the Cruise A/F around 14.2-14.5.



    Keep in mind that if your plugs are already fouled - and yours are definitely on the verge - you will need to install a fresh set of plugs before you resume your test drives. Once the plus are fouled, they will cause misfires - which the Oxygen sensor will interpret as a lean condition - and the system will keep adding fuel. It's a runaway train once you get to that point - so I think a fresh set of plugs would be a good place to start - right after you lean out the A/F ratios (as mentioned in the first paragraph).





    Lastly - I would revert the Pump Squirt and Power Valve Enrich back to their default values (25% and 19% respectively). It is unusual to require such a large deviation from the default values. Major adjustments to these parameters probably won't be necessary once you get the Cruise, WOT and Boost A/F ratios dialed in properly.








  6. #16

    Default 347 w/ Paxton Blower Settings Help!

    Thank you alfalfa426! I swapped the plugs out last night, I opted to stick to the Autolite 3923's that I was using while it was carb'd and it was running well. It is pouring here in Georgia so I will have to wait before I can get a few miles on her. I also went ahead and leaned out my settings. She definitely fired up easier, idle is pretty much the same as always; smooth and steady.



    Last night I also noticed something else; the shop removed my throttle return spring. I'll be replacing that tonight.



    After the car warms up to about 160* the IAC does drop down to 0. I may have to adjust that a little as well but I am not having any idling or starting issues (cold or hot).






  7. #17

    Default 347 w/ Paxton Blower Settings Help!

    You are most welcome - and I'm glad to hear that it seems to be responding in a positive manner. Since you are limiting boost to 5-6 psig, there is no need to run a colder plug - unless you are planning on some l-o-n-g WOT runs - at which point, the plug tip temperatures, exhaust valve temps and piston crown temps will become factors in avoiding detonation. I presume you are also running the highest octane pump gas available in the area (91 or 93 octane)?



    Getting the IAC count dialed in can definitely test your patience; however, it would be ideal if you can adjust the throttle blades such that the count is not zero (0) with a warm engine idling in neutral. In your case, just a slight nudge in the CCW direction (closing the blades) is probably all that's required. Be sure to adjust the front and rears equally. If you get it all out of whack, it's best just to start over with the blades a little too far open - and then sneak up on the desired count by gradually (and equally) closing the blades.



    As others have said, you might have to do this many, many times until you are happy with the results. Just think of it this way - if the IAC Counts are displaying zero (0) at idle, that means enough air (or even too much air) is bypassing the throttle blades. By closing the blades, you force the required idle air supply to be metered by the IAC motor. When combined with the Atomic's ability to control the ignition timing, the system can respond very accurately (and quickly) to changing engine loads and maintain your desired idle speed - but only if the IAC motor has a little "wiggle room". That's why you don't want the count at zero (0), but rather in the 15-20 range. That way, the IAC motor can either close slightly (lower IAC count) or open slightly (higher IAC count) to adjust the idle airflow as required.

  8. #18

    Default 347 w/ Paxton Blower Settings Help!

    Thanks alfalfa for the assist.

    One more thing, please be sure the MSD box has its ground directly to the battery negative post. Other grounds can be inconsistent and the box may not be giving the full output.

  9. #19

    Default 347 w/ Paxton Blower Settings Help!

    I finally managed to get the IAC down to 12-20 at 160* in neutral. When I started the car cold it was at 175 and came down. Still idles smooth, nothing erratic. Somehow I have been lucky without any idling issues.

    I took the car out for a quick drive around the block and albeit the hesitation is way less, the popping is still there. I found a tiny exhaust leak on the passenger tube, just before the x-pipe. I am attaching a photo the exhaust leak, it is very small and wondering if it could be igniting the rich mixture?



    I made some videos again.



    First Video; https://youtu.be/mxYprL5fE58

    Cold start looking at MSD dash, back or car idling, engine bay idling and then back to showing the warmed up MSD dash.



    Second Video; https://youtu.be/7odSezm_Cyg

    I tried to keep my phone on the MSD dash screen while I drove, this proved to be pretty darn challenging. I did manage to capture one popping occurrence.



    I noticed if you watch the MAP that it reads lower as the boost builds and then suddenly it shows what looks like 19 when the popping occurs.

    Attached files


  10. #20

    Default 347 w/ Paxton Blower Settings Help!

    Nice looking car.



    The idle sounds awesome, which exhaust, sound like Pypes.



    It appears to me that you have the Pump Squirt and Power Valve enrich settings reversed.



    Try

    PS = 25

    PVE = 19



    If you still have pop maybe PS to 27



    Just my thoughts here, I had a similar issue with pop and PS fixed that but my motor isn't supercharged.

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