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Thread: Sniper EFI - Truck is now running, first test drive, getting spark knock?

  1. #11

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    Thank you both for the info so far. Danny, I will download the EFI software once I get home from work and take a look through it, and try to familiarize myself with the features & settings on there. I'll also have to read up on how to transfer the files on the SD card as I haven't attempted that yet.

    Gadget, I read through your thread and it sounds like you went through the same issues as I'm having. Aside from the fact that you now have your Super Victor intake and I have a dual plane, are there any other differences in our setups? I'd be disappointed in the fact that I'd have to swap out my brand new intake to make this system work correctly. Those intakes aren't exactly cheap anymore and as a budget build, it feels like a kick in the nuts to have to drop another $400 on something that really should be mentioned by Holley to begin with if dual planes are known to give these kind of issues. However, if that's what I need to make this work, I'll have to pickup another intake. If you would be willing, I would love to be able to match your setup and be able to start off with your tune file if at all possible, if you think you have things worked out. I also like your throttle extension, I definitely need to do the same with mine as it will melt the rear tires under 1/4 throttle!

  2. #12

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    The dual plane can be worked around. An open plenum intake does make the tuning easier with the short straight runners. Also, some dual planes may be better than others and work fine on some engine combos. PM me through the truck forum and I will work on getting you my Config File. Loading what you have onto the SD card is real easy. I'll help you go through what I did and apply it to your truck. Jimmy

  3. #13
    Join Date
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    Quote Originally Posted by Nick_R_23 View Post
    Those intakes aren't exactly cheap anymore and as a budget build, it feels like a kick in the nuts to have to drop another $400 on something that really should be mentioned by Holley to begin with if dual planes are known to give these kind of issues. However, if that's what I need to make this work, I'll have to pickup another intake.
    Your dual plane intake manifold will work fine on your application.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  4. #14

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    Quote Originally Posted by Gadget View Post
    The dual plane can be worked around. An open plenum intake does make the tuning easier with the short straight runners. Also, some dual planes may be better than others and work fine on some engine combos. PM me through the truck forum and I will work on getting you my Config File. Loading what you have onto the SD card is real easy. I'll help you go through what I did and apply it to your truck. Jimmy
    Quote Originally Posted by Danny Cabral View Post
    Your dual plane intake manifold will work fine on your application.
    That's good to hear. I'm not looking for every last ounce of power, just something that runs good and a better setup than a carb.

  5. #15

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    Alright, it's been a little bit but I finally had time to try this out. Jimmy, I finally was able to figure out how to load your file onto my system, and I must say that it seems to be working excellent so far. There's some minor tweaking to be done and definitely some transmission tuning I need to do (seems to want to go into lockup all the time, and I think my governor weights are too heavy, but that's another story). But fortunately, my spark knock seems to be eliminated.

    However, I seem to have ran into a new problem. It seems to be exactly the same issue this user was having: https://forums.holley.com/showthread...ut-new-install

    My symptoms are nearly the same. I can be driving along, and suddenly the engine will cut out and the handheld display will show -20 on the TPS setting, and a red dot in the upper right corner of the screen. Depending on how heavy I was on the throttle, it may backfire out the exhaust if I was into it. At one point during my drive, the problem became so bad & constant, that I had to pull over because the truck was basically undriveable. I let it sit & idle and at one point it stalled, but fired right back up. It seemed to drive back home OK, but it would cut out like this once in a while. Also while driving, when it's actually running good, I notice that my TPS reading & MAP reading will both occasionally highlight in yellow. The truck does not need much throttle for cruising, so typically it's between 5-20% when I'm driving, and the MAP reading is typically between 30-50 kPa. I was able to capture a short datalog when this happened, as well as taking a longer datalog while it was running well. I will see if I can figure out how to upload it here so you guys can view it.

  6. #16
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    It seems like the EFI system intermittently looses the RPM signal and the ECU momentarily resets (Minimum Signal Voltage). Or there's a failing/shorted sensor that shares ECU 5V & Ground, so other sensors display erroneous values too. Since many sensors share a common ground wire, you may have a loose wire/terminal or a defective sensor affecting the others. When this happens, disconnect each sensor one at a time, while watching the Data Monitor (laptop "Online" with ECU). Or use the gauge screen (Monitor) on the Sniper 3.5" LCD Touchscreen unit. If one unplugged sensor restores the system to proper sensor values, then that's the culprit.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #17

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    Thank you Danny. When it first started running bad enough to where I couldn't drive it, I did pull over while it was at idle and wiggle & inspect wires and connections at sensors, and nothing appeared to affect the system at that point. However, both that thread I linked and the page you linked, seemed to pretty much point the finger to MSD distributors as the source of the problem, which I indeed have on my engine. Many users in that thread report the Dual Sync Distributor solving their issues, but one or two claimed to make their MSD work. I'd hate to have to drop that kind of money on another distributor, but I need this to be reliable as I'm about 50 miles from town, and that kind of breakdown or gremlin is unacceptable with that distance. Do you feel that trying the Minimum Signal Voltage adjustment will solve my problem, or is that more of a Band-Aid fix with the Dual Sync Distributor being an actual solution?

  8. #18
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    Quote Originally Posted by Nick_R_23 View Post
    I'd hate to have to drop that kind of money on another distributor, but I need this to be reliable...
    If you purchased the MSD distributor for your Sniper EFI installation, I would've spent that money on the Holley Dual Sync Distributor.
    The Holley Dual Sync Distributor is a proven component that uses far superior Hall-Effect sensors, especially in EFI applications.
    https://www.youtube.com/watch?v=1gI4FDfU2sI (Holley Dual Sync Distributor Installation - Sniper EFI)

    Do you feel that trying the Minimum Signal Voltage adjustment will solve my problem, or is that more of a Band-Aid fix with the Dual Sync Distributor being an actual solution?
    Since you already have the MSD magnetic pickup distributor, I'd first try using the proper Magnetic Ignition Type Parameters.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #19

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    With as much of a hassle as this MSD setup has been, I wish I would've started out with the Dual Sync Distributor too.

    I'll be gone most of the weekend, but I will try to come back early enough to load the new parameters and give those settings a shot. Hopefully I can keep Monday open for test driving & tuning.

  10. #20

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    It's unfortunate that the Minimum Signal Voltage adjustment can not be done with the touchscreen. Maybe a little adjusting of the Minimum Signal Voltage would get the car home.

    Here's an interesting case where a Sniper won't idle if a large air cleaner base is near the Sniper, but not touching it; Holley Sniper EFI cutting out with Cobra air cleaner. That person claims the problem exists with both MSD & Dual Sync distributors. Whatever the problem turns out to be, it's a good example of electrical "noise". Chevys may have less of this problem with the distributor further from the Sniper ECU. Fords have the distributor cap nearer to the ECU & wire harness.

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