BluePrint Engines

Visit our community sponsor

Thanks Thanks:  3
Likes Likes:  20
Page 2 of 2 FirstFirst 12
Results 41 to 65 of 65

Thread: Backfiring, why?

  1. #41
    Senior Member Geoff H's Avatar
    Join Date
    Feb 2011
    Location
    Edmonton, Alberta
    Posts
    195
    Post Thanks / Like

    Holley Forum

    I found found the Holley Sniper forum helpful:
    https://forums.holley.com/forumdispl...?82-Sniper-EFI

    Although not the same history, a quick search found something similar:
    https://forums.holley.com/showthread...-FINALLY-FIXED!

    Geoff

  2. Likes AJT '33 liked this post
  3. #42
    Member
    Join Date
    May 2018
    Location
    Australia
    Posts
    79
    Post Thanks / Like
    I'm not familiar with the sniper but could it be ignition interference? It's hard to tell from the video, but I assume you'll have an RPM value on the display. Is it fluctuating when you hear the pops? You'd also pick this up with a timing light I would have thought.

    Make sure the crank angle sensor (or whatever the sniper uses for timing reference) wiring is well clear of the ignition leads. Spark is generated at 20,000+ volts and will easily induce electrical noise into a low voltage (~5v) signal cable used for timing reference if not correctly routed. I would think the sniper signal cable should also be shielded and earthed.

  4. #43
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    I have no idea what the sniper requires....
    You stated 60 psi first then 75 psi later, what pressure does the sniper require in the manual?
    If you have higher pressure, you will push more fuel through the injector than the computer expects. The computer has To wait untill the hego reaches 600 deg. To get a good reading. If you only have one hego, than the other head is just a calculated guess for afr.
    When it first starts, it will run on the cold fuel table untill the hego starts, then the computer will start adjusting. When you start, it runs ok, then warms up and starts popping. When you turn it off then restart it when hot does it start popping immediately? If it always starts ok then popps when hot, i would look at the computer switching from base fuel when it heats up. Also, does it pop out one side only?
    I know this info does not directly point to a fix. Just some details I found when fighting my FI issues!!
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  5. #44
    Papa's Avatar
    Join Date
    Dec 2016
    Location
    Parker, CO
    Posts
    5,594
    Post Thanks / Like
    This post looks very similar to the symptoms you are having:

    https://forums.holley.com/showthread.php?45658-
    My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
    (Most viewed Roadster build thread on this forum!)

    Delivered: 6/17/2017
    First Start: 12/30/2017
    Completed: 12/7/2019
    Legal: 1/30/2020

    Member of the Mile-Hi Cobra Club
    Dave's Cobra YouTube Channel: https://www.youtube.com/channel/UCbk...npK1UZHj4R-bYQ
    Agora 1:8 Scale Cobra Build: https://thefactoryfiveforum.com/show...l-Build-Thread

  6. #45
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Quote Originally Posted by Geoff H View Post
    I found found the Holley Sniper forum helpful:
    https://forums.holley.com/forumdispl...?82-Sniper-EFI

    Although not the same history, a quick search found something similar:
    https://forums.holley.com/showthread...-FINALLY-FIXED!

    Geoff
    I was searching that same forum about the same time as you apparently, thanks for posting. I'm waiting to be fully approved on that forum so I can ask questions, etc. It's interesting that a nonworking injector has been seen by more than one or two.

    Quote Originally Posted by Papa View Post
    This post looks very similar to the symptoms you are having:

    https://forums.holley.com/showthread.php?45658-
    Yeah it sure does. Although it seems my symptoms are more frequent. That may be explained by the fact he's gone a bit further down the Sniper verification and tuning process than I have.
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  7. #46
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Quote Originally Posted by Just puttering View Post
    I have no idea what the sniper requires....
    You stated 60 psi first then 75 psi later, what pressure does the sniper require in the manual?
    If you have higher pressure, you will push more fuel through the injector than the computer expects. The computer has To wait untill the hego reaches 600 deg. To get a good reading. If you only have one hego, than the other head is just a calculated guess for afr.
    When it first starts, it will run on the cold fuel table untill the hego starts, then the computer will start adjusting. When you start, it runs ok, then warms up and starts popping. When you turn it off then restart it when hot does it start popping immediately? If it always starts ok then popps when hot, i would look at the computer switching from base fuel when it heats up. Also, does it pop out one side only?
    I know this info does not directly point to a fix. Just some details I found when fighting my FI issues!!
    I originally stated 60psi as this was one of the very first starts, there was a lot going on and I actually didn't look at the gauge while it was running. When I stopped the engine, I looked over at the gauge and it was 60 at the time. The Sniper has a built in regulator so it's fine as long as you're providing it with that much or more. I've now established that when everything is running, the input PSI is around 75 for the RPMs I've seen so far.

    Yes, there is only one O2 sensor. That's all the Sniper provides for. I'm not sure if it's popping out of one side only or not.

    Thanks for the explanation on the base fuel map and the switchover. That may be something to look at. I'm wondering though that if that is the problem then why don't the setup instructions deal with this. We are not talking about a wild exotic combination of parts here nor are we talking NOS or forced induction. As such, this problem should be fairly commonplace and dealt with in the standard instructions.

    At this moment I'm thinking that, in order of priority, the to do list is: a) verify that all injectors are working, b) try changing the idle timing significantly, c) if none of that works then try adjusting the fuel maps.

    Still waiting to hear from Holley tech support. In the mean time, I'll try to get a data log - something new to learn.
    Last edited by FF33rod; 05-09-2019 at 12:18 PM.
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  8. #47
    Consummate Learner TxMike64's Avatar
    Join Date
    May 2017
    Location
    Kingsland, TX
    Posts
    403
    Post Thanks / Like
    Blog Entries
    1
    Another idea...

    Disconnect the O2 sensor. As as said above, the HEGO sensor has to reach temp before sending the correct signal to the ECU, then the ECU switches from the open-loop base map to a closed-loop map. With the O2 disconnected the ECU will stay on base map (or go into a safe mode). That may be why it runs smooth for 15-20 seconds, then switches and starts popping. With the O2 disconnected if it keeps running smooth it may indicate mechanically everything is fine, and it's either an exhaust leak or something in the pre-programmed closed-loop map. If it starts popping again, it may be timing or mechanical (sticking valve, tappet, etc). Something to consider, these self-tuning EFI systems need to run for quite some time in closed-loop to adjust all the settings. As such you may need to adjust the map just to get it going, then it can adjust itself from there.

    I don't want to throw too many ideas at you... If all if us get you chasing too many different things, then you'll just get more frustrated... But just trying to think through this for myself as well.
    -- Mike -- TxMike64 -- @TxMGarage
    Gen1.5 Hot Rod '33 #1094 (Stage 1) - 302/AOD '15 IRS - Quad Built - Build Thread

  9. Likes FF33rod liked this post
  10. #48
    Senior Member johnnybgoode's Avatar
    Join Date
    Mar 2011
    Location
    Ottawa Ontario
    Posts
    254
    Post Thanks / Like
    Anyone in your area that could lend you a 650-750 carb? If it ran OK then at least it would isolate your problem to the EFI? Just a thought. Sorry for your trouble. Scott

  11. #49
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Quote Originally Posted by johnnybgoode View Post
    Anyone in your area that could lend you a 650-750 carb? If it ran OK then at least it would isolate your problem to the EFI? Just a thought. Sorry for your trouble. Scott
    I would also need a distributor as well. You can use a Sniper with a standard distributor but you can't use a HyperSpark distributor without the sniper (no mech adv, no vac advance)
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  12. #50
    Senior Member
    Join Date
    Nov 2017
    Location
    Placitas, NM
    Posts
    1,443
    Post Thanks / Like
    Let me ask maybe a stupid question (I know next to nothing about a Sniper)....you said the O2 sensor was in the J pipe.
    The J pipe that came with my '33 was the pipe the exhaust came out of just in front of the rear wheels if I didn't use the rear exhaust (which I am).
    Is this where your J pipe and O2 sensor is located, and not up by the exhaust manifold? If so the O2 won't be reading correctly.
    '33 Hotrod, #1047 Gen 1, delivered on 2/27/18, go cart on 9/24/18.
    LS3 w/Gearstar Level 3 4L65e Tranny, Yank converter, Lokar shifter, Electric PS, Vintage AC/Heat/Def, 8.8" 3.55
    TorqThrust II Wheels w/Toyo Proxy T1 Sport Tires, F 235/45ZR17 R 295/35ZR18
    Garage Built, Driveway Painted.

  13. #51
    Member
    Join Date
    Oct 2018
    Location
    ada minnesota
    Posts
    93
    Post Thanks / Like
    blue print engines can supply a decent distributer w melonized gear for reasonable price
    after running fords for 3 years I think I got about 6 ignition systems hidden somewhere and a
    supply of 8 water pumps that never fit where I want them too

  14. #52
    Senior Member johnnybgoode's Avatar
    Join Date
    Mar 2011
    Location
    Ottawa Ontario
    Posts
    254
    Post Thanks / Like
    Quote Originally Posted by FF33rod View Post
    I would also need a distributor as well. You can use a Sniper with a standard distributor but you can't use a HyperSpark distributor without the sniper (no mech adv, no vac advance)
    I was thinking you could leave all of the electronics connected to run the dizzy.

  15. #53
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Quote Originally Posted by JimLev View Post
    Let me ask maybe a stupid question (I know next to nothing about a Sniper)....you said the O2 sensor was in the J pipe.
    The J pipe that came with my '33 was the pipe the exhaust came out of just in front of the rear wheels if I didn't use the rear exhaust (which I am).
    Is this where your J pipe and O2 sensor is located, and not up by the exhaust manifold? If so the O2 won't be reading correctly.
    Maybe I have the terminology wrong, thought the J-pipe was the first pipe that attached to the shortie headers. Anyway, that transition pipe that goes from the shorties and turns down under the firewall is where the O2 sensor is.

    So here is this evening's update.
    - looked down the throttle bodies and all 4 injectors seem to be working. So the problem of bad injectors mentioned on the Holley forum is not my problem.
    - I changed the idle timing to 20 BTDC from 15, another item that worked for some people on the Holley forum. No joy, same problem
    - lastly I unplugged the O2 sensor, absolutely nothing different at all.

    Unfortunately, my attention for the next few days will be directed towards Mistress #1 so I won't be able to try anything new. That plus business travel early next week means I likely won't be looking at the engine again until mid next week. In the mean time, I'm sure we'll have more theories....

    Thanks again for all the help guys.
    Steve
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  16. #54
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    Curious if checking the compression would show anything if you have a valve problem???
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  17. #55
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    On ford efi you pull the spout plug and set timing. Then re-install the spout plug and the computer runs the timing from there. If you dont re install the spout plug or let one of the plug wires push out and not make contact, it causes all sorts of grief. I discovered the computer couldnt advance the timing because of this and i was trying to chase other causes of my issues. With computer control, you want your timing set, then dont move it!!! Check with a timing light that the computer is advancing the timing!
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  18. #56
    Member CNIdog's Avatar
    Join Date
    Feb 2011
    Posts
    76
    Post Thanks / Like
    Quote Originally Posted by FF33rod View Post
    Okay, so managed to have a first start a week or so ago but didn't have the cooling system finished off so I couldn't run it much at all. So now have that in place and put the mufflers on it so that I could run it in for 20 minutes or so. Gotta say, not a whole lotta difference adding the mufflers! But the problem I have is the engine starts fine and then after a few second I start here "pops", it starts backfiring. Seems to get worse the longer I let it run. I double checked distributor relative to TDC, seems to be close. Then as it was idling I moved the distributor around a little to see if it would help, it didn't. What now?

    Setup - Ford 347, short block with Trickflow Stage 2 cam installed from TRE performance, AFR 195cc heads, Edelbrock RPM Air gap manifold, Holley Sniper and Holley Hyperspark distributor and ignition....

    This is a brand new engine, so I do not have an old standard ignition system to put on it to start off. Have to run with the Sniper controlling the timing. Followed the setup procedure for the Sniper - running the setup wizard sets displacement, # cylinders, etc. As I said, starts fine but then.....

    Is there any chance the dizzy is 180 degrees out of phase? I have zero experience in building engines but I thought that if it's 180 out then it wouldn't even start. Not sure what else to try though....

    Suggestions please. Thanks guys
    Steve

    Edit: note that a video has been added, post 24 below which demonstrates the "popping" issue much better than can be described in a post
    Is the timing pointer index at the 11 o'clock position over the harmonic balancer? I read about a replacement index or new harmonic balancer moving it to the 1 o'clock position causing problems.

  19. Likes FF33rod liked this post
  20. #57
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Started working with the Holley Sniper forum to see if they could give some insight into what's going on. Slowly eliminating different things.
    Today I've pulled the valve covers and plugs, going to double check the hydraulic lifter settings and such.
    Interesting discovery on the plugs - cylinders 2,3,5 and 8 are all fouled (lookiing very rich). Interestingly, these all correspond to the lower plane of the Edelbrock Performer RPM air gap dual plane intake manifold.

    IMG_2843a.jpg
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  21. #58
    Senior Member Geoff H's Avatar
    Join Date
    Feb 2011
    Location
    Edmonton, Alberta
    Posts
    195
    Post Thanks / Like
    I run the same intake. Just a side story as its likely not related to the backfiring you experience, but on first drive mine squealed like I had a belt loose. A bit of searching on the sniper forum and found it was common with a dual plane manifold. The fix was to install a four hole 1/4" spacer.

    Good luck with the trouble shooting.

    Geoff

  22. Thanks FF33rod thanked for this post
  23. #59
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like

    A most embarrassing moment

    Well gentlemen, as the title suggests, I found the problem and it's one of life's more embarrassing moments. When I discovered it, I laughed myself silly.

    The problem was narrowing down to an intake leak so I was looking around the Sniper and intake manifold contemplating on what to disconnect and in what order to get the manifold removed. The rear bolts on the manifold are quite close to the firewall and I was contemplating access when I glanced at the backside of the intake manifold plenum just an inch or two below where the Sniper mounts and there it was staring at me in the face, an unsealed port into the intake manifold. I don't remember ever seeing it before and I have no idea what you would use it before unless you can use that for the PCV instead of a port on the carb but I hadn't sealed it. Not that it would have made a difference but interestingly I just looked at the Edelbrock instructions and the port doesn't even show up on their port diagram.

    So, after I finished laughing at myself, I found a plug, added a thread sealer, put it in and gave it a crank. Started up and purred like it should. I now have the idle and timing setting stuff to do and check but major hurdle overcome.

    Thank you for all your help and sorry to waste your time but maybe you can get a bit of a giggle out of it as well. Definitely a newb moment.

    Cheers
    Steve
    Last edited by FF33rod; 05-20-2019 at 07:37 PM.
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

  24. Likes Papa liked this post
  25. #60
    Consummate Learner TxMike64's Avatar
    Join Date
    May 2017
    Location
    Kingsland, TX
    Posts
    403
    Post Thanks / Like
    Blog Entries
    1
    Funny! Glad you figured it out... Sometimes we get stuck looking for the catastrophic failure when it's really just something minor.
    -- Mike -- TxMike64 -- @TxMGarage
    Gen1.5 Hot Rod '33 #1094 (Stage 1) - 302/AOD '15 IRS - Quad Built - Build Thread

  26. Likes FF33rod liked this post
  27. #61
    Senior Member Joel Hauser's Avatar
    Join Date
    Mar 2016
    Location
    Albany NY
    Posts
    259
    Post Thanks / Like
    Congratulations! And good detective work. Intake air leaks are hard to pinpoint for sure.
    It took me a year and a half to trouble shoot my own miss firing troubles on a more or less stock mustang EFI motor. But unlike you I wasted not just time but also a couple hundred dollars replacing parts that didn't need replacing before I solved my problem with a new ECU.
    From this point forward, as Bob Dylan might say, "might your hands always be busy...may your heart always be joyful." It's smooth sailing from here on out....hopefully.
    Joel

  28. Likes FF33rod liked this post
  29. #62
    Senior Member HVACMAN's Avatar
    Join Date
    May 2017
    Location
    Village Mills, Texas
    Posts
    674
    Post Thanks / Like
    I'm glad it turned out to be a simple fix. Maybe the port for the power brake booster?? It reminds me of a saying my Dad had and it has proven to be true. "It takes 15% of your time to fix 85% of your problems and the other 85% of your time to fix that last 15%
    33 Hot Rod (Gen 1) Stage 1 delivered on 4/27/2017, Stage 2 delivered on 9/21/2018
    LS3 495hp/480 lb. ft., 4L70E, Electric PS, Classic Auto Air, Lokar electronic sport shifter, 13 inch Wilwood front and 11.68 Cobra rear brakes, Ford 8.8 w 3.73 w 4 link, Billet Specialty Legend Series MAG wheels and Mickey Thompson
    Sportsman S/R 26x8x18 front and 29x18x20 rear tires.

  30. Likes FF33rod liked this post
  31. #63
    Senior Member Geoff H's Avatar
    Join Date
    Feb 2011
    Location
    Edmonton, Alberta
    Posts
    195
    Post Thanks / Like
    Congratulations Steve! That's awesome! Good that you could laugh at it all - life's tuition.

  32. Likes FF33rod liked this post
  33. #64
    Senior Member
    Join Date
    Aug 2015
    Posts
    1,213
    Post Thanks / Like

  34. Thanks FF33rod thanked for this post
  35. #65
    Senior Member FF33rod's Avatar
    Join Date
    Jun 2018
    Location
    North Vancouver, BC, Canada
    Posts
    1,554
    Post Thanks / Like
    Quote Originally Posted by wrp View Post
    so much to play with on these.... Thought it was just plug and play, LOL
    Gen 1 '33 Hot Rod #1104
    347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Replica Parts

Visit our community sponsor