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Thread: Random AFR spikes, sometimes it stays.

  1. #1

    Default Random AFR spikes, sometimes it stays.

    I’m having an issue with my AFR spiking to mid-15 AFR from my target and sometimes it holds in the mid 15 until it starts to foul plugs. Posted this issue some time ago and we all thought it was a bad WBO2 sensor, but since then I've replaced the sensor three times and the problems returns. Sometimes within a day and sometimes 3 to 4 days. I can always put it in “Open Loop” and it starts and runs great, so don’t think it’s a tune issue. Just wish I could find the cause. If you look at any of the Datalogs, in the “Mark Data Points” view you see inconsistent data points and I wonder if that gives any clue as to the cause? Also, if you look at “CL Comp” you can see it tries to correct, but for some reason it doesn’t read the feedback.

    For reference this is a 1931 Ford Model A with SBF 302 pretty much stock. Picture of engine area is just to help in investigation. Main Sniper power wires are direct to battery. Engine is ground direct to battery, frame to engine, and body to frame. I've removed the air cleaner and no change. My last thought is to replace the plug wires. They are RFI suppression, but not the best quality. It has Dual Sync distributor. Any suggestions as to where to look or what to check?
    Attached Files Attached Files

  2. #2

    Default

    Really need some help on this one. Would some of you guys that understand the Sniper and it's wiring review the datalogs and give me some ideas where to look or check?

  3. #3

    Default

    That behavior doesn't sound like a bad wideband to me, sounds more like a bad ECU or a bad tune file.

    If the wideband is saying 15:1 and you don't think the tune is calling for 15:1 then you either have a weird tune, or you have a bad ECU. First thing is to check your tune to make sure that you aren't actually asking for 15:1. There are multiple enrichment tables and offsets and such, so it is possible for the tune to have a weird step in it. If you're positive that the tune isn't asking for 15:1 then you have a bad ECU. Either the ECU is corrupted internally and can't process the tune file, or you have RFI noise that is confusing the ECU. My guess is RFI noise since that's a very common problem, but you could also just have a bad ECU. Perhaps some sort of loose connection internally or a defective chip or something like that.

    Snipers with weird random problems are almost always RFI noise related. Another option is a corrupted file of some sort so you can always try updating the firmware and then building a new tune using the Wizard. That trick sometimes works. The Sniper is a Windows based system so rebooting, restarting and reloading are always good tricks to use.

  4. #4
    Join Date
    Oct 2017
    Location
    Los Angeles
    Posts
    399

    Default

    Can you post your Global Config File?
    1964 Chevy Nova, 383 Stroker, AFR 210 Heads, Ford 9inch w/TrueTrac/3.90 Gears, Powerglide Transmission. www.SoCalStreetCars.com

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,085

    Default

    Originally Posted by Danny Cabral
    For further assistance, post your Config File and a short datalog of this occurrence for us to analyze.
    Also, review the datalog and inform us of exactly where in the datalog (time/seconds) the problem occurs.
    Datalog & Global Files can be linked to a document hosting website. I use Dropbox.com.
    Files can also be "zipped" (compressed zipped folder) & attached directly to a forum post ("Go Advanced" & "Attachments").
    Your Config File is in the "Documents", "Holley" folder, "Sniper" folder, "Config Files" folder (.hefi file).
    Your Datalogs are in the "Documents", "Holley" folder, "Sniper" folder, "Data Log" folder (.dl file).
    Someone will analyze/troubleshoot the problem & offer advice.
    https://www.youtube.com/watch?v=iqHOtDNiTNA (How To Record & Email A Datalog)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  6. #6
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,453

    Default

    Quote Originally Posted by smithgolfdan View Post
    I’m having an issue with my AFR spiking to mid-15 AFR from my target, and sometimes it holds in the mid 15 until it starts to foul plugs.
    My first thought when I see this statement is ignition. If the actual AFR was 15:1, why would it foul plugs? Fouled plugs usually happen with a rich AFR. But since it's a WBO2 sensor and reads O2 not fuel, a bad burn will read as lean because of all the unburnt O2.

  7. #7

    Default

    Yes, that is a possibility. If the ignition system is not working properly then the misfires will confuse the WBO2 sensor. The 15:1 reading is a false positive. The ECU tries to add fuel and causes more problems, since the engine wasn't actually lean. This could be what is happening with the OP, but he'll have to do some detective work to sort it out. Changing the WBO2 sensor doesn't solve anything. Pulling the spark plugs is the first thing to do then go from there. Changing the spark plug wires, checking system voltage, running a compression check, etc. are all good things to do.

  8. #8

    Default

    Here is file with Config File, Datalogs and some pictures per request above. I did talk with Holley Tech today and he said it was the coil being to close to the ECU (see picture). I tried wrapping it and doing a Datalog, but didn't see a lot of difference. Also, I tried removing Air Cleaner and covering ECU, but again I didn't see any difference. Just to follow up on some of the comments above, Andy is correct; if you look at the Datalogs you'll see when it goes to the mid-15s the CL Comp goes to 20% (my max setting), but for some reason it doesn't seems to read the correction. I did pull the plugs and they looked good to me with a gray burn look, but I changed to NGK resistor plugs and added new FireCore50 plug wires.
    Attached Files Attached Files

  9. #9
    Join Date
    Oct 2017
    Location
    Los Angeles
    Posts
    399

    Default

    One thing I noticed and needs to be fixed before changes are made is there are no values in your learn table which means the ECU is not learning even though in the data log it clearly says learning. Your GCF is corrupted and you need to start over. If it were me I'd re-run the wizard again, and see if you can start to get values in the learn table. On a side note you clearly have no evidence of EMI.

    Also, your learned compensation limits are set to 10%, and your closed loop compensation limits are set to 20%. If this was my car I'd set the learn parameters to 100% and closed loop parameters to 100% and let the ECU learn. I'd re run the wizard to get a clean non corrupted GCF and make sure those limits are increased before driving or letting the car idle.
    Last edited by RPnova; 11-04-2019 at 05:37 PM.
    1964 Chevy Nova, 383 Stroker, AFR 210 Heads, Ford 9inch w/TrueTrac/3.90 Gears, Powerglide Transmission. www.SoCalStreetCars.com

  10. #10

    Default

    RPnova: The Learn is working. I meant to tell everyone that I Cleared the Learn Table after making the datalogs due to the amount of fuel in was shown that it added due to maxing out the Limits. As I said in the first post, if you put it in Open Loop it runs great. The Limits of both Close Loop and Learn have been reduced as I got good data and it Learned. Everyone has said I don't have RFI, but if you look at the Datalogs in Mark Data Points you'll see a lot of inconsistent data points. Not sure if this is why the ECU is not reading the corrections when the Closed Loop tries to correct. At times it will correct and run fine and others it will stay at mid-15 and start to load up.

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