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Thread: At a loss, backfires big time.

  1. #11
    Join Date
    Dec 2009
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    Connecticut
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    27,037

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    Repair the fuel injector connector. https://forums.holley.com/showthread...618#post241618 (Related Forum Thread)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

  2. #12

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    Quote Originally Posted by Johnret View Post
    Left driver side remains dry.
    Front or rear? If it's the rear, sure you could try the progressive function to make it idle, but anything after that'll require significant GCF change.

    I didn't look at the previous link posted yet, but I will. In the meantime, pull the side cover off and check the connector for proper engagement. If it's plugged in properly, move the injector to another known good location and see if the problem follows the injector.

  3. #13
    Join Date
    May 2019
    Location
    Missouri
    Posts
    11

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    OK, so I sent the Holley Sniper back to Holley. They fixed it. Didn't tell me what they fixed, but my unit came back. One week turn around, with new harness installed. Reinstalled it, seems to be working pretty good. Could someone look at the most recent Config File and datalog to see if I'm doing this right. Thanks.
    X2-21-20-A.zip

  4. #14

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    Too lean at WOT. You have AFR of 13.6, which is too lean. For WOT it should be 12.8.

  5. #15
    Join Date
    May 2019
    Location
    Missouri
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    11

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    I'll change that.

  6. #16

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    After a quick look, I noticed you don't have a rev limit set to a realistic number.

    Where is the WBO2 located? Based on the datalog it looks like you could slow down the CL Comp rate to 2 or even try 1.

    Looks like it's time to Transfer Learning To Base and let it Learn some more.

    If you plan on starting it when it's cold out, you could restructure the A/F Ratio Offset staring at -.6 or so.

    The Base Fuel Table needs some work. I don't like the excessively lean deceleration areas, they generally lead to unpleasant slow tip-in situations. You have some excessively rich decelerations. You have some excessively lean roll in areas.

    You also have some EMI that's worth starting to make adjustments to see if you can find it.

    Based on the datalog it looks like you have a miss or incomplete combustion that may be related to secondary ignition or tune related that'll take some investigating to solve. If you don't feel it during the drive, I wouldn't freak out about it, but I'd like to solve it.

    Even after that quick look, I'm sure you're much happier with the way it runs compared to missing an injector prior to this.

    Oh yeah, IMO there's no need to go crazy with the restructuring of the Target AFR table. There's much debate and R&D on the subject of best AFR for a particular situation. Most situations have a broad range as to what's best and there are a lot of variables that go into it. Basically you have to figure out what works best for what you want. For example, the max best torque AFR can range from 12.5 to 13.5 on a particular setup, so don't get hung up on one particular number as what you have to use. Then that number can change drastically with a small change in fuel chemistry, so for now try not to over think it. With that being said, some of those lean spikes that look like a miss, may be solved with just lowering the Target AFR a tenth or two.
    Last edited by a b c; 11-22-2020 at 11:09 AM.

  7. #17
    Join Date
    May 2019
    Location
    Missouri
    Posts
    11

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    My setup doesn't have the Holley Sniper controlling timing, Holley Tech support told me I didn't have to adjust anything under the Spark parameters. Maybe after I get this thing tuned I'll add controlled timing.

    My WBO2 sensor is located on the driver side exhaust tube behind the header collector.

    The engine seems to start fine in cold weather with the A/F Ratio Offset the way it is, and the Help file says the typical setting of -2 should be enough to use for cold weather starts. I'm a little leery of changing this if the engine is starting OK. I've already had to replace a set of spark plugs due to the injector problem. Trying to stay away from running it too rich, I guess I'm gun shy.

    I'm fairly new at this so I don't understand the terms "slow tip-in" and "excessively lean roll". The Base Fuel Table is somewhat of a mystery to me, I do understand it works with the Learn Table, and the ECU tries to adjust to meet the Target AFR table. But as far a working with a deceleration, or how to change the Base Fuel to affect deceleration has me confused.

    I've had the system for two years, and the RFI/EMI problem was terrible when I first installed the system. I've rerouted all the +12V circuits (i.e. in cab circuitry, alternator) through the front radiator support just to get it away from the Holley. If I have RFI problems they are minuscule compared to where I was. I'll take another look at it.

    The truck drives great now, but I know it could be better. I'll work a bit with the AFR to try & cleanup the lean. Thanks for all the input, I really do appreciate it.

  8. #18

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    If you want to learn it, ask your questions and we'll help. If you want me to answer what appears to be questions about the terminology just ask me to elaborate for you.

    As far as being leery about changing things don't be, that's the beauty of the EFI system. Once you become fluent with opening and saving GCFs, you can have as many as you want and change them out in seconds. Unlike a carburetor, if you want to make significant changes you're going to be at it for a significant amount of time & expense.

    If you don't care to learn it and want it to be as close to as good as it can be, pay one of these pros that frequent here to remote tune it for you.

    For those that just want it to run the way they think it should and don't care/don't want to learn it (which is fine, we all have our niche in life), I think the investment in a package of remote tuning sessions from someone that's very familiar with the Sniper is well worth the money.

    I know there are several pros on here and I'm sure they will chime in. As for now you could look at the EFI Systems Pro website.

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