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440 Mopar stumbling & stalling when cold.

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  • 440 Mopar stumbling & stalling when cold.

    Alright I've been through the forums and can't seem to find a similar topic unless I'm blind. So to start things off, I installed the Sniper system in the summer and had no problems at all with it. Started instantly and ran very well over the summer and into the fall. However, now that it's getting colder it has developed a problem. I now have to cycle the key a couple times to prime enough fuel into the intake to get it to start. It also only runs on what sounds like half the cylinders and any throttle kills it. After a few minutes of the engine running like this can get it into the street where if I'm careful enough I can give it throttle past where the IAC works and it'll run alright. Another problem starts when I'm coming to say a stoplight or parking lot while it's still under 185F. It will continue to stumble and I have had it die on me multiple times. To get it to restart I've got to cycle the key at least four times to get it to begrudgingly start back up. The weird part is this all goes away once the engine is warm. I'm new to the forums and I'm doing this on my phone so I'll post this and add the datalogs I got from today as it was idling and just dies out of nowhere.
    UPDATE: The forum says I cannot attach the DL files, so I'm not sure how to link them.
    Last edited by Rchab; 11-22-2022, 09:21 PM.

  • #2
    The cold Temperature Enrichment & Startup Enrichment parameters need to be "tuned".
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232-244 duration/.623" lift/114 LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM C6 converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, 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.

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    • #3
      I've already upped the percentages on both of those and it did not seem to change the situation at all. Would it need more? I can't remember off the top of my head what I changed the graph to, but if needed I'll run out and get it.

      Comment


      • #4
        Forum members will want to see your Config File and a datalog of this occurrence. This is a copy & paste from one of my other posts:
        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 ("Upload 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 Logs" folder (.dl file).
        Someone will analyze/troubleshoot the problem & offer advice.​
        https://www.youtube.com/watch?v=iqHOtDNiTNA (How To Record & Email A Datalog)
        https://forums.holley.com/showthread.php?21942 (Holley Sniper EFI Save GCF On SD Card & Laptop/PC Usage, LINK - Page 73)​
        May God's grace bless you in the Lord Jesus Christ.
        '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232-244 duration/.623" lift/114 LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM C6 converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, 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.

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        • #5
          Here's the files.
          Attached Files

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          • #6
            When the engine is fully cold after sitting overnight turn on the ignition and navigate on the handheld to the monitors. Compare the CTS & MAT readings. If the CTS is reading 10 or more higher than the MAT, the CTS is faulty. It can easily be 20 off on a cold start and the system will not provide the correct cold start fuel nor the proper cold temperature enrichment. I'll look at your files a little later.

            Your description also sounds like you may have lost one of your injectors. After the CTS check, remove the air cleaner and have someone turn the ignition on. Watch to ensure that all four injectors are providing a prime shot.

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            • #7
              I did check the injectors today and all four are working correctly. I'll check the CTS & MAT tomorrow and post what I find.

              UPDATE: After sitting in my garage overnight.​ MAT 60F, CTS 75F​​​​

              Comment


              • #8
                It might be too rich when cold. I looked at a couple of datalogs that you posted, but the engine was already warmed up in them. You need to capture a datalog when the engine is dead cold and look at it. The AFR will either be too rich, or too lean when the engine is dead cold. Once you figure that out then you can fix the problem.

                Watch this video a few times. It's kind of boring, but there are a lot of details in it so pay attention to the numbers on the screen. This is a cold start of my 600 HP Mopar big block. This car starts dead cold with my foot off the pedal. I can reach in the window and start the car when it's cold and I never have to touch anything. It warms up by itself or I can jump in and drive it when it's cold. https://youtu.be/hK5YA2ab8T8

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                • #9
                  Originally Posted by Danny Cabral
                  Sniper EFI Replacement Sensors - Auto Parts Store
                  CTS Sensor: Standard Motor Products TX3
                  TPS Sensor: Standard Motor Products TH191
                  IAC Motor: Standard Motor Products AC416
                  WBO2 Sensor: Bosch 17025, 0258017025 (LINK/LINK/LINK)
                  (The Sniper EFI 2 bar MAP sensor is internal with the ECU.
                  The Sniper EFI IAT sensor is a circuit board sensor that measures one throttle bore.)
                  Innovate Motorsports HBX-1 Heat-Sink Bung Extender is great for protecting the WBO2.
                  https://www.holley.com/brands/holley...ce_components/ (Sniper EFI Service Components)












                  Replace the CTS with the TX3 or equivalent. They are available from local parts stores. Most aftermarket units work well, but you should repeat the cold reading at some point. If you start changing the tune with inaccurate temperature readings it often makes things worse elsewhere. The Cranking Fuel and After Start Enrichment % are adjusted by temperature, so the colder it gets the more you would have to fiddle with multiple primes, etc.

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                  • #10
                    Thought I got one from cold start, but I'll get a datalog tonight from cold start. Either way the engine was still stalling at idle in I believe it was the third datalog, but I can't recall without looking at them (at work right now). I'll look over them again and find the exact file and time it happened.

                    Comment


                    • #11
                      Here's the datalog from the cold start I had tonight. I've included a video clip as well to show what's going on with the stumbling. It started a lot better than it did yesterday which may be caused by the slightly warmer weather we had? One thing that's new however, is the addition of the little pops in the exhaust as heard in the "cold start with datalog" clip. For reference this engine is pretty much stock so all of the lope is caused by whatever the problem is.
                      Attached Files

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                      • #12
                        That last datalog is interesting. Actual AFR is not reaching the Target AFR for some reason. When actual doesn't reach Target you have a fundamental problem. I don't know what the problem is, but for some reason the Sniper can't do what it's being told to do.
                        You also have a weird issue with the RPM. On a very regular basis the RPM drops out. Appears to be consistent which could be a mechanical problem. Almost looks like a dead cylinder but I've never seen a dead cylinder cause an issue with the RPM gauge before.

                        Comment


                        • #13
                          I think I checked all of your uploaded files and I can't find the actual downloaded Config File. It will be in a folder called Saved GCF on the SD card. Name it something unique so it won't be confused with the Wizard setup files. What's your exact ignition setup? The MAP reading is fairly stable for such a crazy RPM signal. The fuel flow is high and the Closed Loop Compensation is high which could be consistent with low fuel pressure since you checked to see that all four injectors were firing.

                          In the cold start datalog your battery voltage is only 11.9V before the start and there's some noise on the signal before the engine is started. Where do you have the pink wire attached. When it first starts the battery voltage is still only 11.9V or so until is gradually rises. The Sniper tends to not like lower voltages as this can affect injector operation. Fuel pump performance may also be reduced at low voltage.

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                          • #14
                            Here's another cold start with the saved GCF as well. For the ignition I have the stock points style which is running coil - in the sniper. As far as the RPM I have no idea what's going on with that, for me it reads far over a million RPM on the datalog which is clearly wrong. The switch power (pink) wire is connected to where my voltage regulator would be connected up to. I have a one-wire alt now so it was just an open hot connection that I reused. I have upped the coolant compensation, Cranking Fuel, and After Start Enrichment % if that affects what you're seeing. It does seem like it starts and runs better by doing that, less stumbling and it hadn't died on me coming up to stoplights this time.
                            Attached Files

                            Comment


                            • #15
                              You have some power issues somewhere. Once it starts in the 0006 datalog there are seconds-long gaps in the datalog. Prior to the start the datalog data points are properly spaced. You're making tuning changes to a system that's not running properly which often doesn't work well in the long run. Get it to the point where you have a clean consistent datalog of the system at idle and then consider changes.

                              You have a slightly older version of firmware in your Sniper. I can open and view your full datalog using the version 1.2 Build 26 EFI software and it does not show RPM when using version 1.3 Build 50 EFI software. You either need to install the older EFI software version or update everything to the latest firmware.

                              Even with the 1.3 Build 50 EFI software you can see the problem with the datapoints. View the datalog and right click in the center of the graph and select Mark Data Points. If you zoom in or pan across you can see the proper spacing at the beginning and then it goes crazy after the engine starts. I suspect that your pink wire location is the issue. For a test, connect the pink wire directly to the battery positive terminal and have someone start a datalog and then start the engine. If you get a clean datalog this will tell you that you need to connect to the battery using a relay triggered by your ignition switch. I'd avoid any more tuning changes until you sort this out.

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