Stalling When Warm

[Evan_P]

Hello there. Posting up here, hoping for some help. I installed a Sniper EFI setup over the last weekend on a friends early Bronco with a 351W. HyperSpark distributor, HyperSpark coil and HyperSpark ignition box. Install went well, but had some issues out the gate when it came to getting it running. Lots of stalling, idle fluctuations, very hard to start cold and almost unable to start when hot. I verified fuel pressure is good at 58-62 psi. Verified timing is on using the handheld to lock timing and checked with timing light. After some time fiddling I suspected RFI in the system. I had placed the coil fairly close to the engine harness. I moved the coil about four inched away from the harness and that drastically improved things. It will now fire right up cold and go to its elevated idle. Idle does come down over time as it comes up to temp. I'm now facing a stalling issue. It occurs sometimes when cold, more so when warmer. The engine will be running nice and smooth and then shuts off as if someone turned the key off. However, the touchscreen stays awake, the fuel pump runs for its five second prime sequence. The truck will fire right back up as if nothing happened, will run for 10-20 seconds and repeat. I verified the light on the HyperSpark ignition box is staying green until after the engine dies at which point it turns orange. I suspected maybe it was losing the +12V keyed power, so I connected the pink wire direct to battery and tried it and the same issue occurs. I've taken a datalog of the event. First thing that jumps out at me is when it does the datalog, it seems to start back over itself. It's almost as if the system is resetting itself when it's running. I've attached the datalog and Config File. Any help is appreciated.

[Danny Cabral]

Overlay the datalog onto your Global Config File (GCF), and pay special attention to the center paragraph in blue print:

Originally Posted by Danny Cabral Quick Datalogger Information: Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global Config File. Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK). Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize: RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery. Using the Holley EFI software (LINK), look at where the live cursor moves to during this occurrence, and manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing). I find the most helpful datalog function, is overlaying the datalog on your GCF. I'm in the habit of using the datalog Overlay feature every time I review a datalog. Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log". You can literally "playback" a recorded event, and watch it as it happened on any screen. Minimize (shrink) the datalog window, and move it to the bottom of any GCF screen. Then click & scroll anywhere on the datalog, and watch it playback on your GCF (EFI software). http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions) https://forums.holley.com/showthread...s-amp-Datalogs (Datalog Information - Read "NOTES") https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog) https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts # 2, # 4 & # 6) http://forums.holley.com/showthread....2523#post62523 (Read 4th & 5th Paragraphs - Smooth Fuel Graph After Transfer Learning)

[Evan_P]

I've overlayed them and watched back. I see no fault with fuel or spark before it dies. There's no significant movement in the cursor leading up to the stall. There's one instance in the datalog I posted before it stalls where the engine is coming down to target idle smoothly. Just before hitting target idle speed, IAC jumps from 5% to 18%, which leans the engine out briefly and increases RPM before IAC starts coming down again. It eventually reaches 5% IAC, target idle speed of 750 RPM and it's right at target AFR then just shuts off.

[GPatrick]

The datalog shows a reset due to EMI/RFI and that has to be dealt with before attempting any tuning changes as some of the engine stalls can be more than likely attributed to EMI/RFI resets than the tune.

You'll have to go through the usual suspects to solve this. All wires, the condition of the spark plug wires, boots at the distributor and plugs, etc. One suspect area is your charging system. It's difficult to use the cursors on datalogs with resets, but if you look at battery voltage you can see that it's generally low and quite noisy. The voltage displayed in datalogs is from the pink trigger wire. The noisy signal may be due to the pink wire connection point or may be any issue with the alternator. The 1G Ford alternators are generally noisy and often won't provide full voltage at idle. Single wire replacements may provide more charging amps, but can have even more noise in some cases. A 3G conversion gives you an EFI friendly alternator. Try removing the air cleaner to see if it's acting like an antenna for EMI/RFI.

In the Basic I/O setup you have all Fan #1/#2 and A/C functions selected. If you're not running any fans disable all of these by unchecking the boxes. When the fan ground triggers are activated but not used, the wiring can also act as an antenna. This has the potential of increasing the chances for EMI/RFI on an engine that's up to temperature. Using the EFI software in the Basic I/O configuration also go to the A/C IAC Kick setup. Change the Input to Unassigned and the IAC percentage to zero before unchecking the box.

There are a few items in your setup that you might want to check. First, your Base Timing Table has the typical Sniper setup problems and may be partly contributing to stalls when returning to idle. See this for a timing table generator: https://forums.holley.com/forum/holl...generator-tool. You will probably see better idle operating with 18 to 22° of timing at idle. The crank timing is set to 15° so you can adjust the idle timing without affecting starts. You have your WOT timing set to 34° which may be in the ballpark depending on your heads and compression. However, you only have 36 degrees for cruise where 40 or 42 may provide better economy and cooler engine temperatures. Read this article to understand the problems with your current Base Timing Table setup (especially at low RPM, low vacuum): https://www.efisystempro.com/efi-pro...timing-control
If you need suggestions on how to use the Base Timing Table generator I can give you some settings that will provide a good baseline table.

Since the rotor is fixed in the distributor, rotor phasing can also cause increased EMI/RFI when the timing at idle is low. Idle Spark control can drop your timing down to 7°, for example, when the Sniper is attempting to slow the engine down to reach your target. The rotor is pointed at the distributor cap post at approximately 25°, so when the system calls for 7° there's a big gap for the spark to jump. Inspect your cap posts to see if the normal arcing is offset to one side on the post.

The other area that may be causing some runability and start issues are your Target AFR values. Every engine is different, but on a stock V8 with a mild cam at target of 14.5 at idle may be too lean. Timing of 15° and a 14.5 AFR may not be the best combo for reliable idle and return to idle. Your cruise AFR is 14 and it may be better at 14.4 or so, and your WOT AFR on a stock engine is perhaps at little rich at 12.5. 12.8 or 12.9 might be a better Target AFR.

Your first goal before any tuning changes should be identifying and correcting the EMI/RFI. The exception would be the timing setup, however, to minimize the EFI/RMI generated by the distributor.

[Evan_P]

Thank you for the response. I'm currently making some changes to the Config File. I've opened up the Base Timing Table generator and could use some help getting started with it if you dont mind. I'll be looking into the charging system this evening to see if I can remedy the RFI issue. Again, I really appreciate the help.

[Danny Cabral]

https://forums.holley.com/showthread...483#post261483 (Base Timing Table Generator - Excel Spreadsheet)

[Evan_P]

So I have a HyperSpark distributor in this engine. I assume I base timing to what I want at idle (16°-18°), mechanical approximately 20-22° and 0° vacuum advance?

[GPatrick]

In order to use the table properly the first step is go to your Base Fuel Table and set the max RPM on the bottom axis. For example, if your intended redline is 5500 RPM you could set the max RPM in the lower right cell to 6000. After entering 6000, right click on 6000 and select fill row values to produce even RPM spacing.

Next, go to the Base Timing Table. Change the type to 2D Table if not changed already. Then click on Copy Fuel Axes and this will duplicate the axes/scales.

Now go to the Excel spreadsheet. Conservative, but valid values entered into the green cells might be:

Initial Timing	12
Mechanical Advance
Total Mechanical	22
Mech plus Init	34
Start RPM	1000
Peak RPM	3000
Vacuum Advance
Total Desired	8
MAP Start	84
MAP End	54
Vacuum Conversion
In-Hg	5
MAP	84
Table MAX kPa	105
Table MN kPa	20
Table MIN RPM	500
Table MAX RPM	6000

This will give you a total of 34° at WOT, about 20° at idle and 42° in the cruise region. There is no vacuum advance with a HyperSpark distributor, but the table uses this terminology for those familiar with setting up a traditional distributor. The one value that you can initially change is the MAX RPM. Enter the value here that you've selected in your fuel and timing tables. After entering the values, select the entire table contents (the white cells), right click & copy.

In the Sniper EFI software, go to the upper left cell, right click, and select paste. This will copy the Excel spreadsheet data into the Sniper Base Timing Table. Flip back & forth to make sure the copy & paste was successful.

Use Save As to save the revised Config File with a new name. Copy the file to the correct file folder on the SD card. Upload this file into the Sniper and give it a try.

If this is raising the timing at idle you may need to adjust the idle screw to get the IAC Position back into the 2 to 5% range on a fully warm engine. When you have the IAC set properly the Idle Spark control will have minimal influence and will ensure that you don't end up with large dips in timing.

By using the "vacuum" function you will see that the timing in the upper right of the table is close to your base and this is helpful when you're potentially lugging the engine. At idle with the "vacuum" you'll be up at 20° or so. You can play with the numbers as you wish, but most engines respond well to increased timing in the light load higher RPM cruise region. They will generally run a little cooler and you'll see improved economy in most cases.

[Evan_P]

Got the new Config File in. Issue still occurring. Went ahead and disconnected the alternator to try and eliminate it as a source of RFI. With it disconnected there's very little noise in the voltage signal. I'm still having a stalling issue though. Plug wires are new when I put the setup in. Plugs are only a couple hundred miles old. Removing the air cleaner made no difference. It seems to run pretty good right up to the point where it shuts off.

[GPatrick]

If you can, take a picture of the engine compartment and the engine especially around the distributor and the plug wire routing. You can post them here. Routing the wires around the front of the valve covers minimizes potential influences. Where is the spark box mounted, and where are the wires from the spark box to the coil positioned?

Try wrapping the distributor cap with foil to see if this isolates the problem to the distributor. There are plates available from several suppliers that shield the Sniper from the distributor. If you're running electric fans make sure none of the fan wiring is running close to Sniper wiring. Conduct searches on this forum and with Google in general on Sniper EMI/RFI and you'll see some other creative solutions, including wire shielding, ferrite beads, etc.

[Evan_P]

It would appear the issue is coming from the distributor. Wrapped in foil and fired it up. Ran smooth and idled better than it ever has. Held idle perfectly for close to 20 minutes. Within 10 seconds of removing the foil while running the engine shuts off. Repeated this about four times. Each time when the foil was removed the engine quickly died. I went ahead and built a metal shield between the throttle body and the distributor. Was able to take the truck for a drive. Runs far better than it did the last time I attempted to drive it. Idles as it should. I spoke with my friend who owns it and informed him of what was going on. We're suspicious of the plug wires. They were new in the box, but have been sitting on the shelf in his shop for more than 10 years, so I suspect there's a chance the wires are the issue. I think he's going to look into getting a set of new wires an plugs for it. Any suggestions for wires that play nice with the Sniper? Thanks again GPatrick for the help.

[Danny Cabral]

I've never had any problem with MSD 8.5mm Super Conductor spark plug wires. Holley EFI users also have great service with FireCore50 spark plug wires. Also, FireCore50 spark plug wire sets are known to transmit far less electrical interference than others (low resistance and impregnated with ferrite molecular compound used to absorb RFI/EMI).

[GPatrick]

Let us know if the wires take care of the issue. Whether you make up from a kit or premade check the resistance on each wire to ensure the crimps are good. I like to make mine up from a universal kit so I can wrap them around the front of the valve covers rather than up and over as this moves the wires too close to the Sniper. Check the condition of the rotor and the rotor to cap gap as some have found issues that will cause larger gaps between the rotor and cap and more arcing.

Glad you were able to prove the issue. It's nice to make forward progress.