View Full Version : Papa's Random Stall Issue - Data Log Captured!
I was finally able to capture a data log of the random stall issue I've been fighting. The only odd thing I see in the log is a small 0.1v increase in voltage right before the car died. The voltage went from 14.4v to 14.5v, still well within Holley's operating range. I've posted this on Holley's forum and was pointed at some previous discussions about alternator noise causing issues, but I don't see any noise on the other sensors.
https://thefactoryfiveforum.com/attachment.php?attachmentid=215560&d=1751046716
Does anyone have any thoughts?
I don't know about thoughts, but I do have additional questions:
1. What's the time frame on this log? The voltage goes up and stays there. If the car died, wouldn't it drop to zero?
2. What's the fuel pump doing during all this? Is fuel pressure constant? If you have a gauge on your pressure regulator, does it register greater than zero right after the car dies?
3. What changed from the point where there were no issues to now (or should I say when the problems started)? Did you get a tune, or make any other changes?
I understand the frustration of intermittent problems like these, and I'm trying to think of things that could cause the problem. Perhaps you have thought about or evaluated the items I listed, but maybe not...
To try to provide a little history, my first stall happened a few years ago. Driving at 40mph and the car died, like the key was turned off. No sputtering or any other observable. That was with a Sniper on the car. Following that, it did it again a few more times over the next several months. Each time, the car would start right up and drive fine. About two years ago, I started having different issues that turned out to be a result of contamination in the fuel and a clogging fuel pump. At that point, I replaced everything fuel and ignition related: tank, filter, lines, pump, distributor, and all new EFI system from Jim Inglese. The random stalls continued and have progressively become much more frequent to the point that I don't want to drive the car in traffic at all.
The time that the voltage goes up until the car died in the log is less than one second. The car remains powered and you can see the voltage ramp down as the alternator stops and all you get is battery voltage.
weendoggy
06-27-2025, 05:58 PM
Better log is a system log. It'll show you crank and cam signals as well as rpm. Nice thing is you can have it run 100% of the time, and trust me, it'll capture it. What are you using for spark distribution and/or signal? I can tell you some horror stories with Holley I've had, but I'll save that until I hear back. Attached is a system log.
215571
Better log is a system log. It'll show you crank and cam signals as well as rpm. Nice thing is you can have it run 100% of the time, and trust me, it'll capture it. What are you using for spark distribution and/or signal? I can tell you some horror stories with Holley I've had, but I'll save that until I hear back. Attached is a system log.
215571
Hey Glenn,
Thanks for jumping in. I'll have to figure out how to access the system log on the Terminator X. I have the CAN to USB cable and can borrow the wife's laptop.
For spark, I'm using the MSD (Holley) 6EFI box and MSD 82073 Ignition Coil Blaster SS with the Holley Dual Sync distributor. These are what Jim Inglese recommended for his stack injection setup.
Dave
Nigel Allen
06-28-2025, 01:37 AM
Could the small voltage rise be related to either the ignition module or fuel pump switching offf, thereby reducing the overall electrical load?
Glenn,
I just came across your post on the Holley forum: https://forums.holley.com/forum/holley-efi/terminator-efi/38864-dual-sync-drop-out-fixed
I hope my issue is solved by a $100 repair, but I hate to think about how unreliable some of these expensive electronic systems are these days.
Dave
Sharris2
06-28-2025, 09:01 AM
Try putting a fuel pressure gauge on it, while driving. You might find it's a fuel pressure issue, not ignition
Could the small voltage rise be related to either the ignition module or fuel pump switching offf, thereby reducing the overall electrical load?
Try putting a fuel pressure gauge on it, while driving. You might find it's a fuel pressure issue, not ignition
A response I got on the Holley forum was that the bump in voltage may be due to the load being removed from the system as the car dies (fuel pump shutting off, etc.). Fuel pressure has been fine, and a drop would not produce the instantaneous stall that I'm experiencing. I've actually had a couple of cases where it's died, then refired instantly after a few seconds while coasting at road speed. I'm leaning toward a spark related issue and will hopefully know more if I can capture it in a system log as Glenn has recommended.
At the moment of failure it appears the injector pulse width increases dramatically, but the AFR is going lean. So it leads me to believe it's losing fuel pressure and the ecu is adding pulse width trying to make up for it. I would install a fuel pressure sensor so you can log that info. Maybe a faulty inertia switch, or failing pump.
Bob
weendoggy
06-28-2025, 12:12 PM
Agree with testing fuel pressure and you should have a transducer there anyway, just to keep an eye on pressure from the LCD screen. However, the description you give and what you have, I doubt it, just due to my past with "multiple" Dual (stink) Sync distributors. I did look at the T-X software and don't see a System Log under the Datalog tab, eventhough the manual shows it. Must have to have it connected to the ECU. If not, Holley has more work to do. If you can, I'd run a System Log and check it. From my HP, I did that and when it took a dump (occasional like yours) the RPM and data was scewed but sensors read normal. Biggest thing to watch is Tach when it drops and/or Stall mode. It's definitely a scary thing. Also check to see if the T-X can run a batch fire for injectors, so you could do some testing and/or changing without a lot of $$$$ spent.
I doubt the voltage spike/surge is being caused by anything other than the ECU response once it comes back to life. Your volt gauge will stay normal during all this. Believe me, I know.
I don't believe terminator X does internal logging.
To try to provide a little history, my first stall happened a few years ago. Driving at 40mph and the car died, like the key was turned off. No sputtering or any other observable. That was with a Sniper on the car. Following that, it did it again a few more times over the next several months. Each time, the car would start right up and drive fine. About two years ago, I started having different issues that turned out to be a result of contamination in the fuel and a clogging fuel pump. At that point, I replaced everything fuel and ignition related: tank, filter, lines, pump, distributor, and all new EFI system from Jim Inglese. The random stalls continued and have progressively become much more frequent to the point that I don't want to drive the car in traffic at all.
The time that the voltage goes up until the car died in the log is less than one second. The car remains powered and you can see the voltage ramp down as the alternator stops and all you get is battery voltage.
Dave,
I'm reading this and looking at all the responses and I can understand why you are a loss for a solution. Here's what I'm thinking:
You have replaced just about everything fuel related. Does that include everything between the fuel pressure regulator and the injectors? If yes, then you should be able to rule out a blockage. If no, because of the fuel contamination you experienced, you could have a blockage that would contribute to intermittent problems. (I don't know what exactly comes with the Holley system, plumbing-wise.)
If you got the Holley system, you probably got a new Terminator X ECU? I have a hard time believing you would have two different computers ending up with the same problem. If you're using the original ECU, that could be the culprit.
What parts carry over, either spark or fuel related, from the Sniper days to the current state? That's the only place I can see where there would be a probable cause for a problem.
weendoggy
06-28-2025, 02:45 PM
Glenn,
I just came across your post on the Holley forum: https://forums.holley.com/forum/holley-efi/terminator-efi/38864-dual-sync-drop-out-fixed
I hope my issue is solved by a $100 repair, but I hate to think about how unreliable some of these expensive electronic systems are these days.
Dave
Dave,
That was the first failure over three years ago. I was able to get data from a System Log (HP ECU) and see the Terminator-X doesn't provide that, even though the Holley Terminator-X manual shows it as a dropdown. Go figure. Since that thread, I've had four failures in the last three plus years, latest one lasted five months. I have since dropped that POS from my engine and gone with a 36-1 Crank Trigger. I know the feelings you have when it happens because it's a surprise and you're stranded. I actually had a spare Dual Sync in my trunk and had to replace it on the side of the highway once. Easy fix, 20min. and back on the road. Like changing a tire...almost.
Once it happened and I knew what to expect, I knew what to look for/at when it did, mainly my gauges and the LCD screen. All car functions were fine except the LCD would show all sensors good, but RPM stall. Sometimes the O2 would read wacky then good. I was able once to put it in open loop (tune) and get home. If you want to read a cliff notes version of my saga, go here https://www.weendoggy.com/fuel.htm#dsd and have a good laugh. My last track event at Laguna Seca was a disaster with the Dual Sync, cutting out, missfire, etc. Since going to the Crank Trigger, the ignition is solid all the way to 7k plus! Still feeling nervous at times, but believe my problem is behind me. I know you have MPFI and I run a TBI so if you do go to a Crank Trigger, you will have to run a batch fire (provided the Terminator-X allows it) and use the distributor as I did for spark distirbution, or, you'll have to go to CNP and Cam Trigger unit to run your oil pump. You can check out my YT video here: https://youtu.be/PkCjQ6y2omw
Glenn
After following the recommendation to add a fuel pressure sensor that could be logged by the Terminator X, I installed one and took the car out for a drive. Just after getting on the highway and coming up to 70 mph, the car started to die, but quickly recovered and I turned around and headed home. The log shows the fuel pressure dropping to 0 psi and then coming right back up to the ~48 psi that the injectors want.
https://thefactoryfiveforum.com/attachment.php?attachmentid=216069&d=1751996531
So, it looks like something is causing my fuel pump to cut out. At least now, I have some real evidence of the potential problem.
PNWTim
07-08-2025, 12:52 PM
Dave - based on your previous descriptions it strikes me as more of an "systemic ignition" failure than a fuel failure. The pump stuttering may simply be a symptom of the electrical gremlin that's plaguing you. As you have described before "it's like I turned the key off". I am thinking to look at whatever circuits control both the fuel and ignition i.e. your Terminator X.
I know this is somewhat simplistic but you now have evidence your pump lost power and I would be willing to bet it is more system wide. At least, that's where my logic train goes.
Thanks, Tim. I'm not going to rule anything out at this point, but what I find interesting is that the Terminator remained powered and logging though the event, so I don't think I'm losing power system-wide. I may have to drop the fuel tank and inspect the pump and if I do, I'll swap in a new pump to try and eliminate that part from the mix, even though it is basically a new pump that was installed when I did the stacks and replaced all the other fuel-related components.
More unwanted commentary: I think it's good that you saw the pump cut out. That rules out a bunch of things. The pump is relatively new, I believe, as you indicated you replaced that after the contamination issue. If you had a loose wiring connection, you could have a similar problem with the pump, but other than that, I have a hard time believing a relatively new item would fail. And if it did fail, it wouldn't act in this manner. It could pump a low pressure constantly, or die completely. Did you replace the ECU when you got the new EFI system from Inglese? Have you had a tune done on the existing ECU? Can you get it reset to factory defaults? The culprit in my humble opinion is whatever is controlling the fuel pump.
PNWTim
07-08-2025, 01:17 PM
If you need a pump and hanger assembly I have a spare Walbro pump and Pro-M hanger you could use. Just PM me if you're interested.
More unwanted commentary: I think it's good that you saw the pump cut out. That rules out a bunch of things. The pump is relatively new, I believe, as you indicated you replaced that after the contamination issue. If you had a loose wiring connection, you could have a similar problem with the pump, but other than that, I have a hard time believing a relatively new item would fail. And if it did fail, it wouldn't act in this manner. It could pump a low pressure constantly, or die completely. Did you replace the ECU when you got the new EFI system from Inglese? Have you had a tune done on the existing ECU? Can you get it reset to factory defaults? The culprit in my humble opinion is whatever is controlling the fuel pump.
Al,
The ECU (Terminator X) was part of the system Jim Inglese sold me with the stacks. After I installed the stacks, I had the car professionally tuned and other than the stall issue, it runs better than it ever has. The pump is controlled by the Terminator X through a connection to the fuel pump + wire in the RF harness. The Terminator harness has its own relay on that circuit.
OK, something is telling the ECU to shut off the pump. It could be the MAF or the MAP or even the throttle position sensor. I believe those are the most likely candidates in this situation. Or, it's an unintended consequence of your tune. If those sensors are from the "old setup", they could be culprits, otherwise it's programming. I'd talk to the tuner first, but maybe replacing sensors is an inexpensive fix. (I don't know how to test them...) Just my hopefully useful 2 cents.
weendoggy
07-09-2025, 07:41 AM
Al,
The ECU (Terminator X) was part of the system Jim Inglese sold me with the stacks. After I installed the stacks, I had the car professionally tuned and other than the stall issue, it runs better than it ever has. The pump is controlled by the Terminator X through a connection to the fuel pump + wire in the RF harness. The Terminator harness has its own relay on that circuit.
Why not just by-pass the RF pump wire, put a known "point A to point B" trigger or power wire to the Holley pump relay and test. This way you eliminate the RF harness as a culprit. You can also run a simple test light to the RF pump + and run it to see if the light goes out when pressure or symptom arises. Simple trouble shooting.
Why not just by-pass the RF pump wire, put a known "point A to point B" trigger or power wire to the Holley pump relay and test. This way you eliminate the RF harness as a culprit. You can also run a simple test light to the RF pump + and run it to see if the light goes out when pressure or symptom arises. Simple trouble shooting.
That is exactly what I was planning to do next. The RF harness is something that is common to both my old and new fuel systems.
I think I found the problem! As I started looking at the fuel pump wiring, I found this:
https://thefactoryfiveforum.com/attachment.php?attachmentid=216202&d=1752250005
I'd used a Weatherpak connector to attach the fuel pump pigtail to the RF harness when I originally wired the car. It looks like one of the pins wasn't properly seated in the barrel and was not happy. I removed the Weatherpak connector and used regular connectors and heat shrink.
Time will tell, but I think this will solve my issue.
PNWTim
07-11-2025, 11:24 AM
Interesting. I wonder if the Terminator X shuts off the spark if it senses a drop in fuel pressure? Normally, even with EFI, I would think there would be a stumble or sputter prior to shut down rather than the "key off" you experienced. But if the T-X goes into shut down mode if a parameter is failing that would mimic what you have seen.
Either way, I hope you are out of the woods on this one.
I hope this is it! Much easier than the alternatives. Looks like it's time for some test driving!
I hope this is it! Much easier than the alternatives. Looks like it's time for some test driving!
I drove the car for about 30 minutes in various conditions; city and highway and it drove perfectly. I'll keep getting it out on the road and see how it does. By the way, all that black crud on the pin and barrel is plastic from the Weatherpak connector. It looks like that bad connection was heating up enough to melt the plastic. This would explain why the issue has progressively gotten worse over time as. The more build-up of plastic, the less metal contact there was to keep the ground solidly connected. Eventually, I imagine it would have just stopped making any connection and stranded me.
Nice work detective! Keeping my fingers crossed for you.
I'm declaring victory on this issue. I've put about 100 miles on the car since redoing the fuel pump connector wiring and haven't had a hint of an issue. This also fulfills a promise I made to my better half that I wouldn't give up on trying to fix the Cobra after ordering my Coupe.
Bob-STL
07-20-2025, 08:17 PM
Nice work!
danmas
07-20-2025, 11:37 PM
Dave,
I couldn’t be more delighted for you and as troubling as it was I imagine you must feel pretty good about solving the problem. I’m glad it is resolved and more importantly I’m glad you figured out the problem.
Dan
Dave,
I couldn’t be more delighted for you and as troubling as it was I imagine you must feel pretty good about solving the problem. I’m glad it is resolved and more importantly I’m glad you figured out the problem.
Dan
Thanks, Dan. It feels really good to finally get this behind me after close to four years of chasing the issue. My lesson learned on this is to not allow myself to rule out anything. Methodically work through all possibilities until you have eliminated all potential sources. In my case, the fuel pump came on every time I turned the key on, so I ruled out that path without ever checking it until years after the problem started.