Let's see if we can give this thread legs! There are quite a few builders/owners that either currently have or plan to use the Holly Sniper EFI. I'm one of them, and I'd love to learn how to tune the system. I'm ready to be the tester of your expert advice and document what I learn in this thread. So, if you have already gotten over the learning curve and would like to help teach me (and others) the ropes, let's get started.
First, some basic information about my engine:
BluePrint Engines (BPE) 347 purchased in 2017:
Fuel Delivery:
- Fuel Injected, Holley Sniper EFI
Manifold:
- Edlebrock Polished Air Gap
Ignition/Distributor:
- MSD
Block:
- 302ci, 2 bolt main, bored .040
- 1-piece rear main seal
Rotating Assembly:
- Cast steel crank
- 3.4” stroke and Forged 5.4” rods
- 150,000 psi rod bolts
- Forged pistons
- Hastings Moly rings
- Balanced rotating assembly
- High volume oil pump
- Hydraulic roller camshaft
- Heavy duty double roller timing set
My car has been on the road for less than 1000 miles and runs pretty well. The idle is set at 900 rpm, and if possible, I'd like to bring that down a bit as long as the car continues to run well at a lower idle speed. While driving, any lift of the accelerator results in popping in the exhaust. I don't mind a little crackle, but it's excessive as it stands right now and I'd like to clean that up. My measured fuel economy on the highway for one trip put me at about 14 mpg, which I can definitely live with. However, if I can keep the performance and get a little more range on a tank of gas, I'd welcome that, too.
To date, I haven't done any data logging, but I can share some captures of my base fuel map, and learning map.
Base Fuel Map:
Base Fuel Graph:
Learn Fuel Map:
The Decel Fuel Cutoff control is currently disabled by default. I've read that the base fuel table should be finished before enabling this control.
Once I do enable it, what parameters would I want to start with? It seems that the defaults of 0 would engage this control as soon as I lift on the accelerator and would reenable fuel at any RPM above idle. I've also read that this control only triggers when the rpm is above 3000, so it may not fully address my decel popping issue which is happening at pretty much any rpm.
This looks like fun. I'll be watching this as I'm a few months behind you.
Thanks Dave.
MK IV Build #9659, 3 link, 17's, Forte 347, Sniper EFI, power steering, built for a freak sized person with 17" Kirkey Vintage seats, RT drop trunk, RT turn signal, lots of stuff from Breeze Automotive, Wilwood brakes, paint by Jeff Miller
At some point, you'll want to transfer that learn to base. As far as the Fuel decel wait time, holley recommends .5 to 2.0. and 300 RPM for manual transmissions. I have 1Sec and 400 RPM, but your settings may be different.
and another one following.... not driving yet but engine is running. Very similar engine specs to you Papa - a bit more aggressive cam (0.542 int./0.563 exh. lift, 224 int./232 exh duration, 112 LSA), same intake, ignition system is full hyperspark with timing control, I'm using AFR 195 heads with 58cc chamber. You didn't mention your compression ratio, mine is around 10.7 as the pistons are -4cc as I recall.
The Holley Sniper forum isn't a bad resource. There are a few helpful regulars there if you post issues and setup/log files.
There is also some helpful information here: https://www.efisystempro.com/efi-pro...fi-instruction note that EFI System Pro also has some good accessories for the Sniper including a progressive throttle linkage which brings on the secondaries at about 40% instead of right away, makes the throttle much less twitchy.
Steve
Gen 1 '33 Hot Rod #1104
347 with Holley Sniper & Hyperspark, TKO600, IRS, 245/40R18 & 315/30R18, DRL, Digital Guard Dog keyless Ignition
Okay. I transferred the learn map to the base map and smoothed everything and here is what I have now:
It's significantly different than the original base map. I haven't loaded into the car yet as I'd like to get some comments from the experts first. I did back-up the original config file before making any changes, so I can always go back to a known starting point.
and another one following.... not driving yet but engine is running. Very similar engine specs to you Papa - a bit more aggressive cam (0.542 int./0.563 exh. lift, 224 int./232 exh duration, 112 LSA), same intake, ignition system is full hyperspark with timing control, I'm using AFR 195 heads with 58cc chamber. You didn't mention your compression ratio, mine is around 10.7 as the pistons are -4cc as I recall.
The Holley Sniper forum isn't a bad resource. There are a few helpful regulars there if you post issues and setup/log files.
There is also some helpful information here: https://www.efisystempro.com/efi-pro...fi-instruction note that EFI System Pro also has some good accessories for the Sniper including a progressive throttle linkage which brings on the secondaries at about 40% instead of right away, makes the throttle much less twitchy.
Steve
My compression ratio is 10:1. I've been lurking on the Sniper forum and will check out the additional references.
Be careful on the smoothing. If you have areas that have not learned it will more or less average them in with other areas that have learned and can skew the table. I would save the smoothing until it's well sorted out.
I never had much luck getting the cut fuel on decel to work cleanly. These cars are so light that you can end up cruising at 0 tps so the ecu doesn't know what is going on. Of course no fuel will stop the popping, but it's hard to get the transition correct. I gave up trying to make it work. But it doesn't hurt to play with it, just make sure and save a backup tune. Since your ecu is not controlling timing, disregard my comments on the other thread. I would get some data logs and see what the A/F is doing. See if you can post a copy of your config file and a data log of just normal driving. I would like to study it a bit. What altitude are you driving at? I know it's pretty high so the tables will be different than if you were at sea level.
Be careful on the smoothing. If you have areas that have not learned it will more or less average them in with other areas that have learned and can skew the table. I would save the smoothing until it's well sorted out.
Thanks, Bob.
Here is what the map looks like (learn-to-base) unsmoothed:
I never had much luck getting the cut fuel on decel to work cleanly. These cars are so light that you can end up cruising at 0 tps so the ecu doesn't know what is going on. Of course no fuel will stop the popping, but it's hard to get the transition correct. I gave up trying to make it work. But it doesn't hurt to play with it, just make sure and save a backup tune. Since your ecu is not controlling timing, disregard my comments on the other thread. I would get some data logs and see what the A/F is doing. See if you can post a copy of your config file and a data log of just normal driving. I would like to study it a bit. What altitude are you driving at? I know it's pretty high so the tables will be different than if you were at sea level.
Bob,
I'll see if I can get a little time in the car over the next couple of days after work to capture some data logs. My home is right at 6,100' elevation. Local driving around town and surrounding areas will vary +/- a few hundred feet.
I did a data log today from cold start and then over about a 15 mile loop. Here is what the AFR plot looks like:
What would be the best way to get the config and data log files posted? The data log is pretty large (62MB). Zipped, the compressed file is 7.7MB, still way too large to upload to the forum.
I did a data log today from cold start and then over about a 15 mile loop. Here is what the AFR plot looks like:
What would be the best way to get the config and data log files posted? The data log is pretty large (62MB). Zipped, the compressed file is 7.7MB, still way too large to upload to the forum.
Thanks,
Dave
That's a pretty long data log so it makes it hard to break down what's going on. I like to make them just a couple of minutes long under a somewhat controlled driving cycle. That way you can kind of correlate what you see with what you experienced while driving. I have no clue on how to post a file like that so others can see it. You should be able to attach the config file as they are not very large.
I did find a way to reduce the large file to a shorter snippet. Here is a picture of a shorter version with some labels:
I was able to attach my config file, but even the reduced data log is still too large for the forum file upload size limit. It's only a little over 600K but the forum limit for zip files is 488k. I can reduce it more if you let me know what portion you are most interested in.
I agree on the data logs. Shorter is better. Also, when sending data logs, send the file tune that was used during that log. I run a Terminator HP but it's similar to what you're using. You can email me the log and tune if you want. Biggest thing you need to do is get it running where you want then do a transfer after a lot of driving. Too much will skew the file. The AF ratio is the bible. The timing table is next to fine tune. jmo
I agree on the data logs. Shorter is better. Also, when sending data logs, send the file tune that was used during that log. I run a Terminator HP but it's similar to what you're using. You can email me the log and tune if you want. Biggest thing you need to do is get it running where you want then do a transfer after a lot of driving. Too much will skew the file. The AF ratio is the bible. The timing table is next to fine tune. jmo
If you would like to PM me your e-mail, I'd be happy to provide my files to you as well.
Thanks,
Dave
BTW: I like the BOC quote in your signature. One of my all time favorite albums.
The description of the issue seems to match what I'm seeing with the AFR jumping on deceleration indicating a lean condition if I understand what I'm reading. The parameter that the thread recommends adjusting is the Minimum Injector Opening Time (MIOT).
I can vouch for the value of testing for the correct Minimum Injector Opening Time (MIOT), as I too would go 20+ AFR on coast, and then as the RPM neared idle, it would swing way rich as the ECU worked to catch up. The baseline was 1.20 msec, and once I narrowed down through trial & error, that 1.70 msec was too high (coast AFR went to 12), and 1.60 msec was too low (coast AFR went to 20). I settled on 1.64 msec. I was surprised at how much of an impact just .01 msec would have. I don't think the handheld is setup to adjust this value, so you'll really need the cable to hook up to a laptop. It could be done via the SD card, transferring back & forth from the handheld and the laptop, but what a PITA that would be.
My value is at the default of 1.20 msec and it would seem I want to start increasing the value until I get the AFR into the desired range where these spikes are occurring. Should I try this before doing anything else? In my line of work, I understand the value in only making one change at a time when tuning a software algorithm. I think if I can eliminate the popping, I would have an easier time focusing on the fuel map tuning.
The description of the issue seems to match what I'm seeing with the AFR jumping on deceleration indicating a lean condition if I understand what I'm reading. The parameter that the thread recommends adjusting is the Minimum Injector Opening Time (MIOT).
My value is at the default of 1.20 msec and it would seem I want to start increasing the value until I get the AFR into the desired range where these spikes are occurring. Should I try this before doing anything else? In my line of work, I understand the value in only making one change at a time when tuning a software algorithm. I think if I can eliminate the popping, I would have an easier time focusing on the fuel map tuning.
Dave
Just looked at your log. It does appear to be going very lean at the peaks. What is interesting though is the pulse width is still around 1.5, well above the 1.2 minimum setting. It almost appears like there is an exhaust leak or something disturbing the 02 readings. Where is your 02 sensor mounted? I'm kind of thinking those lean spikes are a result of the popping rather than a cause.
Certainly try raising the minimum open time and see the results. But it can also cause overly rich conditions where you don't want them. There are places in your log where a 1.5 pulse width results in the correct A/F, so if you changed the minimum to 1.65 as is mentioned on the Sniper forum it would be very rich at those points. I know Geoff H played with those settings some but I don't remember what he ended up with.
Just looked at your log. It does appear to be going very lean at the peaks. What is interesting though is the pulse width is still around 1.5, well above the 1.2 minimum setting. It almost appears like there is an exhaust leak or something disturbing the 02 readings. Where is your 02 sensor mounted? I'm kind of thinking those lean spikes are a result of the popping rather than a cause.
Certainly try raising the minimum open time and see the results. But it can also cause overly rich conditions where you don't want them. There are places in your log where a 1.5 pulse width results in the correct A/F, so if you changed the minimum to 1.65 as is mentioned on the Sniper forum it would be very rich at those points. I know Geoff H played with those settings some but I don't remember what he ended up with.
Bob,
Thanks for looking at the data. This is certainly a great example of how you can't just look at one aspect of the system in isolation and how all the different pieces fit together. Before I start changing anything, I'll give the header bolts another round of snugging and see if that does anything to improve the situation. My O2 sensor is in a collector in the passenger side header.
I won't have time to get at this until the weekend, but let's rule out a leak before chasing things in the computer.
Dave,
Looking at your collector setup, please tell me those tack welds aren't the only thing making the system tight. You can have a LOT of air sneaking in through that collector seam(s) to cause the fresh air intake on the exhaust vacuum pull. That collector seam should be welded 360°. I know it sounds lame, but you have to take care of basics first. Looking at your logs I tend to agree with Bob on results.
Dave,
Looking at your collector setup, please tell me those tack welds aren't the only thing making the system tight. You can have a LOT of air sneaking in through that collector seam(s) to cause the fresh air intake on the exhaust vacuum pull. That collector seam should be welded 360°. I know it sounds lame, but you have to take care of basics first. Looking at your logs I tend to agree with Bob on results.
I asked that very same question when I received them from GP Headers and they assured me that they are okay and that they crimp them. You can see the dimple at each of the mating points on the collector. I could pull them off (not fun) and have them welded locally or I could try to get the new style headers that FFR is offering, which might address a driver's side pipe fitment issue I have at the same time. I've had several sets of headers on the car throughout the build -- loooong story.
OK, I'm going to ask the dumb question then, "if they ARE dimpled and suppose to be tight, why are they tack welded"? I'm not saying that this is a problem, just that it could be a problem, especially on deceleration when vacuum is high.
OK, I'm going to ask the dumb question then, "if they ARE dimpled and suppose to be tight, why are they tack welded"? I'm not saying that this is a problem, just that it could be a problem, especially on deceleration when vacuum is high.
Yep -- It's on my list of things to try to eliminate as possible causes.
GP Headers assures me that the headers are okay. I checked the header bolts (Stage-8 locking) and all are good with no movement. I may pull the locking tabs this weekend and re-tighten anyway as after several heat cycles, the gaskets could have compressed a bit. Many thanks to bobl and weendoggy for offering to help me learn the ropes. I still haven't made any adjustments on the car, but have been studying the data log I captured earlier in the week. As I mentioned in an earlier post, there has been some discussion about Minimum Injector Opening Time (MIOT) that I find interesting on the Holley Sniper forum. I continue to look at the correlation of my Injector Pulse Width and the AFR spikes and found that in the Sniper software if I set the display axis limits for each that I can easily see the correlation of the AFR to the MIOT value that I'm contemplating adjusting.
In the plot, I set the injector PW axis max to my proposed MIOT value of 1.65 msec and then set the minimum AFR axis value to 16 to filter out the "normal" values. As you can see, the injector PW definitely correlates to the AFR spikes in most cases. There are a few short blips of injector PW below the 1.65 value where the AFR is below 16. If I do change the MIOT value to 1.65, there is potential to be a bit rich in the areas where the AFR is in a more normal range, but the periods are pretty short and I think I can tolerate a little more fuel better than the lean conditions that I'm trying to cure.
You are miles ahead of me with your understanding. As bobl mentioned, I played with the PW a bit but ended going back to the factory setting. The truth is the more I messed with it the worse it got. The base tune that I saved was a life saver for me.
I run the dual sync which really helps for tuning. With Bob's expertise we adjusted the timing table. Drove that for a bit, then did a few datalogs to look closer at the AFR table. We made a few changes in set rpm ranges where it was going lean - I am not going to use the correct terminology, but essentially we changed the range (decreased) the computer could adjust for the AFR within a given rpm.
I have taken it from Alberta (plains) to Yellowstone at 9,000 feet. Ran great the whole way.
You are miles ahead of me with your understanding. As bobl mentioned, I played with the PW a bit but ended going back to the factory setting. The truth is the more I messed with it the worse it got. The base tune that I saved was a life saver for me.
I run the dual sync which really helps for tuning. With Bob's expertise we adjusted the timing table. Drove that for a bit, then did a few datalogs to look closer at the AFR table. We made a few changes in set rpm ranges where it was going lean - I am not going to use the correct terminology, but essentially we changed the range (decreased) the computer could adjust for the AFR within a given rpm.
I have taken it from Alberta (plains) to Yellowstone at 9,000 feet. Ran great the whole way.
Good luck!
Geoff
Well, data analysis I can do. It certainly doesn't mean I understand the root cause and this adjustment may do nothing, but it's worth a try. If I can get the popping to stop I'll be thrilled, especially if it can be fixed with a simple adjustment and not something that I have to tear into the car to fix. I hope to try this out tomorrow, so wish me luck.
With the MIOT setting at 1.65 msec, The car didn't want to idle smoothly and died on me. After a restart, it seemed to settle down and I headed out of the driveway. It seemed to solve the issue at first as I didn't get any of the popping on my initial downhill coast. However, the car wasn't up to full temp and as it warmed up it started to stumble and bog down at lower rpm to the point that it wouldn't run. I was able to get it to run with the rpms up, but that wasn't going to work for normal driving. I swapped the old tune in and it ran fine as I was used to.
Depending on where it was purchased, some of the retailers give free efi tuning support of you purchased it from them.
The Sniper was provided by BluePrint Engines, so not a local retailer as an aftermarket add on. I've talked to a tuner in my area that could do the work, but I'd rather spend some time trying to figure it out first.
Making progress! Weendoggy sent me a tune file that he wanted me to try and it definitely made a difference. The decel popping is gone!!! His tune still had the MIOT parameter set to 1.65 msec, but the car actually ran with whatever the other changes were in the file. I'm waiting to hear back what he did. I felt a little bit of a stumble/hestitation getting back into the throttle a couple of times (not in the datalog), but I think that may just require some additional learning as my last drive I didn't notice it.
Please send me a copy of that data log and tune file that he did for you. I'd like to study it. Sorry I haven't had time to look any deeper into things, I've had 2 engines on the dyno, tuning the efi all week. Finally finished them today. So I have some time.
Does the Holley system have a setting for "fuel cut"? The Megasquirt I used to have had a provision to completely cut fuel during coast down which should alleviate popping in the exhaust but you had to be careful not to bring it in too soon as it would cause the car to buck or jerk at certain times.
Files are on the way. Don't let me interfere with work! I appreciate any time you can share. I think all weedoggy did was clear the old learn table and set all the closed loop and learn values to 100% from 50% where my starting point was.
Does the Holley system have a setting for "fuel cut"? The Megasquirt I used to have had a provision to completely cut fuel during coast down which should alleviate popping in the exhaust but you had to be careful not to bring it in too soon as it would cause the car to buck or jerk at certain times.
There is a setting in the Sniper to cut fuel on decel, but there are mixed reviews on getting it to work. From what I've read on the Sniper forum, it only activates above 3000 rpm, and that value isn't configurable.
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Originally Posted by FF33rod
