New install, Autolite 11 on old, small inline six.

[BorkyDog]

Driving a week now on a Sniper Autolite 1100 on a 1950's inline six, 196 cu in. It had been running fine with a Carter YF carburetor, new rebuild, 6000 miles on it. Stock distributor with Pertronix, for now. Fuel pump is a Holley 12-307, in-tank setup for a Jeep CJ, modified to fit. The in-tank pump is regulated in the tank, so there's one "dead head" line from tank to engine compartment. It's hose out of the tank, then filter, then hard line. Under the hood, hard line to -6AN SS braid covered PTFE, no rubber fuel hose under the hood, to a liquid-damped fuel pressure gauge to the Sniper body. Gauge reads 60 psi (when I can look at it).
WHAT'S WORKING:
It installed by-the-book and initial start went well. Then on the 2nd and ongoing starts, it would fire after cranking then die. AFTER START enrichment has mostly cured that, except for a brief oscillation (rich, lean and stumble, rich, lean/stumble, settles out and idles). All adjustments I make seem sensible and work as intended I think.
For now I have only the TSLCD, I have to go find/buy a Windows laptop or tablet to run the EFI software on.
I can see LEARN and Closed Loop work, and AFR stays close to Target AFR so I'm think I'm in business (famous last words).
ISSUE #1: IDLE
Fuel pulsation. At idle the gauge vibrates, 60 psi. It's LOUD, and coming from the line itself, not the pump. It's worse at idle/very low speed; on the highway, I can hear it, but it's not bad. Feeling the line, it's pulsating strongly. The pump in the tank is quiet. The whole length of the hard line is pulsating. So I've bought a Radium Engineering FPD-R pulse damper, that will arrive next week.
Idle speed and AFR are OK but erratic, 550 RPM plus/minus 50, and AFR +/- 1 or 2. I wonder if this, and the issue below, are related to pulsation, and I'll check after the Radium thing is in.
This engine has a trough "intake", with a cover plate. With the Sniper throttle stop screw all the way out IAC is at 2%. The vacuum connections are: Distributor via the port on the Sniper body, vacuum wipers, and PCV. If I plug all three (even though the distro is on "ported vacuum") there's no change. The Sniper body sits nice and flat on the intake with one thick soft gasket and no sealer. I squirt carburetor cleaner at each fastener, port, and around the trough gasket, no change in RPM or reading.
This is a slow turning, small engine that would idle smoothly at 400 RPM with the carburetor, so it doesn't need much air to idle. I know everyone says this but I don't think I have a leak. It's a super simple setup. I'll keep an open mind and look further.
QUESTION: Could fuel pulsation be the cause of erratic idle.
ISSUE #2: AT SPEED
I have two nice and easy "test beds" for consistent testing, a road I can cruise flat and level at 30 - 45 mph for 5, 10 minutes at a time, and a freeway, 60 - 70 MPH. Actual AFR seems OK, it hunts around the target, but I think it's about right. The problem is that I see leaps to super-lean about once a second or once every 20 seconds. On the highway I can feel it "in the seat of the pants", like a misfire. Each sensor is smooth and steady except for AFR.
It could be a misfire I realize as I type this, so I will go look at that. I want to eventually have the Sniper handle spark.
QUESTION: Could fuel pulsation cause erratic AFR at speed?
I realize I made a newbie mistake of not capturing a datalog file for upload here. I'll do so in the next day. I have to say, it's pretty amazing that Holley made EFI that bolts onto a wide range of engines and actually works well. I know I need to tune more and better, but wow.

[GPatrick]

For fuel pulsations you can use something like this: http://www.radiumauto.com/Fuel-Pulse...Kits-P759.aspx
I'm installing one on my Mustang project since I'm running a regulator in back with no return. I'm installing it because of what I've read regarding pulsations.

Pulsations can indeed cause your AFR to bounce around at speed, but as you mentioned, we need to see your Config File downloaded from the Sniper (use the Save As function since it's easy to confuse the default GCF Wizard file with the actual Config File in the Sniper.

Take one datalog of the engine at idle when it's fully warmed so we can see how the idle is setup and how the Sniper is acting. Then take a datalog of the problem cruise area. Try to keep it to only one or two minutes as it's more difficult to wade through a ten minute datalog and find the problem area. You need to zip those files in order to post them here. You can zip them together as one file. If you have a laptop or desktop computer you can still do a lot of fine tuning and datalog overlays by accessing the files on the SD card from the handheld. It isn't live tuning, but you can make a lot of important changes and evaluate them quickly.

Make sure your timing is correct for your cruise. Sometimes you'll get too much vacuum advance depending on the setup and it will cause a surge that feels a lot like a fuel issue.

[BorkyDog]

For fuel pulsations you can use something like this:

I have one ordered, arrives this week.
AL1100_1 03apr2022.sniper is the downloaded Config File.
I (think I) attached a ZIP file. First time here.
Log file Sniper_0003.dlz is a few minutes of hot-start and idle. I think I've been overlooking a basic ignition issue. Chalking it up to the yard-sale carburetor I've been running while I got around to completing the Sniper install. But you should be able to see the damped oscillation in AFR.

Sniper_0004.dlz is 5+ minutes, sorry. If it's too much trouble to look at skip it, I'll tomorrow create another datalog run of 30-60 seconds of flat and level 60 MPH. This datalog here starts at idle (stop light) accels to freeway speed, then exits, so there's some clean datalog in the middle.

I don't have a Windows computer (Apple, Android, Chromebook) so I can't even look at datalogs till I get one this week. Thanks so much for the helpful reply! Tom

[BorkyDog]

Another issue, or question: I watched Learning happen on the monitor (e.g. the pre-set multigauge AFR monitor) where it would say LEARNG on each Closed Loop & Learn status, and go blue (NoLearn) during Acceleration Enrichment, closed-throttle, etc. Now I see only NoLearn on Learn Status. Today it never went green (Learning). It's warmed up (CTS 190°F), all sensors reporting sensible values (MAT says N/A, the manual doesn't mention MAT, but the TSLCD screenshots show it as N/A) and it's running OK and AFR follows the target. Is this normal?

[GPatrick]

The files came across fine. There are several things to look into. First, at least on the larger Snipers, they tend not to like low idle RPM. If you look at your datalog (when you can) the MAP starts to get a little choppy and this can be due to a low idle RPM or a PCV valve that is fluttering. You may want to set your target idle to 600 to see if sounds a little happier.

I'm not sure how or when the temperature enrichment was changed, but your values from 160°F and up are 103%. When the enrichment is greater than 100% (100.0000Learning g will not occur, which is exactly what both datalogs show. The AFR is tracking the target fairly well and the Closed Loop values are not too bad, but you should make surLearning g is active. Why I said 100.000 is that there have been a few cases where the handheld showed 100, but the actual value was 100.1, for example.

In idle and in cruise you are either getting some random misfires or you might have a little exhaust leak. It looks more like misfires, short little spikes.

Part of the misfire at idle may be due to your Target AFR of 13.5. This is fairly rich and may be loading up your spark plugs. A target idle of 13.9 might smooth it out a little. That and a higher idle should help.

For the PCV, if you're running one, a fixed orifice type will usually help to smooth out the MAP at idle. Let us know how it's currently plumbed.

The idle datalog showed some skipped points, but this may be due to viewing monitors displays while collecting datalogs. The cruise datalog didn't show as many skips.

Last, your battery voltage is inconsistent, especially when you drop to idle. The Sniper likes a steady 13 plus volts and the fuel pump does too. A 600 RPM idle may give you better output as it really drops when it goes down to 500 RPM.

Let us know if you don't know how to change the temperature enrichment values, this is pretty important.

[BorkyDog]

You may want to set your target idle to 600 to see if sounds a little happier.

I bumped the idle to 600 at least for now. I think Sniper likes this more than the engine does, but I'll leave it.

I'm not sure how or when the temperature enrichment was changed, but your values from 160°F and up are 103%. When the enrichment is greater than 100% (100.0000) Learning will not occur

FIXED. This was of course the not-Learn problem. My mistake, not intentional, but I'll certainly remember now. Thanks, learning again.

In idle and in cruise you are either getting some random misfires or you might have a little exhaust leak. It looks more like misfires, short little spikes.

Brand new spotless exhaust from a shop known for quality; but I'll check (TRUST NO ONE. : - ) I'm suspecting spark reliability issues elsewhere and will address those this week. Ordering some parts, improving coil power source, Pertronix 1.5 Ohm coil, new silicone wires. I added an explicit ground to the distributor body; this is a very old Delco-Remy where the entire distributor is rotated by the vacuum advance (yes, the whole body and all the plug wires moves!) and I suspect it's internal ground is lousy. I added here a 14 AWG ground strap, from distributor body to the bolt the battery negative cable goes. Lugs crimped and soldered.

Part of the misfire at idle may be due to your Target AFR of 13.5. This is fairly rich and may be loading up your spark plugs.

This engine really needs 13 - 13.5 idle. I've done a number of the engines and regardless of fuel source "rich" idle is correct. On my Weber carbureted sports car with a hot version of this engine lean drop method ends up at 13.4 or so. I just now tried 13.0, 13.5, 13.8, 14.0, and anything above 13.6-ish gets un-smooth. Pulled a plug this morning, light milk-with-coffee, no ash.

For the PCV, if you're running one, a fixed orifice type will usually help to smooth out the MAP at idle. Let us know how it's currently plumbed.

This was a road draft tube engine, so PCV was determined experimentally (three systems in three years). I'm running the smallest PCV I could determine, 1980 Honda CVCC. It flows very little. It affects idle IAC Position about 0.5; IAC flutters 1 to 2, 1, 2, 2, 1, and entirely plugged PCV barely raises the average of affect idle. This was true with the carburetor. But I will experiment with a fixed orifice. As soon as you mentioned this I did a virtual forehead-slap; this is what I should have done from the start. Far easier to tune. Will do that this week. Thanks for that!

Last, your battery voltage is inconsistent, especially when you drop to idle. The Sniper likes a steady 13 plus volts and the fuel pump does too. A 600 RPM idle may give you better output as it really drops when it goes down to 500 RPM.

This was a generator car, now a retrofit Delco 10SI type alternator, so not much choice of drive pulleys, and yeah, it's low voltage and slow. And you are right again, the low idle voltage cannot help. To eliminate variables I'll play with bumping the idle up, 650, 700, it will be drivable enough to sort this stuff out and I can revisit this later.

Thanks so much for your help. ATTACHED is configuration with 600 RPM idle, Coolant Temp Enrichment 100% at 80°F up, and a datalog of it in operation.
Hot start, idle, then rev to 1300 RPM, held, then closed throttle. Oscillation is small. Revved to 2100, held, then dropped to idle, slightly bigger oscillation.

[AndyF]

Battery voltage looks fine in this datalog, it's 13.5 volts or better. Any idea why your MAT isn't working? I've never seen a bad MAT before. What sucks about it is that the MAT is internal to the Sniper so that's a Holley return for repair deal.
Hot idle looks fine to me, IAC is only 1%, which will limit the ability of the IAC to maintain a steady idle speed. Are you using the Sniper to control the ignition timing? If so, the Sniper will also use the ignition timing to help maintain the target idle speed.

[andrewb70]

AFR lean spikes are either misfires or exhaust leaks. I would pressurize the exhaust system with a Shop Vac and start spraying all slip joints and mating surfaces with soapy water and see if you get any bubbles.

If you never take the engine past 4000 RPM, I would scale the RPM axis accordingly. I would start as low as 400 RPM and use 50 RPM increments to 800 RPM.

You never mentioned the engine timing. Since you're not controlling the spark, what's the base timing at idle? Also, you should probably be using manifold vacuum for the vacuum advance canister.

The MAT sensor is not working, and you need to contact Holley tech support to get this fixed. Andrew

[Danny Cabral]

https://forums.holley.com/showthread...t-Part-Numbers (Holley Sniper EFI Replacement Parts)

[BorkyDog]

Battery voltage looks fine in this datalog, it's 13.5 volts or better. Any idea why your MAT isn't working?

Yeah, alternator pulley isn't too far off, so the 600 RPM fixes it. I'll stop banging my head against the low-idle wall and run 600.

No idea about MAT. It's odd that it says "N/A" and not 0, 999, etc. And it's also not in the initial-checkout list of sensors.

Hot idle looks fine to me, IAC is only 1%, which will limit the ability of the IAC to maintain a steady idle speed. Are you using the Sniper to control the ignition timing? If so, the Sniper will also use the ignition timing to help maintain the target idle speed.

I will eventually have Sniper control spark. I'm about as certain as one can be about no vacuum leaks. Carb cleaner around the trough cover, all fittings, "carb" base, plugged all hoses including PCV. I took the Sniper off and made sure the Sniper+gasket+base cover all the milled out ports on the bottom (got bit by that once), and that it was clean and flat and smooth.

AFR lean spikes are either misfires or exhaust leaks.

I will check exhaust this week after I go over ignition closely.

You never mentioned the engine timing.

I was using "ported spark" with the carb. With manifold advance, cracking the throttle causes vacuum drop, and spark retard, resulting in bog. But I've just replumbed it for manifold vacuum advance. I'll drive land see.

Spark timing is 12-15° BTDC static, and I verified that mechanical and vacuum advance are operating. Last time I measure them they're about 11° advance each max.

I also checked compression: 110 to 115 all six. This is a very low compression engine. Three bumps of compression stroke, if I ran more it would peak higher.

The MAT sensor is not working, and you need to contact Holley tech support to get this fixed. Andrew

Sigh. I'll call them today to ask. This foolish thing is my daily driver.

https://forums.holley.com/showthread...t-Part-Numbers (Holley Sniper EFI Replacement Parts)

Thanks! Alas, the MAT isn't in the list, so I guess I'll call them.

Thanks everyone, seriously, I've already got lots untangled with your help, even if I have more to go. Tom

[andrewb70]

@BorkyDog: Sadly, the MAT sensor isn’t a serviceable item. Andrew

[BorkyDog]

> MAT not serviceable.

Yeah, I have an RMA and will return my Sniper unit for repair later in this month. This is my daily driver, I'll be out of town for nine days the first of May, and I have bugs to fix in the mean time.

I just had a major success with idle and maybe cold start. I found the source of extra air that kept the IAC at 2% max and it wasn't a vacuum leak. It was the Sniper throttle plate not closing properly. A flashlight from underneath made this visible.

The two brass screws are staked so they can't be removed, but I was able to crack them loose a tiny bit, like 1/32nd of a turn. That was enough. Loosened, operated the throttle, tapped the plate very gently from below, tightened the screws. The flashlight revealed the gap reduced to near invisible.

With the throttle-stop screw backed all the way out, on startup the IAC rapidly settled to 12%. From there the throttle stop screw was easy to set IAC to 5%. Idle is better, and unless I'm seeing things I want to see, it seems cold start/after start has improved. I'll let it go ambient cold and get experience and datalogs.

I've owned three or four of these engines and they are not modern. They like a rich idle, but very little air (and fuel). 3.125" bore, long stroke. Will putt putt at 350 RPM, 200 ft/lbs at 1600 RPM. 4500 RPM sounds like it'll self disassemble. It's hard to get Weber carbs setup on them. So the low speed stuff is always a bit off seeming, spec. wise.

I solved my no Windows computer problem by installing Virtualbox on my Apple computer, and installing a free Windows 10 downloaded from Microsoft. It's fully legal and allowed, the catch is you cannot customize the user experience. So no CAN cable, but it can read and write Config Files and datalogs which is all I need. I ferry to and from with the SD card.

I see my Learn Tables look awful. When my Radium Engineering pulse smoother comes, I'll clear the tables and start over.

Today the new spark coil, plug wires, relay arrive, and I'll run ignition power from battery via relay, instead of the 62 year old scrawny wire from the worn ignition switch, regap plugs, etc., and generally eliminate misfire.

[AndyF]

I can tell by your posts that you have the skill and smarts required to make your Sniper install a success.

[BorkyDog]

Thanks AndyF. It might be smarter of me to not work on iron so old and difficult.

Well I got this under control as far as configuration and map and Learn go. I'm ow having a real deal-killer of a problem, below.

The Radium Engineering FPD fuel pulse dampener solved a lot of problems (and the loud noise). Raised idle to 600 RPM which fixed most of the low battery issues, but I'll "soon" put a smaller pulley on the alternator, a generic 10si, since this is such a slow turning engine, unlikely to ever (ever) see 5000 RPM there's no worry of spinning it too fast.

With the FPD and adjusting the TAFR table to be what I know the engine wants (closer anyway) it all started working by-the-book. Learn adjustments were in the plus/minus 10% range and smooth. I had a lot of cold start issues, so I doubled cranking and After Start fuel (gross, but rich at least runs!) and found that what really worked was greatly extending After Start Decay, doubled until it gave no trouble. Then I brought cranking and After Start Enrichment % back down to the original Wizard settings, and a bit leaner. This headed off the hunting (lean/rich/lean/rich/...) during initial warmup. There may be a better way but this at least worked without soaking it in fuel. So this phase of things at least seems tunable.

My big problem: long lean AFR "spikes" seemingly without cause. I reported earlier occasional spikes in lean AFR that we know are either spark or air leak. Well the exhaust is new, a single cast iron outlet, a three bolt flange, downpipe and the WBO2 about 12" down. Looked at the flange, it's gas-tight and silent. (This car is extremely quiet everywhere.) No exhaust leak ticks, etc.

That leaves spark. I had an ancient Delco Remy that I'd personally selected and disassembled and cleaned, it was spotless, near-new bushings, unscored shaft, no slop, etc. Points replaced with Pertronix Ignitor2. It "ran OK", but I did have a felt misfire a week ago. I've always had good luck with them but friends have had problems with them.

I installed a new Pertronix 1.5 Ohm coil, Pertronix 7mm wires, pulled all the plugs, gapped to .034 (.035 tight!), no need for that precision, but eliminating variables. Added explicit ground to distributor body. Added a relay to provide 12V right from the battery, using the old coil + wire to drive the relay. I'm an electrical engineer, I have good wiring practice! Eyeballed the lobe Ignitor gap, no spec, but it's "very close", LOL, probably .015".

Still occasional lean spikes.

So I have another, later, Delco Remy distributor, pretty much a mid '60s GM 6 cylinder distro. It bad been modified, very nicely, for a magnetic trigger and HEI module bolted under the body. I'd collected this after having put the car together. I tore it down (checking for dry bushings, etc) and found that it had been gone through to high standards (knowing the guy I got it from no surprise). Installed that, set Static Timing to about 15° BTDC and it runs great.

Still small lean AFR spikes in the datalog.

So this morning I head out for what was to be a three day tour, and 10 miles from home, it stalls at a stop sign, and won't start. But it wasn't flooded, it wasn't dry, and cranking did nothing, then suddenly it would start. Happened three times, no-start for 3, 4 minutes. I didn't have datalogging on since I was in a busy intersection with commuters on my tail. But I got it going and headed home via surface streets.

With datalogging on and captured some interesting events. This post is long so I'll upload Config File and datalog in a next post.

[BorkyDog]

1200 ms loss of fuel delivery.

Attached is a ZIP with current Config File and a datalog, #34.

The datalog is long, but I can give you two locations in the datalog.

At 911 seconds, I press the gas pedal, TPS increases, followed by increase in MAP, fuel flow, then RPM. AFR drops (enriches). That makes perfect sense to me. Then there's a lean spike. That does not make sense to me. The spike is short so I can understand it not showing dropped RPM, etc in the log due to inertia (engine) and filtering.

911.330 TPS increase, MAP, fuel, RPM increase; AFR decreases.
912.384 Lean spikes to 18.6, MISFIRE, ~400 ms.

But this event at 1323 seconds is much weirder. I was intentionally driving flat smooth steady gas pedal, felt the engine bog ("no spark" sensation), held the pedal steady, you can see in the datalog, AFR goes infinite for about 1200 ms, but RPM drops only somewhat to ~1200 RPM and I looked right at the LCD at this time. I do not remember the number (1200), but was looking for STALL. It did NOT stall. There was no fuel, so the car, in gear, was dragging the engine around. Then it ran again, with no change on my part.

Therefore I know coil current is being switched as the Sniper saw RPM. If there was switched coil power there was spark. Hard to imagine anything going on inside a distributor cap that would be "intermittent" for all cylinders for 1.2 seconds. There was air (foot on pedal). So there was no fuel.

As a reminder, my Autolite Sniper has a bad MAT sensor. I wonder if it has other problems.

There are other events in the datalog, but it's a long datalog.

@1323

On Eagle Rock Blvd, flat level 35 MPH steady throttle 1323.390 all steady yet AFR spike from 13.8 to infinity for 1200 ms. Yet RPM shows ~1200 RPM, LCD did NOT say stall I looked. So coil current is being switched.