MSD Atomic EFI: Tuning Tuning Tuning

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babywag
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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Mon Oct 10, 2016 2:02 pm

that's awful rich no wonder it has a little issue w/ hot restarts.

maybe try 13.6, then 13.7...etc until tou can compromise between two?
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Dr. Marneaus
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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Oct 10, 2016 3:24 pm

Maybe i dont understand how much of a difference .1 is.

I know under WOT conditions it drops to 12.5
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Mon Oct 10, 2016 5:57 pm

Well small changes are the norm when tuning, since you can't access the whole fuel table you're stuck trying to find a happy compromise.
You say it needs to be 13.5 to eliminate the miss @ idle, but @ that setting you have some hot restart anomalies.
13.5 is pretty pig rich for idle, and you're going to have issues like you've seen.
On cold starts it can probably tolerate it because a cold engine needs more fuel.

The target of say ~14.13, is the point @ which on e10 the engine should have the most efficient burn/lowest emissions.
No ethanol fuel is 14.7, e15 is ~13.8, e85 is ~9.7, etc.
Lower than 14.13 your engine will make more power to a point, but past that point you're just wasting fuel.

12.5 @ WOT is probably a little rich as well. 12.7-13.1 would be more in the ballpark.
Again too rich = just wasting fuel, and under extremes you'll actually lose power when too rich.

Cruise you can go on the lean side, you'll pick up some MPG that way, nothing drastic, but should see a gain once dialed in.
When playing with mine I gained ~1.5-2 MPG running on the highway by targeting the AFR into the high 15's., repeatable on multiple tanks.
However you can feel the slight loss of power, and it's more fun running richer, just hurts the wallet more lol.

But, if you can't change it from 13.5 to say 13.6 then nevermind.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Oct 10, 2016 6:04 pm

Cool. I'll keep playing. I think the default setting on the MSD was 14.0 at both idle and cruise. I know that doesn't really even mean anything tho.

FYI I don't have any issues with hot start idle. Just when I get on the gas.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Tue Nov 01, 2016 8:56 am

Been driving it around a bit. It's been hunting on start up again.

Also, within the first minute of driving on a cold start, even if it's been allowed to warm for several minutes, when you step on the gas it bogs and sputters and i actually got it to stall on the road when I was doing about 25mph. then took a second to fire back up, perhaps it was flooded?

It did this same thing to me back several months ago before I started adjusting the tuning to different displacements, etc. Not sure what happened.

However, AFTER that initial drive issue and then putting around in the rainy desert with no issues, the thing was purring like a kitten. It was holding idle at between 650-665 rpm, I was amazed it was steady to within 15-20 rpm, and in park it was super steady right around 800. No the miss is now nearly invisible at 14.0 AFR for idle, and its 100% invisible at 13.8.

I realized also that on this last trip towing, as well as putting around the desert over the course of 175 miles....I got 8.4 which is literally the worst I have ever gotten. Odd. Maybe i should go back to the setting sI was running on my trip to Lassen NP with the displacement set at 400CID, I wasnt toweing but I managed over 13mpg.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Thu Nov 03, 2016 8:05 am

Running richer than ~14.12 will decrease mileage, especially low speeds/idling. Towing will obviously kill mileage as well.
Engines run great richer, but use a bunch more fuel.

If it runs better with the CID increase, then use that setup. It's simply a cheat to increasing fuel globally.

Were you ever able to isolate the hunting/miss to a specific cylinder?
Maybe you have a mechanical problem? You will never be able to fully tune a mechanical problem away.
Ever done a compression test or better a leak down test?
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Fri Nov 18, 2016 1:12 pm

I haven't touched the wagon in nearly 3 weeks. I dont know why, it didnt run all that great last time I drove it (did the hesitant sumble thing as mentioned above).

Kinda over it for now. Dont even feel like thinking about it.

But,, i fired it up this morning because it was like 25* out and wanted to see a "real" cold start. ECT registered 34* when I turned the key. Yeah, fired right up, hit about 1000 RPM, then idled perfect with no hunting or anything, no hiccups, for like 5 minutes. What gives? Runs perfect at 34* but at 70 it stalls. Freakin' figures. Maybe i'll drive it this weekend, but that would require taking all the crap i've piled up on top of it off.....which sounds like more effort than its worth.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby az chip » Fri Nov 18, 2016 10:33 pm

Which since that happened could be a supporting system or part and not the EFI itself. What changes in the cold? Air density.
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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby GaJeep94YJ » Mon Nov 21, 2016 8:23 am

Isn't 34° weather perfect weather for the campah?

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Mon Nov 21, 2016 11:06 am

Cold engines are much more tolerant of overly rich conditions.

If you browse any tuning sites, usually the first response to someone posting about a driveability issue is to post a data log.
Generally when tuning without seeing/having a data log, you're kind of flying blind and forced to use the trial and error/experiment method(s).
Make small changes and tweaks to settings and see if you can resolve/reduce the problem.

Also if you have a mechanical problem with the engine itself, you'll never "tune it out".
You can compensate for it to a point if it is a minor problem, but it will still be there.
EFI isn't a magic bullet, if there is a problem before a conversion it will always be present after the conversion.

Is there any add-on you can buy for your system to get a data log?
Maybe a leak down test to verify that everything is good?
Check the intake w/ a propane cylinder to ensure you don't have a vacuum leak? Check the heater vacuum switch & lines for leak? Check brake booster for leak? etc.
Verify the amount(s) and function of mechanical and vacuum advance units with a timing light?
Verify fuel pressure is remaining constant throughout operation?...no overpressure or starvation...issues.

If the engine is sound, and the tune is good, it should run like a newer EFI car, w/ no driveability issues or flakiness.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Dr. Marneaus
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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Nov 21, 2016 3:35 pm

I've not done a leak down test. I can try this when I have time in the coming weeks.

I have searched for vacuum leaks about 1000 times in the past, both distant and recent. I could be missing it, but I've never found anything.

From what I can see, there is no method to pull data from the MSD Atomic EFI.

I have never seen the fuel pressure change more than about 1 PSI and that isnt a "flicker" or anything, it would depend on outside temp, engine temp, etc. Once the truck is on and running and warmed up I've never seen the fuel pressure change from where I have it set.

I just find it interesting that things vary so much. I need to go back and read what I was setting everything to when I went on the trip to crater lake. The truck drove awesome, but still did the warm start thing. Other than that, that was the smoothest and best running trip I can recall, and I got great mileage. That, I believe, was back when I was at 400CID displacement.

What i've noticed on this tune is that it practically stalls out when i first start driving, from a cold start. when I press the gas with any force, within the first 30-60 seconds of a drive the truck bogs and stumbles and falls on its face, and gets worse and worse until i let off the gas, baby it for a minute or two, and then it drives normal and is responsive. When that happens, the AFR goes through the roof. This is different than the warm start hesitation thing, this situation has actually stalled my truck out while doing 25mph, on a street, near my house. That never happened with the other tune, and this issue is only on a cold start without the engine being FULLY warmed (i've let it idle a few minutes before hopping in and experiencing this).

Right now its driving okay once things are in motion, but it doesnt feel "calm" or "smooth" like it did on the trip to crater lake.

I havent noticed the hot start hesitation as much. currently it's running at 13.6 or 13.7AFR at idle. That has elimiated the miss, and hopefully keeps it from being too rich on hot start. I havent played with that much lately though.

Also, my "cruise" AFR is set to 14.5 IIRC, which hasnt seemed to cause much of an issue, aside from not feeling quite as smooth or calm.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Nov 21, 2016 4:05 pm

But, planning a trip to Portola with my parents in 2 weeks, so that'll give me a good 150 mile drive to feel things out on as well.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Nov 21, 2016 4:07 pm

P.S. by no means is it running "bad" nor is it anywhere near undrivable, it just bugs me that it's not super consistent in how its acting up. The bottom line is that even in this condition, i have driven the thing on numerous trips that absolutely would have sent the jeep into a tantrum when it was running the carb and duraspark.

And I just have a hard time digesting all of this sometimes because i really dont know much at all about the details or workings of EFI.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Mon Nov 21, 2016 5:00 pm

Dr. Marneaus wrote:it just bugs me that it's not super consistent in how its acting up...
And I just have a hard time digesting all of this sometimes because i really dont know much at all about the details or workings of EFI.


That's the thing, it shouldn't be inconsistent or act up. Should just be solid, turn the key and go.

It is a LOT to absorb and understand, that is for sure.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Mon Nov 28, 2016 12:15 pm

Okay, more of the same.

Hunting at cold start, to the point where it almost stalls.

Had a pretty significant "bog session" sunday morning when I went for a drive. I let the truck warm up for a minute or three, then put it in gear, coast out of the driveway, minor throttle to the stop sign 50 yards away, then try to accelerate onto the street and drive normally. The engine bogs and bucks, the AFR goes way up. Let off the pedal, it idles mostly fine, step on the gas (either gently or forcefully) and it bogs and almost stalls. Repeat 3 or 4 times while coasting, or pull over for a moment, and it goes away, then drives normal. I have in the past, gotten it to actually stall while the vehicle is moving, during these conditions.

That's an odd one, but it DID do this once or twice even before the HEI install. That was the biggest thing I encountered, once or twice over the weekend, and I put probably 100 miles or more on it between the few different days.

I'm thinking right now that I am going to revert back to the 400CID tune with the lower fuel pressure, and compare and see if I can get anything similar to happen. I believe the last time I ran that tune was BEFORE the HEI install.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Wed Nov 30, 2016 12:01 pm

No, i know the instructions are for a "general" installation, but any insight as to what would happen if I increased fuel pressure?

The MSD instructions say to set the regulator to a minimum of 45PSI.

I was told, near the beginning by some folks here, to go with a way reduced fuel pressure because that would give way too much fuel across the full spectrum of performance.

After that, we bumped to 400CID, which even with the lower fuel pressure, was a way to globally supply more fuel.

Following that, we went back to 360CID, with fuel pressure up to 35psi. This was in an effort to keep the tune closer to what theoretically should be needed for a 360 in all given performance situations, but adding fuel pressure to give it more fuel.

We had bigger displacement, less pressure, then smaller displacement, more pressure.

So, what if I increase stick with 360cid, then increase to 45psi, which is the "minimum" as according to the instructions? This should provide more fuel globally, yes?
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Wed Nov 30, 2016 12:21 pm

Yep, increasing fuel pressure will globally increase fuel delivery.
Increasing CID results in more fuel delivery as well, but in a different way, done via a calculation in programming, based off injector flow rate and CID.

The problem with large FI systems are the same as a carb that is too big for the engine.
Poor driveability, and hard to tune.

A big heavy Jeep w/ a low compression smog era engine w/ lame camshaft, doesn't need a 600hp FI system.
Look @ the stock specs 8.25:1 compression, ~385cfm 2bbl carb and a whopping ~150hp.
Can you make it work, sure can, but it'll take some effort.

*If* the injectors are linear you "should" be able to get away with a lower fuel pressure setting, than a slightly built AMC 360 w/ maybe an RV cam.
But, if they aren't linear(in flow) a lower setting may not be ideal, they may flow far less than expected? And it may lean out?

Without being able to see data logs it's basically just a guessing game.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Nikkormat » Wed Nov 30, 2016 12:42 pm

Maybe the answer is a more restrictive air filter? Effectively capping the CFM the unit can flow?
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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby Dr. Marneaus » Wed Nov 30, 2016 1:00 pm

Well, bumping fuel pressure in either direction is like a 3 minute operation, so, I guess it couldnt hurt to try, and see if drivability changes, and go from there.

just trying to think about the times I have tuned it and it did not exhibit the major stumble on cold start issues. I also feel like im getting really poor fuel economy right now though, but thats just speculation. I will have the opportunity to gauge that this weekend with a few hundred miles on the highway.
Well it ain't just the smoke and the traffic jam that makes me the bitter fool I am But this four-wheel buggy is A-dollaring me to death.
For gas and oils and fluids and grease, And wires and tires and anti freeze....And them accessories, Well honey, that's something else.

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Re: MSD Atomic EFI: Tuning Tuning Tuning

Postby babywag » Wed Nov 30, 2016 6:37 pm

Dr. Marneaus wrote:Well, bumping fuel pressure in either direction is like a 3 minute operation, so, I guess it couldnt hurt to try, and see if drivability changes, and go from there.

just trying to think about the times I have tuned it and it did not exhibit the major stumble on cold start issues. I also feel like im getting really poor fuel economy right now though, but thats just speculation. I will have the opportunity to gauge that this weekend with a few hundred miles on the highway.


Maybe start a list, write down setting changed and old/new values each time.
Tuning software takes care of this for you automagically, so it's easy to recall when/what was changed in a tune.
Don't change to many things @ once, or you'll never know which specific setting made the most difference(good/bad).

Compare results, frequency of issue, when it happens, etc. etc.
Might help you nail it down, or lessen/hopefully eliminate it?
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.


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