MSD Atomic EFI: Tuning Tuning Tuning

[babywag]

That's true I can always disconnect O2 sensor huh?

When it has a WBO2 error it defaults to 14.7

My target AFR's are 14.0 for idle and cruise, WOT is 12.8 I think. That's all default

Yes, *if* the fuel table is good, you can disconnect o2 and run open loop.
It is a good test to see how close fueling is.
Does your system have an option to run open loop? w/o needing to unplug the sensor so you can still see the wb readings?

[nightglide]

I don't think you should unplug a heated o2 sensor. It will foul rather quickly if unheated and may not be able to clean itself when able to heat again

[Dr. Marneaus]

That's true I can always disconnect O2 sensor huh?

When it has a WBO2 error it defaults to 14.7

My target AFR's are 14.0 for idle and cruise, WOT is 12.8 I think. That's all default

Yes, *if* the fuel table is good, you can disconnect o2 and run open loop.
It is a good test to see how close fueling is.
Does your system have an option to run open loop? w/o needing to unplug the sensor so you can still see the wb readings?

I'm not sure if I can shut it off, like Owen said though it'll foul the sensor pretty quick i think. I know he had experience with that.

do those plugs really not look that far lean? One of them was a little crusty, not just white (the number 1, the leanest cylinder right?) other than that all 6 that i pulled looked pretty dang much the same. No real discernible difference between any of them, and definitely not any that were dark or black or wet or anything significantly different, what its all consistent across the engine.

[Dr. Marneaus]

for what its worth, i do fully intend to purchase ALL new exhausters, from the manifolds back. I'd like new Y pipe with flanges, delete the gutted flapper flange, new muffler, then an actual tailpipe. I just cannot afford to drop like $500-$600 on new exhaust at the moment, so hopefully I can identify any issues.

I have a new donut on the driver side, and a new flat gasket on the passenger. My only area of concern would be the flange/flapper on the passenger side. the flange is pretty bent, and who knows how well the flared pipe seals against the metal donut on the flapper thingy.

[Flip]

Great news on the lack of vacuum leaks!

Definitely look/listen for exhaust leak. Do it with the engine stone cold (metal contracts when cold, so crack, or gap will be larger). In Tony's picture, see how the crack is white-ish. You'll see that but it may be much thinner line or spot. If you didn't remove the exhaust valve, look closely with an incandescent flash light and mirror all around it.
The "hose trick" for listening works awesome just make sure to wear gloves. The colder the engine is, the easier it will be to find a leak.

Next use a vacuum gauge to check mechanical condition. Plenty of YouTube videos on this. here is one example
https://www.youtube.com/watch?v=SdlNwm8OHco
If the vacuum gauge test shows issues, don't stress. We can tune around a lot of this, for now, just by cheating the system.
We just need to know what those issues are, so we know how to "cheat".

If there are no exhaust leaks, and the vacuum is smooth and of reasonable pressure, I think the hunting issue can be limited with tweaking the tune.
We may also want to play with engine displacement, if the tweaking getting exaggerated. But let's cross that bridge down the road.

Once the hunting is mostly resolved, the HEI can be installed. Timing control function of the MSD will be of help with any minor hunting issues left unresolved.

Something to consider on timing. Harmonic balancers slip. So just because your light shows the marks aligned at 13*BTDC, doesn't mean that is really where it's at. Also, "book" timing is just a guide line. Not a hard rule. Elevation, fuel, engine condition, EGR function, all affect timing.

[Dr. Marneaus]

Great news on the lack of vacuum leaks!

Definitely look/listen for exhaust leak. Do it with the engine stone cold (metal contracts when cold, so crack, or gap will be larger). In Tony's picture, see how the crack is white-ish. You'll see that but it may be much thinner line or spot. If you didn't remove the exhaust valve, look closely with an incandescent flash light and mirror all around it.
The "hose trick" for listening works awesome just make sure to wear gloves. The colder the engine is, the easier it will be to find a leak.

Next use a vacuum gauge to check mechanical condition. Plenty of YouTube videos on this. here is one example
https://www.youtube.com/watch?v=SdlNwm8OHco
If the vacuum gauge test shows issues, don't stress. We can tune around a lot of this, for now, just by cheating the system.
We just need to know what those issues are, so we know how to "cheat".

If there are no exhaust leaks, and the vacuum is smooth and of reasonable pressure, I think the hunting issue can be limited with tweaking the tune.
We may also want to play with engine displacement, if the tweaking getting exaggerated. But let's cross that bridge down the road.

Once the hunting is mostly resolved, the HEI can be installed. Timing control function of the MSD will be of help with any minor hunting issues left unresolved.

Something to consider on timing. Harmonic balancers slip. So just because your light shows the marks aligned at 13*BTDC, doesn't mean that is really where it's at. Also, "book" timing is just a guide line. Not a hard rule. Elevation, fuel, engine condition, EGR function, all affect timing.

Awesome, thanks for the good info.

I dont think I've put a vacuum gauge on it since RIGHT after the install. Maybe i didnt even check since installing. Prior to installing the EFI I adjusted timing and idle for best vacuum. I had a pretty darn consistent 17". When I was in vegas I had about 19 IIRC, but I'm told with elevation it'll drop a bit. Also, my Harbor freight vacuum gauge reads 16", but when i put my mighty vac on the HF gauge the mighty vac reads 17" and the HF gauge reads 16", so theres a minor descrepancy. I assume the might vac gauge is better than the HF one, thats why I said a steady 17".

I'll try to fart around with it tonight. It's going to be a 13 hour work day, so we'll see if i even have enough energy to crack a beer when I get home.

[Dr. Marneaus]

Also from my understanding this 1 wire HEI will not support timing control

[babywag]

You may be able to modify the HEI to do timing control? Depends on what they (MSD) require?

Your Duraspark uses the same 2-wire pickup coil as the MSD 8519 distributor.
So see what that distributor needs to control timing using your system, it'll be the same.

That's why most of the DIY TBI guys use the Duraspark, because it works easily, just need to lock mechanical & vacuum advance out.
But an HEI can be modified by modifying it to use a different module internally, and again lock out advance.

I'd still look into calibrating the WBo2 as well.
Is there any settings that can be changed for fuel type?
My $150 WBo2 can be calibrated, by following a short procedure to ensure it remains accurate.
I'd think they should have that ability with a $2k+ system? But, maybe not?

[Dr. Marneaus]

You may be able to modify the HEI to do timing control? Depends on what they (MSD) require?

Your Duraspark uses the same 2-wire pickup coil as the MSD 8519 distributor.
So see what that distributor needs to control timing using your system, it'll be the same.

That's why most of the DIY TBI guys use the Duraspark, because it works easily, just need to lock mechanical & vacuum advance out.
But an HEI can be modified by modifying it to use a different module internally, and again lock out advance.

I'd still look into calibrating the WBo2 as well.
Is there any settings that can be changed for fuel type?
My $150 WBo2 can be calibrated, by following a short procedure to ensure it remains accurate.
I'd think they should have that ability with a $2k+ system? But, maybe not?

This turned into. A 15 hour work day so nothing's gonna get done tonight. I'm familiar with the process of locking out and modifying for timing control on s Duraspark but I'm not planning to use timing control so I went with the BEI

[babywag]

If you have time today...?
Pull o2 sensor and look @ it, if it is white-ish then you're running lean and likely have an exhaust leak before the sensor.

[FSJ Guy]

As they say, timing is everything. I'd recommend rethinking your choice. You spent the $ for a nice system that can do computerized timing control. Why not take advantage of it? <shrug>

[ferrum]

for what its worth, i do fully intend to purchase ALL new exhausters, from the manifolds back. I'd like new Y pipe with flanges, delete the gutted flapper flange, new muffler, then an actual tailpipe. I just cannot afford to drop like $500-$600 on new exhaust at the moment, so hopefully I can identify any issues.

I have a new donut on the driver side, and a new flat gasket on the passenger. My only area of concern would be the flange/flapper on the passenger side. the flange is pretty bent, and who knows how well the flared pipe seals against the metal donut on the flapper thingy.

I installed Howell TBI fuel only year and half ago. I had issues with rough idle and hesitation. Initially, I just locked the heat riser locked open which caused exhaust leak. I didn't want to spend whole bunch of money on new exhaust system so I did next best thing. I cut the flange end of exhaust pipe 5-6 inches below. Kept the removed flapper (I collect pieces that gets removed) and bought a 12 inch exhaust pipe (cut to fit the gap) from o'reilly's that would sleeve over the existing pipe. Welded it in place. This made my system work much better. This was my first attempt at welding so I embarrassed to post up photo but if you want to see it, I will.

[Dr. Marneaus]

As they say, timing is everything. I'd recommend rethinking your choice. You spent the $ for a nice system that can do computerized timing control. Why not take advantage of it? <shrug>

Because from my reading and conversations with others who have done similar systems, if you have a quality functioning ignition system the timing control really isn't thy big of a deal. If you were running points and going with a whole new setup it makes sense to incorporate it.

Part of my experience comes from helping Nightglide with his FItech install, in which he determined that it ran way better and was less to fiddle with by just going with TFI and an MSD type box, and not use the timing control.

Also it would cost me a lot more to get an MSD setup to utilize the timing control or require modding the duraspark distributor which Nightglide didn't have very good luck doing, hei should be a good simple upgrade.

[Dr. Marneaus]

If you have time today...?
Pull o2 sensor and look @ it, if it is white-ish then you're running lean and likely have an exhaust leak before the sensor.

Phew. SAturday was busy and crazy as well. I'm about to head out there as soon as I finish this cup of coffee

[Dr. Marneaus]

I think the O2 sensor looks normal. I couldn't hear any nor see any evidence of an exhaust leak. There are only about 4 inches between the flapper and the O2 sensor. The flapper was remove and the holes welded, but the actual body of the flapper remains

I haven't had a chance to check vacuum yet, will do that after running errands

[babywag]

Yep, O2 looks fine...

[Tatsadasayago]

Very clean in fact!

[Dr. Marneaus]

Only been in there for maybe 300 miles, maybe a little more, but yeah, looked fine.

Im waiting for engine to warm up now so I can check vacuum

[Flip]

WBO2 looks good.
Doesn't mean you don't have an exhaust leak though. Just that your system is making up for it. So, use that hose, a good light and mechanics mirror, to double check the exhaust.

Any way... After confirming no exhaust leaks, the last step is vacuum tests. Then we can start tweaking things. If you see anything weird with the vacuum, or something just seems off. Try and get a short video of it, so we can see what you see.

IAC, and fuel control is all reactionary. Timing control is preemptive. That's what makes it such a great feature. The ECU does things like bump timing as soon as the TPS sees movement, long before the fuel gets into the cylinders for fast seamless transition. Adjusting for AIT, altitude, etc. It all helps make for a smooth running engine.
But like anything it has to be well understood, and correctly used. It can exacerbate a mechanical issue, and is definitely not a panacea. It is more of a fine tuning strategy.
Down the road, it may be something to look at, maybe by running a 6A box. I'm not normally one to add "points of failure", but the 6A is a pretty tried and true unit.

All these long days are great for the wallet. All work, and no time to spend money.

[Dr. Marneaus]

Okay. So vacuum is pretty much the same as it always has been.

As mentioned I believe my gauge to read roughly 1" low, but that could be incorrect.

In neutral at roughly 800rpm it shows between 16" and 17" with the occasional drop coinciding with the miss. It never dropped below 16", so the miss would only cause a dip of about .5"

In gear at about 675rpm it shows 14" steady, except for the aforementioned drop when it misses, which was even less evident (less than .5"). Overall it's pretty darn steady except for the miss.

It may go several seconds without a miss, it may miss just once then go away for 10-15 seconds,or it may miss three times within a second and then be fine for several seconds and miss a time or three again.

As mentioned if I dropped the AFR to 12.0 the miss is about 99% gone. If I drop it to 13.0 the miss is probably 50%-75% less common, in both cases it idles a bit smoother in general as well. Not sure if that is helpful info or not, just something I found.

Lastly allow me to mention I'm not like afraid it's gojng to stall out or something when idling, I've had quite the similar miss for a long time, and have put thousands of miles on the truck. So I dont know if I'm being picky or if my feelings that the EFI setup should eliminate this are warranted. Overall the truck runs 'fine' but I really want to get it as good as I can, obviously.

I understand that if there is anything we can do to fix this unrelated to the ignition, it should be done, but is there no chance that the HEI could just plain old fix the problem?