MHS PI H/C Tuning

[theterminator93]

Don't teachers get Vacations?

Don Pardo voiceover:" For the low low price of a Premium Disney vacation, that knowledge could be yours..."

I feel your pain.

fine, then it's an issue of money, lol.

It not so much the money, it's going to be the fact we didn't spend that money on someone else, lol.

That's what keeps us from doing it; to live thru it, I'd have to spend at least 3x the training cost, total.

I can't get to the ups store till Saturday, BTW.

I had a thought (gasp) about my bucking issue at CT. Originally I was convinced it was the converter locking/unlocking rapidly. So I checked my "bucking" logs for any signs the TC was doing anything it shouldn't have been and found no evidence to support that . So I took the data at face value and decided to search elsewhere for the problem.

I was reading on the SCT boards and found a found a post that excessive EGR combined with a heavier cam overlap could generate a low RPM/TP misfire.

After digesting that information and realizing that I (still) have a bit of drivetrain play, I envisioned in my mind the very real possibility that the "sound" of the converter doing a jig is really just drivetrain thunks due to engine misfires during deceleration. CT, engine misses and a locked converter would definitely cause the car to buck.

Lo and behold, during deceleration my load is upwards of 15-18% (depending on speed) at an RPM of 1100-1400. So I checked the EGR tables and sure enough, EGR is maxed out at 10% in the 20% load/low RPM areas where I'm decelerating. The issue of it only happening after the car's been out on the road at temperature for a while? Seems to coincide perfectly EGR start delay table. All of a sudden, this thing started to make a LOT of sense.

I found a scalar "Min. airflow for EGR enable" and set it to 1.4 #/min, since cruising at 30 MPH shows an airflow of 1.5+ #/min. In theory this will prevent there from being any EGR flow at the load levels I see during deceleration, and in turn cure the engine misfire causing the car to buck at CT.

I also found that the problem was DRASTICALLY reduced when I had the car forced in open loop to re-tune the (slightly enriched) MAF transfer. So I'm also setting my O2 biases to enrich the mixture at the conditions of low speed decel as well. Hopefully this combination of less EGR and a little more fuel kicks this misfire in the butt.

Time to go see if this works.

 

[theterminator93]

Sounds good. Great investigating.

So, Grog... have you had a chance to test the WOT 3-4 127.5 MPH shift lockout value file from Don yet?

Eventually I'm going to re-dyno the car after I finish dialing in this car's program and it'd be cool to be able to wind it out a little higher than the 5800 or so I did last time...

BTW, bucking is not totally fixed yet. Found a section that addresses this in Don's book which has some suggestions I'd like to implement. But it might have to wait, since it's sleeting outside now... Darned lake effect! lol

 

[theterminator93]

I think he was waiting for you, lol I know I am

It's loaded, but no off-road time to find out if it works.

I'm sure one of my buds would Love to see me doing that on the interstate.

There wouldn't be enough azz left to arrest, lol.

Come to the Texas Mile, maybe you can bribe them to let you run tomorrow before they pack up, lol.

The only MN12 I have running right now is Lazarus; he's rough, to say the least.

March 19, 2014

Okay, spring looks like it might be coming sometime before July now, so it's time to continue the quest for the perfect tune.

Now I'm asking myself this question, which I haven't yet read anything about anywhere.

I know the "peak power" lambda is at about .88. The ability to add spark usually means more power. But I also know that the more you lean out the mixture, the less tolerant the mixture is to more spark.

What I'm trying to wrap my head around is the best relationship between optimum lambda (e.g. .88) and peak spark. Is it better to go a couple points richer (say, .86) and keep 2-3 degrees of spark, or get lambda as close as possible to peak flame speed and adjust timing accordingly? Which gets priority, best spark or best lambda?

I have a feeling it's going to be "adjust to your best lambda then dial in for best spark at that lambda" but wanted to bounce this against a couple of you guys.

 

[theterminator93]

you're pretty much right. So long as you can do controlled runs, the acceleration rate parameter is a great value to "look" indirectly at the torque curve. Try a few things out and see which maximizes the accl_rate over a range of RPMs. When looking to maximize torque/power production, saving fuel is of the least concern, so might as well use a tad more fuel if needed. My hunch is that the torque production will vary very little from varying lambda from 0.83-0.88 on such a heavy car. Of course you could see this right away if you run the same spark advance curve, during a course of a few runs, each at say +0.02 lambda points. A few seconds worth of data from say 2500-5500 RPMs locked in 3rd where there will be more datalog points will yield the best resolution for analysis.

Hey guys, sorry for bumping a 3 month old thread, but it has some info in it related to a couple questions I have. If I should have started a new thread, feel free to move this to one.

About injector timing. I'm working on building a tune in PRP for my SVO blown Mustang. In a post a while back, a comment was made about centering the injector pulsewidth as close to (or somewhere nearby) the ICL. Does this hold true for supercharged cars under boost? I assume at low loads it still would, but at higher loads, I have no clue if the velocity profile would be different relative to the ICL under boost.

2nd, just to make sure I thoroughly (enough) understand this (I'm thinking out loud here) : we want the PW to be centered around the peak airflow velocity, which is near the ICL, to ensure the best mixture in the cylinder as possible, as well as so no fuel goes out the still-open exhaust valve. Once the PW widens up a bit, we start spraying fuel before the exhaust valve is completely closed, so we should delay the PW farther after the ICL. Then, as the PW widens up even more (or as the RPM go up), the PW crosses the point where we're still spraying when the intake valve closes (not good), so we delay it back down appropriately, which inevitably results in some valve overlap during the PW. However, since we're at WOT (or near it) when this happens, it's not a very big concern.

All of this ^^ correct? Or am I misunderstanding something? Is there any situation (idle, WOT, etc.) where the above theory may not hold true? I apologize for asking so many questions, but just trying to completely wrap my head around it.

Lastly, how close to the intake valve closing event would you have the PW ending, and how much before the exhaust closing event could you spray? I assume there's some sort of delay between the injector firing and the fuel actually crossing the seat, but I have no clue whereabouts that might be.

I've got all this in a spreadsheet, and can easily change any of it, but just want to get it as close as I think I can before I start fine-tuning the MAF transfer function, idle, and all that jazz.

Thanks guys. This thread was an awesome read and got me thinking and researching a lot of things I hadn't previously thought of.

Let me look into it.

With regards to the PW, you're right and wrong at the same time because some of those things can be circumvented by using "larger" injectors. So it all depends what your injectors are capable of.

Right. I've got 39 pound Cobra injectors. They look like they're going to be well up there duty cycle wise, probably 80-90%.

I can see where larger injectors would be better in that you have a lot more control of firing them at a more precise time. Although it looks like even with 80 pound injectors, they'd still have to be fired before the intake valve opened when at 5000+ rpm. But that's much better than my 39 pounders that'll be fired on a closed intake valve from 3000 rpm up (at WOT).

I have a spreadsheet I customized (which you can further adjust to your needs) to help you calculate your delay table based on your injector size, AFR and such. PM me if you're interested.

 

[theterminator93]

I've read that you can take cobra 39 lb'ers up to 60-70psi, which is something that I might be doing with my fuel system. That would increase their flow capability 23%. Maintaining a proper alternator voltage is also paramount, especially at the times when the duty cycle is the highest.

To be honest, with what I've been reading up on, I don't think it will all make too much of a difference.

www.youtube.com/embed/X3ecq8MNfk0
www.youtube.com/embed/nZorW4yfSbc
www.youtube.com/embed/vTXHXR3cj-Q

Notice how even in the inactive ports, there is still quite a bit of air shuffling around, and what Nick mentioned about his intake porting experience seems to correlate with those flow simulations. Only emperical testing of BSFC would really tell me (us) if I'm right about the whole "better mixing at peak intake port velocity".

I'm still searching for the answer with my coasting miss and I'm starting to think about adjusting the injector delay at the load/RPM it's happening at - for this reason. I just need to force myself to go out and do it.

 

[theterminator93]

Yea, I did the same thing. I've got the logic so that it first calculates the pulsewidth in degrees based on the load, RPM, engine displacement, injector size, etc. Then, at all loads and rpms, I have it default to centering that pulsewidth about the ICL +/- 10 degrees (depending on the rpm). If having this centered pulsewidth results in the injector firing before the exhaust valve is fully closed, it delays the firing just enough so that the start is just after the exhaust valve closes. If this then results in it firing after the intake valve passes the .050 closing event, it advances the timing to keep the end of injection at that .050 point.

I saw your tables a couple of pages ago. Looks similar to what I did. It looks like our timing at lower loads (<.2) is fairly similar. Has that worked well for you concerning idle quality? I'll try and post mine this evening when I get off work.

Hah, I forgot I posted the general formula I used to calculate the delivery method. Glad it was able to get the spark going in someone else's mind.

The idle is good, but there's a miss while coasting below ~1400 RPM which I'm trying to track down. I've tried just about everything I can think of but injector delay at this point...

 

[theterminator93]

In any vacuum, you can't really think of "pressure" or "air resistance".

Manifold vacuum gets close to Knudsen flow or 'Molecular Flow'.

There's very little there to run into, so anything with some velocity and momentum is going to keep going until it hits something; then bounce off in a new direction...

Flow/Conductance in a vacuum is easier for me to model as interaction cross-sections; which change as a function of system dimensions and density of the media that's flowing.

I wonder how that would change during WOT when MAP ≈ 1bar ( <1 in-Hg on a free flowing intake). Perhaps getting the fuel charge in during peak port velocity would help more so than at low-mid throttle settings.

Hmm, I'm using the injector values I calculated, and haven't had any problems. No misfires, hesitations, stumbling, etc. It idles just fine (although I have some tweaking I want to do with how the cam lopes), and part throttle is fine also. Really about the only things I have left to do is finish the MAF transfer at WOT, do the failed MAF table, and get torque converter lockups like I want them.

Oh, and the spark tables. Any hints on how to do that at part throttle and idle? I roughly know where to set it at WOT, but I'm fairly clueless at part throttle, and everything I read says "just do it by trial and error". Which, as an engineer, doesn't exactly satisfy me.

So are you saying that injecting fuel while the valve is open is better since the fuel will mostly go into the cylinder instead of bouncing off the top of the valve back into the plenum?

Or are you saying it doesn't make any difference at all?


Also, I read elsewhere that injecting fuel directly into the cylinder with the valve open could wash down the cylinder walls and shorten piston life. Any way this could be possible?

Unless you're running wayyy rich, I don't see how it is much different than the cylinder ingesting it on it's own. You're not dumping down 1/2 an ounce of fuel with every intake stroke injection. When the valve is open or closed for that matter, there is always something in the cylinder for the tiny fuel mist to physically interact with. It's not like there's a perfect vacuum (even when there is some vacuum in the intake tract, it's nowhere near an actual vacuum) where the fuel mist can go unobstructed. Take datalog readings of the maf signal in lbs/min and there you have it---you have that much air entering the manifold and thus the runners. Alternatively you can take manifold vacuum, and then convert it to absolute barometric pressure and use the ideal-gas-law to calculate the raw air mass actually present inside the manifold at any given time, given that manifold volume is ~ 8-9L.

Even then you have a ~1.75" intake valve in the way, which only opens on average 0.5" off the seat, which is at the end of a curved intake port. (an open intake valve in a ford modular 2V in no way, shape, or form gives you a 100% clear line-of-sight from the intake port straight to the cylinder wall----mock up a cylinder head without valves and you'll see that even without valves, there's only a tiny spot that likely gets blocked by the actual intake valve. When you look at things realistically, then you can see how some ramblings from some internet-engineer conflict with reality.

Pick up both of Greg Banish's books.

Back on the topic of the thread...

I did some experimenting today to hunt down the cause of my miss while coasting. I added quite a bit of spark and a little extra fuel (the extra fuel was tried by its own before adding spark and didn't help) down low and it improved quite a bit. Time shall tell if this is the fix I needed...

I seriously cranked up the EGR at cruising speeds (as much as 20% in some areas) as well to try and measure some extra fuel economy.

 

[theterminator93]

This value file totally works; the tranny I had swapped yesterday apparently has a green gear, when I need the purple one.

It shows ~130 for ~80mph, lol.

I'm getting a weird shift schedule that's making me regret the TC lockup in 2nd, but I'll swap the gear tomorrow.

Thanks for being the guinea pig... Now I don't have to grit my teeth the next time I take the car to the dyno and I want to rev it out past 6000.

 

[theterminator93]

I've forgotten how well Lazarus runs, having driven the tbird for a while.

I passed someone today after dropping to third, and it burnt rubber from when I went wot until I let off, lol.

Poor Prius; I think I made him feel bad. Bless his heart...

Why is it they're always clogging up the fast lane again?

September 12, 2015

Silly question.

I've had my MAF "dialed in" about as well as my current equipment permits for a while now (referencing obvious landmarks in graphs to help match up the graphs in the WB software vs LiveLink, not optimal but it served me well enough thus far). Would it be inadvisable to look at the adaptive fuel trims after having driven the car for a while to make minor refinements to the MAF transfer function?

On another note - I've semi-regularly caught earshot of pre ignition for a few revs during shifts. I've got the manifold volume set appropriately for the transient fuel calculations, but I'm not sure if fueling is off or if spark is too high. I've been reducing spark slowly but surely as I've heard pre ignition at higher loads and I've more or less eliminated that - so I'm leaning towards fueling being off. Any pointers on this one?

 

[theterminator93]

I regularly make small changes to various things, looking for an optimum.

That said, other than shift points, I think the last few were changes with the weather, lol.

Getting all the adjustments in the center is a wonderful thing, as it allows the system the most margin to allow for changes; like a sudden vacuum leak or something.

I'd say graph it for a month every day, and see what you're up against first; you may find that the normal variation swamps what you want to tweak.

Especially if your data is matching your predictions, warts and all.

At least we can just reload the old version, and everything is back the way it was...

If your wideband has enough resolution, you would see this on the air:fuel ratio routed into livelink. At which point you open the transient fuel section of the database. Plot relative throttle position along with wideband air:fuel curve and engine rpms and engine load.

I do want to route the output of the ZT-3 into the analog in on the XCal2, but I don't have the mini DIN connector for it. I'm not above stuffing a couple wires into the connector and securing them in place temporarily with hot glue; I assume I just wire the white wire (analog) output of the ZT-3's control module in to analog 1 and ground?

 

[theterminator93]

yup, 0-5VDC goes into analog1.

The plug is an 9 pin minidin plug that was used as a mac serial cable; if you have dealt with macs, you probably have one.

If you're looking online, this is called the 9b pinout.

It it way easier to get than the others, or was 10 years ago, lol.

BTW, the sockets are tri contact type, and want a round pin.
A standard 0.025 square pin will waste it; If you put it in, don't pull it out, lol.

Pulling contacts from a 4-pin s-video cable would work fine.

I salvaged one off a dead PC subwoofer... Don't yet have a WB to connect it to though lol

I thought that connection looked familiar, lol...

For now I just tinned the end of the wires destined to make contact with the XCal and temporarily (and strategically) used hot glue to keep them from moving around - without getting a bunch of goo into the Xcal so I can use the "proper" harness when I eventually get one.

Nerves are starting to tense up with pre- first pass ever anticipation.

 

[theterminator93]

I had intended to put the WB O2 in at the track, but as it turns out... exhaust pipes are hot after a 1 hour drive. Next time I'll put it in before I head out.

I had a decent first run, but a number of circumstances beyond anyone's control prevented me from getting a second pass in. I did observe a few things from the first run, however.

1) Based on the acceleration curve, my shift points are pretty close to perfect. I'm not changing the 1-2, but I'm upping the 2-3 by 400 RPM.
2) The TCC duty cycle drops to 50% right before the 2-3 shift is commanded, then ramps back up as the shift is in progress and is again 100% just as the shift completes. What should I be looking at in the tune, or additional items to log to help me identify what is in the tune that is causing that? There's a noticeable drop in acceleration as the duty cycle drops...

I'm going to verify my actual lambda is my commanded lambda before I attempt to add more spark, but I was running about 20 degrees for the entire run and I have this feeling as though there's another 2-3 that can be added...

 

[theterminator93]

Look for a timer for the lockup after the 2-3. Zero it out.

I'l dig up my old logs to see what my TCC duty cycle was doing. I don't remember it acting like that, but who knows, it's been years

Well, all the delay timers for lockup after shifting are zeroed out, speed ratio to lock is zero. Steady state slip tables are zeroed... only thing I see is max. amount of desired slip being the default at 1020, although I'm not sure what else would be commanding slip before the 2-3 shift...

 

[theterminator93]

Seems like it's supposed to do that; but look at the tc duty cycle in the datalog.

It will drop first, you'll notice.

Lazarus shifts all gears with the tc locked; the 2-3 at wot makes some interesting noises. I don't really think that's what you want, exactly.

If I do a 3-4 at wot, it will probably leave the tranny on the interstate, lol. Thankfully, I don't drive that fast.

Something has failed internally, not in the VB, that leaves the TC locked other than 1st and reverse.

I've driven it like this for over a year now...

I haven't examined all my logs from tonight but it didn't seem to be doing it as bad as it did the first night. I adjusted the MAF transfer up around 800-900 counts after seeing it go 5-7% leaner than I wanted on the first couple passes, then I did a couple more passes adjusting spark tables to compensate. By the last pass I was running pretty well, but there was so much wheelspin tonight I didn't really get any good passes. Makes it hard to compare data.

The analog input was working most of the night, but I think I need a better way to secure it to the XCal. I only got usable data for half my runs, and two of them it said I was running stoich for 1st and 2nd at WOT (no way that's the case since I'd be in ping-city). The XCal was doing weird things tonight too (it would crash after I finished logging, then reboot and come up with the 'turn key to start' and try and reflash the EEC with something), combined with the fact that it won't power on via USB only... I think I might need to keep my eyes out for another one.

At least I got my 13 second pass in. If only the car would hook I might be able to get a sub 2-second 60' time and get a triple digit MPH at the line. I'll post a vid in the other thread along with my best slip tomorrow...

 

[theterminator93]

well the torque converter has to unlock during the shifts, so that is not an issue. you'd break a lot of things if it didn't slip during the shift. But after the shift, the duty cycle should immediately climb to 1.0

Ground your wideband as close to the ODB2 connector as possible; if there's a difference in the grounds, it shows up in the signal, as well as causing random lockups of the xcal2.

Found that out the first time I hooked it up; there was ~.4V difference between the ground pin from the xcal and the ground pin on the WB.

It worked fine if I didn't connect the ground, but was way noisy.

Moving the ground helped fix the lockups, anyway; it's still kinda noisy.

April 9, 2016

Well, I'm basically done with this winter's maintenance list for the Bird... just an alignment before the weather gets (stays) warm and we're back on the streets.

With the dropping fuel prices one thing that's becoming apparent is the much larger price gap between regular and premium. Around here regular is about $2 a gallon, give or take 15/20 cents. Premium is pretty universally 40 to 80 cents more than that - 20-40% more. Back when gas was $3-$4 a gallon, a 40 cent price premium for the extra octane was only 10-15%, which I perceived as an acceptable price premium for the little bump in fuel economy and performance. Now it's really hard to justify - especially since I've stopped using premium and now use plain regular in the Mark VIII which dynamically adjusts timing to account for the less spark tolerant fuel... and I really haven't observed a significant negative impact to fuel economy.

To the point - I'm going to start working on an 87 tune for daily driving (keep the 93 tune for strip runs etc.). I have seen people say the've run 87 with 10.4:1 headswaps but I didn't see much about those with a cam like mine. Obviously if I have to pull so much timing from the tune that the car becomes a slug I'll compromise and tune for 89 - but is there a "number" out there that I can use to start pulling timing by to start with? 8 degrees? 12?

 

[theterminator93]

Present day!

So, I haven't spent a ton of time tuning the car in recent years, however there have been some things I suppose I should drop in here.

1) I got long tube headers installed at last, then set up my tune with the spark for 93 and have it dialed in pretty well. I then looked at the spark I had set up for 87 that I had been running prior to the LT install, and adjusted the spout connector scalar so that with the spout connector plugged in, the car's spark tables are retarded enough to run 87. With the spout connector removed, it runs at full timing for 93.

2) There's nothing I seem to be able to do to eliminate the low load/RPM bucking that occasionally occurs on 87. This problem does not exist on 93 with the advanced timing. Advancing the timing with 87 does not fix it. Now knowing that and understanding the cause, I live with it. When it happens I just let off the gas for a couple seconds or downshift from 4th into 3rd. I suppose I could also raise my shift points a bit or shell out more for higher octane, but eh...

I did finally build an adapter cable to run the analog output of my ZT3 into the XC2. There are even dedicated O2 bungs on the header collectors for me to put the O2 sensor. But in 2 years, I still haven't gone out to dial-in my MAF transfer function. I'm a lazy slug now.

Otherwise, the car runs well. I got another value file (this time from David Dalke) when the converter unlocked repeatedly on the dyno post-long tube install. Turns out there's a hidden scalar for the torque converter to unlock when it thinks the engine is making over 280 BTQ, so that's no longer a problem.

 

[XR7-4.6]

The ZT3 through the xcal works great, I've got the analog formula memorized ((v*2) + 9.6)/14.7

Tuning never seems to be done, I've got the transfer function *good enough*, some anomalies but mostly within 2% of either end of commanded, WOT is 13-13.2. Right now I'm having ZERO luck getting CFSO to activate even after getting SCT to increase my access to hidden parameters, so I've moved onto trying to get engine braking through dashpot and spark timing instead

 

[theterminator93]

Here's my CFSO scalars... it works well enough but it activates sometimes when it shouldn't - e.g. in 3rd and 2nd gear. But it always turns fuel on before the RPM drops too low to stall.

 

[XR7-4.6]

Here's my CFSO scalars... it works well enough but it activates sometimes when it shouldn't - e.g. in 3rd and 2nd gear. But it always turns fuel on before the RPM drops too low to stall.

View attachment 602

I've tried just about every variation but I'll try your values just to see. These are the latest I have, I've changed N/V both VS, both RPMs throttle timers, and even tried setting switch set to zero to 0, and I never get the CFSO flag in the logs, nor does my AFR change. I'm wondering if its the manual trans swap or if there's some other scaler elsewhere I have set wrong to prevent it.

 

[theterminator93]

The trans swap may have something to do with it. I'm guessing there are a bunch of hidden parameters for it that would shed a ton of light on why the scalars we DO have access to seldom behave in the way we'd expect.

 

[XR7-4.6]

Yeah I was hoping going through that recertification process the last few weeks with SCT would open some of those up, but all it added were the parameters you already had lol Part of me is tempted to get a 96-97 manual trans Mustang PCM but I could have sworn if its a hardware thing I had CFSO working with the auto.

I looked into there possibly being a clutch switch input like SCs have but it's not there in the 96-98 Cobra PCM pinout, it would be shared with the MLPS input if it was