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Discussion Starter #1
Hello All,

MS2, v3.57, FW Rev. 3.4.0.

I dropped the money and got my 88lx tuned by a local guy.

Everything feels fantastic except for one small, yet irritating, issue.

After 2 hours on the dyno and 3 hours on the street, he couldn't figure out
how to fix the following issue.

When taking off from a stop, or just cruising around, when giving the car just a little throttle, around 8%-9% TPS (45-50 MAP), the car goes way lean and then fixes itself.

If you hold the throttle at that spot it will continue to stay lean, but if you accelerate at all more, it easily corrects the problem. It is quite similar it the stock ECU Speed Density/MAP Lag, except worse in terms severity, not lag time. As in, it can have more of a violent jerk once it corrects itself, but doesn't last as long as the stock speed density lag.

The odd part is the VE , AFR, and timing tables are all set up properly. The car feels fantastic and response everywhere else except for that one specific spot. Under WOT the car behaves wonderfully. It is a stock 5.0 with an intake, exhaust, pulleys, fewer accessories, etc...and made 245hp, 295 tq to the wheel.

The tuner said the way he had to setup the accel enrichment was quite strange and wouldn't normally be configure this way, but it is where the car was happiest. We spent 3 hours driving it around and he tried: changing the accel enrichment around (coming in sooner, later, lasting longer, shorter etc), changing the specific area of the VE table where is occurred (leaner and richer).

In the end he wasn't able to get rid of it completely, but only to lessen its severity. Before anyone jumps on the tuners back, we spent 5 hours on the car and all but this one spot is fantastic. He was great to deal with and doesn't charge for tune "upkeep" and is willing to make house calls to fix the issue.

He mentioned it could have something to do with it being batch fire. He would have liked to change the injector timing/phase, but couldn't determine a method to do so with batch fire. This was also his first opportunity to work with the 3.4.0 FW.

Any suggestions? I did read about the "sequenced batch fire" but haven't yet discussed it with him nor tried it myself.

I'm happy to email my current tune. I can't for the life of me determine how to attach it here.....:confused:

I can also log what happens sometime this weekend.
 

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Definitely log it. Yes you can't attach the file here. I use google docs to share files but there's a bunch of options.

If you hold the throttle at that spot it will continue to stay lean
The above makes me think it isn't AE related but you never know. If possible can you include a demonstration of the above situation for about 10 seconds in the log?
 

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What if you add numbers to that spot on your VE table?
 

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what AFR's (how lean is "real lean") are you seeing during the issue... im sure if it was a simple as adding fuel to the effected cells the tuner would have done that. im just curious what your seeing while its doing it.
 

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Discussion Starter #5
Jut got back from a business trip. Thanks for your replies.

"Real Lean" is it maxing out the WB 02 sensor (somewhere in the range of 19.XX:1).

Yes, the Tuner tried modifying the VE table during the 3 hour drive-ability tuning after the dyno. He changed the VE table as much as he cared to without causing other issues. It didn't help at all and even made it worse in some cases. So we got it to the best point and decided to call it.

He had family things to take care of and I think, for what I paid, 5 hours was more than enough. Especially since he doesn't/won't charge for tune upkeep and house visits since he lives close to me.

I can get a log to you asap. Actually, I'll ask the tuner if he can send me his logs from the dyno. I think we was able to capture it then.

Here is the link to the tune.

https://drive.google.com/folderview?id=0BwuZNEwz31xLVVlGOS1ZM2JhY28&usp=sharing

I'll get a log this weekend for you guys and see what my tuner may have.

Thanks.
 

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Discussion Starter #6
Just logged my drive.

Tune and log can be found here.

https://drive.google.com/open?id=0BwuZNEwz31xLVVlGOS1ZM2JhY28

Couple things to add. WUE is a bit rough. If I don't keep pedaling the car during warm up, it will idle at 2k for a few seconds and then stall. So that's why I keep blipping the
throttle. Once the car is warm, it has a very stable idle except...
If I get on it and then put the car into neutral at a high rpm and coast, the car usually stalls. Over-run Fuel cut issue? Too sensitive I'd assume.

At 13:46 (808.3 seconds), I stall it backing up while turning around...that was just my fault lol. So ignore that.

But, back to the bigger issue. As you can see (first example) at time 362.881 - TPS is 6-7.4% and the AFR spikes, RPM drops, but then it catches itself/I let off the throttle.

You can see this issue throughout. At 953 you can see one that lasts for a solid second. If I do it right in first or second gear, it will sit lean for a second or more.

Let me know what you guys think.

Thanks, I appreciate the help.
 

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Discussion Starter #9
That is a log from my laptop. Right in TunerStudio, I hit Start logging.

So I'm not sure what other logging options there are. I know there is the diagnostic logger, but that hasn't worked
correctly/well for me.
 

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Discussion Starter #11
FW3.4 and I have not modified that log in any way.

I started the car and after it running for maybe 5-10 mins started logging.
 

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Discussion Starter #12
Well, even though no one has responded, I'll post an update.

I turned off the fuel cut and lowered lag factors of all sensors to 90.

I found some settings on another forum that people said worked well. I attached an image of the settings I tried based on that other forum.
The first attachment (with the 40% TPSdot threshold) are the setting suggested on the other forum. It made the Accel Enrichment smoother
and less violent when it kicked in, however, I still have the lean spot around 10% throttle. The second settings are what the tuner had set.

My buddy and I were driving around for about 2 hours playing the settings and we couldn't get it any better. Still a pretty large lag. We played
the added ms at the first and second thresholds, adjusting those up and down along with the TPSdot Threshold for when it allows accel to take
effect. We couldn't make a whole lot of progress.

We did try setting the threshold extremely high so the accel Enrichment wouldn't kick in. With small increases of throttle, at that same ~10%
throttle position, there is still that large lean spike and lag. So we are starting to think there is another cause. I did bump up my timing a bit on the
low end which seems to help a tad, but maybe that's just an illusion.

Side note question: My injector Dead Time is a 1.0. MS recommends 0.7 for low impedance injectors and 0.9 for high impedance injectors.
To my knowledge, Fox injectors are low impedance, so should I make that 0.7?

Anyone using that sequenced batch fire? I tried putting that on, but I couldn't get it to run. I wasn't really sure
what I should set the % time to.

Please, someone respond. I'd like to make a little progress before winter hits too bad. Once that happens it
is sitting on jack stands and getting 4.10s and a rear suspension overhaul.

No I didn't log this last run a whole lot since I was change those settings often.
 

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Stock Fox body injectors are high impedance. If you want to really get the dead time dialed in, see if you can get it set so you see the same AFR under no load with 2 and 4 squirts at 2000 RPM and the same MAP reading. You have to turn the ECU off and back on again when the number of squirts are changed.

I wouldn't recommend sequenced batch fire on these engines. MS2 doesn't have a good way to sync it to anything.

Try data logging what MAP readings and RPM you are having the leanness at 10% throttle and using the VE table to dial it out. Don't use AE to adjust fuel at light throttle.
 

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Discussion Starter #14
Thanks for the reply, Matt.

If having my dead time set to 1.0 is acceptable, I'll worry about getting it dialed it later.

Could someone post a VE table that works? So I can see the "shape" difference? I know no two cars will be the same, but I have a feeling there is something else
causing this issue. Should there be a large increase in fuel at higher MAP readings directly above idle? As to avoid this lean spike?

I can tell you how it "behaves" during the lean spikes and post a log sometime soon.

If I hit that "sweet spot" the MAP reading shoots straight up from idle. So, a steady idle @~900rpm, sitting around 35-40kpa, and I hit the throttle at the 10%, rpm drops a bit like it is about to stall, and
the MAP reading shoots straight up into the 60s, sometimes into the 80s, until the car catches itself and the rpm finally climbs.

Giving it a little more time at the low rpm range across all MAP values seemed to help a bit.

Below is a link to the current tune. I'll log the occurrence just sitting in my driveway revving up the car:

https://drive.google.com/open?id=0BwuZNEwz31xLVVlGOS1ZM2JhY28
 

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Try changing AFR Table Load to MAP.
 

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Discussion Starter #16
Forgive my ignorance, since I'm new to MS and TunerStudio...

But aren't ll of the tables (AFR, VE, and Ign) Load in kPa vs. RPM? They each say AFR Load kPa, Ign Load kPa, and Fuel Load kPa. Which I assume/understood as MAP vs RPM.

If I'm wrong, please let me know and explain why.
 

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Please do get that driveway log. Looking at your previous log a lot of data fields are missing, not sure why. Also the TPS signal is very erratic and goes in to the negatives which should never happen. Re-calibrate the TPS and hopefully that will clear up.

I see you have Decel enleanment on and I do see it triggering in the prior log. I'm wondering if your erratic TPS signal is triggering the enleanment but I'd really like to see a "right now" log before we go making a bunch of changes.
 

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Discussion Starter #18
I did turn off the Over-Run Fuel cut, or is that not what you mean by Decel enleanment?

The reason the TPS is going negative is because I calibrate it with the motor off. Once I turn the motor over and run
it, the vacuum is actually sucking the throttle plate closed a bit. I thought about calibrating with the motor running to get
rid of that but just hadn't tried it yet.

And what Data fields from the Logs do I absolutely need? I will make sure they are logged this time. Or I'll try to at least.
 

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I did turn off the Over-Run Fuel cut, or is that not what you mean by Decel enleanment?

The reason the TPS is going negative is because I calibrate it with the motor off. Once I turn the motor over and run
it, the vacuum is actually sucking the throttle plate closed a bit. I thought about calibrating with the motor running to get
rid of that but just hadn't tried it yet.

And what Data fields from the Logs do I absolutely need? I will make sure they are logged this time. Or I'll try to at least.
Yeah decel enleanment is different.

I think a better solution to your throttle would be a more-positive throttle stop. The return spring should already be holding the plate firm against the stop so that vacuum can't close it "more". It's not as much a problem that the tps goes negative as the fact that it went negative caught my eye and in looking closer I see how noisy that tps signal is.

You're going to fight a losing battle using tps-based AE with a throttle that flutters that much. The amount of change isn't great, but tps based AE is all about rate of change (tps dot; difference over time) and the rate of change in the noise is high.

If it's not an option to prevent the flutter you'll probably want to move to vaccum based AE.

All that said, if this is still true...

If you hold the throttle at that spot it will continue to stay lean
..then there's more to this story than AE and I would actually recommend turning of AE and DE completely and then try to reproduce this lean spot. AE and DE are very brief momentary things, they will not cause the engine to stay lean or stay rich in the manner you just described. If we ultimately prove out all other causes that means we've found a firmware bug which is different than a tuning issue.

As far as logging goes, the immediate pain point of your previous log is that there's no injector information. No injector pulsewidth, no injector duty cycle. There's actually a lot of stuff that isn't there. Give me a few and I'll post up an example of one that I believe contains all the fields. I honestly don't know why yours would be excluding some, that might be an option or it might indicate an issue somewhere. It might be worth sending an email to Phil Tobin about it and see if he has any insight.
 

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