Strange 1-2 shift behavior 22 Mach 1

[bkg06gto]

Preface with the car

22 Mach 1 A10
Long tubes, no cats
E85

But this issue has apparently been present before the mods and stated its just became a annoyance

The car when it shifts from 1st to 2nd will bog down incredibly and fall flat on its face. Almost like it?s lost all power. The rpms will drop to 1500ish and then it picks up and drives normal. The issue happens on the 1-2 shift in sport/track/drag. Doesn?t happen in normal because of the 1-3 skip. Seems to be related to lower pedal inputs < 20 percent and slower speeds related to normal driving, taking off from a dead stop. The crazy part is it?s completely random, and impossible to recreate on demand, the once or twice I?ve managed to actually catch it on a log, what I was logging I do t think is what I need to be logging. I?ve tried to dig out those logs with little avail since I?ve been trying to recreate it more reliably they?ve just been lost. From what I saw here are some cliff notes.

Throttle and pedal are constant and throttle doesn?t close

No errors shown

Only thing I?ve managed to catch is spark plummet then come up.

The source says trans shift and one other says torque control.


So my initial question is ideas on what to log?

So I can go out and get one and then maybe diag it better.

Thanks as always everyone.

[engineermike]

This sounds just like shift torque modulation. You can log more stuff to learn more about whats happening but basically its cutting spark to achieve a target shift torque. You can change the shift torque target easy enough but Im guessing some other changes in the tune broke it. For instance if the tr S curve, torque model, or mbt tables are incorrect it will result in incorrect torque modulation.

[bkg06gto]

Makes enough sense, I?m gonna assume it?s spark related, those tables have been modified.

Stock torque tables If I compare to a known stock mach1 file. Stock trans tables as well.

[engineermike]

The mbt tables really shouldn’t be modified much from stock unless you make some major change to the engine like compression ratio or cam profiles. Some tuners just raise all the mbt tables by some amount which really screws up the torque calculation and control.

[bkg06gto]

Awesome, I?ll start there. Looked into this one as a favor, i deal mostly with GM stuff and the gen V stuff has some same ideas but as we know way different ways to get there.

Appreciate you giving me a head start

[veeefour]

The mbt tables really shouldn’t be modified much from stock unless you make some major change to the engine like compression ratio or cam profiles. Some tuners just raise all the mbt tables by some amount which really screws up the torque calculation and control.

Sorry but this is not correct - as long you dont raise load you dont have to change MBT values, even with higher comp or cams.
Speed density model on the other hand - every single time.

Id say you """should""" change MBT to whatever you like and this will not screw up anything as long you you follow the rule 100% torque is where MBT border lies(after some scaling.)

[engineermike]

Sorry but this is not correct - as long you dont raise load you dont have to change MBT values, even with higher comp or cams.

Im assuming you mean max load, not just load in general which is always changing. At any rate, if you lower compression to, say, 9/1 then MBT will be much higher. If the MBT in the table isn't accurate to the engine characteristics, then torque reduction ratio will not be accurate, which can lead to problems just like the ones the OP is experiencing. I've seen this also cause idle stability problems when tuners raise MBT such that it no longer matches the engines physical characteristic.

Id say you """should""" change MBT to whatever you like and this will not screw up anything as long you you follow the rule 100% torque is where MBT border lies(after some scaling.)

If the MBT number no longer matches the engines actual MBT, then I suppose you could fix it by making the torque tables inaccurate as well. I would just rather both be as accurate as possible and not just one error offsetting another.

[veeefour]

Im assuming you mean max load, not just load in general which is always changing. At any rate, if you lower compression to, say, 9/1 then MBT will be much higher. If the MBT in the table isn't accurate to the engine characteristics, then torque reduction ratio will not be accurate, which can lead to problems just like the ones the OP is experiencing. I've seen this also cause idle stability problems when tuners raise MBT such that it no longer matches the engines physical characteristic.



If the MBT number no longer matches the engines actual MBT, then I suppose you could fix it by making the torque tables inaccurate as well. I would just rather both be as accurate as possible and not just one error offsetting another.

MBT is just theoretical - engine does not care. This is not the actual spark the engine will ever see. Stop it...

Of course when you wack it from 30 to 10 at Load 0.2 it will going to change things but changing from 27 to 31 at load 1 is not going to change anything
besides letting you go higher/raising your cap. Just make sure your Borderline+Knock=MBT(with adders and multis taken into account)

Im not sure I love or hate when you say "ive seen what other tuners done" - just like you place yourself above every skilled and experienced pro...
I remember you claiming to fix MY tunes at some point LOOOOL....we al should stop tuning since you are here sensei...no offence cheers bud...

[engineermike]

MBT is just theoretical - engine does not care.

MBT is a physical characteristic of the engine, being the timing at which it's most efficient and makes the most torque. It's not just some theoretical number. The tune should be calibrated to match the physical characteristics and the more accurate it is, the better the tune works. I can't figure out why someone would be a proponent of intentionally putting inaccurate numbers in and modifying the torque model to make it work.

This is not the actual spark the engine will ever see. Stop it...

Mine runs on MBT up to about .6 or .7 load on pump gas. On E85 it runs MBT virtually all of the time.

...Just make sure your Borderline+Knock=MBT(with adders and multis taken into account)

Borderline + knock does not need to = MBT. It will stop at MBT even if knock adders put it above MBT. And there's no way I'm trying to push it to MBT on a pump gas supercharged Coyote, for instance. I know some tuners do this and just let it ride on the knock sensors, but I prefer to build some safety in and stop the knock advance from actually pushing it into knock. I'm also running a lot more boost than most do on pump gas, but to each his own.

Im not sure I love or hate when you say "ive seen what other tuners done" - just like you place yourself above every skilled and experienced pro...
I remember you claiming to fix MY tunes at some point LOOOOL....we al should stop tuning since you are here sensei...no offence cheers bud...

Don't take things so personally.

[bkg06gto]

So quick update. I returned the spark values to stock along with the MTB values, I think this calibration was slightly hacked together and things were changed to ?hide? other issues. . The car overall runs better, its throttle is definitely more predictable and smoother. But here?s the kicker, still very rarely has the 1-2 shift bog down and while testing it, it did an interesting thing. Coming to a stop car died. Instead of returning to idle, it just shut off.

fuel trims look good under 5%, granted it has Flex logic on. but it?s inferred virtually spot on. I tested the e85 in the tank at 75 percent the car has inferred to 76.4.

I?m just not sure what to log to send me in a path to figure this out or give insight to you guys. I realize too I should probably bump up the WOT spark, it?s only hitting 23 degrees and I believe a coyote can take far more than that on E.

[bkg06gto]

To also clarify the ?stalling? only happened once.

[engineermike]

So you have 3 issues remaining? Occasional bog on 1-2 shift, dying when coming to a stop, and low WOT timing?

If the tune is hacked together, it might make sense reverting back to a stock file and starting over. The car really hasn't had much done to it so a stock file wouldn't need much done to work. It sounds like you might be chasing your tail on self-inflicted problems for a while.

[Pistol_91]

Do what Mike said. Changing stuff like MBT on a car that has long tubes and a flex tune is wild. Definitely doing too much. If the car isn't boosted there isn't a whole lot that needs to be changed, at all...

[bkg06gto]

I agree. I got ahold of a stock Mach file and I?m just going to start over. I think this file had self induced problems then was trying to be corrected through other means than fixing the initial problem. I found the MAF curve to be horrendously rich at idle last night.

I?ll keep updating. But my plan is to go back to stock calibration verify maf curve and enable flex settings. Any other tips are appreciated as always.

Thanks everyone for the advice so far.

[engineermike]

Be careful with flex on these. There are 9 parameters for fuel system fuel volumes that are typically defaulted to 0 lb in the m6g. The problem is that when switching fuels on a fillup, the logic will mature and lock into a learned stoich before the new fuel reaches the engine. It will hold this incorrect value until you reinstate learning through either a kam reset or another fillup. Unfortunately, hpt doesn’t give you access to these 9 parameters. You could set it up to never mature but this has its own issues. Also, hpt doesn’t define all the startup lost fuel flex parameters and they’re also typically zerod from the factory.

[bkg06gto]

Would you suggest just going to a straight e85 setup then? This car use pump e85 mainly, same station I use for my Camaro. Tests around 75-77 when I?ve gotten the urge to verify the sensor in my car.

The flex setup would be nice, but it makes me feel like it would be another headache in the long run.

[engineermike]

I love the flex feature but I’m afraid hpt isn’t the best software to make it work.

[bkg06gto]

Fair enough, well I?ll err to your better judgment. I know enough to be stupid 😂 when it comes to this platform.

To clarify testing and running a straight E tune would be your suggestion?

[Pistol_91]

That's what I do. Either e85 or 93. Run it to 0 miles to empty on each fuel change. Swap tunes and drive normal for X miles until any WOT driving. E85 is far easier to make a tune for as well compared to flex

[veeefour]

Every tune I do(like 20 a week) I always modify MBT regardless its n/a or f/i...over and out LOL