Suddenly LOW VE table

[sgilbert1967]

After tuning the MS3 Pro Ultimate, all of a sudden I go out to start it and its really rich..nothing has changed on pressures....I use IDLE VE...so I had to lower from 27 VE to 10-11 VE to get the same AFR...and the engine sounds like it normally would on the target AFR....SO then I turn on VEAL and sure enough it pulls VE out everywhere like more than 30%.....( Deka 80s ).....I see no setting difference..I have a fuel pressure transducer and its the same readings....I then Key On engine off the Baro and Map agree at 101kpa.....I don't get it...the PW at idle went from 2.3ish to 1.3 to attain same AFR...

VERY strange.....

[sgilbert1967]

update to the crazy, the idle and off idle area are in single digits the cruise and transition areas are less than half what they were....BUT the boost areas up say around 6 psi on are similar to before...WHAT...lol...

[billr]

I gotta ask...

Have you flowed the injectors for rate and dead-time? The VE values are so far off from reality that the "reqfuel" is suspect, but the value set is the correctly calculated one, so I'm wondering about the factors that enter into it.

The MAT correction is also rather unreal, so maybe that is contributing to my confusion about VE.

Why no "vacuum advance" for the spark?

[sgilbert1967]

No I haven't flowed the injectors BUT recall this was a perfectly functioning tune with similar VE to what I seen with my previous 60lb dekas in terms of VE ( except obviously duty was less as I had eclipsed what the 60s could handle even with my meth injection helping which is only trigger up in boost AEM system)....just went out and started it one morning and all of a sudden what had been flawless starts and transition down to warm up enrichment ( plus minus say .5 AFR) at 14.9-15.1 was suddenly 10.8-11.2 and you could tell it was really fueling that hard......i opened up the idleVE section and kept having to lower from 27 to 9 now...even less than this tune...lol......

I also compared it to an older tune in case I inadvertently changed something...i run a Windows 10 2n1 tablet and I pop it off keyboard and toss it on my mount and run gauges full screen I love it, but I have bumped a few settings on accident saving out after a drive ect.....
The MAT looks weird on the hot end as I'm just using it as a bit of a safety in case the meth quits...ect but I need to develop it correctly....if you mean AFT if you mean timing vs MAT...i use that as a meth injection safety....if the meth quits that MAT will go up and I do a HARD pull so that I can feel it immediately...i know during a given time of year what the max IAT will be IF meth is going in and beyond that I pull HARD so that as a driver I feel it and let out....

Fuel req...could you take a little time to explain that to me please, I notice that's turned off in tables......this could be it...

on vacuum advance if you look close you will see that I run an AFR blend per mph....this allows me to drive my fax machine off nearer peak torque without stacking fuel on the intake valve with phasing and helps with a severe lean shift sag this combo has...then progressively as I reach cruise mph and the stall locks in its commanding a leaner AFR... ( I also make it a little richer in boost area for traction as well)...then I couple that with another blend for timing per gear for traction and on the 4th gear map at cruise is run 40-50 timing..depending on kpa ( maybe not on this tune ) for a bit of vacuum advance...ive recently been playing with timing a bit nothing world changing....

what's strange is if I look at WOT and compare duty cycle, to rpm to boost...its using the older VE there...and everything is about right.....so the fuel through the injectors there correlates to the old VE and duty cycle, fuel pressure, rpm and boost AFR and frankly feel all seem correct or nearly..... ( hard to tell with this much power on the street )...but idle to transition to cruise to moderate acceleration is drastically less VE...27 idle is now 9, 45 cruise is now 17....but 9 psi is still 72 at a 70% duty...just like before hehe....weird....

I don't understand fuel req so that's probably where I need to be educated and look first?

thanks for taking the time to look at it....

[2swe]

any chance you switched from "multiply MAP" to "don't multiply" ?

[sgilbert1967]

let me look back at old tunes and see...thanks for the suggestion....i tried to look up fuel req he spoke of but I see very little to educate me on it....like that was telling him he didn't trust it....

[billr]

You have a lot of stuff going on there that I don't feel qualified to advise on. However, are we getting confused about what I call "req fuel"? By that I mean the "Required Fuel" setting that you presently have at 7.7 msec That factor is never "turned off". It is always used in the fueling calculations.

That req fuel values is a fixed number that relates the engine displacement, injector flow, and fuel stoich ratio. It is the PW that would be required to have a "perfect" mixture, no excess air and no excess fuel, if a cylinder was to fill to its exact physical volume at standard atmospheric temperature, pressure and humidity.

[sgilbert1967]

any chance you switched from "multiply MAP" to "don't multiply" ?

Its always been set to multiply after looking back

[sgilbert1967]

You have a lot of stuff going on there that I don't feel qualified to advise on. However, are we getting confused about what I call "req fuel"? By that I mean the "Required Fuel" setting that you presently have at 7.7 msec That factor is never "turned off". It is always used in the fueling calculations.

That req fuel values is a fixed number that relates the engine displacement, injector flow, and fuel stoich ratio. It is the PW that would be required to have a "perfect" mixture, no excess air and no excess fuel, if a cylinder was to fill to its exact physical volume at standard atmospheric temperature, pressure and humidity.

Oh yea the base calculation based on CI injector size, fuel pressure ect...ok I was confused looking to deep....i did double check that 7.7 from earlier tunes....

however in the tables field there is a switch to turn a similar field on or off that's where I got confused.....

in the log while going to boost there is a fuel pressure1_psi and kpa field that does a weird going negative dance WHILE the fuel pressure field itself actually increases....so somehow the fuel rail differential lessens but the fuel pressure increases....( it's vacuum referenced just not one to one)......

[sgilbert1967]

log....

[enfini-fc]

I fought low ve tables

if you just bought your ecu recently. get ahold of megasquirt and have your ecu checked out. my ve tables were very low.

https://www.ampefi.com/tsb/

[Matt Cramer]

He did send the ECU back and we confirmed this was related to the TSB issue. The ECU has been repaired and sent back.

Note that MS3Pro Ultimates have rather low injector dead times to begin with. This TSB covers cases where it experiences an abrupt change. Units shipped after April 28th are not affected.

[sgilbert1967]

Firstly,
it should have been noted this never put me down....in fact if you have VE analyzer on it will just auto tune around it but that isn't to say you shouldn't discuss it with DIY when you get home.....wasnt to big a deal really just figured I done something wrong....

ECU was back quickly and I put several hours run time on it Friday Saturday and Sunday.......
I believe I caused my own problems by not having the correct fuse in the feed to my always on power to the unit....I had a 40amp instead of a 3amp....and I did tale battery off with key on multiple time using my battery switch which I know now can cause spikes in the capacitors aka why it's a small fuse......

don't forget that inline fuse and don't confuse 3amp with 30amp