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What are your recommended methods of mitigating torque "spike" on EcoBoost tunes? I see this pop up all the time on some FB groups as what not to do, but rarely does anyone discuss proper method(s) of smoothing it out. I see a few ways of doing it, one is the LSPI tables where a higher than stock (but reduced ) at 2750-3250 RPM? Does anyone else care to share some recommended methods?
Hey Metro,
Real shame you have no replies. I guess your awesome help guides have elevated you to the status of "not to be replied to" as you obviously know way more than most about these, so unfortunately folk worry about interacting with you. Lol. Typical after all your effort, but that’s forums for you eh?
I will have a stab though. :)
The only time I see a torque spike as opposed to a nice flat table is when slight errors are made in the torque/load request that sees the rise in boost pressure become a little “too fast” and even the awesome Ecoboost ECU has a tricky time managing it with a quick throttle closure.
I find the LSPI load limiting table a great place to start taking control a of these.
I like to renormalise them so I have a quite strong control ability after my own personal ACT limit which also allows me to be certain where in LSPI control we are sitting. I don’t like being unsure where we are with load limits due to the interpolation in effect.
example, if you wanted a max full power charge temp of 48C and wanted to drop load from 50 onwards I would linearise like this.
-10
0
20
30
40
48
50
70
etc
that would allow you to run full load up to 48 and make your reductions from 50 onwards.
that way you KNOW while tuning exactly where you are sat and a quick log of load limit would hopefully draw you a decent picture.
Then you can carry on and curve your LSPI load limits accordingly to try and make the transition from 60% to 100% torque a little more controlled. Sometimes it just requires a little less desired TIP to bring it back into the perfect range for throttle control.
The same can be achieved in the 6 max torque with and without overboost tables.
i know some folk strive to do this without throttle control, working hard to keep it wide open, but that’s working backwards in my opinion. Throttle closures are fine as long as it’s happening briefly in order to take control of load. It’s designed to do it, and it does it very well.
Hope I understood the question mate. Lol
Oh, and I would be interested to join any groups discussing ecoboost tuning too if you could drop us a link. :)
Are you only seeing spikes in certain gears or at random times? Have you tried adjusting your Pedal Map Ratio table?
That table seems to multiply Driver Demand Torque based on the factor in the table relative to Transmission Output Shaft Speed. It is the Automatic Trans version of a ?Boost By Gear? option.
Thanks guys for the suggestions. I actually have not personally experienced/seen these spikes with my tunes. I see these on others' dyno sheets from time to time, and the expert tuners on these discussion groups always ridicule those tunes, etc... but rarely does anyone offer suggestions or tips on reducing these spikes. These are the spikes that usually occur below 3500 RPM, and under normal drag racing conditions, this seems to be a rare operating condition other than perhaps launching. The gear ratios on the 6F55, 6R80, 10R60/10R80 keep the RPMs very high after each WOT shift. And even under the hardest of launches, I have yet to see these type of spikes. Maybe these "tuners" were messing with VE or WGDC tables that they shouldn't have been messing with?
I am new here but have been poking through the 2014 F150 tunes for a while.
I have also heard of using load limited to help use the throttle body to minimize boost spikes in the manifold. Basically, have the PCM close up the TB slightly where the expected boost spike would occur to limit flow into the mani and keep a nice smooth transistion to peak boost.
Chances are the spike is a result of a very fast transient response that the PCM isn't reacting to and need to dump a fuel to keep the AFR happy. I know on the F150 Gen 1 3.5, these low RPM spikes were causing fuel pressure issues and a potential lean condition.
Yes indeed this is also my opinion, Boost spikes only happen if the turbos are overspooled due to either missconfigured WG values or just maxing out parameters like TIP or turbocharger pressure limits.Quote:
Originally Posted by metroplex
I also recognize that very often TB values are unnecessarily changed. This leads to situations were the TB is unable to respond to such boost spikes. The goal is to work with the limiters, not against them.
The spikes are usually a symptom of over-spinning the turbo. Good way to cause premature failure, and if you command way too much boost at too low of an RPM, and then the driver commands that much torque under high load you could possibly see internal part failure such as connecting rod failure. Haven't seen it first hand on the EcoBoost, but I have experienced it on the Ecotec platform where people out road racing will try to brake boost and hold full boost at a set rpm and the engine load just skyrockets since their foot is on the brake.