weird boost behavior.. opinions please?

[TopherSho]

Ok TL&DR,  40k, 2010 SHO non-pp, Torrie tuned.
3bar sensor
.28 plugs from his site

Is the following normal behavior ?
-switch to manual shifting..
-drive car until 3rd gear is at a steady 3500rpm on a flat road.
-keep at 3500 rpm 5 or so seconds
-hit the accelerator hard and fast .. *BUT NOT* enough to down shift it.

What I feel when I do this is the car begin accelerating for 500ms,  then it wakes up and the power level increases and we continue on until I take my foot off.

does anyone else notice this behavior on their 2010-2012 ?

The difference in power before it 'kicks it up a notch' is minor.  Not enough for my wife to notice or other drivers.  But I can feel it and have logged it.  it is a very small blip for a short period of time.

Torrie took a look and did not see anything in a few different data logs and there were no 'errors'  he could see, misfires, spark issues to cause the vehicle to retard things.  it just has 2 different power levels for a short half a second when you get into it in this fashion.

2,3 gear is most predominantly where you really feel it.  4th-6th not so much

ideas ?

 

[SHOdded]

Post the logs for the gurus to look over.  Might be a transmission behaviour that can be tuned out, or may need the AJP mod.  The logs should tell the story.  Doesn't seem like a hardware/maintenance issue.

 

[StealBlueSHO]

Logs would help... a half second before it steps up could be the turbos spooling depending on boost being demanded?

Could be lots of things... does it feel like it hesitates or just takes a minute to take off?

I know when I do my 3rd gear pulls from 2K rpms it takes a second for it to really pull..

Mind you the car really starts to wake up around 4500 rpms so it could just be that...

Logs would be a more definitive answer...


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[ajpturbo]

Need to see what desired tip is doing and if there are any tq reductions by logging tq source.....steal blue you feel yours come on after 2500 not because of turbo lag but because i usually wait until 2500 to command the tq....we could bring boost on sooner but the fuel isnt there and need to be mindful of lspi

 

[StealBlueSHO]

Need to see what desired tip is doing and if there are any tq reductions by logging tq source.....steal blue you feel yours come on after 2500 not because of turbo lag but because i usually wait until 2500 to command the tq....we could bring boost on sooner but the fuel isnt there and need to be mindful of lspi

Right but these are not electric motors... you don't get 100% power the moment the pedal hits the floor.. there is a rotational build up of power right..

A half second of delay based on going from 1/4 pedal to full pedal might just be the natural delay of a gas powered motor spinning up...



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[ajpturbo]

I would say most likely a tune characteristic....depending on how he is commanding boost via the pedal...and you probably dont feel it in the upper gears becaus you arent at the same rpm range and dont get the benefit of tear multiplication

Everything starts at the pedal in terms of power delivery so if something is not smooth then you may feel something

 

[TopherSho]

Logs!  Thank for all for taking a look

Both logs are similar.

my reproduction steps::
--I put the car into manual. 
--Then drove *steady* with the RPM static and over 3000 rpm for at least 5 full seconds in 3rd gear.
--Then I *JAB* the throttle hard.  NOT enough to down shift,  but hard enough to reproduce the issue and push the car HARD to accelerate.
--I 'feel' the performance 'blip'
--i feel it go from less power to full power, then I run another second past that,  then COAST back down to the 3000 rpm range.  no braking.
--repeat 3x or more times
--reproduces all day long like this

For both these logs what I am feeling was the most pronounced on the last try for each set.  This is not a world ending issue but I would like to see if we can solve it.  The power blip only occurs as listed above.  WOT has no issue.

I have felt much stronger 'pauses' / 'gaps' .. but was not in any position to log them. 

 

[TopherSho]

Logs would help... a half second before it steps up could be the turbos spooling depending on boost being demanded?

Could be lots of things... does it feel like it hesitates or just takes a minute to take off?

I know when I do my 3rd gear pulls from 2K rpms it takes a second for it to really pull..

Mind you the car really starts to wake up around 4500 rpms so it could just be that...

Logs would be a more definitive answer...


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If this were a NA car, I would call it a hesitation by how it feels.  But this being my 1st boosted car I am out of my element so my commentary beyond what I 'feel' might cloud the issue. 

thank you for looking .. logs (2x) are posted in my previous reply to the thread.

 

[StealBlueSHO]

Sooo not sure what you are trying to accomplish? Looking at the logs it looks like you hit the accelerator for second, let off a bit, then punch it? Honestly... I don't see anything in here that makes me suspicious.. it APPEARS the car is doing exactly what you are asking of it...

Your throttle actual, throttle desired, position relative, position absolute is exactly the same.. your load is fairly low and fueling looks good...

Fuel Trims are OK... Pressure looks good... not sure? You have a bit of KR.. but you shouldn't feel it...

The boost dips but that looks like its in direct response to how you are controlling the accelerator.. again.. not sure what you are looking for?

AJPTurbo will probably give a better read on it.. but from what I can tell... it looks OK.. the car is responding to your request...

My guess is that you are feathering the pedal to keep from down shifting which is why you feel a dip in power? 

 

[TopherSho]

Thanks StealBlue for the reply.

No pedal feathering.  I jab the pedal and hold it as steady as I can. i do not let it up until I feel the power 'dip\hesitation' pass.

in the reproduction steps :
--I hold it steady at 3000+ rpm
--then jab the pedal down.
--until I feel the 'performance/boost blip' change I keep the pedal the same position,  and then ONLY let off a moment after I feel the change in the power.

I have felt very a 'hard and jarring' boost change before when passing uphill. it was in manual mode in the 4000+rpm range where my foot would be on and off the gas hard and then off the gas completely and then hard back on.. but engine rpm was still 4000+ rpm the whole time.  But at that time I was not in any postilion to log that instance . I may need to try to reproduce that instance.  It is was alerted me to the boost behavior I am asking about now and I started testing and reproducing after that incident. 

EDIT .. on and off the gas..

 

[Scott4957]

I see is exactly what you describe, the throttle is closing to about 25% mid pull and I would imagine that is what you are feeling. As to why, I can only speculate. At that point there is a boost spike, a knock event, timing is pulled and the throttle is closed quite a bit. I would love to see a 0-100 run, i'm curious to see what your throttle angle actual and commanded is over an entire run and I think AJP would like to see that as well. I would agree that it is tune related. I bet you wouldn't see that if you put your stock tune back on.

 

[TopherSho]

I see is exactly what you describe, the throttle is closing to about 25% mid pull and I would imagine that is what you are feeling. As to why, I can only speculate. At that point there is a boost spike, a knock event, timing is pulled and the throttle is closed quite a bit. I would love to see a 0-100 run, i'm curious to see what your throttle angle actual and commanded is over an entire run and I think AJP would like to see that as well. I would agree that it is tune related. I bet you wouldn't see that if you put your stock tune back on.

0-90mph WoT good enough?  (attached)

 

[StealBlueSHO]

Thanks StealBlue for the reply.

No pedal feathering.  I jab the pedal and hold it as steady as I can. i do not let it up until I feel the power 'dip\hesitation' pass.

in the reproduction steps :
--I hold it steady at 3000+ rpm
--then jab the pedal down.
--until I feel the 'performance/boost blip' change I keep the pedal the same position,  and then ONLY let off a moment after I feel the change in the power.

I have felt very a 'hard and jarring' boost change before when passing uphill. it was in manual mode in the 4000+rpm range where my foot would be on and off the gas hard and then off the gas completely and then hard back on.. but engine rpm was still 4000+ rpm the whole time.  But at that time I was not in any postilion to log that instance . I may need to try to reproduce that instance.  It is was alerted me to the boost behavior I am asking about now and I started testing and reproducing after that incident. 

EDIT .. on and off the gas..

Well if you are just romping on the pedal and not feathering it, then the ECU is closing the throttle for some reason. I don't see torque source logged, so not sure if there is something going on from a TCS/ACS perspective...

What I don't see, is normally, when you go WOT there is fuel enrichment... your LAMBSE is still calling for 1.. I would expect that to drop...

You are only getting 3.5 in KR which is a bit but I have seen worse without the throttle closing up... It will just pull timing back...

Ideally... like Scott posted, if you could get a 0 - 100 (or close) WOT datalog, that would be informative as well..

As posted, there is not much I think we can tell ya... throttle is closing, fuel trims LOOK ok, but you are not getting enrichment. I dunno...

Sorry I can't help more!

 

[TopherSho]

I see is exactly what you describe, the throttle is closing to about 25% mid pull and I would imagine that is what you are feeling. As to why, I can only speculate. At that point there is a boost spike, a knock event, timing is pulled and the throttle is closed quite a bit. I would love to see a 0-100 run, i'm curious to see what your throttle angle actual and commanded is over an entire run and I think AJP would like to see that as well. I would agree that it is tune related. I bet you wouldn't see that if you put your stock tune back on.

also what is the etiquette on posting a tune file?  I am wondering of that might provide better insight? 

 

[StealBlueSHO]

Most tune files are encrypted... if its a .cef file then we can't open it... thats done to protect the IP of the tuner...

 

[TopherSho]

Most tune files are encrypted... if its a .cef file then we can't open it... thats done to protect the IP of the tuner...

Got it. That's understandable..

 

[StealBlueSHO]

I see is exactly what you describe, the throttle is closing to about 25% mid pull and I would imagine that is what you are feeling. As to why, I can only speculate. At that point there is a boost spike, a knock event, timing is pulled and the throttle is closed quite a bit. I would love to see a 0-100 run, i'm curious to see what your throttle angle actual and commanded is over an entire run and I think AJP would like to see that as well. I would agree that it is tune related. I bet you wouldn't see that if you put your stock tune back on.

0-90mph WoT good enough?  (attached)

I don't see anything glaring in this log file... no throttle closures.. there is a blip on the throttle but it looks like its just that a blip.. probably dropped information from the recording.. it happens..

The only thing I can really see in this log that MIGHT be suspect is the heavy increase in the STFT on bank 1...you are bumping that 20% lean (or increase in fuel) at that point in the log.. usually as AJPTurbo has said, when STFT is off that much, the ECU is attempting to account for something it was not expecting.. however, its not bad enough the ECU is closing the throttle to preserve the motor.

I had the same problems with Torrie's tunes.. so I am familiar with them LOL...

 

[TopherSho]

Super weird question. AND COMPLETE UNEDUCATED SPECULATION ON MY PART FOR BOOSTED RIGS ... Can you punch the throttle 'too fast"? from a 'neutral position'  ... I ask because I drag race and I can flip and hit the gas pedal extremely fast and pull .02-.06 RT's all night long. 

Is this a issue of too much pedal 'too quickly' in manual mode?  When I get back on the gas hard and fast am I overwhelming the ecu's response?

edit not enough diet dew for typing..

 

[TopherSho]

I had the same problems with Torrie's tunes.. so I am familiar with them LOL...

... um .. can you elaborate ?

 

[Scott4957]

I'm just an armchair tuner wannabe but its not what I thought it might be in terms of how it was tuned. I still think its tune related though. No doubt the throttle closing is what you feel, as to why it does that when you ease into the gas in third I am not sure but it doesn't do it on a WOT run. You also have no knock on your WOT run, negative or positive which is surprising, but you do have knock in that part throttle log. I also don't see rail pressure in any of your logs, are you using a different config when logging for your tune revisions? Not sure how anyone is keeping and eye on your fuel pressure with these logs.