Gas Pedal Delay

BGTV8

Folks, there are 2 separate issues here and they are clearly confused.

1. The yaw sensor cuts throttle when it sees enough yaw-based G to convince itself that the car is about to slide, when in point of fact the car has a heap of grip remaining. This is especially noticeable on the track when trail braking hard and deep and will most likely pitch the car to the outside of the corner being entered, which is exacly what you do not want. Fixing this is simple - see here ...

Yaw sensor switch

and here

DIY Yaw Sensor rocker switch

2. The gas pedal deal from low-speeds is the ECU cutting fuel/spark on the basis of under bonnet inlet air temperatures. One of our AU guys in Sydney has researched this and you can find the details here ...

370Z IATs Observations - Engine & Drivetrain - Zclub - Australia's Largest Nissan 370Z and Nissan 350Z Forum

Bottom line is that the standard ECU simply will not give you good throttle response at low speed in even moderate ambient temps based in air temps in the intake tract and the Nissan Engineering requirement to minimize emissions, rather than optimize throttle response (at high ambient inlet tract temps and low vehicle speeds, it is simple to give the car too much fuel which increases emissions).

If you guarantee cool air input temps at slow vehicle speed, then you can tune this out but it won't be simple to engineer a solution for all circumstances and you may create circumstances where passing an annual emissions check could be a problem.

RB

ZForce

I have a lazy foot and the pedal box sends a signal to the mass air flow meter. If I am not getting ANY throttle lag....then I would say it's fixed.

BGTV8

And here is what the yaw sensor fix looks like ... takes an hour or so once you assemble the bits needed.

Attached Images

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H2O_Doc

Is this something that one wouldn't need if getting a tune?

SouthArk370Z

The person doing the tuning should be able to modify the table that handles throttle pedal position/response. There is a thread on this site that gives examples of tables that improve throttle response. IIRC, does a much better job than a pedal box.

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ZForce

It added to my tune, so yes IMHO and thru self testing found that it was a benefit EVEN with a tune.

Tested: w/o tune - found to eliminate the throttle lag.
Tested after tune - found to further increase throttle response.

PedalBox + UpRev Tune =

DTE PedalBox In Action - YouTube

wstar

Anything that goes inline with the electronic gas-pedal's signal and modifies it can't overcome the fact that the ECU limits your throttle at lower RPMs - only tuning the ECU can affect that. What the "pedal-box" type units *can* do is change the shape of the response curve of the pedal itself, e.g. put the 50% mark down at 20%, so that you get more response out of less foot movement, or vice-versa. Ultimately, anything the pedal box can do, your foot can do as well if you move it differently (e.g. stomp gas faster, or use the pedal more precisely). And then of course there's temps vs fueling in the ECU, and the yaw sensor hack, as noted by BGTV8 above

Mostly, I tend to view the pedal-box type things as psychological in nature. You could make the car do the same thing with more foot movement, but the car feels more "edgy" if you barely move your foot and lots of things happen quickly.

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LennyZCSD

You also have an automatic, so there is an extra step in the response. The rev up and the tranny downshift. That's why I only run a manual it's in gear and out of the gate a like gunshot..

juld0zer

aside from the obvious causes (intake air temp, coolant temp and oil temps), what else could be causing this throttle lag???

I've pretty much eliminated IAT as the cause.

I'm now leaning towards the EGR system which involves the CVTC system. EGR is intended to reduce emissions by reducing combustion temperatures....by filling part of the cylinders with exhaust gas to effectively reduce the available volume for oxygen to enter/fill the cylinder.

This is no easy fit-a-blank experiment and will need someone with tuning experience to chime in... i've got an Uprev tuner license so if someone can guide me, i am happy to guinea pig my car for the benefit of everyone as we try to solve this mystery once and for all.

TheBoomSpoon

I have the 7at and never noticed this stock or after bolt-ons with tune. Ill consider myself lucky

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juld0zer

with an auto trans, most of the lag would be masked by te fact that it shifts itself.

Owners of manual 370z's feel it because say you're in 3rd gear and you sink your foot under lag conditions, nothing happens then all of a sudden she takes off. The feeling is most akin to the VDC kicking in and killing the power.

SouthArk370Z

Knock sensor could be causing the problem. Going by what I've read on this site, vibration from the drivetrain or exhaust can also bang the sensor.

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juld0zer

i've pondered that possibility but eliminated it because it seems a bit bizarre for an engine to develop a vibration or harmonic issue at certain operating temperatures. It's not impossible because i know the engine does vibrate a lot. I have the plastic engine covers removed and to avoid losing the nuts/bolts, i just nipped them up on the intake collector. I pop the hood once a week and 70% of them have become loose by several turns.

Cant be a bad batch of knock sensors either because of the widespread awareness of the problem.

The other issue is it seems that most people are complaining about the lag in 1st gear only. Assuming that most folks are running stock intakes, i'm willing to bet that they are experiencing heatsoak of the IAT sensor - ie, ecu sees the air entering the engine as being hotter than it actually is; due to radiant heat influences from the headers, radiator airflow etc.

There is, without a doubt a difference in throttle response between oil at 90*c or less with coolant at 87*c or less versus oil and coolant temps above these approximate figures. The simple stab-the-pedal test shows this in a no load scenario. Someone on here datalogged the lag and it clearly shows a delay of several seconds between pedal activity and throttle body activity with VDC off during a 1st gear takeoff - this was done with IAT at 104f/40c which is definitely in the high territory. This is the lag that keeps you at the lights while the wanker in the bone stock Civic takes off.

I have experienced severe 'heatsoak' by intentionally using a different IAT sensor (one which reads higher, ie different resistance curve for those familiar) and it will affect you even when you're moving. Overtaking is scary. Gaining speed takes an eternity. Not fun.

I'm wondering, for those of you with remapped throttle tables - do you still experience the acceleration lag both on take off and in-gear acceleration?

SouthArk370Z

High IAT will cause the ECM to retard timing (and probably other things). IIRC, it starts backing off around 85-90F. I've noticed some lag/bog in stop-and-go traffic in the Summer. Usually clears up once I get moving and measured IAT drops to closer to ambient. There does appear to be significant thermal mass to the sensor and/or housing as it takes a while to drop.

My IAT reads 6-7F high but it hasn't been a big problem for a DD.

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Zed-Hed

Why is it that no tuners are familiar with the gas pedal delay. I've talked to several and they don't know anything about this.