Gas Pedal Delay

cheshirecat

That's just it- owners shouldn't have to do an "investigation" over why this specific model of car produces specific issues in specific scenarios, especially if they just want to report an issue and see if someone else has experienced it. This issue is specific to the 370- even the 350 didn't experience it (as an owner of both cars with over 150k miles between the two- the 350z forums also don't have a similar thread) It's not a matter of VDC according to the posters here, but there is a common observation of ambient air temp being a possible issue.

Your observation that it may be a dirty MAF sensor, or loose wiring doesn't explain these observations. You suggesting it's a lack of torque "since 4 cylinders exhibit the problem" is nonsense. If you had truly felt this problem, where there's literally close to no power for several seconds before the car "surges" forward, you would understand.

While I appreciate your comments, it's not the place of the consumer to diagnose and fix a design flaw (if that's what this is). All we can do is report our issue and try to root out a common cause, which is what's going on- it's not a "mob", it's a group of owners who are frustrated by their cars exhibiting a hard to diagnose problem that goes beyond your "it's a v6 it doesn't have a lot of torque" diagnosis.

wstar

The only time I've felt anything similar is issues with UpRev's revlimiter when I switch back from a low mph/rev -limited map to an unlimited one. If I switch and quickly take off, or switch on the fly while already rolling out through a parking lot, there can be delay before it opens up the limits.

I've felt lots of minor bog issues in this car related to various intake issues, VDC, and the inherent throttle opening delay on this car (which isn't a fixed timer, it's more like the throttle won't open fully until the revs get higher at current throttle settings).

My point about the v6 comparisons is that if the problem is any of these various minor issues with intake parameters, heat soak from high external temps, stock throttle limiting at low revs, etc.... those effects are not normally anywhere near strong enough to describe the problems some people describe in this thread (the multi-second delays with no throttle response at all). Even taking all of those factors into account, there should way more than enough acceleration in this car to avoid serious issues.

Whatever you're facing, it's not the stock throttle map's failure to open fully, it's not just the engine's timing when breathing hot intake air and/or having high coolant temp, it's not a minor intake volume adjustment, and it's not the normal way that the engine limits torque. The only thing that comes close to those symptoms in my experience is VDC limiting wheelslip when you floor the gas more than traction allows for while turning out onto a road.

Other than that, I think anyone that's having such a severe problem has to have a malfunction that needs to be diagnosed. Most of our cars *don't* have this problem, or there would already be a massive recall underway. Even everyday drivers who know nothing about cars wouldn't accept a high rate of cars just completely ignoring gas pedal input for several seconds inexplicably. They'd all be back at the dealership in mass numbers and this would be a huge issue.

If you can reproduce the issue reliably, but you can't figure out what it is on your car that's failing unlike most of the other cars out there on the road, then go reproduce it for a qualified technician (dealership or otherwise) and have them diagnose it. There's got to be something broken and fixable. Either that or a commonality between everyone who really has this severe issue that points at a common defect (e.g. they're all 2009 cars from a certain VIN range which have a certain option).

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Journal thread / Car setup details

DIGItonium

It is unfortunate that much of the cars have this "issue" out of the box. Yesterday the car would not accelerate at all. I've added a shimmy to the brake switch which solved the issue the first year of ownership. New switch ordered. Next up is to clean the throttle body and PCV. Last is tune, which I hope will eliminate flat spots and help with response. My car is already modded so this is what I need to do anyways.

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DIGItonium

Bring back from the dead with update. New brake switched seems to have resolved my lagging throttle and poor low end acceleration issues I've been dealing with since '09.

The shimmy added to the brake pedal helped with the brake switch contact 2 years ago, but it did not eliminate the hesitation and rough acceleration feeling as if the engine wasn't sure what to do.

So I convinced my dealer to install a new brake switch since I was told some Altima owners experienced similar issues. Plus, some users here complained about difficulty accelerating which felt like limp mode. The week prior, I was in a situation where all of a sudden the car lost power. I floored it in 1st and 2nd to redline, and it took awhile to get there. Plus, boost wasn't building up at all. With the pedal to the floor, it felt like the throttle was as barely 1/4th and wouldn't ramp up past 50% (enough to get the turbos to spool).

Anyhow, the car feels great for the past week. Acceleration is brisk and smooth. From tip in I can feel the car want to scoot, and as I slowly press down on the pedal power kept building up without hitting the wall. I'm also able to get the car moving fast from a stop when making a left turn.

So for everyone out there with such issues, try to convince your dealer to change out the brake switch. Vibration might cause some sort of intermittent behavior, or the signal out of the switch is wonky.

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ZForce

^ Interesting, I may try to convince my dealer to replace it. Still a bit confused as to how the brake switch would effect throttle lag.

cab83_750

I'm confused also, but heck I hope this is it. Note that perhaps give us another update after 4-5 more weeks of use. It has been cold also so I am unsure if low temps are suppressing the occurrences.

W.O.W. 370Z

Part number? How much ?

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IcedZ

PLEASE keep us updated in the coming months. I'm not 100% sold until it warms up. I know you know exactly what the problem feels like DIGI, so I would consider buying another one if you say this works (but not until July / August).

ZForce

Thinking the same, although I did have a few occurences in 42 degree weather.

On the theory of the faulty brake switch, maybe the brake switch shorts to the "on" position when gunning the throttle causing the ecu to kill the throttle...dunno just speculating.

DIGItonium

I forgot to get the entire print. The switch costs a little over $100. There are two switches in the brake pedal assembly, and so far only one was the culprit.

Below is my post in Mike's thread with pictures of the switches. His brake switch was out of adjustment, and he mentioned throttle was limited to 15%. When throttle is cut, there are no codes or warning lights. My switch couldn't be adjusted, so I had to shimmy it. My car was stock at the time, and the motor screamed. It sounded different. Plus, I was able to easily break loose the tires as I gradually depressed the pedal to the floor.
I have a serious engine problem

Fast forward to today, when I had power issues in 1st and 2nd the ambient temps were in the 40s. Oil temps were around 180F. I tend to get the car going under 2k RPM, so there's an annoying stall under 2k RPM before quickly ramping up afterward. It's pretty inconsistent and difficult to drive smoothly. There are times I feel a dead spot as I press down the gas pedal. I can feel the power build up to about 3-4k RPM, and then it stops abruptly. Pressing further down to the floor didn't make a difference. The linear feeling wasn't there. Boost would ramp up slowly in parallel with the tach, which was unusual. I had issues getting out of vacuum beyond 3k RPM at times, so I thought there was a leak.

So far the car is running great, and the ambient temps are in the upper 40s and 50s. I've had the oil temps as high as 200F and power feels consistent. I can feel the power build up from tip in regardless of the gear I'm on. It is easy to exceed the speed limit while gradually depressing the pedal down to 50%. So far I haven't felt any dead spots. Power continues to build up as I depress the pedal. Also, there's a nice feeling at highway speeds in 5th and 6th in which I can get the car to scoot with little effort. Basically starting out in 1st does not feel like starting out in 2nd. I've not had that feeling.

Also note I never had cruise control problems. So far it never disengaged on its own, so perhaps the other switch disengages cruise control. [shrugs]

I don't think this fix will resolve the power issues on super hot days, so an oil cooler is still recommended.

[EDIT] 370zgirl had this problem and had the switch replaced:
09 370z engine sputtering while accelerating

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ZForce

Thanks digi, I have some reading up to do on Mikes thread from your provided link. I am going to see about getting the dealer to replace it under my extended warranty.

DIGItonium

Awesome! I had to pay the $50 deductible. Bleh.

BTW, I had the A/C running tonight since it was cool and rainy. I didn't have any issues with low end power and RPM rise felt very nice and consistent.

I really hope this works out for you guys because I've been dealing with this since 2010.

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ZForce

Same here, deductible is $50 for gold plus extended warranty.

Menace370Z

Just reading this thread for the 1st time. I just ordered a 13 Z and am pretty worried now.

Does this issues affect all years? or mostly on the 09-10 models?

DIGItonium

No one really knows, but it pretty much explains why some people have it while others didn't. I experienced all sorts of weird problems and thought I was going crazy. It has been over 2 weeks and I'm still enjoying the car. Last night I downshifted to 2nd at 35-40mph, and the car hauled arse. I didn't even completely floor it. VDC was going crazy, but the car got moving real fast.

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