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.

Part number? How much ?

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

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).

:iagree: 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.

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.
http://www.the370z.com/engine-drivet...tml#post664697

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:
http://www.the370z.com/engine-drivet...ml#post1862054

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.

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.

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

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?

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.

It's not your old school RWD car that you slam the gas when it's wet out and you do a 180 or Go Fishtailing.

The car has some features which, if you drive like an :nutswinger: then the car will interrupt your program until it feels stable :icon14:

I have learned to turn VDC off when it isn't raining :tiphat:

Both Z's are getting the brake switch replaced under extended warranty. $50 deductible might be waived by dealership. So I will have two cars to test if this resolves the problem. BTW they are running with 25 row oil coolers and INJEN CAI's.

Monday morning is appt day. Replacing the brake switch that controls the computer (not the brake light one). No issues with cruise control.

after trouble shooting again after so long since i had given up,i tried something today that fixed my throttle issues after applying the brakes.i thought that maybe i had a bad brake switch also.

in my case,something inside my brake booster was giving the map sensor a bad reading with the vacuum.found out after putting a T on the brake vacuum hose at the i m and then running a hose to the map sensor by the brake booster and plugging the hose coming off of the brake booster that went to the map sensor.to my amazement,this worked.

i have said in the past by doing this and that it fixed my problem.what i was doing was making the car run richer until the computer compensated but the problem always came back.

since the map sensor is now bypassed from the brake booster.my problems with throttle problems have disappeared.i had all but given up on this car until today.this may or may not work for the people that cant figure their problems out with throttle problems either.its completely reversable and i have run the crap out of the car during my testing.

i also notice,my oil runs cooler and my gas mileage went up with normal driving.i know for a fact that the map sensor by the brake booster was making my car run lean as hell.it would smell like gun powder after i got on it.i dont smell that anymore either.i went from hating this car to loving it again.

so far,there are two culprits of throttle problems(excluding vdc) that i know of,brake switch and map sensor by the brake booster.one cuts throttle and one leans the car out

^Very interesting. You make it sound so simple, but for the non technical mechanical members (like me) what you did is foreign language.

Any pic's would be appreciated, as I would be interested in trying this once the brake switches get replaced.

Update: they are replacing both brake switches on both cars. Good thing, might as well, will take any guess work out of it as to which one is causing the throttle lag.

Digi... IIR is the brake switch you had replaced the one that is called the XXXX ? Or is the one that triggers the brake light at the rear of the car?

Nice news. It explains a whole lot. Especially the inconsistency of how bad some have lag vs others.

Design lag, e.g. drive-by-wire, VDC ON, VDC that can't be turned off, mashing the pedal too fast, conservative throttle maps etc; those explanations never made sense to me when I occasionally got 2 second lag, with good oil temps, smooth throttle engagement and no heat soak. I'm definitely going to see if I can get these brake controls replaced.




Tapatalk & such etc

I don't remember because they forgot the hand me the paper work with the brake switch change. If you look at the pics from my earlier post, you can see which switch was the culprit.

Ambient temps were close to 60F yesterday, and I had the oil temps close to 200F. So far so good. I can still feel the push in 6th while cruising (versus no feeling, but just a louder exhaust note. It still gets glitchy once in awhile, but VDC is definitely pretty sensitive.

Ok..well both switches are being replaced and here are your pics. Looks like it was the one on the right, the one with the black casing. I will check with dealer to see which switch it is. My guess its the one the sends a signal to the ecu to kill the throttle becacuse the brake is "ON".

Here is your post from other thread.

http://www.the370z.com/664697-post50.html

I didn't read all the way up so you may have already mentioned.

But how did you present the issue to the dealer and get them to do the replace so easily?


Tapatalk & such etc

i wont edit this post^ in case someone else wants to try it.dont waste your time.apparently,it IS my brake switch also.the brake switch that is farthest to the right(closest to the foot well ) is the one that kills cruise when you apply the brakes.

i adjusted this one out to where i dont have cruise atm.but guess what,by doing this,the computer no longer thinks im applying brakes when im not.so there it is.BRAKE switches.and i put the map sensor back to stock.car is running great.so if you want to try and trouble shoot your brake switch,take a 14mm open end wrench and loosen the switch im describing,unscrew the switch about an 1/8th of an inch,maybe more,then tighten the nut back down and go for a drive.

what i believe has happened in my case is the nipple is wore down on the switch that controls the brake lights and the other switch isnt letting the brake light switch be compressed all the way.drove this morning to work and back home for lunch and back to work with ZERO throttle problems and i tried to get it to show its ugly face again and wouldnt come back.and the car definitely feels easier to get rolling.

Kenny ^ thanks bro for the 411 update. So it's the same as in digi's photo on the link I posted above. The one on the right hand side, closest to the gas pedal.

If I understand you correctly is that:

Number one switch: on the left hand side in pic with brown housing is the brake light switch. Which is NOT the faulty switch.

Number two switch: on the right hand side in the pic with the black housing is the switch to control the ABS and cruise control. Which IS the faulty switch.

Damn...this is like "who's on first and who's on second and I don't know whats on third".

I started out with explaining that the throttle lag had been an issue since day one - March, 2009. The service manager and I have previously had discussions over the years on the issue and how I was waiting for UpRev to crack the Varible Valve on these Z's. So he has been aware of my concerns for sometime. Last week I presented the fact that a member here tested it with some cardboard and masking tape and the car screamed with NO throttle lag and is on week three with no issues. I also threw out that the same issue is occuring on the Altima's. With my rapport with the service manager and he knows how I take care of the car, he took me on my word to try it.

It might not be as easy with a dealership/ service manager that you have not dealt with much. A little back graound with my dealership - purchased 2 each 350Z's and 2 each 370Z's since 2005 and have extended warranties on the 370Z's.

I also bring in bagels and cream cheese occasionally for the service writers and technicians in the shop.

G/L :tiphat:

yeah,the black cased switch(the one on the right in his pic) is the cruise killer when brakes are applied.thats the one i backed out.the other one(brown cased one)is the brake light switch.

Thanks ZForce. That the perspective helps a lot. I think I'm going to talk to my service manager this week.


Tapatalk & such etc

So how did it go? Notice the motor sounds a bit different when you give it at least 50% throttle input?

We had record breaking highs yesterday at 75F, and I tried to get the oil temps up to 200F. Power-wise, it's not as exciting with the warmer ambient air, but I can still feel the continuous power increase as the throttle opens up.

Previously, power would build up and fall flat as I continue to press my foot down. My passengers think I lift my foot off the throttle.

Can you please see if your MPG changed?

Can you please post if your MPG changed?

Yea, it got worse. I find myself having too much fun. ;)

Kidding... it shouldn't change. My average is about 22.4 MPG, and it's pretty much the way I drive. I've not had anything worse than 19 MPG, and that's the least I can do to have a bit of turbo fun.

HOLY S***!!
I NEVER got 22.4 unless I cruised at below 70 on the interstate.
My average city driving was in the 18's, and 16's in the summer (less efficient / A/C probably) That was a huge factor in getting rid of the damn thing. If I actually got closer to 22, I would get another.

yes,motor has that metallic reverb now as it should be.if i start driving hard,i will start to get a delay but that is in part due to heat.driving normally shifting at 4k,car runs perfect.WAY better than before.feels like i got rid of the "anchor" i felt like i was dragging.

:tup:

My parts did not come as planned, partial order. So no workee on Monday. Parts did arrive yesterday and both cars are going in next Monday. Will update thread soon after testing.

Disappointing to hear there is still the ambient heat issue causing some throttle lag. Then again IIR are you not running with a TT ? And we would not be comparing apples to apples (as in car setup), correct me if I am wrong. :tup:

For the record my car never sees more than 19mpg, then again a ot of city driving. I think if straight highway I have seen 23 mpg. The bros Z a little better, lighter foot on the pedal. :driving:

Happy to see the issue resolved for you, Kenny. Yea, powerband is a bit glitchy sometimes even after a warm start or when ambients exceed 75F. The car still doesn't fall flat on its face, though.

Haha... my daily commute consists of freeway driving, and it's about a 15 minute drive to work. So my car is on the freeway roughly 75% of the time. If I drive my dad's '05 Xterra for a week I would go nuts because that thing really guzzles gas no matter how conservative my driving habits are.

Anyhow, it has been nearly 30k miles since the TT install, so I'm going to do a bit of Spring cleaning with the filters, pipes, TBs, etc. Is it necessary to clean the PCV and hoses?

we

Wow. That's all I can say.

Is it the Brake Switch?
 

ZForce, did replacing the brake switches solve your problems as well? I'm experiencing exactly the same symptoms as Digotonium, you, and a few others on this thread. I've read all 64 pages of posts...and am HOPING this is THE fix. I've brought up the issue with my service manager several times, but each time, the tech hasn't been able to reproduce it...It's so frustrating.

Please let us know! Thanks.

Overall....no. It did solve the immediate lag...but as mentioned above and now that we are into the heat of the summer, it DID NOT fix the overall throttle lag. It's back to an ambient tempure with heat soak issue.

If your Z is still under warranty, you may be able to convince the service mgr that the gap between the contacts is more the 1 mm and should be replaced.

That's true. I had intermittent lag regardless of temps even when my car was stock, and changing the brake switch resolved much of it.

Then the lag I had recently was pretty bad after an engine start, but it was also intermittent. I could hold it down in 1st and 2nd, and the engine felt like it had half the power and boost didn't even build up. It appeared to be caused by my HFC wanting to clog up (confirmed) due to running rich with the turbos. I also found an exhaust leak in which my last tech did not reuse the gaskets for the HFC.

My car is running so much better now with the test pipes. There are still times it doesn't seem to want to open up, but it's nowhere near as bad. Next up is filter cleaning after over 30k miles and also clean the throttle bodies. It might be sticky.

^Good info. To add, I have Berk HFC's with no exhaust leak and clean my air filters every oil change. I have also swapped out the air filters for new ones. Issue is still the same.

It sounds like we're all sh*t out of luck to a certain extent...short of brake switch replacement and an ECU tune as last resort. Even then, that's not guaranteed to fix the issue.

I did jiggle and play around with each of the switches behind my brake...and noticed a big difference in how she responded. It was only temporary, but still leads me to believe that's where some of the issue is stemming from.

Oil cooler is on the wishlist - it reached 118F here last weekend, and my oil temps always hover around 220+, even in cool weather.

Thanks for all the input guys - I've gone through and read most of the pages to this forum post. My issues are closest to Digitonium and ZForce, and I definitely can't fathom trading her in...nope, not yet.