This happend to me on my old 350z. Throttle problem...

I believe this was mentioned in this thread, but I can't find it. Maybe it has to do with Octane? I am considering buying a BRZ / FR-S (Juke just isn't quite sporty enough - and I hate front wheel drive). I have been reading some interesting threads on it where people in some states cannot even purchase >91 Octane gasoline. The manual recommends 93+. 91 will not void warranty, but some people are saying stuff about the car being a little lethargic. Has anyone put octane booster or racing fuel into their car? I would LOVE to get another 370, but refuse until this issue is identified. Good luck to all of you with with issue.

Honestly, I can not tell ANY difference between 91 and 93 octane as both are available here. I used to use an octane booster in my 94 Firebird Formula when I went to the drag races and I really didn't feel any difference either. I know some pumps in the area carry racing fuel (102-104 octance) but at the prices that they charge, I'll keep using my 91 or 93.

I haven't experienced this yet, but I am also not home during the summers anymore (not by choice). I was reading though all the post and very well could have missed it, but were people who have vented hoods having this problem? I was reading a bunch of different post about hood vents and saw one from modshack about removing the hood gasket above the firewall and how that has helped in the past with heat, if heat is one of the potential causes of this.

I know what you're saying, but I'm just wondering if maybe ethanol content has to do with it, or maybe 93 gas isn't as pure as it should be?

Octane in my opinion has nothing to with it. I have used 93 since the day I bought it and it's consistently there everyday. Do people with gtm supercharges and tt kits have this hesitation? I'm just wondering with the FI tune and the added power if you can feel these hesitation issues.

Sprint Booster doesn't really fix anything. It's more of a psychology fix: it changes the gas pedal input sensor to react as if you'd pushed the pedal down further before you've actually done so. You could get the same effect by just changing your pedal habits.

http://www.the370z.com/tuning/43384-...tle-uprev.html <- this has my throttle map and the stock one to compare to, and various other bits of data on the subject. There are definitely aspects of this problem that can't be solved through the throttle map either, but this helps (and smooths out the response curve for predictability rather than mucking it up and making it jerky).

Yup... looking forward to making these changes once my car gets a proper tune.

A lot of this may be heat soak. When it is hot out and the car has been running a while everything under the hood is super hot including the air boxes there is no ventilation in the engine bay and it acts like a a huge convection oven.

When leaving work for the day my cars both the 370z and the Nismo are parked in a garage staying nice a cool. When I first leave the cars are very responsive and throttle reaction time is quick and brisk. Once I have been driving for 20-30 miles it start to slow down on acceleration even though my oil temps are 200 degrees. At a light if I am sitting for two minutes when I press the gas it just sit barely moving until I get to about 10-15 mph then it kicks back in. This is heat soak. If you have a decent OBDII scanner you can watch your intake temps. They will be soaring at idle at the light so when you accelerate you get the bog. Once moving again they cool to ambient.

Having a tru CAI will eliminate this problem. Short rams won't do it, a lot of the kits I have seen won't work. You need a way to bring in cold air as close to the ground as possible preferably taking in air from the front away from any heated part.

You also want the tubes inside insulated from the heat of the motor. The way they designed the two TB intakes on either side of the mother just over the manifolds is to say the least retarded! The problem of heat is compounded.

The corvette, and other sports cars the TB intake in in the front of the motor away from the heat of the manifolds. The intake has a short run from the front of the motor to the TB so intake temps will stay lower. An intake design change of the 370z motor moving the TBs to the front away from the heat of the manifolds would add a lot more performance.

The best solution is to find a way to let heat out of the engine bay. I know my 5.4 in my Expedtion does no put off half the heat the 370z does. I pull into the garage and it will heat up my house so much heat is pouring out and it stays that way it won't cool,down for hours. I habe to leave the hood up. It even heats my house nice for winter , but summer no! I don know on this maybe vents in the hood or side something to vent that heat out.

The bog is purely heat soak though.

i have counter acted this problem 90%.throttle body bypasses on this car are a must !!.removing the rubber seal under neath on the front of the hood will allow air to get in there.just ask the bugs that i now collect on top of my air boxes.i have drop in filters and post maf tubes.i still didnt feel there was enough air getting to my filters in the stock box.so i opened the outer corners and removed the rubber that goes over the angled outer radiator supports.

i also copied another members idea on here that modified the front half of the engine cover for his catch can hose connections.doing this will also aid in heat escape from the pcv hoses not being able to add additional heat onto the im via engine cover.i bought the car used and i have made the car way more efficient by doing what i did.the computer on the car said i was getting 18.2 miles to the gallon when i bought it.

i now get or average 23 miles to the gallon in city driving shifting at 4-5k.take it for what its worth.i will add a pic for your reference.love it or hate it,these mods work well for me.air boxes still look stock when you pop the hood.also while its just a theory,i think the 02 sensors start messing with the fueling after they get so hot from this engine.i will add spacers to the stock setup sooner or later to test my theory.

EDIT;also in the 2nd pic,i have added cell foam pipe wrap on the maf tubes to aid in heat protection from the engine at idle.and when i can figure out where to put 2 catch cans on this car while keeping the oem air boxes,i will do that also.i know from experience on another car that besides the cans catching oil,they will also provide a little more cooler air going into the im.just dont know where i can mount a couple of small cans.

http://www.the370z.com/members/kenny...-satisfied.jpg
http://www.the370z.com/members/kenny...g-progress.jpg

Hot intake air (and the contributing hot engine bay) is really a separate issue from true throttle lag / unresponsive-ness though, it's best not to confuse the two. Killing VDC and running a modified throttle map will help.

Another thing that helped me (but may not apply to everyone else) - my dyno tuner had intentionally set the area of the A:F table that deals with low rpm + low throttle input (top-left-ish) fairly lean to conserve fuel on the highway. It's just a standard thing they do. I bumped those values back a little bit richer and it helped some (a bit more fuel available on initial tip-in from low throttle).

Reducing heat in the bay and focally in the intake tract is helpful in general; colder air makes more power. It's not a throttle-specific issue, however. FWIW, I'm pretty happy with Stillen G3's sitting on top of LTH's, but I've also made some minor related heat mods. Mostly, I've shielded the intake tubes with a thermal wrap (Thermo-Tec : Cool-Air Tube Heat Shield), and I also bypassed the throttle body coolant lines.

since i have read on here how to disable the vdc 100%,there is more power for sure.i was thinking the lag also had something to do with how hot the 02's were getting.but now that you have stated the afr issue.it makes perfect sense.but i wonder if putting non foulers on the 02's would help at all without a tune with minor bolt on's ? it seems that after the 02's gets so hot,the afr's go too lean from the factory setup ?this is all speculation as the little lag i have now doesnt start right away.

Killing VDC doesn't do a DAMN thing for those of us with the serious problem. It sounds like you guys just don't like the throttle mapping. This thread has to do with a serious problem where occasionally the car falls flat on its face with the pedal to the floor then gives you whiplash.

The basic problem with the stock throttle map is that it refuses to fully open the throttle when you nail the pedal at low RPM. It gradually lets the real throttling open up as the revs rise. This is a form of pedal delay that tuners try to fix, etc. Your problem does sound different...

How long is the delay before the car reacts? Is it from a standing start in first, or rolling in some gear? What RPMs and pedal position did you start at? Getting data on that particular issue is the key to understanding it. I wonder also if there's any commonality in setup between people that have a large, complete delay? Perhaps large intakes (G3) without going through the procedure to re-learn the intake tract's Idle Volume after install, or something like that?

I read the updated post in your thread. You're right about the gradual throttle ramping with the RPMs. It's so unnatural and feels artificially held back. That explains my boost gauge gradually getting out of vaccum and slowly or barely building boost at times. I do feel the roughness of the throttle similar to rough engagement of the clutch and not being able to keep my foot still on the pedal haha.

What's interesting is that when the car is fairly cool I can get boost to build up at half throttle and low speeds since the BOV flutters at light loads. It's pretty fun in the neighborhood. After awhile I can't get boost to build up unless I hold down the throttle and let it rev past 3-4k RPM, which is not good in the neighborhood (easy to exceed the speed limit).

I even showed my friend by punching it in 1st while turning out of the parking lot with VDC off. The car slowly ramps up, but doesn't spin out of control. His Lotus is so much better on the throttle response even after some hard driving.

This year is definitely a bad year. We're breaking records over here. The car gets so hot that when I press down on the pedal the throttle opens up, and then it hits a ceiling and refuses to do anything else.

Also, do you guys feel it's difficult to quickly rev match with this car? I usually bog on the downshifts because I end up not revving it high enough.