Hi everyone,

I have an 04 auto Z w/ 74k (completely stock) that I bought a few weeks back. I'm noticing a little bit of throttle lag when I'm cruising around 50mph on the freeway then I step on the gas pedal all the way down and it takes about 2 seconds for the transmission to shift down. It's an automatic and I'm not expecting faster throttle response like I would expect from a manual, but I was wondering if it's normal. This lag usually only happens when I step on the gas pedal fast and not when I slowly step on the gas pedal.

Also, I noticed there's a lack of power from about 60-90mph.

Is the throttle lag normal?
Does the throttle body need cleaning at 74k?
Would unplugging the battery to reset the ECU help?

 

Power delivery of both a manual or tiptronic, should be very linear and should pick up quite quickly, bearing in mind it's not a turbo though. Looking at your new join date (new car to you) maybe it just needs everything serviced including all and I do mean all the oils and filters, get the MAF & throttle body checked too.

You never know what sort of treatment it's had before.

 

Thanks for the reply. I'm learning more about the Z, which is pretty exciting. So far I've done: oil & filter change, transmission fluid, and coolant.

The previous owner had the service records which was nice. But you're right, who knows how hard/soft the previous owner drove it.

 

Sounds odd, are you complaining about the transmission or throttle response.

 

I'm complaining about the throttle response. I drove about 3-4 other auto Z's when I was searching for one, but I never jammed on gas pedal because I was too afraid of the horsepower (coming from a much slower car). It's probably all in my head.

Another thing is I thought that the amount of time it takes going from 0-60 is the same as 60-100 but I'm probably wrong again.

 

What kind of wuss buys a sports car with an automatic transmission?

Thought I'd get that out of the way since it's bound to be coming at some point.

Two things to keep in mind:

The Z has a drive-by-wire throttle.
The AT torque converter needs to come out of lockup before it will downshift.

Both take a teensy bit of time, but two seconds sounds excessive. I wouldn't be surprised if the ECU delays the throttle opening while it gets the TC out of lockup to protect the transmission parts.

As long as it's not obviously slipping excessively, I wouldn't worry about it. How often do you really need to do full throttle downshift? I've been driving since 1961 without needing to do one.

 

thats just how an auto works. the computer reads that you are hitting the throttle hard and wants to get max rpm out of each gear it's in. if you slam the throttle for a second, then let off, then slam it again for more time it will downshift faster. autos are stupid and you have to trick it. ive found that it only wants to shift up quickly, not down. and yes tricking it to down shift and slamming it will hurt the auto trans.
btw my my Z is a MT, my camaro and LS1 truck are auto.

 

Haha, love your first sentence. i was waiting for that

Yeah, everything is smooth with the car. The transmission shifts smoothly, no slipping or other funny business. Could the possible lag be caused by the ECU being used to the old owners driving habits? (previous owner in his early 70's. No idea how he drove it but I'm guessing very lightly)

I'm not looking to speed or race or anything like that. I wanted to see what the Z is capable of now that I own one (been wanting one for 11 years).

 

Thanks for the clarification. I'll definitely take it easy on the pedal. I just wanted to learn my Z so I figured that it wouldn't be a bad idea to step on the gas hard every now and then.

 

Cleaning the throttle body is a good idea but I don't think its gonna help
with the "lag" that you are experiencing.The common sense stuff,clean/replace
the air cleaner filter,maybe some injector cleaner in the fuel are in order.
Auto trannies will have some lag.But what is lag to one is not too bad to others.
If you want to improve on what you call lag,get a tune.The tuner can "crisp up"
the shift points to a certain extent.Of course the installation of a Transgo valve
in the trans is another option.I'd do the tune first.The Transgo will shft faster.
However,can be rather harsh

 

YOU BOUGHT AN AUTO CAMARO?

i couldn't help it.

 

its a 73 built for drag racing. it upshifts faster than manual 95% of the time. thats why 95% of drag cars are auto.

 

also throttle lag is programmed into many cars with an automatic. newer silverados for example have bad throttle response in stock form. its a safety thing, so if you accidently slam the gas for a second and release it will not lunge forward. its one of the first thing a programmer(tune for Z) fixes along with better shift points. it still wont downshift on cue tho.

 

I think I know what the problem is. Your car is trying to commit suicide because it's a automatic sports car. My Toyota Camry does something similar to what your Z is doing. Maybe it's time for a tune up.

 

There is a company that makes a sprint booster to reduce the lag you are talking about. I don't know what if it works or not but if you are concerned about the lag, look into this product.

 

Look into transgo shift kit. Definitely an good upgrade to have for AT

 

I think you should get a new Throttle Body and it is not too expensive for the re-manufacture one. Happened to my Auto Z also replaced the throttle body no more lagging and sudden lost of power on the road!

 

Doesn't your 04AT have a dual gate shifter? If it does, compare power in normal shift mode with power when you select shift points. That would tell you if its the tranny or engine. Good luck!

 

You say there is a lag.. What trim do you have?.. If it is an enthusiast or above and you are equipped with a VDC on/off, it could be the traction control kicking it to not spin your tires and provide the most grip throughout acceleration.

 

The Sprint Booster isn't just a waste of money, it's a well-documented waste of money, just like the Turbonater, Slick-50, fuel magnets and all the other useless junk people get rich selling. All it does is change the resistance reading on the drive-by-wire system so that the throttle opens further with less pedal input. If anything, it makes the car less manageable and more difficult to maintain a constant speed. I discussed the product with a respected owner of a speed shop in Microsoftville (Redmond, WA) who works on million dollar cars and used to to sell them and his educated opinion was that the product was snake oil.

I wouldn't recommend you clean your throttle unless you know what you're doing. Get a copy of the FSM, read the how-tos and know that on the 350Z, if you screw up even basic steps with your throttle cleaning, you can destroy your ECU. However, by all means, do your fluid changes if there's no record of them having been done in the past. It's best to know that your (new) used car has fresh fluids in it. Based on the gazillion threads about which fluids to use: Use whatever quality oil you prefer and for all the other fluids, stick with Nissan OEM (and that includes their $25 a gallon coolant). As mentioned earlier, at 74K miles, your car is probably ready for a tune-up.

Finally, to answer your original question, yes, it is perfectly normal for there to be a lag when you're driving at speed and suddenly go to WOT. The computer needs to make a lot of adjustments to correct for the sudden air/fuel mixture change and in your case, the slushbox transmission is going to need time to spool up. There's nothing abnormal about what you're describing.

I hope you're enjoying your new Z.

EDIT:

One last thing, it occurred to me that if you're getting a two-second lag, it may be time for a transmission flush. Dirty or contaminated transmission fluid can cause a delay when the car is shifting gears, which it certainly would if you go to WOT while in motion.