Jerky Acceleration Under Load?! 27,000 Miles?! Fuel Starvation?

[takemorepills]

I have a new Titan Pro-4x with the 9AT.

Nissan has already applied one campaign and one TSB to it. It does drive much better now.

It's likely the transmission, much like the 7AT, the programming of this transmission is garbage.

Fuel starvation would likely throw a code/CEL for a lean condition.

 

[MCN1SMO]

I have a new Titan Pro-4x with the 9AT.

Nissan has already applied one campaign and one TSB to it. It does drive much better now.

It's likely the transmission, much like the 7AT, the programming of this transmission is garbage.

Fuel starvation would likely throw a code/CEL for a lean condition.

i think it might be starvation as it kind of seems similar in RPM drops to this video and there are no codes thrown

I clipped the part out

 

[qellman32]

That's interesting. The first time it did this, I was coming out of a turn. Maybe that is the problem. Is there a fix to this? Maybe the upgraded high-pressure fuel pump? I'll have to do some testing at higher fuel levels.

 

[SavedByFaith_]

That's interesting. The first time it did this, I was coming out of a turn. Maybe that is the problem. Is there a fix to this? Maybe the upgraded high-pressure fuel pump? I'll have to do some testing at higher fuel levels.

I think there are some "kits" that fix this
Maybe looking into resolutions in the 370z space may help

Here is a link for something sold at Z1
No clue if this fits the z, or how much retrofitting needs to happen

https://www.z1motorsports.com/z1-pr...IsfwR49ec3PEvtryCMprP2wfrnEe7DZBoCxhYQAvD_BwE

 

[takemorepills]

Seeing as how this isn't a new platform or drivetrain, why am I only hearing about it in regards to the new Z?

I tried to find reports of it occuring in the Q cars, there's one or two mentions of suspected fuel starvation, but it ended up being more likely the 7AT. I had the "G37" Q60 and can confirm that the hesitations rarely reported on the turbo Qs definitely occurred on my VQ37 7AT car.... I freaking hated that transmission.

What's different about the new Z? The 9AT....

Really miss the old 5AT now that I've had both newer transmissions....

Has this been noticed on 6MT Z's?

 

[MCN1SMO]

Seeing as how this isn't a new platform or drivetrain, why am I only hearing about it in regards to the new Z?

I tried to find reports of it occuring in the Q cars, there's one or two mentions of suspected fuel starvation, but it ended up being more likely the 7AT. I had the "G37" Q60 and can confirm that the hesitations rarely reported on the turbo Qs definitely occurred on my VQ37 7AT car.... I freaking hated that transmission.

What's different about the new Z? The 9AT....

Really miss the old 5AT now that I've had both newer transmissions....

Has this been noticed on 6MT Z's?

so ive heard its been talked about and been around since the 350z days. ive owned 2 350s and never had it happen.

to me based on the limited research I did on it was its because the fuel tank has never been changed and the fuel can slosh around and deprive the fuel line? that was my take away. its weird on the new Z I can hear the fuel moving around in the tank more than other cars.

the GTRs for example use saddleback style tanks that help the fuel from shifting all to one side during high speed cornering.

 

[takemorepills]

so ive heard its been talked about and been around since the 350z days. ive owned 2 350s and never had it happen.

to me based on the limited research I did on it was its because the fuel tank has never been changed and the fuel can slosh around and deprive the fuel line? that was my take away. its weird on the new Z I can hear the fuel moving around in the tank more than other cars.

the GTRs for example use saddleback style tanks that help the fuel from shifting all to one side during high speed cornering.

I have read a few times that the Z would suffer fuel starvation on extended high G loads, pretty sure I've heard people say it still happens on the new Z, on a track. Ridiculous that Nissan belligerently continues using an unbaffled tank.
(Same goes for Akebono brakes, nice looking, but not much of a braking upgrade).

I just want to include the possibility of the AT because, likely a very plausible culprit, along with fueling. I just don't think people are starving the pumps on the street.

Maybe Nissan spec'd out a cheaper fuel pump. But I've got money on the 7 and 9 speed just being crappy transmissions.

 

[MCN1SMO]

im wondering if putting the car in manual and then trying to replicate it while in a higher gear 6-7 ect would rule out the transmission if it did it while in that single gear

on my 2023 performance i noticed the fairly common 1-2 shift slip where you would see the RPMs jump an additional almost 1K before the gear change. thats one reason why NISMO added the extra clutch packs. but once in gear and even shifts past 2nd no issues

 

[takemorepills]

im wondering if putting the car in manual and then trying to replicate it while in a higher gear 6-7 ect would rule out the transmission if it did it while in that single gear

on my 2023 performance i noticed the fairly common 1-2 shift slip where you would see the RPMs jump an additional almost 1K before the gear change. thats one reason why NISMO added the extra clutch packs. but once in gear and even shifts past 2nd no issues

I have definitely noticed, that in my 7AT and 9AT, the first 2 or 3 (hard to tell which gear exactly as these vehicles don't display it in auto) the trans seems very "slippy". I don't get good torque and proper RPMs until it's past 2nd or 3rd, feels like a slippy torque converter until then

Did I mention I like the 5AT better!?

 

[bpeckham]

Has this been noticed on 6MT Z's?

The only thing I ever notice on the 6MT is a little turbo lag.

However, I must do more research to collect more data. I'm at about 1/4 tank right now. I'll do some pulls. We must be thorough.

 

[bpeckham]

The only thing I ever notice on the 6MT is a little turbo lag.

However, I must do more research to collect more data. I'm at about 1/4 tank right now. I'll do some pulls. We must be thorough.

Okay, reporting back. My 6MT doesn't have any jerkiness issues. It's much more likely that the 007s will break loose. But it's 55° here, which might be part of the problem. More research is required.

 

[qellman32]

Okay, reporting back. My 6MT doesn't have any jerkiness issues. It's much more likely that the 007s will break loose. But it's 55° here, which might be part of the problem. More research is required.

The S007's did better than I thought they would (based on track-focused reviews), but I've changed my tires because of the weather change (Michigan winter). I have Atlas "Ultra High Performance" All-Season tires lol. They work at least as good as the S007's.

However, this particular problem isn't a traction lose thing. No tire spin. Maybe a Traction Control thing. I'll have to try it turned off and I'll try in higher gears. Don't know if It'll have enough torque to fuel starve though.

I also get the weird 2-3 gear "slip" weirdness. I figured it was a quirk. The dealership (in all their wisdom) said that everything was within tolerance. I do enjoy the 9AT. It shifts better than any transmission I've ever had (except the ZF 8AT in my Jeep Grand Cherokee I had. That was perfect...).

 

[bpeckham]

The S007's did better than I thought they would (based on track-focused reviews), but I've changed my tires because of the weather change (Michigan winter). I have Atlas "Ultra High Performance" All-Season tires lol. They work at least as good as the S007's.

However, this particular problem isn't a traction lose thing. No tire spin. Maybe a Traction Control thing. I'll have to try it turned off and I'll try in higher gears. Don't know if It'll have enough torque to fuel starve though.

I also get the weird 2-3 gear "slip" weirdness. I figured it was a quirk. The dealership (in all their wisdom) said that everything was within tolerance. I do enjoy the 9AT. It shifts better than any transmission I've ever had (except the ZF 8AT in my Jeep Grand Cherokee I had. That was perfect...).

With your issue, does the problem occur *before* the tires cut loose? If so, I'd suspect traction control, transmission problem, or fuel supply issue.

With my 6MT, I was able to accelerate hard with no jerkiness up until the back end starts to get squiggly, so I'd expect no fuel issue, at least with my car.

 

[qellman32]

Ok so, I think it might actually be fuel starvation.

Apparently there's a chance (maybe 1 out of 5 times) it will have the symptoms at just above half tank. I tried a few times after this picture (which I took directly after an "episode"), but it wouldn't do it. It also wouldn't do it around full tank, but that needs more testing. By the way, this is at full throttle from lower coasting speeds up through 100mph. Sometimes turning out of a parking lot (it might let you do a drift from said parking lot etc, then have the episode), sometimes racing a Challenger from a red light (and still winning tehe), but always at full throttle.

I have been using Sam's Club 93 octane religiously because it's cheaper than everybody else. Today's 87 was $2.58 and 93 was $3.28.

This happens before breaking traction, as in, it does not break traction at all on dry streets when it does it. I'll have to try this with Traction Control off. Anybody's who doesn't have an episode at 1/4 tank or less, I wonder what's different...

 

[qellman32]

Changed the title from:
Jerky Acceleration Under Load!? 9-Speed AT Stock, 4 Months, 18,750 Miles
to:
Jerky Acceleration Under Load ?! 27,000 Miles?! Fuel Starvation?

Did this to get more eyes on this situation, see if anybody else has this issue and get their feedback!