Z does not accelerate

Vicster

I've had almost the exact same issues. Dealt with it myself for a little while but eventually it threw a CEL so I took it to the dealer. They said it was the K&Ns and that oil from them damaged the MAFs and they would need to be replaced and not under warranty. I decided to just clear the CEL myself, clean the filters and ensure no excess oil, and spray the MAFs with MAF cleaner.

It got better immediately and I didn't have an issue for some time. Eventually though I started to get the feeling of overall decreased performance and recently I've had the codes (not the CEL though) thrown. I've cleaned the MAFs a second time which seems to restore some performance but the reaction is sadly random and not very consistent.

I'm beginning to think that maybe the dealer had one thing correct and that is that the MAFs actually need to be replaced. If this is the case I believe K&N warranties their product under Magnuson Moss and will reimburse you for the replacement of parts not covered under manufacturer warranty "apparently caused" by their filters. Thing is, if replacing the MAFs helps and the cause was the filters/oil I wouldn't want to use them anymore (and for that matter any of the CAIs also utilizing oiled filters, which immediately limits some of my favorites. However Stillen has released a new Gen3 dry using AEM filters.).

The other problem is that some of the issues mentioned relating to the throttle sensor definitely make me wonder if that is the problem. Interestingly, before reading this thread my instincts where telling me that it was primarily throttle response which seems to be the symptom. Hard to say exactly what is the problem so I'm very interested in seeing what your experience turns out like.

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-Chris

'13 Z34 Touring Sport | ARK GRiP CBE | Stillen G3 CAI | AAM HFC | UpRev | 20mm Z1 Spacers | StopTech Drilled/Slotted Rotors | StopTech SS Lines

P's_Z

Coincidently, SES light came on today. And I do have K&N filters also. Its dissapointing to think that the oil messed up the MAF sensors,ive used K&N filters in all my previous cars and never had an issue, so that says a lot about how crappy our MAF sensors are. Ill definitely try and go to the dealer this week, really dissapointed in my Z right now

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Zeta

P's_Z

Just a little update, took my car to the dealer, did routine check up but have mostly been working on another forum members car(carlitos Z) which was first before mine. They have done tons of testing and changes in carlitos car, from reprogramming ECU to changing maf sensors and they have still not solved his issue let alone mine. They even tried to blame the motor oil we are using on our car as part of the issue, as neither of us uses nissan ester oil. We gladly responded: "well youre the ones that think this is the issue and are stomped, if you pay for the oil change, well gladly take your oil" They have yet to confirm if they are going to replace it of course. Last but not least, it is rumored that some people in the states that have had this problem have had it resolved by replacing the throttle bodies, which i read here somewhere. Of course being this an expesive alternative to solving our problem, dealer will gladly keep our cars in the meantime checking on other bull****! So, thats all i have to report for now, ill be picking up my Z tomorrow while they work on carlitos car. That we know of, there are 6 people with this issue in PR, some are even forum members. Again, this has been a very dissapointing experience, between the bogus and misterious issue we have that no one seems to be able (or capable) of solving, to the inneficient product that nissan has cooked up. Dont get me wrong, i love my car, and will most likely keep it if the problem is solved, but im definitely frustrated right now. Thanks to all who have written and have been giving me their input on this, as ive even had to give these pointers to the certified mechanics who are working on our cars. I will most likely be writing a very interesting letter to nissan in the upcoming days....

For now...

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Zeta

juld0zer

hey mate, at least you got a CEL!! i have nothing to go by. Just instinct, determination, constant research and speculation.

what mods do you have? how about carlitos?

carlitos_370z

First of all... Thanks Pedro for open a thread with the problems that our Z's have right now... i know this will work with other members in the future...

Ok I dont have to much to say cause Pedro already talk about that... currently Pedro's Z dont have any mod... they remove all the mods to see if the problem go... but still there... From my Z.... right now the only mod that they have is the HPS Post Maf Tubes... Oem catback and oem drop in filters cause the first time i leave my car under warranty they said that the problem was the K&N drop ins... they told me that i have to recharge them... i said they only have 10k miles and we know those filters you have to recharge them every 50k miles... well short story... i put the oem ones and the car still with the problem... I have some friends in this forum with post maf tubes and k&n drop ins for more than 3 years and never had an issue...soo that is not the problem. Today when Pedro pick up his car.. with nothing to do on his car... The person of customer services said that finally are going to clean my car throttles bodies and make an adjustment on them to see if that works... They are going to do that before proceed to change the throttle bodies... if with just cleaning them and the problem go... they are going to do the same on Pedro's Z.

Anyway we are going to keep this thread updated... and we hope that this people finally fix our cars cause this is my 2nd week with out car ands that is my only car right now....

P's_Z

Hey mate!

I didnt a CEL at first, but dealer was able to pull the code anyways, so maybe you can get that looked into anyways.


As far as mods, only the ones on my sig. However, i took all the parts out from my Z and its bone stock now and still have the issue.

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Zeta

DIGItonium

Check the brake switch if you haven't done so. I used to have the same issue. When accelerating briskly the car made no power after shifting into 4th... I held the pedal down, but the RPMs were dropping.

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P's_Z

Thanks! Not sure if the dealer did this. However, i posted an update on what was done on 2 Z's here in PR with this issue. So far, so good.

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Zeta

DIGItonium

Thanks. I plan to do this as well. Possibly later this fall.

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P's_Z

Well, a quick update: two weeks issue free. Carlitos Z(who also had this problem), has also been issue free. Looks like the throttle body clean up and recalibration actually worked! Good to have my Z healthy again

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Zeta

Kabestro

Guess I'll have to clean mine...

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Stillen Gen 3 CAI / Fast Intentions HFC and CBE 12" Res. (#730) / Swift Springs / 20mm H&R Spacers / Clutch Helper Spring / UpRev Tune 322whp.

carlitos_370z

True!!! 0 issue for now.. the car is running like new... fall in love again with my Z

juld0zer

Pedro & Carlitos, how are your cars these days? I finally cleaned my throttle bodies today. Took about 3hrs but i disconnected both and also operated the butterfly valves manually to ensure i removed as much carbon and gunk as i could. I already have the coolant hoses removed from both sides so that saved a lot of time and mess. I'm currently waiting for engine to cool down to perform the relearn procedure trifecta (first two must be done with coolant below 25c). Car felt no different after driving with the cleaned throttle bodies but the idle did hunt between 800-1200rpm - which is to be expected since i did disconnect both bodies and removed them from the engine bay for cleaning.

There wasnt a huge amount of gunk but most of it did require some rubbing several times with a cloth soaked in carby cleaner.

When i sprayed both throats, i noticed one held the fluid in a pool on the butterfly while the other dribbled out the other side fairly quickly. My first thought was that the one that doesnt leak is the least likely to be causing problems - sort of like if the throttle valve is at rest, it should be completely shut. After cleaning both thoroughly, i gave both a final blast down their throats and realised now BOTH dribbled freely out the other end!! So the carbon build up must've been so severe that it formed a seal between the butterfly and the wall of the throat, impairing the full range of the butterfly.

Both throttle bodies seemed to have a loose rattly sound when tapped on the black cover...

What is the mileage on your cars when this issue started?

I'll see how the relearns go in about 2hrs time.
Prior to cleaning throttle bodies, my idle kept sagging to 500rpm at the lights also.

P's_Z

it mustve been a lot of carbon then!!!

Well, so far both our cars are issue free after the throttle body clean up

I had about 10K miles when the problem started, carlitos i think 20K (not really sure, but ill let him chime in if that wasnt his mileage). From what the dealer told me, they recommended to do the TB clean up once a year.

Good to hear you also did this, hoping this finally solves your issue since i know youve had this problem for a while. Keep us updated with results my friend!!!

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Zeta

juld0zer

i'd say once a year would be too frequent, maybe every 1.5-2 years if it's a daily. But that depends on how it's driven, oil choice (and whether or not a catch can is used), and heaps of other factors.

i did successfully perform the trifecta of relearns last night but now the throttle response/pedal response seems to have dulled. in gear acceleration isn't as jerky as before but i kinda liked the jerky pokey feeling whenever i tapped the pedal. i'll give it 1.5-2 weeks because that's how long it usually takes before the issue resurfaces after each attempt to resolve it.

so far i've replaced:
- both cam sensors
- gas pedal
- map sensor
- left VVT solenoid
- all VVT cover seals, 3 rings on each VVT cover and the gauze filter on each bank for VVT.

The VVT related parts did resolve the engine's lack of enthusiasm above 4000rpm, and that can still be felt today so i'm happy with that. The rest... i guess was all in vain.