Z does not accelerate

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

Update here:

Cleaning throttle bodies

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Zeta

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.

P's_Z

Wooow! Youve definitely had it bad man

Believe me, im rooting for you to finally get this thing fixed! congrats on not quitting and selling/trading your Z because of all of this

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Zeta

juld0zer

mate, i'll be honest - i'm close to giving up. i've ventured into a lot of unchartered territory and despite all my hours of datalogging and troubleshooting, almost $1000 in parts and many up's and down's it's really frustrating to have the problem resurface within a fortnight.

it sucks being in a country where there are no Z specialists or Nissan specialists who are knowledgeable enough to know these cars inside and out. dont get me started on dealership staff attitudes... the lack of support here is beyond belief. they do anything to avoid dealing with the problem

P's_Z

And i thought i had it bad

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Zeta

carlitos_370z

Damn dude sorry to hear about the problem that your Z is having... well my Z like Pedro said... at the moment when the problem starts have around 20k miles. Saying that i see that you clean your throttles and a few things more. Well one of the things that i dont see that you do is calibrating them... Thats one of the things that i think that resolve our problems... Cause the mechanic that work my car in Service told me that one of the throttles open 100% and the other 50% or least causing that the car go into limp mode and not accelerate like they have to do. After they do that i dont have any issue on my Z... The price for that labor i think is arround $40-$60 for each one but i dont remember the correct price. Check that and let us know if that work

juld0zer

oh, nah i just didnt mention the recalibration/relearns because it's assumed that the 3 relearns (gas pedal rest position, throttle body closed position and idle air volume) must be performed successfully if the gas pedal, throttle bodies or even the intakes are disconnected/replaced/renewed.

i took a big risk by disconnecting both throttle bodies from the harness AND manually opening the flap and jamming it open with a broom handle while i cleaned the carbon. luckily i didnt suffer the same fate as a lot of G37 owners where they were unable to successfully perform the idle air volume relearn procedure. my idle was high and fluctuating immediately after i reconnected everything (this was before i did the relearns, because the gas pedal & throttle body relearns can only be done on a cold engine with coolant temp below 25*c). the car still drove reasonably, SRM worked etc. The only thing wrong was the high idle.

Your mechanic's theory sounds logical. i think someone here also mentioned something similar, like both throttle bodies must be in perfect sync. I assume they mean the output voltage of the throttle position sensors must be identical. I have datalogged my TPS and they are within 0.02v of each other. I never noticed anything different in the logs leading up to a limpy lag episode so thats why i ruled out throttle bodies until now. I know on the R35 they can do a power balance procedure which basically syncs both banks, not sure if this is available in Consult3 for Z34.