350z wn

Hello everybody

Please help from z expert owners 🙏🙏

Rpm dropping/ stumbling at 1k and around 2000k

https://youtube.com/shorts/NIlHb-Qcj_o?feature=share

Sorry for long topic 🙏🙏

I have an issue ongoing almost for one year now with my 350Z 2008 VQ35HR automatic 151000 Km 100% stock, which is the rpm is dropping / hesitating / stumbling just for one second at 1k RPM and around 1800 RPM (( only when it’s warmed with slow acceleration when starting to movie from signal or stop so I can feel it while I am driving And absolutely perfect when it’s cold just for first 5 to 10 mins driving )) without cel or any error codes .

it’s Like the car about to switch off but it’s not , just need to press little harder gas to avoid the hesitation .

This is happening while I am driving , P or N , so I don’t believe it’s transmission issue .

No any lights or error codes at all

Note

oil pressure is cold start around 75 and after warming up around 10-12 , I know maybe gallery gasket needs replace too

This issue gone twice before , both after I replace all parts above and no good

First time : I went to mechanic who was working in Nissan dealer just trying to figure out , He just cleaned sensors and under the air intakes manifolds ( the black box on the engine) ,then put tap on the very little cracked piece in air intakes pipe and the problem totally solved , I kept asking The mechanic what is the problem was and he has no answer ( just by luck ).

After few month The alternator gone and needed to be replaced, while replacing the battery has been disconnected for night , and I got the issue back when I received the car .

Second time : after researching I decided to do exhaust valve control timing relearn which is keeping the RPM between 1800 - 2k for 20 seconds then the problem almost gone and not irritating me like before at all .

Replaced
Spark plugs, throttle bodies , cam shift sensors, maf cleaned and air filters .

No coolant, oil leak outside the engine , compression test is fine as per Nissan dealer

It’s fine to replace the gallery gaskets but I want to confirm that is the correct time .

Now I confused , what I should check ?!

-Gallery gaskets
-variable exhaust valve, VVT
-vacuum leak

what do you think please

Really sorry and I appreciate any help or thoughts

here is the video

icer5160

iTrader: (4)

The oil gallery gasket failure is very concerning, this can cause premature wear and failure of your entire engine! (bottom end bearings and even top end valve train). Poor oil pressure due to a failed gallery gasket may also cause VVT issues since this system dependent on oil pressure. If it was my Z, I would get the gallery gasket fixed first and troubleshoot from there. Common codes are P0011 & P0021. This is a serious repair and I would recommend having a Nissan experienced shop handle the work. If you plan to keep this car a long time, I highly recommend getting a complete timing kit done + water pump. Make sure the shop checks your oil pick-up + pan for any bits of blown out gasket material. Expect a large bill for this amount of work, but still worth it in the long run if you love the car and plan to keep it.

If fixing the gallery gasket does not resolve the issue, then the next items worth checking are crank + cam sensors. This can also be caused by your VTC assembly failing (big money to replace). VTC assembly failures will usually throw P0011/P0012.

If a mechanic previously discovered some cracks in your intake tubes (patched with tape), then you could have rogue air (unmetered air) entering your engine, this will also cause poor running conditions. Tape is not a long term solution, I would closely inspect your intake tubes for leaks/cracks and replace them if you haven't already. There are plenty of aftermarket options that are probably cheaper than trying to purchase new OEM parts.

Cheers!
-Icer

350z wn

Omg 😳

so all solutions will pay a lot

I am just wondering that has been fixed before when the mechanic clean the manifolds

I understand that it’s mandatory to replace the gallery gaskets but I am sure there is another reason too causing this issue because it’s obviously fixed before when the mechanic cleaned the manifolds

I believe too that something related with part needed to replace because I got back the issue when the battery has been unplugged for whole night

I will replace the gallery gaskets but I want to save some good money before since I will replace the vvt, water pump, thermostat at same time due I will open the front engine already

i am getting the rpm dropping two times on specific rpms 1000k and 1800k

I think if oil pressure is the main reason so I will get this rpm dropping not at specific rpms special I am not 0 psi I still getting around 10 after warming idle

also I need to consider that the weather here is extremely hot in dubai like something 40 plus degrees

I really appreciate your consideration and please advise me , I am not bad in mechanic but for sure I have no experience with vqs and I am sure most of you here in my350z better than me 😂😂😂

350z wn

Thank you so much for your reply

omg I am dead 😂😂

I totally believe that the oil gallery gasket needs to replace and i Already planned to replace asap

but I believe that there is other reason too causing my issue because why it was fixed when the mechanic kept cleaning the manifolds

I believe not sure this rpm dropping caused by worn part like sensors

this rpm is dropping at specific rpms 1k and 1800k I think if the main reason is the gallery gaskets so the engine weakness will be presenting everything now and then not only at specific rpms

I did not face any issues when the mechanic cleaned the manifolds

the possibilities that I see causing this issue

maybe under manifolds leaks , or some sensors and I have read a lot of people fixed the same exact issue after replacing exhaust valve solenoid

I know it might be hard to fix it even after I replace the gallery gaskets and I have seen a lot of people just fed up and sold out their car without solving the issue

I am not bad in mechanical but for sure there are here a lot of people experience more than me with vqs 😂😂

so I am really sorry

can you share with me the exact parts name or pic of the parts that you want me to check I will really appreciate that

I have searched about these parts that u mentioned but it’s showing me many different pics

350z wn

I have now thing that I cannot understand

The car is being better with vacuum leak?!!!

finally I got experienced mechanic

he unplugged the passenger side breathing hose same that I marked in the pic, then the problem gone ?!!







so how is the car running better with vacuum leak ?!!!!

as the mechanic he said that ,since the problem gone when I have that leak then the car might be poor running at high rev and that mean I have vacuum leak somewhere else ,saying that when we plug the hose properly the vacuum pressure effects that unknown somewhere leak and causing the rpm stumbling

any idea about that , Any common problems ?

any other common leakage spots like plenum gasket , hoses or valve cover gasket

Do I have leakage somewhere or blockage

350z wn

Hello guys

Finally I got the direct key of my issue like how get it and remove it

I did these 4 tries to confirm what all of you said

These results confirmed by driving long distance with every try just to confirm the results

1 - disconnected both sides = issue gone

2 - disconnected right side only = issue gone

3 - disconnected left side = issue gone

4 - plugged both sides = got the issue back

Really want to confirm before I waste more and more money

I know the gallery gaskets needs to replaced but for now ,This sputtering will be fixed after I replace this vtc or the oil pressure will be the main issue? , I know and saw in groups some guys their oil pressure is less that 8 psi and they don’t have this sputtering


if the replacement will fix , do I need to replace both sides full covers assembly or just the variable valve timing solenoid


is there any possibility of any other warn parts effecting the vtc functions like bad pcv valve or others