Jump to content
View in the app

A better way to browse. Learn more.

300ZX Owners Club

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Well after spending the weekend looking for a vacuum leak and being unable to find one and playing around with the maf to no effect a new symptom cropped up today.

 

The car really struggles to accelerate now in any gear, at any speed, at any revs. When i brake the engine cuts out, and when cold the oil pressure is nearly off the top of the guage. Am i right in thinking that this is a definate sign of PCV valve failure? Im crap when it comes to mechanics and so are my local garages, wanna make sure that if i am going to attempt to replace something its the right part. Looking at the how to guides its pretty straight forward, but just a pain.

Featured Replies

Well after spending the weekend looking for a vacuum leak and being unable to find one and playing around with the maf to no effect a new symptom cropped up today.

 

The car really struggles to accelerate now in any gear, at any speed, at any revs. When i brake the engine cuts out, and when cold the oil pressure is nearly off the top of the guage. Am i right in thinking that this is a definate sign of PCV valve failure? Im crap when it comes to mechanics and so are my local garages, wanna make sure that if i am going to attempt to replace something its the right part. Looking at the how to guides its pretty straight forward, but just a pain.

 

zeds are pain but well worth it .. good luck with finding problem or tow it to zedworld mate ..

Timing? (the oil pressure is high when cold, and the stock gauge is inaccurate too) Have you had any work done to it recently?

  • Author

havent had any engine based work done to it in about a year. only brakes and wheel based repairs.

 

Its hard to tell if there is white smoke with the temps been so cold all the time but once the engine warms up the steamy exhaust gas goes away, and the engine still runs like shite. Feels like its just constantly flooded with fuel no matter what speed, but its the stalling with the braking thats leading me to the pcv valves, or do other parts cause that too?

have you tried unpluggin the coilpacks one at a time and seeing if any of them don't make a difference? you should hear the engine note change as you unplug each one.... maybe it's running on 5 cylinders, might be worth cleaning all the connectors up too matey.... also check the connector on the temp sensor (on the top of the two sloid water pipes at the front of the engine) also check mf connections (under the nose panel) HTH... let us know how you get on...

  • Author

checked the maf and maf connection the other day, the look like new. Okies ill give them a check, so i just unplug the coil packs whilst the engine is running and listen for a note change? and if there isnt a note change that one isnt working? (yes i am an idiot when it comes to this kinda thing :-P)

Try running the engine with the maf disconnected, although it will not run above 2.5k revs it will run in a default mode, what this will do though is take away any issues with the maf and any complications caused by air/boost leaks.

 

So use this as a test and see how the engine runs, if it runs markedly different it points to air / maf issues, if it makes little difference then it has at least eliminated the maf and air leaks as the issue, let is know how you get on.

 

Jeff

  • Author

Test Results:

 

Last night, Air temp -1c,

engine cold: 1250 revs (stable),

engine warm: (300-1200 revs on idle) car stalling, revs all over the place, very poor acceleration (compareable to a 1l corsa).

 

Today, Air temp 7c,

engine cold: 1250 revs (stable)

engine warm: 700 revs, after 10-15 mins the problems begin:

 

Revs drop to 300, car revs itself to 1250, revs drop to 400, rise to 800 then level at 700 then stable. Repeats every 1-2 minutes.

 

(Note: if the demister is on the revs are perfectly stable at 1000 revs. Air con belt was removed last year due to broken air con pulley)

 

Without MAF:

 

Enging revs perfectly stable at 1000 revs, never changes. But when i push the brake pedal the revs drop to 800 then rocket to nearly 2k revs and flucuate until settling at 1000 revs again. (cant test acceleration problems that appear after 3.5k revs for obvious reasons.)

 

Is this info of any use?

could it be your idle controll valve? have u tried cleaning it out thin there is a how to on here somewhere ? u take the hose off that draws air int to the valve the spray wd40 in the pipe while engine is runnig this cleans it short term i think!, or take it off & soak in some meths or other cleaning fluid?

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

Recently Browsing 0

  • No registered users viewing this page.

Important Information

Terms of Use

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.