2008 idle issue
Hey guys, new to this forum stuff, but I need help. Really hoping someone can help. I picked up a 2008 350z 2 months ago with 55k miles and it has had a idle issue since i bought it.. it idles at around 500-600 and is always within that Parameter but every second. It like breathes every second. I didnt think it was going to be such a big problem but now I seem to realize that maybe thats why they sold it, who knows. I tried everything possible, cleaned TB’s, cleaned MAF, cleaned intakes, Connected everything tightly, disconnected battery, attempted to do all the relearns, spark plug change with the OEM spark plugs from Nissan, and nothing seems to fix it. Hopefully you guys can help me, thanks!

 

Have you done a vacuum leak test? You can borrow a gauge from AutoZone etc.

 

No i have not, never done that before, I will give that a try and hopefully i find it.. what should i look out for when i plug it in? Decrease in pressure? do u think it would help plugging in a OBD reader?

 

Good question but no, all you have to do is borrow a vacuum gauge. Remove the black shroud over the intake manifold and remove any small hose from the intake manifold and plug in your gauge with engine warm and running. The vacuum reading should be steady. In a perfect world around -22 psi or lower. (This is typical for engines that surge at idle- high then low, may not be your case.)

If it varies wildly it's likely you have an intake leak somewhere. Either in manifold gaskets or towards the filter. GL!

 

okay, so plug in gauge to the hoses from intake manifold side, while engine is running and warm, i will try that. Wouldnt the engine run worse when I disconnect a hose? Wont really matter because I’ll have the gauge plugged in tho right. Ill let u know how this works! Does ur Z idle perfectly without any surging what so ever? Mine is a little better but still does it at random stop lights

 

Does the idle increase with A/C on?

 

yes, it idles right below 1000 rpm with the AC on just how i imagined it, no surging.

 

That would be the vacuum leak you think?

 

I doubt it. As I stated above surging idle (changing more than 150rpms with foot off gas) up and down is. Still, as cheap as it is to test why not? Rule it out.
Before that- if you can't remember the last time you changed your air filter, do that 1st then report back. GL!

 

i cleaned the k&n filters that the previous owner had and re installed them, those filters shouldnt be the issue i dont think, i will do the vacuum leak test and come back!

 

My 350z does the same thing(tuned with bigger injectors) i just keep the a/c on all the time

 

idk why i feel like i dont get enough power with the AC and the clutch feels different too, like it doesnt engage properly.