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Okay, so last year my car would turn off on me after I put it in neutral while driving. I figured that it was because it idles too low when in neutral so I messed with the gas pedal sensor a bit... I got it to idle at a higher RPM but only when in gear. Anyway, after swapping out my CAI filter, and seafoaming the Z twice, it would only turn off on me very rarely.
This year, I replaced my throttle body and did the gas pedal relearning thing or whatever it's called. Now it idles perfectly when in neutral but I feel like I idle way too high when driving.
For example, I'll be in 4th gear, going around 33 MPH and idling at 2k RPM. Is that high or what? At 45 MPH, I'm in 5th, idling just above 2k. I like to keep it at 2k RPM when cruising so I end up being in a gear higher than what I feel like I should be in. In neutral, at normal temperature, I'm idling at around 500-650.
What do you guys think? Am I idling too high when driving or is it just me? Any ideas on what I can do to fix this? Any suggestions are appreciated and any comments making fun of me are also welcomed.
If you are in gear at a certain speed, you are not idling. The only thing that would affect what you are describing is your gear ratio. I think it is all in your head lol.
I agree it's all in your head you are only idle when in neutral or if your holding down the clutch.
If your going down a hill in 2nd gear going 25mph you might be at 5000 rpm as the engine works to slow you down, going back up the hill at the same 25mph in 2nd gear you might be at 3000rpm...
In your example thats just the rpm the engine stays at to maintain the speed in your selected gear.
It has nothing to do with your idle, and everything to do with gearing and the transmission.
If your going down a hill in 2nd gear going 25mph you might be at 5000 rpm as the engine works to slow you down, going back up the hill at the same 25mph in 2nd gear you might be at 3000rpm...
WTF
25mph in a manual is always going to be the same rpm in 2nd gear no matter that the incline/decline
25mph in a manual is always going to be the same rpm in 2nd gear no matter that the incline/decline
Im mostly used to big trucks that need to be in low gears so I dont fry the brakes but they have torque converters and automatic transmissions. So yeah bad example by me...
But the explanation is the same its got to do with the gearing of the transmission and rear axle that determines the engine RPM.
When the clutch is locked, the rear wheels are locked to the gear box which is locked to the crank shaft which IS the engine RPM, i e the wheels are locked to the engine rpm (manual transmission). A certain engine speed will always produce the same travelling speed, or vice versa, (providing you're in the same gear of course) through a series of constants (gearbox ratio, diff gear ratio, wheel diameter etc) and will not change wether you're driving in an incline, flat or decline... UNLESS your clutch is slipping, which is a whole other matter.
But to the matter, just above 2k at 45mph in 5th sounds about right. Don't worry you're fine.
When the clutch is locked, the rear wheels are locked to the gear box which is locked to the crank shaft which IS the engine RPM, i e the wheels are locked to the engine rpm (manual transmission). A certain engine speed will always produce the same travelling speed, or vice versa, (providing you're in the same gear of course) through a series of constants (gearbox ratio, diff gear ratio, wheel diameter etc) and will not change wether you're driving in an incline, flat or decline... UNLESS your clutch is slipping, which is a whole other matter.
But to the matter, just above 2k at 45mph in 5th sounds about right. Don't worry you're fine.
Thank you for your response, it's reassuring. The previous owner had one of those flash tunes from Osiris, so I'm also trying to figure out if I may have messed it up.
About 2nd or 3rd I like that motor to run... But for cruising around town probably 4th or 5th
I know what you mean that the 350z runs at a higher rpm then lots of non sports minded vehicles, on the highway at highway speeds the Z will be at 3000rpm in 6th gear going 70 (example not actual) while in a juke you might be going 70 on the highway and it will only be at 2200rpm... Its because the cars gears are set up that way.
Its most noticeable on the highway, and is something you realize especially when your Z isnt your daily driver.
My only suggestion is to up the rpm your trying to cruise around in... 3000rpm and below is your sweet spot for cruising 2000rpm is too low
Thank you for your response, it's reassuring. The previous owner had one of those flash tunes from Osiris, so I'm also trying to figure out if I may have messed it up.
Previous owner could have upgraded your gears also... If he put some 4.08s in the back just enjoy the acceleration upgrade.
About 2nd or 3rd I like that motor to run... But for cruising around town probably 4th or 5th
I know what you mean that the 350z runs at a higher rpm then lots of non sports minded vehicles, on the highway at highway speeds the Z will be at 3000rpm in 6th gear going 70 (example not actual) while in a juke you might be going 70 on the highway and it will only be at 2200rpm... Its because the cars gears are set up that way.
Its most noticeable on the highway, and is something you realize especially when your Z isnt your daily driver.
My only suggestion is to up the rpm your trying to cruise around in... 3000rpm and below is your sweet spot for cruising 2000rpm is too low
Thank you for your reply, it's greatly appreciated! I feel much better knowing this is normal.
Thank you for your reply, it's greatly appreciated! I feel much better knowing this is normal.
No probs, I actually drove my car tonight and paid attention to RPM and mph... 5th gear 43mph 2000 rpm with bald *** 245/45/18 rear tires. So yours sounds exactly the same...
04-22-2016, 05:42 PM
Idling Too High In Gear?
I agree it's all in your head you are only idle when in neutral or if your holding down the clutch. 
