Notices
2003-2009 Nissan 350Z

Significant decrease in MPG - root cause?

Thread Tools
 
Search this Thread
 
Old 01-22-2008, 06:31 AM
  #21  
Britx
Registered User
iTrader: (2)
 
Britx's Avatar
 
Join Date: Aug 2007
Location: houston
Posts: 65
Likes: 0
Received 0 Likes on 0 Posts
Default

^^^
No. Actually you should do that, but it does factor into total average mpg. I have always let my car warm up. My basic rule of thumb is not to let the oil pressure get over 90psi in the morning and let it idle for about 5 min. or more before driving. I actually use the oil pressure guage as my tach.
Old 01-22-2008, 07:27 AM
  #22  
maxpowers
Registered User
iTrader: (3)
 
maxpowers's Avatar
 
Join Date: Aug 2003
Location: Toronto, Canada
Posts: 1,090
Likes: 0
Received 0 Likes on 0 Posts
Default

I would agree that its the colder temps. You burn a lot more fuel at startup when the vehicle is in sub zero temps (remember pulling out the choke in the old days).
Old 01-22-2008, 07:44 AM
  #23  
sno
New Member
iTrader: (4)
 
sno's Avatar
 
Join Date: Apr 2007
Location: Portland, OR
Posts: 3,397
Likes: 0
Received 1 Like on 1 Post
Default

Winter blend gas is the biggest problem, relating to overall mpg. I saw, at least, a 75 mile decrease in total miles for a full tank. That, and idling (or warming up) the car in the cold mornings burns gas without any mileage.
Old 01-22-2008, 11:54 AM
  #24  
Silkk
Registered User
Thread Starter
iTrader: (11)
 
Silkk's Avatar
 
Join Date: Aug 2005
Location: Harrisburg, PA
Posts: 2,014
Likes: 0
Received 0 Likes on 0 Posts
Default

I thought it may be the weather! Glad you guys confirmed...

The car definitely doesn't like to start on cold mornings - my garage isn't heated. But hey, at least I have a garage, I suppose.

Still doing the preventive maintenance though as necessary... Thanks again guys.
Old 01-22-2008, 12:16 PM
  #25  
meaj82
Registered User
iTrader: (31)
 
meaj82's Avatar
 
Join Date: Jul 2006
Location: Houston,Tx
Posts: 676
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by sno
Winter blend gas is the biggest problem, relating to overall mpg. I saw, at least, a 75 mile decrease in total miles for a full tank. That, and idling (or warming up) the car in the cold mornings burns gas without any mileage.

+1 I have been noticing that this past month. I have been going through my tank a lot more faster than ususal.
Old 01-22-2008, 12:53 PM
  #26  
Gooey
New Member
iTrader: (18)
 
Gooey's Avatar
 
Join Date: Dec 2005
Location: MD
Posts: 2,057
Likes: 0
Received 0 Likes on 0 Posts
Default

Man Im lucky to get 17mph....I usually average somewhere around 15-16mpg. Damn my lead foot.
Old 01-22-2008, 01:40 PM
  #27  
whitetrack
New Member
iTrader: (1)
 
whitetrack's Avatar
 
Join Date: Feb 2003
Location: Connecticut
Posts: 374
Received 3 Likes on 2 Posts
Default

Ethenol blend reduces MPG. That happens to all my cars, not just the Z. Plus a little of what everyone else mentioned.
Old 01-22-2008, 01:44 PM
  #28  
iStan
ZR
iTrader: (29)
 
iStan's Avatar
 
Join Date: Apr 2006
Location: Las Vegas
Posts: 6,444
Likes: 0
Received 3 Likes on 2 Posts
Default

Originally Posted by Gooey
Man Im lucky to get 17mph....I usually average somewhere around 15-16mpg. Damn my lead foot.
14.3 on the streets. Damn you boost and 275 Tires Oh and warm up time kinda kills it to.
Old 01-22-2008, 01:45 PM
  #29  
r_seng
Registered User
iTrader: (9)
 
r_seng's Avatar
 
Join Date: Apr 2007
Location: SoCal 626
Posts: 2,818
Likes: 0
Received 0 Likes on 0 Posts
Default

as i said before, its the weather, my over all mpg per fill-up has tanked about 06 - 70 miles less.
Old 01-22-2008, 03:33 PM
  #30  
ZTMYDUST
Registered User
iTrader: (13)
 
ZTMYDUST's Avatar
 
Join Date: Apr 2007
Location: Upstate, NY
Posts: 49
Likes: 0
Received 0 Likes on 0 Posts
Default

I didn't notice a change in mpg with my Z when the temps dropped here in Western, NY but i took my Z off the road in November (wishes he was from PA, atleast they don't use materials on the road that lead to rust ie:salt).
Old 01-22-2008, 03:48 PM
  #31  
iceburns288
Registered User
iTrader: (3)
 
iceburns288's Avatar
 
Join Date: May 2006
Location: UIllinois
Posts: 1,188
Likes: 0
Received 0 Likes on 0 Posts
Default

It may also be due to the fact you are using the heater more due to the cold- this would decrease your mileage.
Old 01-22-2008, 03:59 PM
  #32  
DavesZ#3
350Z-holic
iTrader: (26)
 
DavesZ#3's Avatar
 
Join Date: Jul 2003
Location: Louisiana
Posts: 15,887
Likes: 0
Received 23 Likes on 18 Posts
Default

Originally Posted by bailey bill
You will always get lower mileage in colder weather.

1) The ECU sets a richer A/F as temps drop

2) Winter blend gasolines also result in increased fuel usage.

bill
I thought the mix was richened when the temperatures get hot to help prevent detonation, not the other way around.
Old 01-22-2008, 04:19 PM
  #33  
Silkk
Registered User
Thread Starter
iTrader: (11)
 
Silkk's Avatar
 
Join Date: Aug 2005
Location: Harrisburg, PA
Posts: 2,014
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by ZTMYDUST
(wishes he was from PA, atleast they don't use materials on the road that lead to rust ie:salt).
I'm pretty sure our roads get salted also, so no big advantage to moving here. Plus our roads are $hit...
Old 01-22-2008, 04:30 PM
  #34  
sk26dett
Registered User
iTrader: (16)
 
sk26dett's Avatar
 
Join Date: Nov 2006
Location: G-ville/Pembroke pines, FL
Posts: 791
Likes: 0
Received 1 Like on 1 Post
Default

On a side note, The digital gauge is actually pretty good (to my surprise). I calculated my MPG manually and it was within .1 of what the gauge said.

The speedometer on the other hand isn't as accurate. At low speeds like below 50 its almost dead on. Between 70-90 mph it reads between 2-3 mph high. Over 100 it's more than 4-5 mph high, and increases as you go faster. (All assuming that the GPS speedometer in my head unit is accurate)
Old 01-22-2008, 05:57 PM
  #35  
MA4
Registered User
 
MA4's Avatar
 
Join Date: Jan 2003
Location: pa
Posts: 376
Likes: 0
Received 0 Likes on 0 Posts
Default

I was getting bad fuel economy...turns out my pop-charger was filfthy...I cleaned it and oiled it up, now MPGs are back to normal.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
bcoffee20
Zs & Gs For Sale
5
11-19-2015 06:39 PM
kyin
New Owners
12
10-15-2015 05:54 AM
nanotech
Exhaust
6
10-02-2015 05:02 AM
codek
Intake Exhaust
11
09-28-2015 03:03 AM
FromGtoZ
Intake Exhaust
2
09-20-2015 03:41 PM



Quick Reply: Significant decrease in MPG - root cause?



All times are GMT -8. The time now is 03:28 PM.