MPG in clod weather

[SardarQ]

My follow NICO brothers.....

Why is it that in cold weather (15F)... my MPG drops from an average of 24-25 MPG to 21-22 MPG?

97Q 88K.

Some history..

The MIL came on twice... both times it was the right bank O2 sensor... so I decided on the second trip .. it was time to replace. I changed it out with NTK O2 sensor (stock = bosch). My MPG ever since than has been lower. But its also been a lot colder since then ... so what is it about the cold weather that lowers MPG... or is it my sensor. But the sensor readings are good.. and no more MIL.

BTW.... Bosch O2 sensor suck BIG time The old NGK NTK sensors in the old Q's 94-96 worked longer and much better... got 170k on a 94Q without changing them

ANyway... thoughts on the MPG would be helpful. BTW.. Bosch O2 sensors SUCK BIG TIME.

[Q451990]

BTW.. Bosch O2 sensors SUCK BIG TIME.

Both of my 90's had Bosch JAPAN O2 sensors... so I'm not sure when the changeover to your preferred NTK took place.

MPG should improve in cold weather... at least after the car has warmed up fully. Reduced spark knock should allow the ECU to lean out the fuel mixture, plus less load from the A/C compressor. Now, if the car isn't warming up fully and going into closed loop (e.g. bad thermostat) then it may be a different story.

Heath

[duck3986]

One major reason is that tire air pressure drops as much as one PSI per 10 degrees drob in temp. So you may be running on tires that are well underinflated.

[qship96]

and lower quality oxygenated gasoline

[maxnix]

Longer idling period for warm-up.

Idling MPG = 0

[SardarQ]

Thanks for the replies... I do warm the car for about 30 seconds to 1 minute. Like Max. said... idling = 0MPG. HOwever, until the car is fully warmed up, it doesn't drop into the final gear. So 30 MPH = 2000 RPM, until its warmed up.

The funny thing is that when I warm it longer (3-5 minutes=0 MPG), I get better overall mileage??? Go figure. Why would that be?

BTW - I could be mistaken about the NGK/NTK O2, I thought the old Q's had NTK sensors. When I was looking them up on the internet, many places showed the stock sensor for 95/96Q as the NTK. 97-01 was listed as Bosch. I have a 97 Max whose same sensor went bad at 60K miles!!! I'm not impressed with these sensors.

[Q45tech]

Different design in O2 sensors for OBD1 vs OBD2....96 and later are lucky to last 60k....................last as in work as new at high efficiency.

Also oxygenated fuels throw the whole design off and skew the mixture towards excessive richness by 2.7-3.5% as the ecu thinks the excessive oxygen is from a too lean mixture and thus adds more and more and more fuel to try to reduce the oxygen in the exhaust.

The up to 5% lower BTU per gallon of oxygenated means you have to burn 5% more per mile to yield the same power.

A few other blending changes make the whole mess 10% worse also any water in fuel is even more dramatic.

Cold tires are far away from their optimum friction point and cold rear diff fluid is terrible power waster.

Those of you who live where it gets below 40F would benefit in winter from Redline 75w90 rear diff fluid..........probably would pay for itself in one winters fuel cost savings [price of fluid] especially if your cold drive distances are 10 miles as it takes 10-20 miles at speed to warm diff up.Older Q are worse since the fins on diff provide extra cooling.http://www.drivetrain.com/redlinedifflube.html

[Q45tech]

The graph shows how bad diffs are at low speeds vs 60 mph and how you can gain up to 2-3% in rear power at launch - low speeds just by changing to a full synthetic rear diff fluid!

If you save 15 gallons of gasoline per 15,000 miles that's $35-$50 per year.

I'll bet changing diff to synthetic will reduce cold temperature ET by at least 0.1 second like adding 10 HP to engine.

[Q451990]

I wonder how Redline and Mobil 1 compare regarding cold viscosity?? I just put a fresh batch of it in both Q's within the last month...

Heath

[elwesso]

good info tech... Ill switch over to redline.....

[Q45tech]

Now that gasoline is more expensive, lots of things make even more sense now.Synthetic fluids [especially those that can last a year or 18 months], marginal thermostats, and O2 sensor replacements. When you use 900 gallons........5% improvements [0.9 mpg] are now very significant ...........

[qship96]

I can vouch for Redline products- used exclusivly in my engine, transmission,differential,and power steering system for the last 70,000 miles{first 100,000 I used mobil 1 products for these}

[qship96]

forgot to add this tidbit for all- locally redline motor oil,transmission oil,and gear oil is selling for about $9.00 per quart- have had great fast turnaround ordering from http://WWW.MYOILSHOP.COM for 7.00 per qt,no sales tax added,and cheap shipping when ordered in bulk{24 qt oil,15qt transmission,2 qt gearoil} which fill your annual needs to properly feed your Q!