Bad MPG Completely Stock

[chigga311]

Hey,
I'm a DISI and Mazda noob.
I do know about Nissan Ecu's & Engine's.

I just bought a 2008 MS3 sport with 13,500 miles on it.
It was owned by a 37 Yr old.
Still has stock tires on it.
I don't think the car was beat on or modified in anyway.
When I got it, it was 100% Stock.

I drove it 4hrs from St. Pete, FL to Ft. Lauderdale and noticed the gas mileage was bad.
Din't think much of it since I was getting on it some.

Now driving it daily and babying it, I'm getting About 10 MPG.
I did notice it running rich. The tailpipe has a lot of soot in it and the back of the car is dirty.

I tried searching and could not find anyone with as bad gas mileage as me 100% Stock.
If you know of any threads please direct me to them.

This weekend I'm going to:
Seafoam the engine
Clean the MAF
Check the Air filter
Change the Oil
Check the Spark Plugs
And....... DONATE and download the FSM
Then check the parameters on the O2 sensor
Maybe check the EGR valve and pipe.

Any suggestions??????

BTW I have NO CEL at the moment.....

Thanks in advance

P.s. I'm going to try to make it to the Velocity Factor meet in Boca on Sat.

 

[Domino81]

I'd check fuel pumps... at least I'd start there.

 

[chigga311]

Fuel pumps?
Like if they are pumping too much.pressure?

Does anyone have the password to the Megaupload FSM file?

 

[njaremka]

are you 100% sure you are only getting 10mpg? with a 13-14 gallon tank, that means you're only getting 120 miles before you have to stop for gas!?

 

[Domino81]

Too little fuel pressure. Fuel pools. It's an idea. But may not be sound.

I thought it was a 15 gallon tank.

 

[njaremka]

Too little fuel pressure. Fuel pools. It's an idea. But may not be sound.

I thought it was a 15 gallon tank.

even at 15 gallons, 10mpg would make the light come on at 130 miles. that means being able to watch the fuel gauge drop as you drive.

 

[In4am0sPuN]

Im also in the same boat. Bought my 08 ms3 gt about a month ago bone stock w/ 40k , with mixed driving im getting about 260 miles a tank. my msp easily gave me 320-350 to tank.

 

[b e z]

^ thats not the same as the op. Your 260 is normal for speed 3's. Last time i tracked mine thats about what i got. 10mpg would be drastically different.

 

[meicalnissyen]

Hey,
I'm a DISI and Mazda noob.
I do know about Nissan Ecu's & Engine's.

I just bought a 2008 MS3 sport with 13,500 miles on it.
It was owned by a 37 Yr old.
Still has stock tires on it.
I don't think the car was beat on or modified in anyway.
When I got it, it was 100% Stock.

I drove it 4hrs from St. Pete, FL to Ft. Lauderdale and noticed the gas mileage was bad.
Din't think much of it since I was getting on it some.

Now driving it daily and babying it, I'm getting About 10 MPG.
I did notice it running rich. The tailpipe has a lot of soot in it and the back of the car is dirty.

I tried searching and could not find anyone with as bad gas mileage as me 100% Stock.
If you know of any threads please direct me to them.

This weekend I'm going to:
Seafoam the engine
Clean the MAF
Check the Air filter
Change the Oil
Check the Spark Plugs
And....... DONATE and download the FSM
Then check the parameters on the O2 sensor
Maybe check the EGR valve and pipe.

Any suggestions??????

BTW I have NO CEL at the moment.....

Thanks in advance

P.s. I'm going to try to make it to the Velocity Factor meet in Boca on Sat.

just replace the air filter with a cai
toss in fresh plugs,
clean the maf

should do it

 

[Jdm_Mica]

^^sounds like a simple tune up may help. Tire pressure??

 

[chigga311]

OK, So I started opening up the car and driving her hard for short periods.
The car started to get better mileage.
It seems I guess its just needed to be played with.

I Changed the Oil, Air Filter and Cleaned the MAF.
Then I reset the ECU.
And Rotated tires.
The guy never did it, so the Front tires are original but almost on their way out.

So far I'm getting about 18mpg reg/boostin a bit.
I've also noticed that I've been driving MUCH faster than I thought.
I've been cruisin at like 90 and I didn't think so.

I'm going to Seafoam the car and then see what that does.

I'm looking to either get a AP or a SRI/CAI soon.
I'm more inclined to get the AP so I can monitor the engine and do a couple logs.
Plus I want to disconnect my EGR valve, so I can use the AP to get rid of the CEL.
But the SRI/CAI will give me better flow ~ better mpg ~ hopefully some more sound so i don't drive so fast lol.

And yeah... I could Literally watch the Gas gauge drop. (not that i was paying attention at the time)
From my little 10 mile boost to school It dropped a 1/4 tank.

 

[b e z]

Glad to hear it is getting back to normal.

 

[Russm]

Back to normal, my 08 with a MSCAI and MSCBE driven hard as you can on public streets and interstate will return 24-26 MPG and driven easy 30 MPG and I have 77K on it, I'd say you have some other issues unless your driving on a race track full speed all the time!

 

[b e z]

Glad to hear it is getting back to normal.

Definetly not normal but a hell of a lot better than 10. When i look at my dash hawk it says my average is like 29 so i imagine that is off by like 4, seems that in the mid 20s is good to go.

 

[meicalnissyen]

^^sounds like a simple tune up may help. Tire pressure??

yes, big fan of it

 

[meicalnissyen]

cai will give better flow.

which the maf will report to the ecu

which will direct the injectors to add fuel
less mpg

OK, So I started opening up the car and driving her hard for short periods.
The car started to get better mileage.
It seems I guess its just needed to be played with.

I Changed the Oil, Air Filter and Cleaned the MAF.
Then I reset the ECU.
And Rotated tires.
The guy never did it, so the Front tires are original but almost on their way out.

So far I'm getting about 18mpg reg/boostin a bit.
I've also noticed that I've been driving MUCH faster than I thought.
I've been cruisin at like 90 and I didn't think so.

I'm going to Seafoam the car and then see what that does.

I'm looking to either get a AP or a SRI/CAI soon.
I'm more inclined to get the AP so I can monitor the engine and do a couple logs.
Plus I want to disconnect my EGR valve, so I can use the AP to get rid of the CEL.
But the SRI/CAI will give me better flow ~ better mpg ~ hopefully some more sound so i don't drive so fast lol.

And yeah... I could Literally watch the Gas gauge drop. (not that i was paying attention at the time)
From my little 10 mile boost to school It dropped a 1/4 tank.

 

[chigga311]

Just filed up.yesterday. 10.75 gal
I got 18.34 mpg (calculated) , 197.... Miles with the gas light on.

I hope the seafoam helps out.
I was only boostin a little bit.

I think ok going to clean off our change the plugs.
Maybe that could be the problem.
I do notice a bit of a drop in power at about 20% guessing

A CAI OR SRI would get better mpg, due to less restriction.
The only.way you could get worse mpg is if the Maf housing is not not diameter.

Btw is the Cobb SRI stock diameter?
I know the SURE AEROS is 2.75 - 2.50".
70.5 - 64.1mm average of about 67.3mm, but I don't know where the Maf.is.placed.
Or how the transition affects the reading.

 

[bbrich57]

From what I've read, the Speeds run a bit rich and therefore build up carbon pretty quickly in the EGR system.
That might be worth a look. If the EGR is clogged and not working, or the tube is clogged, that could just be your whole problem. If it's clogged badly, Seafoaming thew car will do nothing for that. You will have to remove it from the car and completely clean it out.
Just my .02.

 

[Wurf]

How does less restriction give you better mileage in a fuel injected car using a MAF system?
If the air filter is dirty, you get less performance from the car - that's it.
Bad mileage is bad or dirty sensors IMO.


Cleaning the MAF sensor would be the first thing I'd do, but I'd toss the factory intake system for SRI or CAI while I was at it.

 

[njaremka]

How does less restriction give you better mileage in a fuel injected car using a MAF system?

because fuel usage is also load based. if the engine is working harder, the ecu will inject more fuel. a less restrictive intake and/or exhaust will let your engine work easier, a decrease in load, so it needs less fuel to achieve a similar power output. i know its a different car, but my protege went from high 20's mpg up to low 30's mpg when i changed out the intake and exhaust for intake/header/cat-back.