High fuel consumption QX4 2001

[lockz]

Hello all,
I have a Infiniti QX4 2001 and i have very high fuel consumption. Until May 2013 consumption in city mode about 18 liters per 100 kilometers, and after may about 30-35 liters per 100 kilometers. Driving style has not changed. Check engine light is on, but it on before and showing error P1302 Ignition Signal. I was cleaning MAF sensor, vacuum tubes, air filter and throttle body, change spark plugs, but all unsuccessfully.
Anyone any idea?

[Towncivilian]

Welcome to NICO.

What is the manufacturing date of your QX4? Certain months had ignition coils prone to failure.

[lockz]

I don't know. In the automotive document there is only a year 2001. I read FAQ, but manufacturing date doesn't exist on the driver door jamb. I can provide VIN code.
In carfax in history section there is a record:
Event date ____ Location __ Odometer reading ___ Source ________________ Details 
10/05/2000 ___ NJ _______ -------------------- ___ Independent Source _____ VEHICLE MANUFACTURED AND SHIPPED TO DEALER
Is this a manufacturing date?

[lockz]

I tested ignition coil using owner manual "ENGINE CONTROL SYSTEM DTC P1130 SWIRL CONTROL VALVE CONTROL SOLENOID VALVE" and it's pass test.
Any idea?

[Chuck Tribolet]

Are you sure about that P1302 code? P1302 is not in the 2001 PF FSM.

Chuck

[Towncivilian]

I'm sure he meant P1320 IGNITION SIGNAL - just a small typo.

10/00 would be a 2001.5 model year with the revised ignition coil packs. If you provide your VIN and country, I should be able to pull it up and find the exact manufacturing date and determine which type of coils are used.

Have you tried following the diagnosis procedure starting on page EC-504 of the factory service manual to the best of your ability?

[lockz]

Chuck Tribolet
I'm sorry P1320 of course.

Towncivilian
My VIN code is "JNRDR09Y01W213741".
Yes, i followed the diagnosis procedure on page EC-504 and it tested was successfully. In previous post i made a typo it "DTC P1320 IGNITION SIGNAL" diagnosis procedure.
My ignition coils part number cyl #2-#5 22448-4W011, cyl #6 22448-8J115, cyl #1 22448-4W001.

[Buzzman]

Hello all,
I have a Infiniti QX4 2001 and i have very high fuel consumption. Until May 2013 consumption in city mode about 18 liters per 100 kilometers, and after may about 30-35 liters per 100 kilometers.

That is some serious gas consumption.
I usually average in the 15 litre/100 km range, and I have my truck loaded down with tools and supplies (I do home renovations).

There have been problems with the MAF's on 2001's.
You can replace it with a Maxima MAF, which is considerably cheaper than the Pathfinder/QX4 MAF, even though it's the same part. Go figure.

[4xq]

How did your old plug insulator tips look when you removed them?

Light brown / tan means fuel air mixture is correct. If you are running that rich, you should have black sooty plug tips from too much fuel. Try pulling a new plug and see if it looks ok. If you can get a good obdii code reader that reads live data, look at short term and long term fuel trim.

A bad engine temp sensor may not be telling the computer that the engine has warmed up. The computer will keep the mixture rich because it thinks the engine is still cold. That will not set a code for fuel trim because the engine does not go "closed loop" (engine fully warmed up and all sensors report ok.) . It will be in perpetual "open loop" ( cold engine, o2 sensors ignored).

If plug color is ok, and you are not setting engine codes, your problem maybe elsewhere than engine.

Might want to start thinking fuel leaks - check around the fuel filter.

Maybe you need a locking gas cap?

[lockz]

Buzzman
I was cleaning MAF sensor with MAF sensor cleaner. I checked the intake manifold for air leaks and it's OK.

4xq
Spark plugs I have not looked yet.
I'm ride around the city and collected statistics on fuel correction.
Long-term fuel trim:
Bank 1. from -0.8 to 9.4
Bank 2. from -0.8 to 9.4
Short-term fuel trim:
Bank 1. from -7.0 to 9.4
Bank 2. from -8.6 to 7.0
After engine warm up OBD2 scan program showing "Closed loop, using O2 sensor for fuel mix"

I think i need to clean O2 sensor's, because we have a very bad fuel quality. It may help?

[4xq]

Yep, sounds like cleaning the O2 sensors is a good step to try. After that, you can look at the O2 sensor switching rate and voltages with the scanner . Kind of think they will be ok. There are websites or youtube to help you with that if you haven't done it before.

Your short term fuel trims are swinging pretty wide - they normally stay closer to zero than they are. That might improve some with clean sensors - not sure.

Your coolant temp sensor is working ok. See if cleaning the O2 sensors helps - if not, then I think you may want to try a new maf sensor.

Just curious - they haven't started using ethanol in the gas where you are have they? It is not good for gas mileage at all.

[lockz]

Strange, but with onset of cold weather fuel consumption decreased to 23 l per 100 km.... Outdoor -20С.

[marioc89]

So do you know what the ultimate problem was? Because I'm having similar issues.

[lockz]

So do you know what the ultimate problem was? Because I'm having similar issues.

Has not yet understood, there is no free time. For the beginning I'll check for fuel leaks, then I shall clean or replace the oxygen sensor, then replace the MAF sensor. This is my plan.

[CanuckQx4]

make sure if you do replace the MAF sensor to go with the maxima MAF as they are exact same but a fraction of the cost, well documented on this forum

[marioc89]

So cleaning my maf will increase my gas mileage?

[Buzzman]

make sure if you do replace the MAF sensor to go with the maxima MAF as they are exact same but a fraction of the cost, well documented on this forum

The Maxima MAF replacement idea does not apply to all model years.
Be sure to check which build you have, and if the Maxima MAF will work.
The R50 MAFs changed from one year to the next.

[CanuckQx4]

Ive never seen that information, care to share? Id love to see if my truck was compatible

[Buzzman]

If I recall, the 2001's (first year 3.5 engine) are compatible. Not sure about the 2002-2004 models.
I recall reading about this on this forum, but it has been a while (years even).
I'm not good at searching, but if you're patient (which is not one of my better traits...lol) then I think you'll find it.

Edit: Ok I did a little searching and found this thread:

post5928567.html?hilit=2002%20maxima%20maf#p5928567

Not sure if it clears things up, or makes things more confusing.
Either way, it makes good reading re: Maxima MAF's.

[CanuckQx4]

Town do you know if 2001.5 are compatible for the maf swap?

[Towncivilian]

I believe they are, the pinout looks the same from the photos. The 2001.5 and 2002 Pathfinder MAFs even have the same pinout so I'm still not sure whether the Maxima MAF is incompatible with 2002+. 2002 is the starting year for drive-by-wire on Pathfinders, isn't it? Maybe that's why the Maxima MAF won't work - dunno.

[Buzzman]

I just pulled a MAF from a 2001 Pathy at my local wreckers, and it fits in my 2002.
(I also looked at a 2000 Maxima that was in the yard, and it had a different MAF)

FYI, my '02 Pathy is not drive by wire. It's the tried and true throttle cable.