I have a 2003 SE A/T with about 130,000 miles on it.

I was checking my ignition timing tonight with Car Gauge Pro and with Torque and both show my timing between 13-14 in PARK. As soon as I put it in DRIVE it drops to around 9, a solid 9 usually but a 9. Is this normal?

I tried to bump the timing 2 degrees and I felt like my car drove worse and I was getting pinging around 2k rpm, so I bumped it back down to stock.

Is my knock sensor going?

Also, if it's my KS, are people having long term success with the cheaper aftermarket senors from Ebay?

I also notice that my B1S2 O2 sensor is not staying consistent. It will stay consistent and then all of a sudden it start fluctuating up and down sporadically. Does this mean it's time to change that O2 sensor or that cat is going bad. I have a cali spec car.

Thanks in advance for any advice.

EDIT: I have no codes or ghost codes either, just thought I'd share that as well. The car also runs great with spot on idle. I don't think it's getting the gas mileage I usually get though. I'm getting around 15.3 as compared to 17 - 19.

 

First off what octane do you typically use? that will determine what the ECU will retard the timing to in your case 9.

Don't know a lot about KS, but like most things you get what you pay for so don't expect a lot from an aftermarket KS. I would search more on KS there is plenty & more than plenty of info here.

I would change the fuel filter it is an instant 2-3 MPG if you haven't changed it yet. Then look into spark plugs etc. If you have old sparks that will def gain some more MPG also.

 

Your Timing is always going to change with different loads on the engine. I wouldn't worry about that. But if you are going to bump the timing you need to be using PREMIUM fuel. Also changing the plugs is always a good thing (NKG Iridium or better), as is the fuel filter if it hasn't been done yet. That MPG is not good at all unless your always in the throttle heavily.

The O2 sensors will also fluctuate voltage with the different engine fuel consumption levels. The only time a sensor doesn't fluctuate is if it has shyt the bed.

 

I have done a ton to this car trying to help my MPG. Also, I ALWAYS use premium gas which is 91 octane (I'm in Cali) and every year I get the fuel induction system cleaning from the dealer (i know expensive but i usually like the feel of the car afterward)

Things I've done:

Just replaced plugs with OEM right from Nissan (just recently)
Replaced the fuel strainer
Replaced both primary O2 sensors
I have a newer MAF (2001 to 2003 with thermistor)
Replaced both valve covers with 6th gen (this I just did)
Also, inside my valve covers was super clean, no varnish or sludge. i change my oil on time every time. And I get all my fluids replaced on schedule or when I feel it needs it after inspection.
replaced rear cat just recently
I have newer tires with proper pressure.
I'm not really a lead foot, but i have my moments. But I do drive mostly city and I'm driving up and down big hills as i go to and from the valley.
I have no other mods and I use a K&N drop in airfilter.

looking at the MAF readings in car gauge pro and torque and it is operating in spec with what the FSM says.

I just had a smoke test done to find any leaks and nothing was found. I was going to have a fuel pressure test but my mechanic didn't have the adapter for the maxima, so i'll have to wait until he gets that.

I just don't get it because my car runs very smooth, rock solid idle and pretty darn good response after i recently changes the plugs and cleaning the oil out of the rear tubes and getting that new rear cat.

I also thought that secondary O2 sensors don't really fluctuate voltage just the primaries did. Lesson learned, I'm thinking about replacing them anyway.

Everyone talks about their great MPG and mine keeps going backwards. Maybe at 130,000 miles I'm losing compression.

Also a reminder, I'm pretty new at doing and understanding everything with my car but I'm learning a lot just reading this ORG all the time.

Thanks again for any advice.

 

Seems like the car should be running like a top or it actually is....... Your mpg is tanking cause of the hills...... No doubt.... Just for testing purposes I would fill up your gas tank, do some highway driving and then fill up your gas back up, do some meth and see what kind of numbers you come up with.... Stop and go is a killer with our cars....

 

that's what i'm thinking it's the hills and stop and go. i would actually not use my A/C just to see if it got better, actually didn't affect it too much and it was too damn hot not to use it.

i will try to do some highway miles and see how it goes. the only problem highway miles in LA is stop and go!

I'm telling you the car feels great, just not getting the MPG that everyone talks about and it's making me nuts. oh well, i should be happy i have a great running car. i keep it VERY well maintained. when i sell this car someone's getting a great ride.

 

By everything you have posted, you should really be seeing at least 19 MPG even in the city. Now if you literally are sitting in "rush hour" traffic in your average drive with the car than 17 MPG is pretty good for that. And just to make sure you are calcing mpg manually correct?

I am not saying you don't know this but maybe study more FE (fuel efficient) driving practices. After learning the smallest details on what do do and not to do while driving, I have achieved HWY mpg mileage in city/town driving with lights and traffic etc. There are critical ways/ how to's on how to drive on hills traffic, etc. etc. pm if you want a great forum that I have been on. But it has been proven you can achieve 30% more efficiency by driving style alone period.

Just checking, by replacing the fuel strainer do you mean the same as in replacing the fuel filter?

If you are greatly concerned about mpg also try upping your tire psi to atleast 42 all around, and it is safe as long as your sidewall max is not below 44 psi.

 

prophecy99 -

I calculate my mpg with a program on my phone. i log in all the numbers precisely and it gives my my totals.

yes, the fuel filter, the one that's part of all the write ups here on the org.

I do want that info. I will PM you when I get back home.

It's hard to have a "regular" driving day. In my profession I may have to drive all over the place one day and not drive for a couple of days. But most of the miles i put on my car are stop and go miles.

thanks for the tip on the tires.

 

Your car's in great shape. It's those hills, stop and go, and constant AC that are killing your mileage.

Also, while upping tire pressure to 40 some odd psi,

You will improve mileage (smaller contact patch, less rolling resistance = better gas mileage). And, at the same time:

you sacrifice ride quality (more harsh due to stiffer tires)

braking performance gets worse (smaller contact patch means brakes cant apply their full force to the ground)

worse cornering (smaller contact patch means car will lose grip sooner taking hard corners)

Adjusting tire pressures is always trade off.

 

thanks for all the info. I read some people talking about all their great MPG and I wonder why I'm not getting that kind of mileage.

 

Me too

 

NmexMax - nice. how's your car running? how's your MPG? have you done anything special with your car? mine's pretty much stock and runs great but i've been putting some money into it recently. just doing stuff that i feel needs to be done to keep it going and running great.

 

Check the evap canister and valve.... After swapping both parts I'm able to get 400-500 km easily vs barely making it to 350 km....

 

george - I had the car smoked and i was watching from a distance. there was a lot of smoke coming from that area but the mechanic said it was normal and that it was supposed to do that.

did you have any codes? did you replace them with genuine nissan parts or aftermarket?

 

+8 OP you have everything done and more. Amazing!
I wish I could say I have everything done that you have.

I was looking into the primary 02 sensors but.. haven't replaced them yet. I am debating on what to do with the precats in general.


Yes all true and good points, but I would say the trade off is not as big as you think, maybe I should try low psi and see how diff it is, I have been on 40+psi so long now I am used to it.