Ok here's the deal my 95 max with 172,000 on it gets about 14 miles a gallon. I do drive 100% city , but drive slow and rarely punch it. I have a brand new fuel filter , new plugs, just recently cleaned iacv and just cleaned the maf too. I also have relatively new injectors and ignition coils. Any idea's as to what would help??

One more thing, I know the car is running rich because I smell fuel alot.

 

new injectors you say? my guess is whoever installed the injectors screwed it up, and one or more is leaking excess raw gas into the CC. have your oil analyzed for excess fuel dilution.

EDIT - actually, a quicker/easier check for this would be to pull the spark plugs and look for carbon fouling. a leaky injector will carbon foul the associated plug.

 

I'm guessing the knock sensor on that one

 

Fuel is definitely your problem, considering you've installed two fuel related items and you're running rich.

 

The raw fuel smell could be your purge solenoid valve, and charcoal canister (the box under your rear driverside quarter panel). When mine went bad on my 97 that was bad along with my ks.

 

NO NO NO. stop perpetuating this myth. a bad KS with NOT cause 14 MPG.

 

and now everyone chimes in naming every single component to a Maxima based solely on a guess.


Have a lot fo junk in the trunk? Pulled out your plugs to see if they were coated in carbon (new plugs can become very coated in carbon if there is already a buildup in the engine)? buildup on valves can cause imcomplete combustion and poor mileage. Having hard starting issues? There could be a million causes. Need a little more to go by.

 

I did the injectors myself and the mileage was the same before they were changed.

and the KS is also brand new.

 

No starting problems and my plugs look pretty good.

 

that doesn't mean it's not an injector(s). why did you replace them? maybe you made a mistake installing them? inspect your plugs for carbon fouling.

 

did any compression tests? junk in the back? fuel treatments? are they gapped properly (they come gapped too close)?

 

Just recently had a compression test and all 6 cylinders were within spec. The plugs have no build-up on any of them and are gapped to .044. There is no leaky injectors or bad plugs

 

ok - but you said you have new plugs. how new? have you actually pulled them out recently to look at them? how long ago? if there was no build up before, then why did you replace them? and why did you replace the injectors?? if you are running rich you will have carbon build up in the CC no matter what the cause. if it is as clean as you say, then you are not running rich. have your oil sampled to confirm.

 

I replaced the plugs like 5 months ago (3-4000 miles ago) and just checked them recently, but like i said its always gotten bad gas milage before I changed them. The reason I replaced was because they were old I replaced the injectors because I had a few go bad (misfiring)and just said F it and replaced them all.

I really don't think its worth it to get my oil sampled.

 

thats odd. have u by chance seafoam'd it???

 

Just recently. I've tried everything thats why I'm so pissed! I can't figure it out.

 

that's your call. IMO $20 is a small price to pay to find out so much about the health of your engine. if the oil is not diluted with fuel and your plugs are clean you can focus your efforts on something other than combustion-related systems (external fuel leak somewhere?? IDK)

 

If my compression is perfect then how would there be gas in my oil?

 

there's always some blow-by no matter how good your compression. if you are running rich the excess fuel will get past your rings and into the oil. this can also happen (to a lesser extent) for excess idling and city driving. if your oil report turns up more than about 2% fuel then you can be assured you have a problem somewhere related to A/F or combustion (fuel injectors, plugs, coils, T-stat stuck open, O2 sensor, or anything that the ECU uses to calculate A/F, etc etc). if your oil report doesn't turn up excess fuel, and your plugs look good, then you are not running rich and all those systems are working properly and you can look elsewhere for the cause.

 

Thanks for the explanation. Where can I get a oil test done?

 

http://www.blackstone-labs.com/free_test_kit.html

 

I use these guys...
http://www.blackstone-labs.com/

edit: link-blocked by 2da!

 

Thanks. I just ordered a kit.

 

a few more things...
- you want to have at least 3k miles on your oil before you draw the sample. any less and there may not be enough data to tell you anything useful.
- don't dramatically change your driving habits right before you sample (e.g. a long 500 mile road trip) as it will skew your results. you want the sample to be representative of your normal driving.
- sample the oil hot.
- if filling the sample bottle from the drain plug, wait until a quart has drained out, then fill the bottle.
- be careful not to get any contamination in the sample bottle.

 

ok just one more thing -- try not to add any top-off oil. it will also skew your results.

 

I don't need too. My max doesn't burn any oil whatsoever or leak any.

 

first check the fuel pressure regulator, then check a few sensors- Could be o2(s) (probably not), or ECT (engine coolant temp) sensor, or ECU.

 

I think it could be the ecu because everything else checks out perfect or has been changed.