I have had this stuttering for over a year now.....it happens when warm or cold, more noticable around town with lower rpm's (under 3000), but does also have issues accelerating (lags). It idles around 600 rpm and when it stutters is drops to 500 and back up to 600. It is a bit better with the car in neutral, but is still there. It really gets bad once in reverse, barely backs up at all.

Here are the things that I have done.......
Cleaned TB and IACV
Replaced spark plugs twice
Replaced MAF
Checked coils (fine)
Checked injectors (fine)
Knock sensor replaced
Replaced boost sensor
No current ecu codes

I have spent 4 hours at the dealer ship where they put in test coils and new spark plugs, they think its the MAF, but they aren't 100% sure (and its a $700 guess that I have to pay for) I have replaced it with one I got from an .org member, to no avail. They said that the fuel ratio? was 115% under 3000 rpm (way high?) and normal 90% over 3000 rpm. Other than that they are completely stumped....at least they only charged me for and hour of labor.

My gas milage absolutely sucks around town, but is just right on the highway (even with hills, a/c)

Does anyone have any suggestions? I just put in the replacement MAF, and that did nothing, I don't really know where to go from here.

Thanks!!!

 

bad fuel pressure regulator and/or fuel injector grounds gone bad might be causing excessive fuel to be sprayed when at a normal duty cycle have them test fuel pressure if you cant do it youreself and 700$? for a maf? yea right you could get a used angine and trans for 100 dollars more dont go for that crap i have a fuel rail with injectors for sale as well if you find that is the problem

 

Is there a tool or something I need to buy to test fuel pressure?

Ya $700 is high....gotta love living in canada.

 

$700 is ridiculous. Do you know ANYONE at all with a 4th gen maxima? Swap MAFs with them to test it. If it's not the problem, you just saved $700; otherwise, buy one off ebay for 1/4 that price.

 

Check to make sure the vac line to the FPR is hooked up. As slinky87 said, it almost sounds like the FPR is sending max fuel pressure through at all times, hence rich low end and normal top end.

 

Unfortunately I don't know anyone with 4th Gen....I did buy one off Matt (org member), and that didn't make a difference.

I'll have to try looking at the vac lines, and maybe get the dealership to look at the fuel pressure. They always want to do thier own diags first, hate it.

 

I'd replace the fuel filter and PCV valve... might as well go with the cheap possibilities first.

 

Holy crap, you've been on here since the beginning of the .org and you only have 32 post's! That's crazy!

FPR get's my vote also.

 

What can I say...my Max has been great to me....regular maint, and a few sensors here and there. (300,000+ kms...i think, odo stopped working)

 

yea with over 200,000 and change miles id be willing to bet on your vacum lines going to hell open up the hood and listen for hissing or whistling from the intake manifold area maybe just maybe a new vacum line will solve your problem

 

thats crazy, this is awesome -- welcome back!

 

thats happen to me and i got new injectors and all fine now.