OK here is the issue. My 99 maxima (automatic) has been running great for along time and at the begining of this summer I replaced the front 2 O2 sensors and it ran even better 0-60 in about 7.5. After I replaced those i got an internship that requires me to drive 100 miles a day and for awhile it was running fine. but a few weeks ago it has been taking longer to start and when im going fast at around 80-90 when my car shifts it will flutter for alittle around 4000 rpms and the same when I reach around 120. So I seafomed my engine and did fuel treatment and that did nothing so I replaced the O2 sensor and its still the same.Today, I checked my 0-60 and it was 8.9 which is incredibly slow. All my mods and repairs are in my sig and have all been done within 35000 miles.

 

I'm sorry the o2 were replaced at the begining of summer. I ment to say I recently replaced the maf sensor.

 

cleaned your egr lately?

 

Nope do you think that would result in this much power loss?

 

What are you short and long term fuel trim readings? Whats your base MAF intake volume at idle and WOT? TPS % readings at idle and WOT? What about the o2 sensor voltage readings, high and low? MAP readings in/hg? Spark advance degree? Trying to diagnose your problem without this info is absolutely pointless.

 

Ok let me just get on that for you, in the mean time anyone else?

 

codes?

What did u replace coils with? New or used?

ECTS, fuel filter, plugs, PCV all good??

 

The plugs were replaced around 30,000 miles ago, it is showing no codes, yesturday I replaced the PCV valve and nothing happened and this weekend I am going to clean my egr tube and replace the fuel filter. I have not checked the ECTS though yet. I replaced only one of the coils with a new one from autozone last summer.

 

I replaced the fuel filter and spark plugs then I cleaned the egr tube and took it on a test run it ran better but still not like it should. I looked at the plugs and compared them to a haynes manual and according to that I'm possible not getting enough fuel. So I ordered a fuel pump and we will see where that takes me. Also my egr wasn't that clogged (possibly from only using shell or bp 93 and changing my oil with mobil 1 fully synthetic ever three thousand miles, idk). But while that is coming any more ideas?

 

O2's are not in the picture at WOT, they would not effect your 0-60 times.
If you weren't getting enough fuel you'd be throwing lean codes.

Check for a hidden knock sensor code.

 

Christ dude, you ordered a new fuel pump because it looks like the plugs having been running lean? Seriously, WTF? Did you even bother to check fuel pressure? Theres a good god damn reason I suggested finding out what your fuel trim readings and o2 voltage readings are at. But its your car, so go ahead and fire the parts cannon at it without getting any real data to interpret.

Let me give you the normal answer Im surprised I havent seen yet. "yo, put in some new plugs. Also clean tb, egr, maf, and iacv. New fuel filter too homes. Oh, and throw some chevron techron in that bish, it will be like new yo. Oh, and put some seafoam in that hoe, **** will take half a seond off you quarter mile time, guaranteed."

 

lol U took the words right out of my mouth mang

 

Its got 170,000 miles on it, as far as im concerened this is all maintnence untill I get to the problem. I wanted to do all this stuff anyway someday so I wouldnt have to worry about it. And nothing has been that expensive so far, so I guess I will just keep firing "the parts cannon" because by the time I find the problem itll be running better then it did before the problem started and im ok with that.

 

Running "better"? Unless the stuff you plan to replace is actually faulty it wont make a difference. You would gain a hell of alot more by rebuilding the motor with fresh parts.

Replacing a fuel pump isnt exactly a standard "maintenance" item. If it aint broke dont fix it. But its your money and car, so feel free to replace whatever you feel necessary. All im sayin is that without proper data its impossible for anyone here to tell you exactly what your problem is. People can offer up common items but without any real scan data its pointless. Besides, youve already done the regular stuff. Sure, you could just get retardedly lucky and it will actually be the fuel pump, but the odds are seriously stacked against you.

Have you considered that your 0-60 times might be caused by the summer heat? You said the times at the beggining of the summer were better. Now its middle summer and its hot, here anyways. Add to that your "CAI". Unless its a true cold air intake taking air from the fender well it will compound your problem. Point is, atmospheric conditions undoubtedly play a role in performance.

 

I have considered the heat but they were both done at night in around the same temperature, and my CAI is not in the fender anymore but it but, it hasnt been for a year and a half. And this car has been in my family since it rolled off the show room floor, I personally have had it for 4 and a half years, I know how it runs year round and when its not starting correctly. But I was just looking for ideas from anyone else who has had anything similar happen to them.
Also there are no ghost codes.

 

yo man, i have a pretty good idea u know what u doin and understand "mbm = maintenance before mods".

Alot of noobs come here and ask whats wrong with my car. The usual answer is, they need a tune up. U sound as if u already done that.

As for your problem, since u a 1999 i wd say check the ignition coils. seems ignition related to me. Check for vacuum leaks too.

 

Thanks man, I have thought about that and since that'll be 500 dollars with shopping around to get new ones I'm trying to hold that off for last, and I think it could be that but when I had that one fail it was pretty sudden and no noticable symptems before hand. And as far as vacuum leaks I don't think so but I might just go replace some old hoses because that is pretty cheep and seems worth it. But I will update after I replace the fuel pump and knock sensor this thurday or Friday.

 

I just took the car out after replacing the knock sensor and it was running better but still missing something the 0-60 is down to 8.5 and it no longer flutters at high speed. It launched hard but seems very low on power after 4,000 rpms and i already replaced the MAF. This is just an update and i will probably be replacing the fuel pump tomorrow and we will see.

 

It's well known around here the a "cough" CAI or realistically your HAI cone intake setup and the 4th gen equipped with an automatic transmission = lack of throttle response.

Put the stock intake back in place.

 

It has been on there for years, also It has a K&N filter which I clean regularly. Its not the problem. I have no problem with throttle response and I get better gas milage. If i were to do anything it would be to put it back in the fender. Thanks though.

 

I know I haven't posted on here in awhile but there is still something wrong with my car, and I would like some help.
Since august I have replaced everything in my signature from the fuel pump on, Including the battery and spark plugs. Nothing I did showed any results until this last time I worked on the car when I replaced the fuel injector and the battery. I did this and it started up right away and sounded great and almost had all of its speed back, but then it started getting random misfires that are continuously getting worse, and I was trying to see what it could be and the only thing I can see is the plugs are black and sooty now. Before I did this, when I replaced the valve cover seals I also replaced the plugs again with the Bosch 4 prong plugs, and at the time they made no noticeable difference. I guess my question regarding this is that, now that I have better fuel flow is it possible that the plugs may not be the best for the car and this is causing the car to run rich? That is all I can think of right now and I doubt that the plugs are the problem but any suggestions would be great.
Thank you

 

Get rid of the Bosch plugs and run the factory NGK! A lot of people have problems with running anything but NGK.

 

Check your tire pressure.

If thats OK then;

DO a manual flush of your tranny. Drop the old fluid, measure how much came out, then replace with same amount of new regular tranny fluid, like dexron III or better. Dont bother with synthetic tranny fluid.

DO NOT take your car to those flush places.

Also, clean up the grounds for the transmission control module if needed. i believe the tranny computer is in the passenger side footwell.



DW

 

seriously, trash the bosch plugs and put in OE NGK plugs. Our cars do NOT like bosch plugs

 

NGK is the only way to go. My Turbo S only welcomes NGK plugs.

 

Could OP have an issue with his cat? Not fluffy, I'm talking the catalytic converter...
Over on the forum for my current vehicle (pontiac GA) and wife's car (Subie), lack of power at the higher RPM ranges is one symptom...

as an aside, is there ANY car that likes the Bosch plugs? On both my other forums we avoid Bosch plugs like the plague.

 

i'm not sure, but on our zx2 forums we avoid them as well lol

op, check this chart: http://www.ngksparkplugs.com/techinf...q/faqread2.asp

if these guys suggest ngk, you might as well give them a try. also, since you've mentioned injectors. do a thorough check on them as well. http://www.google.com/#q=injector+ch...w=1280&bih=829

 

Well I Replaced the spark plugs and checked the fuel injectors and cylinder 1 went out and it was a new fuel injector so i replaced it with one of the old ones and the car isnt misfiring anymore but it is still having hard starts. anyone have any ideas on what it could be?

 

FUEL PRESSURE REGULATOR!

 

Should I get an adjustable one or a OE lol

 

OEM style....they are like $70 at autozone

 

clean your TB, always helps. Knock sensor was a safe call, that always improves something on just about any max.

 

As it is my area of expertise, it seems to me from the limited information you have provided that your problem is something electrical. Have you checked all of your grounds? If your stuttering at the same RPM every time then it seems logical to me that your trans control module might have some sort of issue. What? I have no idea but if it isnt getting steady voltage then it will cause problems. lol I wish I had your money and could replace all of these things. I just fix and replace as a last resort. Lastly, are these Bosch plugs avoided like the plague for any legitimate reason based on facts and figures or just rumors and old wives tales? Ive always had Bosch since my first change and have never had a problem, Bosch makes a nice product and has since before I was born and they developed the first ignition source for internal combustion engines so I think they know what they are doing. Just because nissan puts them on their cars from he factory doesn't mean they are the best. It only means they had the cheapest bid. Im just curious why so many dislike them, i've never heard this gripe before

 

i am going to change my trans fluid and buy a new fuel pressure regulator. we will see what happens but in the past i have had no problems with bosch spark plugs. but i changed them anyway. hopefully the fuel pressure regulator will help this problem i really want to get his fixed.