2001, 4AT
238,000kms (148,000 miles)


Hey guys,

My car doesn't have much acceleration power when I need a quick get-up. Under normal city cruising it's perfectly fine, but when I need to floor it or pass someone on the highway, it accelerates more like a Sentra than a Maxima... RPMs go up, engine revs like it should, but speed increases verrrry slowly.

Also when I first start the car in the morning when the engine is cold, the car hardly revs and almost stalls. I have to wait a minute or two for it to warm up before it's driveable. If I try to start it up cold and move, the car hesitates, hardly moves at all as if it's in neutral, slowly rolling along for a few seconds before it actually goes. It's just not getting power.

I've had it checked by literally about 5 mechanics and they all seem to think it's different things... one said the cat converter might be clogged, one said coilpacks, one said knock sensor, etc. Here are the codes it throws:


P0171 and P0174 (Fuel system lean, banks 1 and 2)
P1300 (Random misfire)
P1211 (ABS)

And the last code I heard my mechanic say was P0323, but I must have written it down wrong, after googling around that code doesn't seem to exist.. so I'm guessing he said P0325 (Knock sensor, bank 1).



One mechanic from a muffler shop tried driving it without the o2 sensor plugged in and the problem was still there, so he said it's not exhaust related (true or is he an idiot?). Cat converter temperatures were normal, tranny was normal and threw no codes. And I've cleaned the MAF already, a little hesitant to do a full out replacement of it unless there's a code for it or all those other codes don't fix the problem first.

Whats up with this thing?!

 

Might want to look into those Fuel System a lean codes

 

What would be the best way to go about that?


Just realized I put this in the wrong forum.... could a moderator move it to the 5th gen section please? Thanks..

 

O2 sensors won't really affect the car's performance. And in this case, they are probably OK.

The P0325 knock sensor - there is no bank 1 or bank anything associated with this code. Don't worry about this code. I will probably go away when you fix the problem.

P1300 - there is no such code. P1320 is random mis-fire.

Over all, you have a bad MAF and the ECU is not sending the proper air/fuel mixture to the engine.

 

+1 To the bad MAF.

 

What prompted you to clean the MAF? And yes there is a code for the MAF. If that was the problem you would barely be able to drive the car. Bad MAF causes major drivablity issues.

It sounds like you need to do a full tuneup. Especially plugs.

If you have already done so, post what u have done so we can suggest other fixes. But i would start with a tune up

 

I had the dreaded P0325 code earlier this winter...Trust me, it does exist and it is indeed the knock sensor which affects peformance. A board member actually replaced my KS for me. "Dennis Mik"- I'd do more research before telling someone not to worry about certain codes.

 

Might want to look at how long he's been here, his massive amount of posts, and the sheer number of people that he has helped, before calling him out.

 

I cleaned the MAF because I know it can be the culprit for a lot of power loss problems so I started with that because it's the cheapest fix. Obviously it didn't fix the problem though.

So far I haven't really done much other than that, except visit many mechanics who all say different things. Which is why I'm confused as to what I should try to fix first. Replacing the KS is an expensive job so I'm trying to be almost 100% positive that's what it is before I fork out cash.

Basically I'm torn between: replace knock sensor, replace cat converter, or full tune up. I guess replacing the MAF is now an option too based off previous posters' opinions.


The reason I think it miiight be the cat converter is that one mechanic said the temperature of one of them was a little higher than it should be. But then another mechanic said they're all normal..... (once again, multiple opinions confusing me ). I do notice that there is a loooot of ticking from under the car after I shut it off, which is usually a symptom of a cat going bad isn't it? I know it can be normal for there to be a few ticks, but the car will literally tick every other second for like 5 minutes before stopping. But it doesn't turn red as a sign of overheating...

 

if you have never replaced the plugs at 150k miles then replace them. NGK plats. Nothing less.

knock sensor on ATs could cause performance issues as well, especially if you are using regular gas. On manual trannys the affects of a bad KS isnt as pronounced.

Bad plugs also cause performance issues.

It really could be a bunch of issues like Dennis sd. And if you are trying to keep your car at top performance then do the tune up, clean the TB and MAF, replace the KS, and run a bottle of chevron techron in that bish!

 

fixed

 

Replace the knock sensor yourself, its not that difficult ... just takes a few hours

As for other parts, browse through the classifieds and youd be surprised what all you could fix on a tight budget (I just recently replaced all 6 of my coilpacks with lower mileage parts for less than the stealership wants for 1 of them)

 

Hmm thanks for the tip...

Btw, I'm ordering coils.. these seem good?

http://www.ebay.ca/itm/Set-6-Ignitio...vxp=mtr&_uhb=1

 

what makes you think u need coil packs? 99s are known to have unreliable coil packs. ebay coills are hit or miss

OHHHHH!! you have a 5th gen. your in the wrong section.

I still say do the tune up before u buy all that stuff. Tellin u man, fresh plugs go a long way. Plus, i think their is a specific code for coils other than just random misfire.

 

A bad cat shows itself once the engine is warm. Typically, on a cold start you'll have close to normal engine performance. Then as the cat heats up and blocks exhaust flow, performance becomes noticeably worse.

Being you stated the engine isn't operating correctly cold, I would definitely rule out the cat as the issue.

A good mechanic who knows how to use a good scan tool can pinpoint a bad MAF by looking at the signal. It's pretty simple to see it. You step on the accelerator and the MAF signal doesn't respond like it should. Basic automotive troubleshooting. Might want to look for a new mechanic.

 

Ok, so I'll start by replacing my plugs and see if that helps anything. Which forum do I post in to find local members who can help with repairs?

 

Look in the regionals section.

 

Richie ill tell you how to fix your car on the cheap.

first buy NGK Copper Plugs. 6 of them. Should be $15 for all. Look for how to video on youtube. Easy Stuff. Should take an hour.

next buy a fuel filter. OEM is the way to go but part store brands arent bad. $10-$15. Video is also on youtube.

Clean your maf or just get a used one locally ( craigslist/junkyard)- $25-50 ish. Easy to swap if you have more than 2 brain cells.

Knock Sensor. Again not hard just buy the right tool. Part is $7 on ebay and tools should be $10 if you dont already have them. Should take about an hour and there are multiple videos on youtube.

Clean the Throttle Body and IACV. About $25 in parts/gaskets from you local Nissan Dealer.

If you still have problems (missing),etc. then you have bad coilpacks or injectors,etc. Come back here and tell us. But don't worry you didn't waste your money since your car probably needed all the maintenance I listed above.

EDIT- just saw you have a 5th gen. All of this stuff should be the same except the fuel filter. I think the filter is in the gas tank. Or is that the 5.5 not sure. If its in the engine bay then swap it out if its in the gas tank fuhgetaboutit

 

5th gen + is in the tank.

 

So I just tested the MAF by unplugging it while the car was running, it kept running and hardly revved when I pressed the gas (sputtered and choked)... so I plugged the MAF wire back in and now the car hardly moves at all, won't even get to 60kph. It's basically undriveable now. WTF?!?! Does it need a re-learn of the MAF or was the MAF the problem?

and the cat was ticking like craaaaaaazy when I shut it off.

 

make sure you didnt pull any wires out of the plug. Im not sure if the 5th gen needs to "relearn" or anything

 

All wires look fine to me, I was gentle

 

Sounds like your car has entered fail-safe mode, which means you're running on default/stock setting tables and the ECU is not using the MAF readings for intake air. You should have limited power at this point, but the car should feel smoother compared to before despite the limited power.

Considering that you've plugged the MAF back in, and now the ECU is not getting any readings from said MAF, it's not being used. I would say, you might possibly have a bad MAF.

 

Agreed on bad MAF



5th gens had teh pre-cat issues as well, may want to look into gutting them, replacing them, or getting a Y / headers

 

The multiple misfire codes are a p0300 code. This could be plugs and the coils I did the tune-up on a 02 maxima that had the same misfire code, took care of everything.

 

Change your spark plugs with NGK. Coppers wear out quicker than platinum or iridium but copper conducts amazing and the copper ones are cheap like $2 a piece. I run copper NGK plugs and change them every year because they are so cheap. Check the maf and coil packs. The FSM (factory service manual) has a lot of info that could help.

 

I vote you try the ngk coppers, reset your ecu, run the tc-w3 in your gas. You may also try the seafoam treatment BEFORE you replace the spark plugs..

 

Well, I took it to Midas (where they have the types of code scanners that regular mechanics usually don't) and lo and behold................

He said the MAF was completely dead and that's what's probably creating all the other codes. It had basically no life whatsoever on the graph that monitored its readings.

So I'm gonna change that on Monday or tuesday and post here and let you guys know if that solved my problem or not. Also gonna change the spark plugs too because that never hurts.

 

Well if you guessed MAF...... you were right. Just swapped a new one in and WOW. THAT VQ POWAAAAA!!! Next up, NGK plats Thanks for all the help guys.

 

Glad you got it fixed, congrats.

For the plugs, you can go iridium if you want them to last longer. Plats are cheaper (not by much) but do the job again in 80-100k. Laser iridium will generally last you twice as long if not more, long as there is no premature damage to the plugs for other reasons. Just an FYI, good luck with the car!

 

Iridium are unnecessary for our cars unless you're boosted. Platinum last 100k no problem, it's the coppers that need constant changing

 

You going to man up and eat some crow?

 

It takes time to learn this stuff. Eventually it will happen... maybe.

 

Ok so I decided to clean the throttle butterfly while I was replacing the MAF (didn't take the throttle out, just cleaned it while it was attached).. used throttle body cleaner, clean lint-free cloth, etc. But now the car idles very high.. it varies. Sometimes it will idle at 1000 and sometimes as high as 3000. The car moves without my foot on the pedal as if it's getting gas from a slightly opened throttle. While idling in park, a slight tap on the gas will make it jump up like 2k rpm and stay there for a few seconds before coming down.

I tried the idle relearn procedure but I couldn't get the damn brown connector off the throttle body to complete one of the steps. Is there another way to relearn the idle? Already tried adjusting and loosening the cables too.

 

Bump..

 

I just cleaned the hell out of my IAC this past weekend and got some horses back. It accelerates like crazy once again but my idle drops to 400 while stopped at a light. I need to reset the ECU and I think that will fix my idle issue.

Cleaning the sensors will help.