SteveS

Been lurking around this forum since I inherited my father's 1996 maxima a couple years ago. Very informative. However I'm not able to diagnose my issue and was wondering if anyone has some thoughts...

For the last 8 years (yup...) when the temp drops below ~50 degs it's necessary to feather the gas for a few seconds when cold starting the car. Been told this was IACV. So finally I broke down and got one on ebay. Coincidentally, when driving last week the car stalled while I was at a light. I was able to get it started but it ran real rough. Pulled into gas station and filled it up thinking maybe the gauge is wrong and I ran it out of gas. Ran rough for another 10 minutes but smoothed out enough to drive 30 miles home. On this drive I noticed some hesitation in the throttle. Car would surge slightly either under load or cruising. So I installed the new IACV, replaced fuel filter, and cleaned the TB after all this mess. For the last few days the car ran like a champ. No more cold start issues, smooth idle, and much better throttle response, however yesterday I noticed the surge & hesitation came back. Engine light is still on (2 months now) throwing knock sensor and EGR codes. I don't see how either of these would cause the car to hesitate...but I could be wrong. If they were bad the car would always do this - but it doesn't. It's more hit & miss. The car has 265,000 miles on it - it's an absolute workhorse!

Any ideas? Thanks all...

cashoit

Clear those codes and see what other codes pop up.

Im taking a guess and saying its your MAF sensor. It could also be the fuel pump as well.

For now, clean the MAF and, if u can, test fuel pressure.

You may want to check/ replace your plugs

Alaskus

Check vacuum lines. I had something similar occur

I split the bottom of the rubber accordion hose that connects the airbox to the TB putting it back on when I replaced my IACV ...so I assumed symptoms were an issue with the new setup.

SteveS

I guess I didn't set up notifications - had no idea I had replies. But thanks guys.

I checked hoses - visually - but didn't see anything. I tried to clear the codes but these autoparts stores no longer clear for you. I may have to breakdown and buy a scanner. I have a dashboss that I use on my other cars - more for tuning - but it doesn't read this maxima. i guess the software is too old on the ECU(???). I'll try to find someone who will blow these codes away for me. Is there a way to reset codes without a scanner on this car? I did see on the 5th gen that there's a reset/relearn procedure - but haven't found anything for 4th gen.

Looking at the maint history - the EGR valve was never touched in 17 yrs. How would that impact this hesitation or stuttering issue I'm seeing? I wouldn't think so but I'm no mechanic...

98maxaholic

theres a screew on the ecu near the gas pedal...that should clear em up.... youtube has vids on how to do it!....if thats what your askin

D.Stillwell

EGR = exhaust gas recirculation. Affects emissions, and can impact engine performance if stuck open for example.

Bad Knock sensor = retards timing, there is your hesitation. Replace knock sensor, should fix things.

theWalkinator

+1 for knock sensor and EGR system, I had this before and after I cleaned EGR tube, replaced knock sensor, it hasn't had cold start and hesitation issues for 2 years. Also, clean MAF too to see if that will help. Pull codes next time CEL is on.

LTXMitch

This has been discussed endlessly. Knock sensor makes a night and day difference start with your CEL codes. Never heard of a stuck open or clogged EGR hurting performance.

D.Stillwell

Never said clogged, I said stuck open valve. EGR should open/close at specific times and is used to lower combustion temps and reduce emissions. It affects AFR, can possibly hurt performance but not very likely.

Anyway OP's #1 priority right now should be the knock sensor, and it will make a world of difference. And who cares that it's been discussed endlessly, we're here to help.

SteveS

I'll review some vids on how to change the KS. It's in a real tough spot. I don't want to get involved with taking the upper and lower manifolds off. Have to get my hands on long extension and swivel.

I'll look for that screw near the gas pedal to reset the CELs.

Thanks all! Very much appreciated!

98maxaholic

amen

rickmastick

The knock sensor was easy for me after I shot some maf cleaner on it and used a Bar to gain leverage on the wrench also removing the green connector clip was helpful gave me room to see and work. If you have the money or the tools adjustable extensions are nice and would do the job. A cold engine is preferred. Although I don't think the knock sensor would cause your car to sputter out and run ruff. Best of luck

SteveS

I reset the CEL last night so we'll see what pops back up. The car runs great now since cleaning the TB and replacing the IACV. Huge difference!

Now for new brakes....

SteveS

So as I stated above I reset the CEL, ran the car 30 miles to work...no hesitation. Worked all day then returned 30 miles home. On my way home I get hesitation - mostly when the car is under load (up hill or accelerating). No CEL though. Again I drove the car to work this morning and nothing. So we'll see how it is going home tonight. Any thoughts on hesitation issues when the car is under load? I haven't replaced the KS yet.

DBear

I second cashoit's post--check your plugs, and make sure they're NGK.

SteveS

I will - thank you. I haven't driven the car since my disaster ride home from work last Friday. Took two hours because the car would not run. This weekend I'll dive into it. I may also look to clean the EGR tube and sensor. Hasn't been done in 265,000 miles.

SteveS

So I changed the knock sensor. The old one was cracked and slightly charred. I guess after 265,000 miles that'll happen. While I had the air box out I thought I'd clean the MAF too. Got everything back together - she fired up no prob. Idling nicely. I give it a couple revs and it starts bogging down. It's happening around 2300 rpm. Consistent bucking. Engine light is back on now too. Checked all hoses and made sure all clamps are tight. Did I kill the MAF by cleaning it? I was super carefull with it.
I need to pull the codes off this thing but before I do this - any thoughts?

Alaskus

check the codes - no sense in speculating until then...

DBear

Did you use MAF cleaner or something else?

SteveS

MAF Cleaner

cashoit

if its not reving past 2500 rpm, bogging down, hesitating, and/or shutting off, then your MAF is toast.

There are soldering pins in the MAF that can be resoldered that should fix it as most often times the solder comes undone. SEARCH for Lukegxe95 pic of what to solder.

Or just pick up a MAF from the junkyard

SteveS

I searched but couldn't find anything. I assume Lukegxe95 is a user name? I searched on that name alone and had 0 results. Do you by any chance have that link?

SteveS

I picked up a code reader tonight - P0100 MAF. Plus knock sensor but that's brand new so that's not it. Also air temp sensor - again probably tied to the MAF. Time to get one....

maxinout93

Yah another maf should fix your problem, also the air temp sensor is right next to the maf inside of the air filter housing on top.

D.Stillwell

Knock sensor/IAT codes should go away w/ MAF replaced.

A good MAF makes a huge difference, I'd get a brand new one (around $100) not a junkyard one, no need to go into the why... Also, don't get an aftermarket MAF (OEM only) or you might have further problems/code coming back.

The re-soldering thread is here:
http://forums.maxima.org/4th-generation-maxima-1995-1999/629788-p0100-stalling-bucking-problem-fixed.html\

It has a pic of the MAF opened up, there are 3 connections inside but I highly doubt that's the culprit.

SteveS

So I purchased a used OEM MAF from someone on this forum, reset the codes, and drove the car 65 miles to & from work. On the ride home the CEL came back on. I scanned it and it’s a P1400 – EGR solenoid/valve. The engine seemed very smooth but with slight hesitation when it was cold. Once it warmed up it was good to go. I also noticed the cold idle was higher than usual (1400-1600 RPM). It was around 750 when warmed up.

So how difficult is it to change the EGR solenoid? Where is it located? I’ve read that the EGR tube is under the IACV and would probably need some cleaning out. Based on the look of the old IACV and TB I can image the EGR Tube is pretty plugged up. Is it worth the effort to clean this up too – assuming the solenoid & tube are in the same location? I’ve replaced the KS, IACV, MAF, and cleaned the TB – I guess this is the last of the “must cleans…”? Thoughts?

SteveS

As for an EGR Solenoid - should I stick with OEM or is aftermarket ok? Car has 265k on it and I've decided to sell it so don't want to sink too much into it at this point but also don't want something crapping out on me or the next owner (my conscience....). Thanks

bprice92

iTrader: (2)

Here's a video I found showing its location and how to test the solenoid.



Some have had success taking it apart and cleaning it. I'd grab one from a junkyard before buying a new one. Aftermarket will be fine, not one of those "OEM or bust" parts but last time I checked prices at the parts store it was like $75+