All,

Last week, my vehicle suddenly started stalling while I was driving, so I took it to Autozone to check for the codes. I got a P0325, which was a bad knock sensor. So, I replaced the knock sensor over the weekend myself & drove it for about 50 miles without any issues. I did notice that the idle rpm was up from 650 (with the bad sensor) to 900 (after it was replaced) and also the fuel consumption seemed a little on the higher side.

The vehicle was running fine until this morning, when it stalled again. Went to Autozone to check for codes, but it did not come up with any. I do notice a slight vibration on the steering wheel when it is idle, although I am not sure if it's the engine knocking.

I had changed the spark plugs a couple of weeks back & also cleaned the TB thoroughly. However, I did not clean the IAC, but am not sure if that would cause the stalling after the sensor was replaced.

Any ideas?

Side noob question: Is "clearing" the ECU codes the same as resetting the ECU?

Thanks!

 

a bad/fixed KS would affect the idle OR cause stalling. Might wanna clean your IACV and install a new gasket. Did you install a new paper gasket for the TB? (did you even take it off?)

 

KS does not make your car stall, there is no way, even if u take the KS out of the engine the car will still run fine, the timing will be retarded (ecu is in safe map mode) but the car will always run.

vibration comes from a low idle (less than 550 RPM) and not from engine knock. and you can pull the codes yourself next time instead of going to autozone (check the stickies)

You're GLE = auto, so i dont know, but many 5spd experience stalling for various reasons.

Did you reconnect all the hoses properly when u reinstalled the TB? check for vacuum leaks is my first guess...

 

I am pretty sure I reconnected the hoses properly after cleaning the TB, but will double-check. I will also check for vacuum leaks as you have suggested....

What puzzles me is that the symptoms of the car suddenly stalling (and I can fell the loss of power right before it stalls when I hit the gas pedal) are the same as before replacing the knock sensor. The only difference is that earlier I got a P0325 code, and now nothing (after replacing the KS).

I drove for about 8 miles this morning, before it suddenly lost power & stopped. Another possibility (and I don't know if it is related) is that this sudden loss of power only happens after I have driven for about 6-7 miles, when the engine is no longer cold & reaches it operating temperature. Could it be because of the engine thermostat?

Thanks!

 

well does the temp gauge go up or down? does it suddenly shoot all the way to hot?

yes it is possible that the thermostat is kaput, but the gauge would show the needle play.

Understand this: the Knock sensor has nothing to do with stalling. Its there only for one reason, to detect knock, the way it does this is by reacting to the frequency of knock, which nissan engineers have found, experimented with, and created the piezo-electric element that sits inside the KS. when such a frequency is detected the element changes its resistance and thus the voltage changes and thats what the ECU detects.

Your check engine light never came on when this happened and you never knew of this before because the KS is not an emissions related component. Since the VQ was designed to be operated at a higher compression ratio (10:1:1) it requires the use of 91 octane. 87 can be used but the engine will knock, the KS detects this, and retards the timing (ie slows it down to save/preserve the engine from fatal damage).

So as you say the fuel economy is better which is a result of the KS replacement.

Also your idle is too high at 900 rpm, is this in P or D (car must be warmed up)?

 

The temp guage does not shoot all the way & neither does it go up & down. It comes to stop just before the half-way mark (and this is how it has been all along). I read one of the posts on this forum where the person had similar symptoms of the car stalling after the engine getting hot (to it's operating temp) & someone said it could be the thermostat, which I was planning to change anyway during this week.

As for the fuel economy, it has actually gone down as I mentioned in my 1st post. The consumption has gone up after the KS was replaced. I have been using 93 octane all along.

The 900 rpm is when the car is warmed-up and in "P".

Thanks!

 

you could have clogged injectors. do you put fuel injector cleaner in your car at all?

 

Yes, occassionally I put the Chevron fuel cleaner.

 

Ok, this is what I did yesterday:

1). Cleaned IACV, replaced gasket
2). Replaced thermostat
3). Replaced ECTS
4). Replaced PCV

I am going to check the fuel consumption after driving a little bit. My idles are still high when in "P" & "D", but am going to wait for a few days before attempting to adjust. It is about 900 in "D" & slightly higher when in "P". The steering wheel still vibrates slightly for example when I stop at a traffic light while it is still in "D". Not sure if this is because of the high idle or something else... As I said before, I can feel the knocks/vibrations on the palms of my hand when on the steering wheel. Anyone?

Thanks!

 

It won't vibrate at too high of an idle, and it should only vibrate and shudder around 500 RPM and below.

It could be missing at idle, watch the tach when you feel the vibrations. Does it flicker or jump around at all? It won't be that much, but noticeable.

 

my 97 doesnt do this but my 93 ve does. i just did a k/s job and now im going back to replace injectors seems tho mine are not functioning correct. it started stalling with cps being off and now its running rich. i is sometimes steady sometime not goes to about 1100 and back down. got an injector stuck open heres a video. http://s6.photobucket.com/albums/y21...t=SUC50772.flv
if your is something like that check your injectors

 

The tach stays steady whether it is in "P" or "D". Today, when I was driving, it felt unresponsive a couple of times when I hit the gas pedal & was almost going to stall. Not sure if I didn't do the knock sensor job correctly. I haven't re-checked for the codes yet, but am pretty sure to get a P0325, since the current symptoms are exactly the same as before replacing the KS.

I read on motorvate.ca that if you over tighten the KS, it will be too sensitive and if you under tighten, it won't be sensitive enough. All I did was to hand tighten it first & then turn it 90 degrees more.

Does anyone know what the symptoms are of over or under tightening the KS?

 

OK, I tried to extract the codes, but nothing comes up. I then replaced my fuel filter yesterday thinking that it would fix the issue, but no go. I still lose power suddenly while driving, at random intervals. Although, I didn't replace the fuel pump, it seems ok because I can hear the whirring noise when I switch the ignition on & off.

Could it be the O2 sensors although I am not getting a CEL?

 

you can also run fine with no O2 sensors.

Whatever you car is doing, it's not normal, although it could be coils, plugs, etc..etc..

If you have the time to mess with this....go right ahead...if you don't, hopefully you know a mechanic you trust. I would have already reached the level of diminishing returns no this one....

 

Is it possibly caused by a bad maf?

 

I was sort of thinking the same thing......I had a problem a long time ago...it was just something loose...I think it was the MAF, but I really can't remember, the symptoms sound the same.....