So lately my 99 SE 5-speed has been giving me one little problem after anouther, and I have been throwing money at this thing thrying to keep up... I am almost done, and have a problem that just started, and am looking for a little advice before I proceed...

My car just started cutting out at high RPM's. When it cuts out the RPM's keep going up like normal, the engine sounds normal, but it lags in power. It almost feels like a bad clutch, but I know thats not it, as my clutch is fairly new, and still strong... It has been throwing a Knock sensor code for some time, and we have been ignoring it while we fix other problems, planning on saving it for last. I was under the impression that a bad knock sensor would adjust some settings, but I have heard nothing about it cutting out. My mechanic drove the car with his CPU hooked up to it yesterday, and told me that the engine is running lean, and keeps thowing the KS Code every time it cuts out...

He wants to replace the knock sensor as a first step, but I have a bigger issue to deal with that I need the cash for first (Timing Chain Tensionor & Guides), was hoping there is a simple answer like fuel filter or somthing.. I dont want to chase this problem if I dont have to..

Any Educated Ideas would be greatly appreciated!!!!


Thanks Guys

Running lean = MAF sensor
Bucking = MAF sensor


www.car-part.com
Air Flow Meter

I mentioned MAF to him, and it didnt seem to phase him...
I think he wants to get rid of the KS code before he chases a problem. I read some of the postes here about bad MAF, and they all seem to have idle problems,and notice issues with RPM's.. mine is fine all the way up till I hard accelerate then it starts cutting out... not really a bucking more of a lag...
I'll look into it, but any other suggestions?

I was just reading through a few more MAF threads, and ran across a thread about leaks in the intake causing a similar issue, and sure enough there is a leaf in the gasket flange just before the MAF.. any Idea if this could be the culpret?

PIC.. http://memimage.cardomain.net/member...47_21_full.jpg

The KS code does not affect performance as in your case. It's fairly cheap and easy job to do on your own. Fixing it shouldn't be that much of a problem.

What you need to do is get the codes that he pulled and psot them in here.

As for the MAF supposed leak, there will not be a lean problem if there is a leak pre-MAF, it is post MAF that will cause a lean condition because the MAF is not seeing the air entering through the leak, therefore, the car is seeing unmetered air. In this situation, the AFA / ECU cannot compensate for this, therefore leading to a lean condition.

If that is a leak by the flange, it will let dirty unfiltered air enter the engine.


Also, MAF's are dirt cheap on that site I provided, it couldn't hurt to eliminate that possibility.

I agree i think its your maf for sure, it might still run now but eventually it will blow if it goes too lean and can't take the heat and pressure anymore!

Although this is true, once the ECU detects that the MAF is dead, it will throw a code for it, and not let you go over 2.4k RPM. This is so that the engine is protected and WONT 'blow'. in the meantime, you're stuck w/ intermittent problems as the OP is explaining.

Yes, I would definitely take care of that. If you have a leak right there that means that air is getting introduced too close to the MAF sensor and has non-linear flow over the sensor element, and at that angle it is probably getting in unsensored, thus you are getting more air in the system than the computer thinks which is why it isn't driving right with the right mixture and thus also why you are getting codes saying it is running too lean. Also, some unfiltered air is getting in and if you drive through dusty conditions you can gunk up a bit more than normal in your intake, plus get a dirty MAF sensor.

I would definitely fix this and also check for vacuum leaks around the intake manifold gaskets and vacuum lines.

Even if it IS a leak, which I doubt, since the air is traveling through the housing, it is being accounted for through volume.

Oh, one more thing to add, if your engine is running too lean, it is important to get the knock sensor in working order as well, because a lean condition makes the engine MUCH more prone to pre-ignition knock, and without a knock sensor to detect and adjust accordingly, this can be bad for your engine.


I am surprised the knock sensor code is a shadow code for Nissans, because usually the knock sensor is a pretty important component.

When the KS malfunction is detected, the ECU drastically reduces timing.

Considering you have a 99........Not sure about the lean issue, but a bad coilpack would cause the cutting out symptoms at high rpms that you're describing. What do you guys think?

Very Common.

if it where the coil packs wouldn't i get a misfire code?

What codes did you get?

On 99's it's semi common to have coil problems w/o throwing any codes.

Nope, not always. When my coilpacks went bad I never got a code, but experienced the cutting out symptom you described.

the only code is the knock sensor...
I'll check the coil packs tonight or tomorrow, and fix the air intake leak with a new gasket... I'll let you guys know...

Thanks, keep the ideas coming...

I had that problem your talking about, it is very possible that it is a coil pack. my car ran horrible after about 4-5k rpms. and on the code, it only told me that there was misfire in piston #2 (i replaced my coil pack, and problem gone )

One quick thing to try - get a fresh set of copper NGKs ( they're really cheap) and gap them down to .035, then drive the car again and see what happens. If things go back to normal, pat yourself on the back. If the top end is still crappy, get another set of coils from a 95-99 Maxima. They are basically all the same, just front and rear banks use different coils.

Since you asked...

When my coil was messed up, the whole car was shaking while driving or idling and I've experienced tremendous power loss(5 cylinders are not 6 ). After I have replaced the ignition coil I got rid of this problem, however got anther one. Before(even before car shake) on speed 78Mph - 83Mph I heard roaring sound from engine, now there are no extra sounds, but the steering wheel and the car is shaking, once I am passed 83Mph it all goes back to normal. So far I've replaced my front brake rotors, but it gave no changes. Any suggestions?

maybe i was looking wrong ... but $150 - 400 isn't what i'd call cheap.

what's the update ???

I got mine for 45$ shipped. I just checked the site, and found many for 35$. Look harder son.

LOL .... I am a tard. I found them, but I was looking in the wrong place before. Nice site and now it's bookmarked.

Cheers