Roachjuice

i have a 96 se max that i need to rewire the knock sensor. i need to completely bypass the harness under the hood.
before you say search, ive already done a search. multiple times. i get a vague answer.
first i have a few questions.
what the hell is that bare wire tied into the knock sensor wire itself? some kind of shielding i assume. where does the shielding wire actually connect to on both ends?
next. do the 2 wires coming off the knock sensor connect to the single wire from the ecu?

Roachjuice

im getting 2 codes. p0503 and p0304. rear bank o2 and the knock sensor code. im pretty sure its the actual harness wiring causing the knock code. now the o2 code im not sure. its stumbling pretty bad anything over 1/2 throttle and sometimes less. idle is good but a bit low. 600-700 rpm. feels like its lacking power. ive replaced all the coils with used coils from the salvage with no luck. i havent found anything anywhere that the ks will cause a stumble. only thing ive found is that it will retard timing. so if someone knows how to bypass the harness i would greatly appreciate it. do i need a shielded wire or not? thanks

JvG

The knock sensor is not causing your current problem.

Worry about that later on. Some drive for years with a defective one.

Work on other problems first.

Did you change the spark plugs when you did the coils?

reallywildstuff

JvG is correct - the KS code is a symptom, not the cause, and you can't just "bypass" the KS.

Re: your question about wiring: I sliced open my KS harness apart after it and the KS disintegrated upon disassembly, and the two wires at the ECM side of the harness are joined in the middle of the harness into one wire, which connects to the KS. I do not understand the electrical theory that's involved in this working the way its designed to and welcome someone else explaining it.

The correct wiring harness for the Knock Sensor, what Nissan calls a "Harness EGI Sub", is Part Number 24079-31U01.

There's one for sale here for $33.12:

http://www.ebay.com/itm/like/120785837677?ul_noapp=true&chn=ps&lpid=82
However, I paid $19.20 for this same part @ www.orderinfinitiparts.com.
The KS is Nissan Part #22060-30P00 - $183.95 @ orderinfinitiparts.

Roachjuice

no i did not. i would figure that it would throw a code for a certain cylinder if it were misfiring on one cylinder. but i may have to swap the plugs out.
i pulled them all out and they looked fairly new. largest gap on one was .049 none of which were fouled. coming from the turbo world, looks can be deceiving lol.
but thats what i needed to know if im chasing the wrong thing or not.

Roachjuice

the sub harness isnt the problem. its the actual harness over the front valve cover that was giving me fits. thats why i mentioned just running a new wire to the ks from the ecu. i didnt know if i needed a special wire or not. also did the 2 wires from the ks itself just hook into that one wire or does the black and yellow wire go somewhere else?

JvG

I opened the cable which connects to the knock sensor. One wire connects to the rest of the harness. The other just shields that wire.

I suppose that the knock sensor acts as a ground when it detects a knock. Perhaps that explains why only one wire goes into the harness.

When I have missing issues like you do, I always replace the spark plugs. Then I can be sure that they are good, while other things might not be.

By leaving the plugs in there, you might be chasing your tail by trying to fix other, more expensive things before returning to the true cause. The plugs.

An oxygen sensor alone, or associated with the KS code would not make your engine run that way. Something else is up.

Roachjuice

alright ill swap em out and report back this afternoon.
when you opened your harness, where does that black with yellow stripe wire go?does it tie into that shielding or the signal wire?
thanks

JvG

I don't remember.

Again, the knock sensor is not causing the problem you are having. Deal with it sometime in the future. It does increase performance and mileage, (if you use premium).

You might investigate the symptoms of a bad maf.
I haven't needed to replace mine yet, but the symptoms seem familiar. Other members could tell you more about the maf. I'm just guessing about this.

Roachjuice

i replaced the maf, cam angle sensor and coils yesterday. the maf has a good signal. checked it with a meter.

JvG

Noticed that you have a k&n filter. I do too.

Some say that over-oiling the filter could cause maf problems.

I haven't had any.

Have you sprayed maf cleaner into the maf?

The cleaner is made by crc, worth a try. I maintain mine that way.

Roachjuice

no i havent oiled the filter. i may try that crc stuff ive seen it before. i remember i had a 94 thunderbird with a 4.6 i bought. had a similar issue. cleaned the maf and it was good as new. ill try that first then the plugs then go from there.

JvG

By the way, the Maxima does best with the plugs made by NGK.

Roachjuice

Just a little fyi for anyone else having the same issue. I resolved it by running a new wire to the knock sensor. There is a broken link in the factory harness that I'm not tracing down.
Just a recap. I fixed it by making a new wire from the ecu to the knock sensor. Both the clear and black/yellow stripe wire hook up to the ecu together.
No other changes were made. I did not clean the maf or change plugs.
I'll report back after a week of driving.

DennisMik

iTrader: (2)

The knock sensor is an interesting little critter. It has a 2 wire connector but only uses one wire. If you take an ohmmeter and connect it to the unused connection, you will find that it goes to ground. More specifically, if you have the knock sensor off the car and in your hand, you will discover that the unused connection is connected to the metal body of the knock sensor.

The knock sensor is just a coil of wire wound around a metal core like an electromagnet. But it is not a magnet. It is more like the secondary winding in a transformer. When the engine isn't running right, it is making abnormal vibrations that are picked up by the knock sensor. With the help of some mica washers inside the knock sensor, these vibrations are converted to electromagnetic waves that are picked up by the coil of wire (the transformer thing) and sent to the ECU.

About the only thing that can cause the knock sensor to go bad is that the plastic shell of the knock sensor will crack. A person's first response to this is that it is just a plastic cover. Yes it is, but it is also more. The electrical connections from the plug are not soldered to anything inside the knock sensor. They are just pressing on the pieces inside and the plastic cover is what applies the pressure. If the cover cracks, it loosens up and there goes the pressure connections.