Nissan XTerra Forum banner

KS relocation mod question

5K views 34 replies 9 participants last post by  ShiftingSkys 
#1 ·
I'm getiing ready to do the knock sensor relocation mod on my 2002 SC xterrra because it is apparently stuck in safe mode due to a faulty knock sensor. I have the parts and the instructions (thanks guys!) but the x in the photos is different from mine and i'm not sure where on the intake manifold to mount my new ks. any ideas? here's a pic of mine, and a link to the instructions i'm using with pics at bottom
http://tunfs.yuku.com/topic/363/Knock-Sensor-Relocate-2002-Fronty-ODB2-code-P0328-or-PO327?page=1
 

Attachments

See less See more
1
#27 ·
the KS is not redundant, i beleive the word youre looking for is ineffective.

But the KS is effective - at least on the SC. On the SC when the KS is tripped it opens the bypass valve on the S/C and you get the performance of the non-s/c engine, minus the restriction caused by having the tiny little bypass valve as the only means for air getting into the engine, and a timing map with retarded timing.

The problem supposidly lies in the design and/or placement of the sensor itself. Whether its the placement or the sensor itself is the topic of hot debate. As a mechanical design engineer I believe the problem is there are a lot of non-knock related noises/events that set off the KS and it has nothing to do with the sensor itself or the placement. I believe the placement is correct - even though it is a PITA to get to. However, I also believe they could have found a place that was just as correct which was less a PITA to get to. My $.02 on that one.

Regarding your question on the additive, yes if you put enough additive to raise the octante to what would be a 91 rating, for example, or your put 91 rated fuel in from the pump the engine does not know the difference. As was posted by shiftingskys octane is simply a rating of resistance to ignition/burn. The higher the octane the higher the resistance.

Now I would be careful with those additives. Some of them have ingrediants that can be caustic or dillute the oil. And they are usually just gimics. For example a common commercially available product in the states claims it adds 10 points* to the octane rating for up to 26 gallons. Then you spin the bottle around and find the * and it says in very tiny print that 1 point = .1 octane. So 1 bottle (~$4) was worth 1 point of octane. In that case it would have been just as cheap and simpler to just pump the higher octane rating from the station and be done with it. YMMV just be aware of what all is out there.
 
#28 ·
The knock sensor is not an obsolete component of ANY engine. All vehicles have a KS and some even have multiple helps determine which cylinder US having the ping/misfire. The KS works in conjunction with the ecu to maintain proper/efficient ignition timing. If a vibration, ping, knock is detected, the ecu will retard the timing until the knock ceases. This prevents damage to the engine internals such as valves, cylinders, etc. But it does this at the expense of fuel economy and power.

In the VG33ER (supercharged 3.3L), the ecu puts the s/c in "safe mode". Basically the air coming in to the engine bypasses the supercharger. This results in a horrific reduction in power. The previous explanations of octane and combustion are correct but to simplify it, lower octane fuel is more apt to cause "valve ticking". You'be heard this when on the highway and you make a hard acceleration. The ticking sound is the valves. This ticking can be hard enough to be detected by the KS. The s/c engines are much more sensitive to this which is why higher octane fuel is a necessity.
 
#30 ·
so this is the third time Ill be trying this post...
They're going to undo the KS by-pass I did and do another code scan after they replace the clutch. As far as I know the KS was functioning properly and all my probs stem from the clutch. The guys seem to think I have a perfectly fine engine also. So since I've been running good gas in it for the past 3 or 4 tanks it should be ok? I've never heard a knock or a ping or any strange noise from the engine ever.
As for the other code, if it comes up again I'll deal with whatever needs to be done. Hopefully just an o2 sensor, like they say. I guess we see tiomo...
Also, thanks for the info on the s/c. I'm doing my homework because I want to keep this truck for a long time. So I want to understand how everything works and why so I know how best to care for it. I'm also just interested in knowing whats happening under my hood :)
 
#31 · (Edited)
@ mac11 That is a good point about the compression as I did not look it up or know it off the top of my head. I assumed it was higher because of the supercharger.

Now here is my question. A Majority of the time a higher octane fuel is required for a vehicle is because of the high compression ratio. Seeing as how the Supercharged X has a low compression ratio why does Nissan Require or HIGHLY recommend the use of Premium in the supercharged X's?

Since as stated before the octane is simply the rating of resistance to burn and the compression is not jacked up what makes the Sueprcharged X's Ping/Misfire/Detonate with 87? It is pretty much the same engine as the non supercharged. The ignition timing is the same on both engines as is nearly every other spec.

Also At Orlanda. You are on the right track. Wait for the codes to return and deal with them as they pop up.
 
#32 ·
somehow they got the wrong clutch kit and so I won't be getting my truck back until tues at the earliest, as mon is a new stat holiday in this province, "family day".
good thing i'm going to vancouver this weekend, so won't miss it too much. also seeing soundgarden on sun nite and marilyn manson on mon nite should help to take my mind off it...
 
#34 ·
Yay finally got my truck back today! can't believe the difference! holy POWER!!! It never had power like this before, I am amazed!!
So the grand total was $2200. New clutch and new exhaust. The secondary cats were actually breaking apart and plugging up my exhaust! So they removed them and put in place a straight pipe (no air-care here :))
They say the primary cats will need to be replaced eventually, but not for maybe a year or so, even the amount I drive. Hopefully I'll have the dam thing paid off by then!
Here's a pic of the broken bits that were plugging up the exhaust, it's really hard to see in the photo, but if u hold up to the light u can see where it was plugging up. They tell me that's what's happening to the other ones too...
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top