First of all, just replacing your knock sensor probably won't cure all of the VE "heat soak" problems, but it's probably thge major cause of it. If you don't know what this "heat soak" problem is, just search for it. Basically a VE will kick *** when it's cold, but when it warms up to operating temp it's very slow and lethargic.

The knock sensor is the last thing I have replaced in a series of items including:

1) Brand new VTCs (they were clacking and I got a killer deal)
2) New OEM coolant temperatue sensor and new harness (corroded)
3) New OEM TPS (tested slightly out of spec)
4) New OEM oxygen sensor (tested fine but decided to replace after 125K)
5) All new vacuum lines
6) New OEM NGK platinum spark plugs
7) New OEM fuel filter

MAF checked good, ignition coils checked good, fuel injectors checked good. The only drivability problem I had was the lack of power when warmed up. So, I decided to replace my knock sensor and the subharness that connects ot it. I found that the connections were severely corroded and the knock sensor had some hairline cracks in it. I got it back together and let the car sit overnight with the battery disconnected to reset the ECU, and the hesitation is gone the next day.

I normally drive 20 minutes on the highway to work each day, and getting off the offramp, accelerating onto another road in 2nd gear (usually pulling from 2000rpm) the car would be extremely slow to accelerate until hitting 3400+ rpm. Now, it's just like the engine was cold. Still, the VE is not a torque monster down low and it has a bit of lag to it, but it is MUCH better than it was, and I think this is just the nature of the VE powerband. One more thing I will replace are the harness connectors to my VTC solenoids since they are cracked and somewhat corroded (but have been cleaned).

It also seems like I have more power throughout the entire rpm band. Passing cars on the highway in 5th gear is pretty easy at 70-80mph. Drop it to 3rd and the cars I pass seem like they slammed on the brakes

I definitely recommend replacing your knock sensor if you have a VE. The sensor was about $130 from Courtesy and the harness was about $15. You do have to remove the intake plenum and manifold, it's an all day job for the average mechanic, but it's worth it! I will be completing a detailed writeup and FAQ shortly.

 

great info! thanks!

when you get the writeup done, post it here and PM me and I'll put a link to it in the FAQ.

 

Very nice thread and information. Most definate FAQ info!

 

That write is going to help a lot of VE owners here. Did you get a chance to take some pictures of the install and the old and new sensors and connectors?

 

Yup, sure did. I still need to take a few more and edit them. Should be done this weekend. Here's a picture of my old sensor and connector:

 

KUDOS!

Great job man. Not a job I look forward to, but I bet this is going to make a ton of people happy!

Now I just need to sell mine before the knock sensor fails...

 

It's on now! This is definitely the next thing I am going to do. All mods get put on hold until I replace my KS. Thanks Rosenken.

 

After all these months, are you finally calling it heat soak
It seems with cars like ours (some being 10+ yrs old) it's not uncommon to have corroded/dirty connections thru-out the vehicle, good find.

 

Psssh, yeah I guess, just for ease of searching. And it seems to be what everybody else is calling it.

 

This qoute taken from Rosenken

"Just an advisory, if you still have bad VTCs, don't expect all your power back...Remember I got a big surge of power back when I put in my new VTCs. I think the "heat soak" problem is a combination of VTCs, knock sensor, oxygen sensor, and corroded connectors (in the small 2-wire connectors that have the small metal wire clip to keep them in place). Don't expect a new KS to cure everything"

I just wanted to add this into this "heat soak" debate

 

to mount a new knock sensor somewhere else feasible like under the plenum so all you do is unplug the harness and plug in the new KS and mount it there? I have the same prob on my 93 but I'm hesitant in removing the plenum and maifold to replace the KS.


Also I've been reading 'poorcollegeboys' solution in tricking the ECM.
I think this is what he did: http://www.charm.net/~mchaney/knock.gif
What do you guys think about this?

 

i actually disconnected the ks completely and replaced it with a 470k ohm resistor. very easy. i read somewhere on the org that a brand new ks is a little less than .5 mega ohms (500k ohms). the car is running GREAT. no more hesitation after the car gets warmed up. no codes. i recommend to pull back the timing if it's advanced and still use 91+ octane just to be safe though.

 

Do you have a write-up and maybe a diagram on this? I'm interested in seeing if this is the case with my car. I know this is a temporary solution since it's important to have a functional KS to safeguard your car but want to try and see if I do have a faulty KS.

 

I might use this method in determining if it's my KS that is bad or not. Then, I will replace it if it's bad.

 

The write-up and FAQ are up and running now. Check them out at:

http://www.4dsc.com/articles/

 

Very nice writeup.....

I can tell you put alot of work into it. I really appreciate the time and effort and I am sure everyone else appreciates it also.....

Thanks.

 

Update via Kaleb:

The P/N 24078-30P00 is not the correct part number for a VE30DE knock sensor harness. While it does plug into the knock sensor, there is a specific harness for the J30/VE application. The part number is 24079-96E00 for the correct one and the price is $18.75 w/ 4DSC.com discount.
-=Kaleb=-

 

Question? does anyone with "Heat Soak", have leaky manifolds?

I had my manifolds redone (Broken Bolts), and the heat soak was gone. I figured the sensors were out of wack due to the exhaust leak.

Since then it's started leaking again and power loss was back. My max is back to the shop and being refixed.

 

Leaky exhaust manifolds will suck quite a bit of power. When I got done doing my engine swap, I accidently bumped the Y pipe 0-ring gasket off it's groove. When I torqued the 3 flange bolts it didn't seal that flange right. I could hear the leak and could feel a small power loss. I jacked up the car, loosened the bolts and realigned the gasket(it wasn't in too bad of shape). Once the leak was sealed, the power was up. If you have a leak right at the head, the power loss is probably worse.

 

In another thread on this topic, I suggested that this was a bad idea. After thinking on it a bit I have reconsidered. A package of five of these resistors is $.99 at Radio Shack... I "installed" mine in the parking lot today in 45 seconds. The "34" code on the ECM went away, and it runs like the VE I used to know.

I'm not suggesting this as a permanent solution necessarily. It's just that it's still too cold out to dig into the engine, I have no place to work on it right now, and if I have to take that much stuff apart there's other things I will do all at once (VTCs, injectors maybe, etc.)

Meanwhile, the engine runs great (better MPG too I hope) until I can make it right. I feel this is ok because I still have the stock ECM- which doesn't fully make use of 92-93 octane anyway- and my timing is still spec., so no worries, mate.

This also a good diagnostic tool to confirm the ECM code and other tests you perform on the KS and circuit, and can get the engine running back to a level where you can diagnose other potential problems... hopefully ones you can get to more easily.

 

Would a bad knock sensor ever cause occassional stalling after braking?

 

I rarely come on here mainly cause of the same ol questions posted, springs, interior, rims, never really anything tech related, but its been a few months now, it seems a bit more cleaned up and improved.

I had to do another smog test since two years ago, and it failed due to timing being very advanced to compensate for power loss. Anyway, back it up to stock specs , it passed, but is very mucha a slug.

So i took it back to a mechanic i know that used to work for nissan with a consult to diagnose. Well, this time it finally showed the knock sensor being faulty. A year ago it was intermittent.

I too have changed the following on my VE.
O2, Eng.temp. sensor, cleaned all injectors, NGK laser platinum(thumbs up!), my vtc's are okay i guess since ive always used mobil 1 5w30synth. and high flow cat an muffler, also changed ecu since the last one had dead VTC output. Each time i changed something, it got a bit better on power, but still a slug. I just advanced timing to compensate whatever was wrong.(now i know for sure it s the KS.)

I will post later after i change what i hope is the last thing on my maxima, the KS.

 

Well, Maxima is in the shop getting the KS swapped, along with new harness and new intake gaskets and injector O rings.
Will post later how it runs after this.

 

What exactly is required to try that test with the resistor. I am very interested in replacing the knock sensor. I dont think it is something I can (or want to) do myself, and would rather not pay the money if it may not cure my problem.

 

well, maxima is finally totally cured, and is what its supposed to be, quick!! I forgot to post here. The KS is definetely worth the time and money to change. Otherwise, its no point driving a maxima with a handicap.

 

I have read all of the info for the VE K/S replacement, but can't seem to find anything on replacing the K/S for VG. Are the part numbers the same as VE? Does a bad K/S on a VG create the same problems as it does on the VE?

 

My VG FSM (90 SE)calls it a "detonation sensor" and it is on the back side of the engine closest to the firewall on the end of the engine opposite the Oil Filter.

 

More knock sensor information. Specifically the TSB info issued by Nissan about it.
http://forums.maxima.org/showthread.php?t=179903

And more info on the knock sensor and related stuff.
Basically it's a thread to say DO NOT use the Resistor mod that's so common.

http://forums.maxima.org/showthread.php?t=247543



For any other questions or posts about the knock sensor, resistor mod, or heat soak, please start a new thread and quote these as reference.