ls1121

are they important? mine were tuned out because he said they were bad. Should I get new ones and have them turned back on? I have a Tune.

ls1121

So in the Scan & Tune Forum we have 101 views and no one understands my question?

enoniam

If it were me I'd want them functional if for no other reason than to have the PCM be able to pull timing if I were to get some bad gas for instance.

tblu92

Knock sensors are there to protect your engine and reduce timing in case you get a tank of bad gas or have to use other than premium fuel- Deleting the Knock sensors is a practice used by dedicated race cars the use race gas all the time-----On a Daily driver it would not be a good practice as fuel quality changes from station to station and if the ECM does not remove timing for bad gas you risk detonation (pinging) on your engine which in time can melt sprk plug tips and cause aluminum peppering specks from the tops of your pistons--not to mention overheating----
If your car is a daily driver---I would absolutely NOT DELETE them--It is a pricey repair mostly all labor--This is a very common issue on most 97-2000 C5's

ls1121

I ordered a pair of GM sensors and was wondering if an aftermarket wiring harness would suffice, GM is like twice the price of aftermarket, after all it is just a wire. :

Cliff8928

Aftermarket harness is fine, it's what I used. You can also follow the TSB for how to seal them up.

https://www.corvetteforum.com/forums...06-04-023a.pdf

ls1121

thank You for the link.

ls1121

can I re use the old valley cover gasket or do I need to buy a new one? RTV?

JBoyle997

Once your car is dyno tuned does it tune out the knock sensors? Or are they still there to protect from to much timing?

Cliff8928

No reason to remove the valley cover unless you're doing other work aside from the knock sensors.

enoniam

Tuning, dyno or otherwise, can either remove or leave in knock reduction. If running an aftermarket cam a tuner will often reduce the sensitivity of the knock sensors due to most aftermarket cams making the valvetrain noisier.

tblu92

Yes they are still in place----
The exception is-----on some cars with certain mods especially LT headers or aftermarket rockers or larger cams --the engine becomes noisier -----this is common--- However these new noises are often mis interpreted by the knock sensors as "knock or pinging" called false knock--- So lots of timing is falsely removed---In response to this false knock tuners will have to "desensitize" your knock sensors so they don't pick up this new engine noise as pinging---It's simple to tell by using a data logger----IF you hear NO audible pinging yet your ECM seems to be removing timing for KR then you are getting false knock-- and desensitizing them would eliminate the false knock

ls1121

So I went to Gear Chatter and read the directions on how to check the knock sensors and I am getting the proper resistance between the sensor and ground and when I checked them on AC voltage and tapped on the block near the appropriate sensor I got a reading of I think it was 0.02 volts so it looks like the sensors are fine. I am only have issues with sensor #1. Could it be where the harness connects to the PCM being that the PCM was unplugged when the motor was remover for work? I had never had an issue with knock sensors prior to removing the engine.

tblu92

No --- Tuners will only tune out the knock sensors if you ask them to---However many tuners will "desensitize" your existing sensors if they deem from data logging that you are getting "false knock" False knock is common on many cars--Especially those cars with long tune headers---cars with aftermarket valve train or camshafts-- All these mods make your engine noise louder or different than stock So the knock sensors will mis interpret these new noises as knock when in fact there is NO detonation

ls1121

I replaced the knock sensors and wire harness with AC Delco parts and had another Tuner turn them back on. (99+ sensors and harness)
I'm getting code P0327 only no other codes. I read the GearChatter post on how to test them and I think my results are Good.

Checking at disconnected harness I'm getting 100 KO on each sensor and then I did the AC volt on the meter and knock on the block test and both sensors read the same.

I disconnected the Blue connector from the PCM checked there and got the same results. 100 KO
I removed the PCM and checked between the pins (68 & 69) and the body of the PCM and got 4.83 & 4.84 KO

I'm thinking it's in the tune, am I correct? I get the same reading off each sensor and only 1 throws a code.

ls1121

836 views..... where are all the smart people???????

enoniam

Have you ohmed out the wiring itself? It looks to me like you are giving us resistance readings through the sensors. Have you verified 5v getting to the voltage supply side of the knock sensors' harness at the knock sensor ends?

ls1121

No I have not verified voltage at the knock sensor ends themselves, I would have to remove the intake to do so. I thought checking the resistance would confirm that the wiring was good.

enoniam

I really don't think the tune would cause a P0327 error. I suspect you've got an intermittent problem with the wiring.

ls1121

I spoke with a tuner today and explained everything here that I have checked and he said the he could just turn off that particular code for that one sensor but will it still work? It's a low voltage code whatever that means.