Knock Sensor

[Dr.Evil]

I am still trying to dianose the perfromance problem on my 90, and have been told that the knock sensor, if bad, can be restricting power. Has anyone here replaced the sensor and noticed a noticable performance gain? I ordered one and just want to know if it is indeed worthwhile to try a new one.
Thanks

 

[sdpatt]

The knock sensor is a problem only if you are hearing uncontrolled knocking from the engine. The engine's output is decreased when the knock sensor detects a knock event and retards the ignition timing as a result. If the sensor is not producing a signal, you will hear the possibly damaging knock, but not notice an appreciable performance loss.

What are some of the other symptoms that you are noticing?

 

[shoinoff95]

Just a question---where is the knock sensor located? Just getting a feel for knowing where everything is under the hood!

 

[Dr.Evil]

Its under the fuel rail between the heads.

Please see this post for what I am experiencing/trying to fix:

Other thread

 

[yamahaSHO]

When Chris(AutoSHO) was trying to diagnose his power lose, he changed the knock sensor and said that really helped on power. From what I know, he did not experience any knocking.

 

[AutoSHO]

sdpatt:
The knock sensor is a problem only if you are hearing uncontrolled knocking from the engine. The engine's output is decreased when the knock sensor detects a knock event and retards the ignition timing as a result. If the sensor is not producing a signal, you will hear the possibly damaging knock, but not notice an appreciable performance loss.

What are some of the other symptoms that you are noticing?

I had exactly the opposite going on, my engine doesn't (and hasn't ever had) any audible knock, but trying to pull away from a stoplight was almost impossible because the computer was retarding the timing so much. It hurt overall power considerably as well. The new replacement resolved the power loss as well as the driveability problems.

Still no knock, either!

 

[yamahaSHO]

I would think a bad knock sensor would retard the timing automatically just to keep the motor from knocking. Kind of like the ECT making the motor run rich when it fails.

 

[Dr.Evil]

AutoSHO:

sdpatt:
The knock sensor is a problem only if you are hearing uncontrolled knocking from the engine. The engine's output is decreased when the knock sensor detects a knock event and retards the ignition timing as a result. If the sensor is not producing a signal, you will hear the possibly damaging knock, but not notice an appreciable performance loss.

What are some of the other symptoms that you are noticing?

I had exactly the opposite going on, my engine doesn't (and hasn't ever had) any audible knock, but trying to pull away from a stoplight was almost impossible because the computer was retarding the timing so much. It hurt overall power considerably as well. The new replacement resolved the power loss as well as the driveability problems.

Still no knock, either!

Im willing to bet this is one of if not the only problem....At least I hope so! I guess I'll find out tomorrow.

 

[AutoSHO]

Definately worth a shot.

Needs a BIG socket, make sure you test fit it on the replacement first so you know you can get it out! Don't overtorque it!

 

[ckinart]

AutoSHO:
Needs a BIG socket...

Indeed. I had to buy a 1-1/8" deep socket to replace mine.

 

[projectSHO89]

Instead of going through all the trouble of replacing it to see if it is bad, just unplug it and see if your engine responds differently. If there is no change, the knock sensor is not contributing to your symptoms. You may experience audible knocking/pinging with the sensor unplugged. If you do, you know the sensor has been working.

Same thing for the BARO sensor. That one will cause a CEL while unplugged, but the same idea applies. If engine performance is improved by unplugging the sensor, the input from the sensor is causing a degrading of engine performance.

Notice I didn't say the sensor was bad (it might be, but I did not say that).

Steve

 

[ckinart]

projectSHO89:
Instead of going through all the trouble of replacing it to see if it is bad, just unplug it and see if your engine responds differently.

Correct me if I'm wrong, but in order to unplug the knock sensor, I think you'd have to remove the intake and fuel rails anyway, wouldn't you?

Corey

 

[Dr.Evil]

Is the BARO sensor the same as the MAP? If not, where/what is the BARO sensor?

 

[projectSHO89]

ckinart:

projectSHO89:
Instead of going through all the trouble of replacing it to see if it is bad, just unplug it and see if your engine responds differently.

Correct me if I'm wrong, but in order to unplug the knock sensor, I think you'd have to remove the intake and fuel rails anyway, wouldn't you?

Corey

Good point. Forgot about that rascal can't easily be unplugged.

Dr. Evil

Yes, Same thing.

Steve

 

[Dr.Evil]

Well unfortunatly it did absolutly nothing different. Oh well I guess...good way to spend an afternoon.

 

[SonicRiot]

I too have heard good things about replacing the knock sensor. I have no idea if replacing mine would help. Should I try it anyways? I need to do some maintenence (valve-cover gaskets, spark plug gaskets, all that business), so I want to do it all at the same time. Reccommended?