Hi, I don't have a safe way of getting under my car, so I had a mechanic buddy of mine put in a knock sensor to replace a bad one (knock sensor circuit malfunction error at emissions) and it seems to have completely changed the feel of the throttle. I would describe it as feeling now like there is a lot more pressure in the system, although obviously it's a cable. I wonder if a feeling of increased throttle resistance is normal or if perhaps he may have altered something else by accident. If I depress the accelerator as I did before it sort of has a feeling of flooding the system and it bogs for a second, so maybe by default it is much more sensitive?
It's hard to tell if I am imagining an increase in normal performance, but it does seem like VTEC seems to engage with less of a boost.
The problem is that I have no frame of reference since I bought it with a bad knock sensor.

This is a stock 1997 base model.

If anyone recalls the before and after of a bad knock sensor, please let me know how it was.

Thanks.

 

When my KS was broken it made no difference at all other than a check engine light.

 

a KS code will put your car into limp mode. I've experimented with the H22's knock sensor a few times. I bored my cylinders to 89mm, and the knock sensor picked up the differenct frequencys, which caused a CEL. The car would go into to limp mode. Sounds as though your car may be in limp mode. Do you still have a CEL?

 

That's the thing, I never got a CEL at all. Do 5th gens throw one when the KS goes out?

 

Yes they do...

 

Does it display the entire time or just when you start?
If the former, is it possible that the previous owner disabled the display of it?
I'm going to run it through emissions again today to see if there is anything wrong with the OBD.

 

Ran it through again and got the same knock sensor malfunction error.
I think if you have a bad KS you go into limp mode, but if you replace it and don't reset the ECU you go into ultra castrated mode.

So, uh, how might I reset the ECU's memory?

 

You can either pull the negative off the battery or find the ECU fuse and pull it. This will clear out the memory on your ECU. I know for a fact if the KS is detached/damaged that your car will throw a CEL soon after starting it up.

You may want to check for continuity from the sensor harness to the ECU. The knock sensor is a pretty simple sensor, and rarely go bad unless they have been physically damaged. They are also expensive.

 

I guess there's a chance that it was on for so long that it just burned out.

 

IF you unplug your primary O2 sensor and start your car you should see the CEL come on. If it doesn't then the previous owner did something to disable the light. Your car will run like a freaking dawg without KS on an OBD2 lude. Your ECU will retard the heck out of your timing.

There are numerous sensors that you could unplug which will throw CEL's. MAP sensor or EGR if you dont want to crawl under your car.


Modified by Yuleluder at 10:45 PM 9/27/2007

 

I tried disconnecting the negative terminal last night and all it did was make the cat and o2 sensors read UnReady at emissions. I just tried pulling out the ecu fuse for a while and it didn't make a difference.
This is one of those rare times that I wish my dash was displaying a CEL.

 

Your ECU must log a certain amount of data, before all the Readiness tests are complete. By reseting(disconnecting neg terminal) your ECU, you completely wiped out all the data the ECU had stored. That is why you will have to log sometimes close to 60 miles before you can go get an emissions test.

If I were you I would check continuity between the KS clip, and the ECU. At the very least you could rule out any opens in the wire. The knock sensor wire is a single wire, using the block as its ground. Basically, the KS vibrates at a certain frequency which your ECU is programmed to look for. If your ECU doesnt see this frequency it will throw a code.