I was reading through a lot of old threads about this earlier and I didn't see a clear solution, but I think that I may have stumbled upon it. Basically, I just bought a 97 base model and I tried to pass emissions but failed due to a knock sensor circuit malfunction code. So, a mechanic buddy of mine with access to a lift puts it in no problem and my car starts driving like total ****. With a bad knock sensor it drove normally without any hesitation or anything, but with the working sensor it is completely crippled with no torque at all. Whereas before I would accidentally peel out a bit on occasion, with the hesitation it was almost impossible.

Anyway, I thought that maybe this is how Preludes were or something since I fixed the part, so I go to try to pass emissions again and I fail for the same reason. So the part is working but the code was never cleared out. I then go to AutoZone and borrow their obd-II scanner (they make you pay a fully refundable $150 deposit) and take it out to the parking lot and it throws the same code and I just delete it. Scan again, no code.

I then drive home and the car is 100% perfect.

Let me say that I had attempted to clear the code on my own after I failed the second time by taking off the negative battery lead (which only reset my o2 and catalytic converter data for emissions and required me to perform a full drive cycle before retesting) and by pulling the clock/radio as well as the EAT ECU fuse. Doing these things does not appear to have any effect on stored codes.

The conclusion that I have arrived at is that the ECU requires two conditions to be met in order that it puts you in **** mode. The first is that the knock sensor circuit is complete (working sensor), the second is that there is a code that states the opposite. Apparently the conflicting conditions of receiving data from the sensor alongside the known condition of it being broken causes the ECU to go haywire and cripple performance.

1) It ran perfectly with a bad knock sensor and bad knock sensor code.
2) It ran shitty with a good knock sensor and a bad knock sensor code.
3) It ran perfectly with a good knock sensor and a good knock sensor code.

I want to also say that during the course of this entire fiasco, there was never ever a single instance of a check engine light. The only way I had any idea that there was any issue with the knock sensor was as a result of an obd-II scan.

I'm not saying that this will work for everyone, but it seems like this is a pretty easy thing to try in order to fix this. I suppose that you could either unplug your knock sensor, or replace it and clear the code. One thing I am not sure of is if the performance is better in the aforementioned scenario 3) vs. scenario 1). My guess is that it is, so it is worth the 100 bucks to replace the part if it is actually bad. I think the ECU cripples performance slightly with a bad sensor, but really punches you in the ***** if it gets mixed messages.

Anyway, I hope this helps someone out, because it has completely cured my problem.

 

I have a 97 SH, and I think that Im going to check this out. Sometimes I get way too much power and sometimes it bogs out. Im going to replace the ignition system first, and then go from there. How much did the new sensor cost?

 

I've seen them from $100-150. What you would want to do is go to an auto parts store and borrow a scanner to see if you are throwing that code before you spend any money.

The problem I'm referring to is the weird hesitation around 3K rpms that a lot of people have gotten.