sturovo

The stock knock sensor on my car has gone open. Previously I think I measured it at 560 k ohms.

Does the stock ecu pull timing as a safety measure when the knock sensor circuit is open?

I think I read that 7 degrees can be pulled by knock control? If there is some corrective action for open knock sensor then would it be throughout the entire rpm range or step in at a particular value?

I need to get a new sensor but they are not stock items here. Has any one used a substitute knock sensor to replace the stock one?

Any suggestions welcomed.

flounder

That's a good question.

I was messing around with my upstream 02 when I first installed my emb a couple years ago. I was trying to see if I could lock the ecm into a base map by unplugging the up o2 and using my piggyback to change values so I would not be fighting with 14.7:1 afr when transitioning into/out of boost.

It didn't work, I got a bunch of knock in the upper rpm range regardless of how much timing I pulled on the emb. After plugging the o2 back in, the problem went away instantly.

If anyone has more info about the nb knock sensor I'd like to hear more about it.

JasonC SBB

My guess is the factory ECU doesn't pull timing when the knock sensor is bad.

Did it throw a check engine light?

sturovo

I think you might be right.
I tried using a 560 k ohm resistor instead of the knock sensor. As far as I can tell it runs the same with and without the resistor supporting your idea that the ECU does not pull timing when the knock sensor is bad.

It is hard to verify as I have no way of logging timing afaik with high tech EMB pictured below.

No CELs....but I have an obd1 set up that seems to never throw CELs or have any faults when I check with a diode. (If I pull ABS fuses or TPS plug the CEL comes on so I guess it is working.)

flounder

Nice spot for the mbc.

I used to have that one, then I switched over to a ball and spring type and the boost response is way better. It hits your desired boost level quicker and harder than that style one.

sturovo

You are right, this one is not so good! It overshoots by around 3 psi dips and then settles out just in time for the next gear change. I will probably try the ball spring type too.