P'cola FD

Hi, I currently have the bribery post going on https://www.rx7club.com/forum/showth...389#post515389 and I think my knock sensor might be FUBAR. I have tried the procedure in the manual, but it's pretty unclear. Does anyone know how to test this thing? Thanks
--Danny

Want2race

i believe you let the car idle and take a hammer and tap it on the houst point softly and wait to see if the engine does anything about it...

P'cola FD

The problem is, that my ECU is retarding the timing already. I need to find out why. I need to know an actual procedure. I tried the one in the manual, and it was showing battery voltage the entire time, with no reaction to taps, but I could have been doing the test wrong.

P'cola FD

Someone's got to know a good way to test this.

Tim McCreary

The test information is located in section F Page 185 in the shop manual. There is an electrical test. If you do not have a manual, there is a copy on the net. If you cannot find it, email me and I will copy the page for you. Email me at mccreary@cove.net

Tim

P'cola FD

Tim, I have the manual, but it is unclear as to how to test. It says to hook up a voltmeter to the MEN terminal, but it doesn't say where to hook up the othere voltmeter lead(i.e. to ground or to positive terminal). It doesn't say whether or not you can do the test with the engine running. I followed the manual's instructions to the best of my abilities and with the car running, it was showing 13.4v. When I tapped it had no effect. It is not sending a code 05, but if I disconnect the sensor, nothing changes. My timing is all screwed up, and I think it might be from my knock sensor, but I'm not sure if I'm doing the test wrong.

DK

iTrader: (5)

Danny ...

My understanding of the manual instructions is this:

The key ignition is on, but motor is not running. What you're doing is giving the system power, but you don't want the motor running to interfere. Got that much?

I think you connect both leads of the volt meter to the MEN terminal. I haven't done it, my car doesn't run yet ... but I think what you're just looking for is a voltage response to the MEN terminal when you tap the block with a hammer. I would think that if my interpretation is correct, with the key turned to "on" (motor off), the MEN voltage should read 0 unless you tap on the block.

Now someone help me ... I finally got one of the three knock sensors that I had coming in the mail yesterday (yes three!) to replace the one that I never got back. I have NO CLUE where the wire plugs into. I know what the wire clip from the ECU harness should look like, but I don't think I have one. I do have a single wire coming out of the airpump/I&J solenoid area that has the clip broken off (I've had several of these, they raped my car), but the metal slide is still on the end of the wire so I can tell that it was in a keyed clip and not one of those black ground slides. This is my guess as the correct wire, but I'm not certain they'll reach each other. The wire that I have is black, no striping, just black. Could someone help me? Could you tell me where the knock sensor wire comes out of the harness and/or the color? Thank you!!! (PM would be nice so I don't have to hunt down this thread.)

reza

I think the knock sensor is basically a microphone for the computer. It may sense only certain frequencies. Perhaps you can use ohmmeter to see if there is any reaction.
Someone good in audio may be able to help.

Its hell to replace the knock sensor, did that myself. Its about $145 for the parts, and took me about 4 hour to replace. well thats my first stab at the car mechanically. I had to take out the elbow, intercooler pipe and the altenator to reach the knock sensor connector.

Oh ya, I replace mine since the engine check light came on.

Reza

reza

DK,

When I did mine, its located behind the altenator, I had to take out the altenator, and the vacumm box behind it to get to the wires. I forgot the color, but its a single connector. I think you need only one Knock sensor.

Reza

DK

iTrader: (5)

Thanks, reza. That's where my wire is coming from, I just don't have the plastic keyed shroud on it to be certain. That's where Danny PM'd me that it's coming from, too ... somewhere around there.

P'cola FD

Alright DK I looked at my wire and tested again. My wiring harness has been spliced into, but it looks like the wire coming out of the harness is black.
I did the test with both leads on the MEN terminal and got nothing.
I did it with the positive on the MEN and the negative to ground and turned the car on. The voltage jumped to 12.6 and then went back to .4v. The manual say that after you tap on it, you have to turn the key off and then on again to retest it. That could explain why tapping it is useless. DK, if you have any sensors left over would you hook me up?
Anybody, could I have a problem with my knock sensor and not get a code?

DK

iTrader: (5)

Danny, I don't have any sensors left over ... sorry. A friend in Okinawa sent one two months ago and it never made it ... I had another coming a couple weeks ago that I don't know what happened ... and finally I got one from Jedon yesterday. If the one from Oki ever shows up, I'll hook you up ... but I'm not counting on ever seeing it.

I'll put the wires together and try some tests and see if I get anything different than you did.

DK

iTrader: (5)

SOmetimes my head doesn't work, especially when it comes to car electronics. I think that the ( + ) goes on MEN terminal and the ( - ) should be grounded. Now if i only knew which one the MEN terminal was ... I'll find it in the book somewhere one day.

paw140

P'cola: When I tried to test my sensor, (positive lead on the MEN terminal and negative to ground), I got battery voltage right when I turned on the ignition, and then it went down to .04 volts after a second or two. Tapping on the engine did nothing. It seems we're getting the same results, and my knock sensor should be good.

DK: MEN terminal is in the diagnostic port, the same port where the TEN and GRD terminals are. They're all labeled.

Tim McCreary

I have not done the test yet as my engine is removed. I believe the terminal MEN should have the red probe connected. The black probe connect to a good ground. The TEN and GND need connected with a jumper wire. Turn the ignition to ON and after everything settles down, take a hammer and tap the engine mount. If the sensor is working properly, there should be a change in state of the voltmeter. I assume the signal would be in volts. Check it this way. If not, then check in OHMS. The only thing you would look for is a change in state. If you are at .4v, it should jump up to 5-12 volts. Some digital voltmeters (cheaper models) will not show the state change due to the miniscule timeframe of the change. If this is the case, an older dial indicated meter would work better.

Try this and see. Even though the jumper wire is connected to GND ground, don't use this. Once connected to TEN, there is voltage corruption. Use the engine block or somewhere close to the sensor or use the negative terminal of the battery.

Tim

PS Page Z-112 if you have the small version of the manual with the wiring diagram. If not, the top row has 4 holes starting from Left to Right FEN MEN TEN +B The next row Starts with GND just under FEN and slightly to the left.