jtabraham

iTrader: (46)

So for the past couple weeks my check engine light has been on with a P0328 Knock Sensor code.

This afternoon, I replaced both the knock sensor and the knock sensor harness. I re-assembled everything (lower collector, lower and upper plenums and tried restarting.


For the first 2 seconds, everything sounds normal; then an incredibly loud medium-to-high pitched shrieking noise comes on. The revs start to drop as the engine struggles to stay on, and then it shuts down. If I tried to give some throttle, the engine doesn't respond, the noise continues and the motor shuts down.

Anyone have any idea of what this could be? Fuel issue? Vacuum issue?

Thanks,

Jason

z2g

iTrader: (20)

got a vid?

ZU L8R

iTrader: (84)

vacuum leak

jtabraham

iTrader: (46)

I'll try to take a vid this afternoon if I can find my camera.

ZU L8R. Is a loud noise like that typical of a vacuum leak? Could the same thing happen if I mismatched the vacuum lines?

Thanks

jtabraham

iTrader: (46)

Well...I took apart everything again, and made sure to clean off the gaskets, and re-tighten all bolts according to the FSM again.

Started the car up and...success??! No more loud noise....wish it was that simple though.

I shut the car down to bolt back the strut bar, and to clean up. Went to restart the car again to go for a drive, and the check engine light came on and the car was in limp mode. Ugh...back to square one and exactly where I was before I started this little project.

I don't have a scanner, and I can't make it anywhere in limp mode, so I can't be sure if I'm getting the same knock sensor code. Since this is exactly what I was going through all last week, I assume it's still the same P0328 code for the knock sensor though.

I've tried the ECU reset procedure about 3 dozen times today, and it just isn't working. I was resetting it fine all last week, but today it just won't do it. Not sure if there is another safety system that is preventing me from resetting, or if it's picking up the code again immediately after the reset.

Aside from towing to the dealership, I'm not too sure what else I can do.

xxbrokkxx

Do you happen to have a Kinetix Plenum? I once learned to actually use torque specs and i cracked my plenum before. Really hard to notice but i doubt you will crack the stock manifold, but yeah once i cracked mine sounded like baby's scream.

Z1 Performance

iTrader: (564)

I would go back over the plenum install and ensure the lower collector and lower plenum are sitting squarely. You've got a major vacuum leak going on, hence the limp mode and noise. The codes should indicate random misfires as a result (my guess)

jtabraham

iTrader: (46)

Yep, I did that yesterday, cleaned off the gaskets and ensured everything was seated properly (the fist time around, I probably over-torqued the bolts on the lower collector). When I reassembled everything, the noise was gone and the engine was running smoothly for the few minutes I had it on; which makes me think that I corrected the vacuum leak.

The problems only started after re-starting the car for the second time yesterday. The CEL came back on, the car immediately went into limp mode, and as much as I tried, the ECU reset procedure would not do anything. Even in limp mode though, I noticed that the car was idling much smoother than it has in a long time and after listening to the motor, I couldn't hear anything out of the ordinary.

Could it be possible, that I corrected the issues and the CEL just needs to be reset?

zen350z

Did you forget to plug a sensor in after unplugging it to pull the plenum? also Id try pulling the cables off the battery and let it sit for a bit, then plug it back up and see if the light comes back on. Just double check with a fine eye all the connectors on the plenum and surronding sensors like MAF-s if you had taken that off.

jtabraham

iTrader: (46)

Update:

SO i got everything taken care of on Monday but forgot to post earlier.

After everything, I don't think my knock sensor or knock sensor harness was faulty at all. I checked the old sensor against the new sensor for resistance and continuity, and got identical readings. I did the same for the old harness vs. the new, and got the same results there. Either way, since I had the new parts, I figured I would do the replacement.

As Adam from Z1 and ZU L8R pointed out, I had a vacuum leak after reassembling everything and they were correct. I removed everything and re tightened all the bolts and the leak and subsequent noise disappeared.

After resetting my ECU by unplugging the battery for 24 hrs, I took it down to Autozone to get the codes read (no CEL on). This time I was getting a P1121 Electronic Throttle Control Actuator code, so I got that throttle actuator assembly replaced and it fixed the issues.

Looking back on everything, I think this is what may have happened: My CEL may have been coming on not for a faulty sensor, but because I was truly getting excessive knock in the engine. Perhaps I got a hold of some bad gas, because a faulty sensor and the P0328 code should not have caused my CEL to turn on (The dealership told me this, and I verified it in the factory service manual, Page EC-297).

The throttle actuator may have been an underlying problem that Autozone's code reader didn't pickup on originally, or I may have damaged/shocked it during disassembly (although I was extremely careful with it).

Either way, it's good to have my car back to normal.

Thanks for everyone's help!