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View Full Version : Maf causing knock sensor code theory


mr.nismo.
11-03-2013, 04:54 PM
Ok. So.... When I first swapped my sr in I kept getting code 34 for knock sensor. I took a wild guess and got my single cam KA maf and swapped it. Code went away and that was it. Well recently I had multiple breaks in my harness from being old, etc, and fried my ecu. I bought another E5 ecu, put in a wireing specialties sr pro tucked harness and new knock sensor since I had it laying around. Second I started it and went for first test drive it instantly bogged. Once warmed up it bogged till 5k then opened up. So of course I thought maybe knock sensor was throwing code and sure enough it was. I reset ecu and turned it back on for 15 seconds then checked again and it was back. There were tons of breaks in my old harness and the pin that fried on the ecu was for the ignition so it could've been anything. But from my past experience could maybe this maf got shorted? I'm not around any other 240's to test so I'm just taking a stab again but consulting before I buy another maf

mr.nismo.
11-03-2013, 09:27 PM
Any ideas anyone? I've got another maf on the way but other ideas are always great.

DMMonroe
11-03-2013, 09:41 PM
Hope you figure it out. I had code 34 and replace the knock sensor but still getting code. After seeing this ill try a new/differnt MAF.

OnTheChip
11-04-2013, 10:52 AM
Code 34 is specific to the knock sensor and has nothing to do with the MAF.

mr.nismo.
11-04-2013, 11:06 AM
So brand new knock sensor brand new harness and the fact my old maf caused this problem before, you have any other ideas? Considering with my old ecu was in I had code 55

OnTheChip
11-04-2013, 11:23 AM
So brand new knock sensor brand new harness and the fact my old maf caused this problem before, you have any other ideas? Considering with my old ecu was in I had code 55

That was either a coincidence, or a harness problem that went away when you jiggled the harness changing the MAF (just a guess).

mr.nismo.
11-04-2013, 11:25 AM
I guess well find out when the new maf gets here lol. I'm wondering if the maf got fucked up when the harness shorted. Idk what wire fried he ecu but if the maf wires are what did it maybe it fucked it up

mr.nismo.
11-06-2013, 05:51 PM
Ok well it didn't fix it this time. Replaced maf, cleared so ecu flashed 55, start up for 10 seconds, recheck codes anddddd code 34 :-/ it's a fuckin new sensor and new harness. It instantly throws the damn code when the engine is turned on. Da FAQ man... It wasnt throwing a code on the other ecu

rellik27
11-06-2013, 06:09 PM
try another knock sensor, could just be bad even though its new.

mr.nismo.
11-06-2013, 06:15 PM
Just weird that it would work and be ok before and now not work.

RedtopTech
11-09-2013, 06:36 PM
Did you tighten the sensor bolt to spec? Not only will the torque have a drastic effect on knock sensor voltage ooutput but it is also very easy to damage the sensor by overtorquing

mr.nismo.
11-09-2013, 06:56 PM
Enough to not overkill it but enough to where it won't move. I clocked it at 9 like the other one was

GeneStarWindGSW
11-09-2013, 07:16 PM
I've had issues with new KS going bad. Make sure its a genuine OEM knock sensor (hitachi/nissan). it never came back after putting the right knock sensor on. Also overtorque can cause issues/break your KS.

last resort, this works also (did this on my last s13)
How to Bypass Knock Sensor. S13 Ka24DE OBD1 - Nissan 240SX Forums (http://www.240sxforums.com/forums/ka24de-ka24e/149395-how-bypass-knock-sensor-s13-ka24de-obd1.html)

mr.nismo.
11-09-2013, 07:19 PM
I don't think it's an oem sensor. I guess I should replace it with one. I know I can do the resistor trick but I'm a little sketch about doin it

ultimateirving
11-09-2013, 07:24 PM
I don't think it's an oem sensor. I guess I should replace it with one. I know I can do the resistor trick but I'm a little sketch about doin it

Just by pass it pussy. It's easy and you don't need the knock sensor. BY the time the Ecu retards the timing from detecting knock it's probably too late anyways.

mr.nismo.
11-09-2013, 07:25 PM
Just cause I eat pussy doesn't make me one ;) but agreed and I guess if it's off by 4k it's kinda useless anyways

mr.nismo.
11-11-2013, 05:51 PM
Checked KS voltage. 4.8 in and none out. Dafuckkkkk. Guess I found the issue

muhammadki
11-12-2013, 12:44 AM
I had code 34 and replace the knock sensor but still getting code.http://esmallgame.com/11c.jpg

mr.nismo.
11-12-2013, 01:09 AM
Check your harness? Mine was a new (not oem) and it went out