How to rewire knock sensor wire? - 4agze

**mookschank** · 21-07-2012, 10:20 AM

Howdy,

Been having a problem with my AFM 4agze in that it bogs down (& jerks) at low revs, where I have to rev it out at times to get it moving, at higher revs it's fine. I noticed on deceleration popping from the exhaust which is unusual I guess for a pretty stock setup.

The engine is stock except for a 165mm pulley, late model supercharger & FMIC. I have checked the codes and the ECU is telling me everything is normal.

Why I think the knock sensor is the issue is that the KS wire was cut and a regular wire and bayonet fitting added to the last 15cm of the loom plus the KS plug was cut up and siliconed. I'm not sure if the ECU would tell me if the knock sensor is in degraded condition, possibly only working or not?

Now my question is, how to fix the KS and KS wire? I can buy a new KS from the US, but how would I fix the loom? I believe the cable is shielded, where does the outer sheath connect to - earth? Should I buy some coax and run from the KS right back to the ECU connector pin? Or should I rip a KS wire from pick a part and splice in? Is it possible to repair a the KS loom and splice in a cable? My electrical prowess is a bit limited, so any advice would be great....

(I'm also looking at the O2 being the source of the problem as well. I have already swapped around another ECU and AFM and hasn't made a difference).

Thanks for looking, cheers,
Mook.

**TERRA Operative** · 21-07-2012, 11:38 AM

You can just use stuff like this:
http://www.jaycar.com.au/productView.asp?ID=WB1500

The shield is connected to ground IIRC back at the ECU (the brown wires in your loom are the ECU ground, best to double check where it's actually connected). DO NOT connect the shield at both ends as you'll make the interference worse.
You can replace the whole lot if you're keen, but a splice job is acceptable as long as you make good joins (solder and heatshrink).

Also, how do the capacitors look in the ECU? Pretty much every ECU of this age needs new caps.
I can provide a set of new top quality Japanese capacitors (none of this Chinese Jaycar rubbish) for the cost of postage and parts, or do the swap for you.

**mookschank** · 21-07-2012, 04:23 PM

Thanks Jared,

Checked some dodgy (but helpful) 4agze wiring diagrams I have and yes the shield goes off to BR brown. I will see if I can splice straight into the existing cable, friend of mine is pretty good with electrical work so might get him to help. Should I keep the shield going up as close to the KS plug as possible? Will probably scour pick a part for a compatible KS plug as well...

**TERRA Operative** · 21-07-2012, 05:33 PM

Yeah, keep that wire shielded as much as possible. A few CM at the ends won't matter, but try to keep as much shield there as you can.

**JDM hachi** · 21-07-2012, 06:32 PM

when my small port 4age had a knock sensor problem, (due to a crush on the shielded wire which caused the knock sensor to have continuity to earth) it showed a code on the self diagnosis function. I fixed the problem, and got more power/driveability (as felt by the arse), by cutting the earth part of the shielded wire off of the earthing point, and insulating it. I still haven't suffered any problems yet, however i must state that this car is a hack, i thrash the piss out of it and smile while doing so , while it's slower than my other cars , it's just as much fun!
I'm feeling that your problem is not knock sensor (or ks as you put it) related, due to the codeless thing, so in my un-expert opinion, I'm gonna say afm or ecu. Also I always get smiles from cleaning out the TB, or throttle body.

Have you set your tps (throttle position sensor) at alll???

**mookschank** · 22-07-2012, 02:34 PM

Yeah I'm not sure it's the knock sensor which is the problem. However I have swapped out the ECU and AFM and also the TPS and also have set the TPS as per the manual up with the multimeter. I've also cleaned out the ISC on the throttle body which was typically gunked up with muck...

I'm running out of potential causes, so thought as the knock wire install was pretty dodgy, thought it would be good to do.

Is there any way to test an O2 sensor for being in spec?