Cut Knock Sensor Common?

[volcomtruck]

hi!

A friend and I were trying to resolve a issue with missfire at 4.5-5.5k rpm and we tried a ecu diagnostic, coming up with error 34 (knock sensor)

we had already inspected the coil packs for cracks etc (http://www.skylinesaustralia.com/forums/Missfire-Boost4500-5500-t32356.html)

so we had a look at the knock sensor sub harness and it was cut (intentionally by the looks of the cut) so we decided to solder it back together (both copper and outta shielding) and see if we could get that error code fixed.

now when we start the car, it idles normal (800rpm), but as soon as i touch the accelerater it splutters and sounds terrible / undriveable.

read around and is the ecu going into safe mode R&R? i wasn't getting this issue before i repaired the harness. still error 34 after resetting the computer (press brake 1 minute neg off battery)

so we revert to putting the knock sensor back to normal and cut it with plugs left in sensors/loom like before, but still same issue (obv not smart but worth a try)

would leaving the negitive off for 48 hours fix the issue? (advised by a friend)

buy genuine harness from nissan with 2 new sensors as my ones are prolly faulty?

are the knock sensors sub harness usually disabled/cut on standard or upgraded r32's for any reason?

my car is r32 gts-t 1989 stock boost 10psi / exhaust / walbro 550 / FMIC

any suggestions would be great thanks

[mosquitocoils]

I can't think of a reason to cut a knock sensor... I would probably try getting new sensors, or if possible, try and diagnose the condition of the current ones (if there is a way).

Leaving your negative off for 48 hours is doing exactly the same thing as dc-ing your battery and applying the brake - it means that there's no charge left in the battery at all, so there's no point doing that if you've already done the brake thing.

[volcomtruck]

I can't think of a reason to cut a knock sensor... I would probably try getting new sensors, or if possible, try and diagnose the condition of the current ones (if there is a way).

Leaving your negative off for 48 hours is doing exactly the same thing as dc-ing your battery and applying the brake - it means that there's no charge left in the battery at all, so there's no point doing that if you've already done the brake thing.

thanks for the reply, what has happened is the connector from one of the lines of the sub harness became detached when installing, so we fixed that and did another ecu test.. code 55 All OK !!

only thing is the symptoms are still occuring, is it just coinsidence that the knock sensor repair had given me terrible stuttering and when i rev it to 3.5-4rpm im getting vaccum the whole time, no boost?

We actually had changed the fuel pump to a walbro 550 hp pump that morning, so possible a faulty fuel pump??

so i hope that with the bigger fuel pump its pushed a lot of crap into the fuel filter so im going to get it replaced now.

anyway ill have a hunt around the forums since i think i know what the issue is now and get some ideas

one step at a time

cheers