Knock sensor -engine light coming on after 2 mins of running

[Rumbul]

Hi guys I am trying to find the fault that is causing my engine light to come on after the engine has started and run for a few minutes . It's a jspec stock standard vr4 and I just rebuilt the engine .

It's got new coils and plugs and the injectors were cleaned also.

Any ideas where to start ?
When I drive it , it seems to struggle a little bit before boost comes on .

 

[micky_vr4]

Have you tried checking the diagostic code?

When I drive it , it seems to struggle a little bit before boost comes on .

You mentioned knock sensor, is it the above which makes you think knock sensor?
Maybe O2 sensor not warming properly and giving faulty readings...

But first things first, check http://www.vfaq.com/index-main.html for how-to guides and then go from there

 

[Rumbul]

Sorry yeah diagnostic code is telling me its the knock sensor .

 

[blackvr]

Probably damaged the sensor wiring loom while you had the engine removed.. or is it just not plugged in. Its pretty common when removing the engine to forget to unplug the knock sensor, stretch the loom, before realizing it has to be unplugged. Carefully check the pins and wire loom.

 

[CLuTZ]

These cars are getting old now... I wouldn't rebuild a motor without a fresh knock sensor. Phantom knock can seriously hold your car back when it retards the timing. I replaced the sensor on one of my old Galants and from the seat of the pants dyno I reckon I picked up about 25kw atw.

Pull the sensor- it's on the back of the block under the intake manifold. If it looks like this- you need a new one!

It should look like this:

 

[Marc]

Yeah just realised with mine fresh engine, needs new knock sensor, looks not as bad as the one CLuTZ posted above, but still borked.

Where do you guys get yours from?? Meek wanted $198!!??! Looking at getting from US for bout half the price +$20 postage.

Whats the diff from a 1g and a 2g sensor, i seen somewhere you can do a straight swap as the 2g communicates better or some shit?? Any truth to this fellas??

 

[BMGTZ]

also check that the sensor is in the correct position on the block. There are two threads it will fit into....dont put it it the bottom one

 

[Marc]

Yeah in between 2 & 3 clyinders but near the head

 

[BMGTZ]

is it tight?...tight ....but not as tight as the nuts on the harbour bridge?

after one rebuild where the block was acid dipped and then painted..... we ran a tap ionto the thread and cleaned out the paint but the sensor worked loose in about 50k and would light up the check light. retensioned ...all good

 

[Marc]

yeah at first it wasn't that tight, then tightened it up good and proper, still very flat performance.

the rear had a small bit of the screw exposed, knew it had a good chance of being fucked, tried anyway just incase.

 

[Rumbul]

I have a new knock sensor coming later this week . Hopefully that fixes it . My new front bumper just arrived from Nz and is being painted so I can fit it up today . So she's all finished ready for some engine running in kms then I will fit my Garrett 28rs and see how she goes .

 

[Marc]

I ended up buying a 2nd hand job because i'm impatient, and it worked a treat, no more sluggish/flat performance, now it really responds well coming on boost.

 

[Rumbul]

Woohoo jst fitted my new knock sensor and the light isn't coming on anymore and it drove perfect . Managed to get the final parts of a fellow forum member in Brissy , now it's time for a road worthy , rego and some run in kms !

 

[blackvr]

Hope you had fun replacing it LOL Not my favourite job...

 

[Rumbul]

Hahaha I only had to chop up a 24 and 27mm spanner to half size and stretch my arm out !!!

 

[Marc]

Why the 27mm??

I'm lucky in some way, that i don't have aircon, and mine is FWD, so i could just slide under the car and reach up and undo/replace it. But i ended up just hacking a cheapo 12 inch shifter down instead of chopping up my good spanners. Either way, not a job i feel like doing again in a hurry, i feel for you bloke with A/C and AWD.

 

[Rumbul]

The old knock sensor that came out was a 27mm . Yeah it was tough getting the arm in there, ripped the started motor out to get better leverage .