Testing knock sensor?

[B_Man]

Is there any way of testing to see if a knock sensor is OK out of a car? Apart from normal cracking etc?

Multi-meter hooked up to it and it will display a voltage or anything?

Thanks all

[xsvpwr]

boostin said using multi meter one end attached to metal bit in middle of sensor and other end attached to plug, resistance should be >0.400 from memory (may be wrong figure). Then to understand if it's working under heat lightly clamp it in a vice and get your missus hair dryer and slowly heat it whilst tapping the vice gently with a hammer to see if resistance is changing....

All of that from memory so sorry if it's a bit off

[Guest]

 xsvpwr said:

boostin said using multi meter one end attached to metal bit in middle of sensor and other end attached to plug, resistance should be >0.400 from memory (may be wrong figure). Then to understand if it's working under heat lightly clamp it in a vice and get your missus hair dryer and slowly heat it whilst tapping the vice gently with a hammer to see if resistance is changing....

All of that from memory so sorry if it's a bit off

the most important thing to remember, dont get the missus's hair dryer covered in grease and crud from the garage lol, most of them dont like it for some reason.

-smurff

[Garryg]

Another stupid question!!

What does the knock sensor do??

Cheers

[marc]

listens out for detonation. If det is picked up sends signal to the ecu and ecu retards the timing..

[Pappu1]

 marc said:

listens out for detonation. If det is picked up sends signal to the ecu and ecu retards the timing..

couldnt have said it any better ;D

[gazzy2000]

 pappu']

[quote name='marc said:

listens out for detonation. If det is picked up sends signal to the ecu and ecu retards the timing..

/quote]

couldnt have said it any better ;D

yer, essentially it is a microphone that is designed to listen for a certain frequency, it retards timing if too much det is detected

here is some info http://www.clubsub.org.nz/forum/index.php/topic,7978.0.html

[Garryg]

I thought this may be the case!

I have problems with detonation and had the car in the garage a couple of times, neither has identified a fix.

Would it be worth changing this to see if it helps??

If so, where about is this positioned in the engine bay (B4 BE5)...

Just thought I'd add...I'm not getting any codes identifying a fault, but am at the desperate stage!!! Will try anything to get rid of the "pinking" issue!

Cheers

[Guest boostcut]

if you are getting a knock sensor fault code, its probably because your car is knocking its head off, more than it wants to listen to, then it will log a fault in the ecu. and because its the "knock circut'' its hardly going to log a fault for the afm.

[gazzy2000]

Maybe the best/better/cheapest solution in regards to pulling timeing to reduce the det etc would be to get an after market ECU... i.e. so you can tune to suit?

I mean you wudnt want to pay for a dyno sesh n reflash then get bugger all results aye.

Plus a after market ECU opens up possibilies for mods in the future.

The older generation possum links are fine (and cheapish... well cheaper than a G4 storm or the like)

I have a possum link insert in my gen3 BH (mine is not revision D, it is a C, but same compression ration)and its fine, got single turbo conversion done though. It was $700 and was luckily pretuned from another single turbo BH, so all i had to do was a road tune to pull the timing.

A full tune on a dyno isnt cheap but you were looking at getting one done with a reflash on your existing ECU anywho.

[gazzy2000]

dunno if these fit gen3 BHs http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Subaru/ECUs/auction-330197404.htm

but thats the sort of thing i was thinking about, youd still need to do a det listening test and air/fuel ratio test... on a dyno preferrably, but good tuners have the kit to do it on the road.

[Garryg]

Gazzy,

Thanks for the info....

The reflash & Dyno was around $1k, so willing to spend that on whatever will fix the problem.

Only thing is I don't know where to start! Even if I bought an aftermarket ECU, doesn't mean this will solve the problem either??

I spoke to Dave at torque performance and he said that the reflash should resolve the issue...

Open to suggestions!!

[Guest boostcut]

buy an aftermarket computer. just expect to spend another 1000 on tuning to get similar driveability as your factory ecu.

[gazzy2000]

i dunno man, i figure if its too far advanced timing causing the det, aftermarket ECUs have a large enough scale to adjust the timing to 'whatever' the engine needs.

Where-as a reflash may only pull the timing a certain amount and you cud end up deting under boost if timing isnt pulled enough.

An A/M ECU is way more flexible/tuneable for timing issues or any other issues i.e. fueling, ecconomy better power curves etc etc

[gazzy2000]

 Garryg said:

Only thing is I don't know where to start! Even if I bought an aftermarket ECU, doesn't mean this will solve the problem either??

Oh it will fix the problem alright (if indeed advanced timing is the issue), i am just thinking if you spent $1100 on a reflash and it didnt fix teh problem youd be guttered.

I base this thinking on the fact that ppl have said the reflash sometimes dosent fix the prob.

Where-as a second hand A/M ECU cud be anywhere from $500 to $2000 (depending) then the cost of a tune and the knowledge that if you have any other issues you can simply tune it out ;D

[gazzy2000]

@boostcut

what about those fuel and ignition controllers, the ones that tap into the factory ECU and are adjustable, that cud be a cheaper option (at the risk of confusing garryg lol)

[Guest boostcut]

theyre not really too controllable. a link is a far better option, if he decides he doesnt want it, he can sell "something" not like a reflash where you dont actually get anything for your money.

[gazzy2000]

yikes! they prolly sell these at 'the warehouse'

http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Performance/Electronics/auction-330765528.htm

[gazzy2000]

anyways man, truely.. i went through sooo much agro with the det issue on my BH and was no expert in the begining, it truely just about did my head in... i soo didnt want to make the wrong expensive decision, and FARK ME did i have the missus on my back :'( for a while there the only trips i got out of the Bh were guilt trips

But was lucky enough to bite the bullet and get the link, Problem solved!! EDIT: please read on... link ECUs are not the solution for rev D legacy detonation problem, mine IS a gen 3 but is a rev C with the single turbo conversion done and the det problems i encountered although similar are not applicable to a twin turbo rev d

Its fine as a daily driver, you wud not know any different infact the missus drives it not me

But yea, i feel your pain, you wud not regret a link!!

theres an old saying i just made up " if you want a job done properly.............. then do it properly"

Good luck

[gazzy2000]

dunno if you seen this already, a dude with the same problem in zimbabwe asking the same questions lol

http://legacygt.com/forums/showthread.php/detonation-help-subaru-legacy-b4-rsk-2002-145397.html

[Garryg]

Thanks for the advice!

I'll be spending the money anyway, so from all your experience, if a link is the best option for me then quite happy to do this.

Only thing is, with limited knowledge how easy is this to set up? Is it just the case of "plug and play"?

The other option to me was just the easier one....

Cheers

garry

[gazzy2000]

Fark it, i just rang NZEFI in CH-Ch (they are highly recommened down this way)

Please read Garry..

This is what he said:

- They said there is no Link ECU for the rev d,

- No link ECUs support sequencial turbo control

- said the det problem is rampant in the rev ds, they reflash heaps of them

- A reflash will fix your problem

- I said "I have heard that the reflash has not fixed the det problem in some cases" he said "all of their reflash tunes on the dyno have fixed the det on rev D leggys no worries, the problem lies if the reflash is done for 98 fuel and the customer goes and run 95 octane OR if there is something unforseen causing the det, this is uncommon"

- I said how tunable are they when reflashing, i.e. with links you can keep pulling the timing until the det is gone" he said "they just keep reflashing until the problems are fixed and they are happy, so yea they are very tunable just not by conventional means, but the result is very much the same"

- He said " some times we have to reflash 30-40 times to keep pulling the timing, that is normal, but we dont let you drive away until it is spot on"

- he said "they can tune for 95 Octane but it takes a little longer

- they fully recommend a 98 octane tune

- their price was $1152

So there we go, i learned something (will delete my last post)

To summarise, as long as the tunner you go to is as good as these guys sound, a reflash is the way to go.

I humbly appolgise if i have miss led you on this matter but feel we have a solid answer to this now.

[Garryg]

 gazzy2000 said:

Fark it, i just rang NZEFI in CH-Ch (they are highly recommened down this way)

Please read Garry..

This is what he said:

- They said there is no Link ECU for the rev d,

- No link ECUs support sequencial turbo control

- said the det problem is rampant in the rev ds, they do heaps of them

- A reflash will fix your problem

- I said "I have heard that the reflash has not fixed the det problem in some cases" he said "all of their reflash tunes on the dyno have fixed the det on rev D leggys no worries, the problem lies if the reflash is done for 98 fuel and the customer goes and run 95 octane OR if there is something unforseen causing the det, this is uncommon"

- I said how tunable are they when reflashing, i.e. with links you can keep pulling the timing until the det is gone" he said "they just keep relashing until the problems are fixed and they are happy"

- He said " some times we have to reflash 30-40 times to keep pulling the timing, that is normal, but we dont let you drive away until it is spot on"

- he said "they can tune for 95 Octane but it takes a little longer

- they fully recommend 98 octane

- their price was $1152

So there we go, i learned something (will delete my last post)

To summarise, as long as the tunner you go to is as good as these guys sound, a reflash is the way to go.

I humbly appolgise if i have miss led you on this matter but feel we have a solid answer to this now.

GAzzy...your a star! Much appreciated..

No problem with your previous advice...ur only trying to help!

A Big Thanks...

[gazzy2000]

 Garryg']

[quote name='gazzy2000 said:

Fark it, i just rang NZEFI in CH-Ch (they are highly recommened down this way)

Please read Garry..

size=3]This is what he said:

- They said there is no Link ECU for the rev d,

- No link ECUs support sequencial turbo control

- said the det problem is rampant in the rev ds, they do heaps of them

- A reflash will fix your problem

- I said "I have heard that the reflash has not fixed the det problem in some cases" he said "all of their reflash tunes on the dyno have fixed the det on rev D leggys no worries, the problem lies if the reflash is done for 98 fuel and the customer goes and run 95 octane OR if there is something unforseen causing the det, this is uncommon"

- I said how tunable are they when reflashing, i.e. with links you can keep pulling the timing until the det is gone" he said "they just keep relashing until the problems are fixed and they are happy"

- He said " some times we have to reflash 30-40 times to keep pulling the timing, that is normal, but we dont let you drive away until it is spot on"

- he said "they can tune for 95 Octane but it takes a little longer

- they fully recommend 98 octane

- their price was $1152[/size]

So there we go, i learned something (will delete my last post)

To summarise, as long as the tunner you go to is as good as these guys sound, a reflash is the way to go.

I humbly appolgise if i have miss led you on this matter but feel we have a solid answer to this now.

GAzzy...your a star! Much appreciated..

No problem with your previous advice...ur only trying to help!

A Big Thanks...

My pleasure, happy to help, please do let us know how you get on

[Garryg]

 gazzy2000']

[quote name='gazzy2000 said:

Fark it, i just rang NZEFI in CH-Ch (they are highly recommened down this way)

Please read Garry..

size=3]This is what he said:

- They said there is no Link ECU for the rev d,

- No link ECUs support sequencial turbo control

- said the det problem is rampant in the rev ds, they do heaps of them

- A reflash will fix your problem

- I said "I have heard that the reflash has not fixed the det problem in some cases" he said "all of their reflash tunes on the dyno have fixed the det on rev D leggys no worries, the problem lies if the reflash is done for 98 fuel and the customer goes and run 95 octane OR if there is something unforseen causing the det, this is uncommon"

- I said how tunable are they when reflashing, i.e. with links you can keep pulling the timing until the det is gone" he said "they just keep relashing until the problems are fixed and they are happy"

- He said " some times we have to reflash 30-40 times to keep pulling the timing, that is normal, but we dont let you drive away until it is spot on"

- he said "they can tune for 95 Octane but it takes a little longer

- they fully recommend 98 octane

- their price was $1152[/size]

So there we go, i learned something (will delete my last post)

To summarise, as long as the tunner you go to is as good as these guys sound, a reflash is the way to go.

I humbly appolgise if i have miss led you on this matter but feel we have a solid answer to this now.

GAzzy...your a star! Much appreciated..

No problem with your previous advice...ur only trying to help!

A Big Thanks...

My pleasure, happy to help, please do let us know how you get on

I'll need to come down to CHCH.....

Just been quoted $1697 in Auckland for the same thing (Torque Performance)

Anyone else know where to go?