Knock Sensor Went To 75-help

[700HP-GTR33]

Hello all,

On the freeway tonight going slightly up hill I put my foot down in fourth gear.

As increasing speed the car started to jerk like a mule and the engine light flickered on and off for about 2 seconds.

Looked at the PFC handcontroller and had 75 reading on the knock sensor.

I have been having some mis-fire problems and it has lead me to believe I have a faulty AFM.

Just wanted to know if it could be something else ie TPS(Throttle position sensor)?

Any ideas?

Thanks in advance

Tekin

[tridentt150v]

Fuel starving?? Pump maybe?? This would make it lean out and increase the knock.

[paulr33]

have a read of the powerfc faq in my signature

covers all of the common questions and howto's for working with knocking problems.

i don't believe its a any of those and just a few points have some timing thats a bit too advanced.

in the warmer weather its knocking a bit more and also when you place the car on load, typically when rpm is low and you up are going up a hill youll find via map tracer

that you may be going into map areas that you dont often go into, or that haven't been tuned correctly

as its hard to go over the entire map on the dyno and cover all scenarios, so it could just be 1 or 2 spots with a bit too much timing

[SXR]

yeah i think the timing is abit advanced but jerking like a mule could be anything...im guessing plugs or coil packs.

[Cubes]

With regards to misfiring.

I and Bl4ck32 have coils that are on their last legs, we have both observed increased knock levels when the misfire occurs. Not always but often.

[700HP-GTR33]

Thanks for the replies boys,

New Pump,new regulator,new coils ,new plugs..........

I do suspect it to be tune or Afms playing up.

Still missing everyday even after earthing the ignitor.

But then again could be a few things.

[paulr33]

use temp ign adjust (covered in the faq on how to use it)

and take out 3 degree's timing, see if you still have the same problem

[700HP-GTR33]

use temp ign adjust (covered in the faq on how to use it)

and take out 3 degree's timing, see if you still have the same problem

Ok for you to say....suppose I'll give it ago.

Cheers

[paulr33]

MAIN MENU

SETTING, IGN/INJ

PRESS DOWN 3 TIMES

ADJ for IGN COR will change to -3

Try and drive around and see if you can replicate the knocking / misfiring.

When you power the car off this correction goes back to 0 (zero). This is by design and how its meant to be. It's here as a test/tune mode and not meant to be a permenant correction method.

[700HP-GTR33]

MAIN MENU

SETTING, IGN/INJ

PRESS DOWN 3 TIMES

ADJ for IGN COR will change to -3

Try and drive around and see if you can replicate the knocking / misfiring.

When you power the car off this correction goes back to 0 (zero). This is by design and how its meant to be. It's here as a test/tune mode and not meant to be a permenant correction method.

I will give it a go tonight on the way home and in the morning tommrrow.

Thanks Paul........just about to ask you what number in the FAQ...bit confused.

[paulr33]

yeah whilst there is no "heres how to temp ign adjust" in the FAQ its covered in there. the problem is theres no english manual thats upto date so you either have to use the old school rx7 english manual or the japanese one

[700HP-GTR33]

So the Adj: Reading should read -3 when I enter or +3.

[Cubes]

Minus is minus.. So you need minus 3 degree's.

[paulr33]

-3 means 3 degrees retarded timing

+3 means 3 degrees advanced timing

to help combat knocking, you can try and take out some timing (retard) to see if it takes away the knocking (usually does). try -3 which is 3 degrees retard across the whole map

[tridentt150v]

I've had readings of 95 knock, but no miss. So how does a reading of 75 end up with a miss?/? You have to be rattling your motor to bits to get a miss when pinging. Guessing here, but I'd reckon readings heaps higher than 100. I've had motors where I have had it, and they where knocking very loud, like a rattle.

By the way, you won't do any damage as long as you:

1. Don't hold it there, or push on.

2. Get it fixed promptly so that it doesn't happen again.

3. Use a trailing throttle when going up steep hills etc keep the load off the car [although if you retard the ignition by 3 degrees then you'll have to still try it again to see if it's fixed it].

I'd be interested to see if it solves the whole problem. Maybe the 'lean out' has shown up another fault only showing up under stress?

[Cubes]

I've had readings of 95 knock, but no miss. So how does a reading of 75 end up with a miss?/? You have to be rattling your motor to bits to get a miss when pinging. Guessing here, but I'd reckon readings heaps higher than 100. I'd like to learn.

By the way, you won't do any damage as long as you:

1. Don't hold it there, or push on.

2. Get it fixed promptly so that it doesn't happen again.

3. Use a trailing throttle when going up steep hills etc keep the load off the car [although if you retard the ignition by 3 degrees then you'll have to still try it again to see if it's fixed it].

I'd be interested to see if it solves the whole problem. Maybe the 'lean out' has shown up another fault only showing up under stress?

The Op's has been having a miss problem; likely to be related to ignition. Your ignition system clearly is perfectly fine and your det is simply too much ign.

As I mentioned with shagged coil packs on 2 different cars I have observed an increase in knock over what was before a perfect low knock tune in all conditions.

Most likely not the case here and most likely just a tune issue. But I thought it would be usefull to mention it.

75knock really is too high, might be worth taking the car back for a touch up as a load condition may have been missed when it was on the dyno. It is difficult to simulate road conditions on a dyno; which is why its so important the tuner takes it for a quick spin. From what I've seen the dyno tends to miss partial throttle on boost load points and low rpm high gear (up hill) lugs where it makes reasonable boost; even though on the dyno we did hit these load points on the road it was 'just different'.

[paulr33]

yeah it will be timing related

i saw 65+ the other night

take out 1 deg timing and it drops to low 20's

so a few deg's can make a bit of difference

[paulr33]

also tekin, when you are seeing these knock levels what is airtemp under monitor? you can set ign retard in the PFC based on airtemp's but its only for 70, 80, 90deg plus. so if its 55deg theres no correction

[700HP-GTR33]

Thanks again guys for the remarks.....

Set back ign as paul indicated......car runs smoother and has not missed tonight.

Even going up hill i planted it and all was good...excellaration came on nice and strong.

Paul, can I set back the ign by -2degree permanently and see if it happens again?

Should I use one of your saved tunes instead and modify it to my mods?

And has the tune been conducted in colder weather and this is why this has happened?

Lots of question......

[paulr33]

gimme 5