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Pfc Knock Values


Fry_33
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I was just curious as to what everyone's knock levels are like with a PFC. I know they will all vary from car to car but at least it's a bit of a guide.

I want to know cause my car at idle will see a knock value of 10-15. The ign value is only at 15deg for the idle map position.

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I have a front mount, bleed valve @ 12psi, Stock Turbo, 3" Front/Dump Pipe & CAT back, Splitfires, newish fuel filter, and air filter.

I was hoping to advance the timing around the lower section of the map as it wasn't touched ign wise in the tune I got. I was checking the knock before and it was a lower, it seems to fluctuates a bit, more than I'd like. If I blip the throttle it will more often than not go into the 10-15 knock range.

Before I start going looking for problems that aren't there I thought I'd check a few settings.

What Idle speed are you guys running? What are your settings in the rev/Idle screen? Don't get thrown by the second setting as it's an FC PRO.

Mine are this (Air Conditioning is OFF):

post-13456-1190453850_thumb.jpg

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According to the workshop manual I have the idle should be at 650rpm, mine sounds like if it went to much lower in revs it'd stall. Do you have a description for all of the actual settings on the Rev/Idle screen? I couldn't see it in the FAQ.

Maybe my timing light isn't working fantastically but when I check the timing, by letting the car warm up and then removing the lower brown plug from the TPS, the marks are jumping about. I can't get a confident reading. I was getting the signal from the large white wire going to Coil 1.

post-13456-1190456011_thumb.jpg

I tried to take a picture with the camera to see if it could pick up what was going on. I ended up getting one pic to work but because I can't replicate the photo I am still not 100% convinced. it appears to be about 13deg BTDC.

post-13456-1190455454_thumb.jpg

My ignition value at idle, and in that entire area are the standard values that come with the PFC.

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Map trace shows that it is using the usual location for idle.

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Thanks.

Edited by Fry_33
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Hey man,

Nice work with the photo's, you should get some good responses. I cant help with specifics but..

Knock at idle - cylinder fill / chamber turbulence is so poor, even if you did get a proper knock, the peak pressure seen would be harmless. That non effect plus the car to car variance you pointed out, plus general mechanical noise, means i wouldnt worry too much about idle knock levels. Id go so far as to say that <20 is a non event.

I set the idle speed as low as it will go before stalling (too low and the stepper valve wont catch the falling revs though)

I find using a timing gun on a RB often gives sketchy results. Have you tried using the stray black wire up the back of the head for a reading?

As for details on PFC particulars, paulr33's Resources are fantastic

Hope Iv helped, Good Luck

Edited by GeeTR
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what else tells you its a pro version? didnt know there was one for the GTST.

looks to me the f/c AC OFF is set to 7370, i thought that should be set to around 1200 and the ON 1300, that controls when the fc returns fuel to catch the idle!

as far as idle goes the fc is 900 from the factory and thats were mine is!

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The second line in the Rev/Idle screen is the Launch Control RPM. If the car is doing zero kmph then it will cut the ignition at the RPM value set here. I am not using this function yet as I still have my standard ceramic turbine wheel so don't want to unnecessarily punish it. I will eventually.

I didn't realise til now there was an english version of the FC Commander manual (RX7) around, going by that it says the following.

3rd line is: F/C A/C ON = Deceleration fuel cut recovery RPM setting when Air Cond. is ON

4th line is: IDLE A/C OFF = Sets idling RPM level when the air conditioning is OFF

5th line is: IDLE A/C ON = Sets idling RPM level when the air conditioning is ON

I'm sure I read somewhere once that there is somewhere else to set the actual F/C A/C OFF value in a different screen.

It looks like I might just set the idle to 900 and see how that goes.

I've never looked so I may as well ask where are the knock sensors located? Is there any point in having a look at them. Can you clean them? don't think so just thought I'd ask.

Is there any common engine bay noises that have been known to show up as knock?

I was finally able to get a steadyish reading using the timing light. Appears to be around the 13-14deg mark like the photo shows, probably closer to 14 than 13. My CAS is quite advanced as I have an exhaust cam gear that's retarded 4 deg.

post-13456-1190470535_thumb.jpg

Edited by Fry_33
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I have had another look at the knock levels today. I was able to look at what happens when it was cold when started. It started up and was at around 1200-1300rpm and knock was 1-2 which is good. As it started to warm up it the revs dropped down and I started to see the knock values rise, 10-14. Once it finally settles around 900-950 rpm the knock values lower to around 5 max.

I am noticing the noise of my timing belt more at idle and it gets slightly louder at about 1000rpm. Maybe the noises by the timing belt drive are being picked up by the knock sensor. I was living with the noise of the timing belt as it was only intermitent but I think I will retension it next weekend.

I have read some of the info on here about changing the timing belt. I don't need to change the water pump, idler and tensioner as that was all done with the belt by a workshop. I think I need to remove the Harmonic Balancer to retension the belt but I was wondering if you can work around it. If not, I'll just have to get a puller.

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Thought I would post my Q in here, to keep the Thread Numbers down so,

Car was tuned about 3-4 weeks ago. 1 time i did see it knock above 50,but the rest of the time, It never goes over 20. It was a really hot day today. and I filled up with Ultimate 98, at Warwick, before heading back to brisbane.

When i gave it in 2nd. I noticed my knock went up to 118!!. its never ever been that high before. After this instance, i see normal driving and idle knock is higher than it used to be. I am asuming the fuel that was put in, was crap. But I mean Im really worried that this instance of high knock- Detonation, has possibly damaged the engine somewhat. I believe my tune may be too advanced for this heated summer.

Can anyone give me some insight, into if it should be still ok, or what I can do about it.

Have they seen their knock go up that high, and its been ok?.

Am I looking at a tuning issue. And If so, could there have been damaged caused.

really appreciate any responses.

cheers,

dale

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ok cheers, yea I actually took it all the way back to 0.3 bar. to be safe. as i noticed anything over 0+ now and it knocks like crap. got to about 5 psi in third and saw a knock of 36! and it never would go over 20. so yea a little worried.

Im runnin all the fuel out and will refull asap and see how it goes, and rule out fuel as the issue.

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it shouldnt knock at idle

some cars do dont worry. some cars with differrent drivetrain components will knock to 15-25 on start up.

ie changed a clutch and it starts picking up the plates on startup.

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yeah thats more attributed to mechnical noise which is ok and acceptable

but no car should be detonating/pre-igniting at idle

exactly and this guy is getting 10-15 which aint pre ignition or detonation.

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Thanks for the responses guys.

I am thinking it is just mechanical noise as it varies quite a bit. At idle it will sometimes be 1-3 and at others 5-10.

I blipped the throttle at idle the other day and got 18 knock, reset the values tried to do the exact same thing a few times and the most I got was 6-8.

My timing belt is noisy at the moment and I was hoping to retension it on the weekend and quieten it down. One of the threaded holes in harmonic balancer was stripped so couldn't use the puller I had and I ended up running out of time. So I put her back together without achieving anything.. very frustrating! Will try again in another fortnight when I get a chance.

I have recieved FC-Datalogit and was able to connect it up. I haven't had a chance to try anything with that yet.

Seeing as how Paul and Jono might read this (others will know too), what is the difference between advanced Knock and basic knock on the PFC.

If I was to use Datalogit and log the knock values would I be safe in assuming that if the average knock levels are fine then the max knock values for the cells can almost be ignored as they could be caused by outdie influences. I'm assuming that if there was detonation then there would be tuning factors causing this and it would occur frequently and therefore the avg value would be high.

Thanks again guys.

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