Power fc knock reading ?
21 January 2007, 08:34 PM
#1
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Power fc knock reading ?
Ive only had my Impreza a couple of weeks and i'm not too familiar with the knock readings im getting on my fc commander.
I was led to believe that a reading of over 25 was bad,well ive just been out in my car and im getting readings of upto 75 but that wasn't even on boost !
What sort of reading is deemed as unsafe and why would I be getting such high readings when im not even on boost ?
Quick spec:
Hybrid fmic
550cc injectors
Apexi Power fc and commander
Apexi boost controller
GenII ceramic coated heaters and up-pipe
Hayward&Scott full system
I was led to believe that a reading of over 25 was bad,well ive just been out in my car and im getting readings of upto 75 but that wasn't even on boost !
What sort of reading is deemed as unsafe and why would I be getting such high readings when im not even on boost ?
Quick spec:
Hybrid fmic
550cc injectors
Apexi Power fc and commander
Apexi boost controller
GenII ceramic coated heaters and up-pipe
Hayward&Scott full system
21 January 2007, 08:43 PM
#3
Could be a whole host of things but 75 is very high.
A quick check would be to set the FC commander to Knock then press the enter button again to get the graph up rather then the digital display.
Go for a drive and see if the knock is a very sudden spike on the trace or if it is a gradual increase with RPM.
If it is a spike I would advise you get a tuner to check it with detcans to see if it is really knocking.
If it's a gradual increase, chances are somethig else is causing it i.e loose knock sensor or something rattling near to the knock sensor.
A quick check would be to set the FC commander to Knock then press the enter button again to get the graph up rather then the digital display.
Go for a drive and see if the knock is a very sudden spike on the trace or if it is a gradual increase with RPM.
If it is a spike I would advise you get a tuner to check it with detcans to see if it is really knocking.
If it's a gradual increase, chances are somethig else is causing it i.e loose knock sensor or something rattling near to the knock sensor.
21 January 2007, 08:45 PM
#4
75 is way too high, especially if you're not thrashing it. Drive very carefully indeed and get a engine mapper to investigate the problem.
A well setup engine will give knock count less than 20.
If you are far away from a mapper, see if they will travel to you.
There are too many causes to list and without knowing certain facts, let an expert check over the setup and mapping of the apexi.
A well setup engine will give knock count less than 20.
If you are far away from a mapper, see if they will travel to you.
There are too many causes to list and without knowing certain facts, let an expert check over the setup and mapping of the apexi.
21 January 2007, 08:48 PM
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75 is way too high, especially if you're not thrashing it. Drive very carefully indeed and get a engine mapper to investigate the problem.
A well setup engine will give knock count less than 20.
If you are far away from a mapper, see if they will travel to you.
There are too many causes to list and without knowing certain facts, let an expert check over the setup and mapping of the apexi.
A well setup engine will give knock count less than 20.
If you are far away from a mapper, see if they will travel to you.
There are too many causes to list and without knowing certain facts, let an expert check over the setup and mapping of the apexi.
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21 January 2007, 08:54 PM
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Cheers,ill give that a try and see if it improves things. Also,I was under the impression that the cel light would illuminate if the knock reading was too high but it didn't ??
26 January 2007, 07:00 PM
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My car is due to go to Zen performance tomorrow for the knock levels to be investigated but I wanted to ask you guys for some more advice before that.
Been out in the car today and set the fc commander to monitor just knock on the graph mode.
Flat out on 1.0,1.2 and 1.4 bar boost im not getting much activity,around 10-15 ish peak figures.
The worst I had was at around 3500rpm in 3rd just holding the throttle at that point.Loads of activity with peak figures around 50-60 !
Is this a sign of something wrong or am I reading the figures wrong ??
Been out in the car today and set the fc commander to monitor just knock on the graph mode.
Flat out on 1.0,1.2 and 1.4 bar boost im not getting much activity,around 10-15 ish peak figures.
The worst I had was at around 3500rpm in 3rd just holding the throttle at that point.Loads of activity with peak figures around 50-60 !
Is this a sign of something wrong or am I reading the figures wrong ??
26 January 2007, 09:07 PM
#17
Sounds like it's fine when it's under real load but not in the midrange.
Probably just a bit of timing needs pulling in the middle of the map somewhere.
I could tell you how to do it using the monitor mode, but I think it's best for you to take it to Paul @ Zen.
Probably just a bit of timing needs pulling in the middle of the map somewhere.
I could tell you how to do it using the monitor mode, but I think it's best for you to take it to Paul @ Zen.
27 January 2007, 06:42 PM
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Just got back from Zen performance. What can I say,Paul is a very helpful and pleasant chap.
He said there is no det with the car at all,the peak knock readings are basically false. He couldn't tell me exactly what is the cause of this but said to change the knock sensor and see what happens.
He changed a few settings in the map but said that the car is fine so I can stop worrying about the knock readings for the moment
Anyone else experienced something like this ?
He said there is no det with the car at all,the peak knock readings are basically false. He couldn't tell me exactly what is the cause of this but said to change the knock sensor and see what happens.
He changed a few settings in the map but said that the car is fine so I can stop worrying about the knock readings for the moment
Anyone else experienced something like this ?
27 January 2007, 09:40 PM
#20
I had a knock of 49 today, when going down the motorway for about 1-2 sec, i tryed to drive the same but nothing else, so am putting it down to something hitting the engine or something, the peek boost was 1.3 bar so nothing strange there, so prob just one of them things
27 January 2007, 11:06 PM
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Im going to replace my knock sensor after what paul@Zen told me today. Do I need to get a genuine subaru sensor or can I replace it with a bosch one like the one used for fitting a knock-link/detalarm ??
27 April 2007, 06:59 AM
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Im thinking about getting a knocklink or Detalarm and see what happens with that.
