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Discussion Starter #1
Have a Zetec with mild mods, cat back, SVT intake, tune. 180 deg stat, ambient temps are -5 to +10 deg C. Have had the car for approx 20,000 km so have no idea of service history other than clearly the basic maintenance was done well and I've fixed the rest of it up quite well since owning it. While data logging I've noticed that my knock sensor is retarding the timing up to 7 deg under light loads (typical of normal to moderate acccel).

I've removed the tune, and noted that the pids behave the same. Inspection of knock sensor reveals nothing out of the ordinary, connections good, etc. Pulled plugs to check for carbon buildup, no boroscope but tops of pistons are clean. Had a coworker (Ford tech) recommend running a tank of 94 with a bottle of octane booster to see if the knock changes or stops at all so I ran the tank empty and filled up with higher oct and booster but have seen no change. There's no knock if I put some load on it stone cold but as soon as it starts to warn up at all the KS lights up. No CEL, no codes.

Tom has sent me a different tune to send him data log of which I intend to do once I get my tank back to 91 octance. I'm just interested in getting a discussion going to see what others have experienced with this.

What have you guys experienced and what do you think about real vs false knock?
 

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I am not sure if the focus shares the same knock sensor with the zx2, but many people have issues with it being overly sensitive, most unplug it, not that I'm recommending that.
 

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ZX2 guys unplug them mostly because they dont want to buy a tune and thy dont want the timing retarder because a few that didnt know what they were doing tuning back in the day said the ZX2 knock sensor was to sensitive which it isnt and the knock sensor needs to be plugged in even on the ZX2

You need to send me those logs and I can fix this with a tune , 7 deg is a lot and needs to be addressed

Tom
 

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Discussion Starter #4
Thanks Tom. So you'd say that there's actually a knock sensor issue here that is common rather than a mechanical issue?
 

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I'm subscribing for results out of curiosity. I doubt this helps, but on my Evo, I swapped to pretty aggressive cams, which caused me to get some phantom knock, I guess from valvetrain noise/vibration. I ended up making a conservative timing map (which would not knock under normal conditions) and running 110 race gas. Then I adjusted the knock sensitivity until it stopped showing knock. I put an aggressive tune back in it and ran it on pump to make sure it still showed real knock, and everything was back to normal.

While I was troubleshooting my Evo issues, I read that some people had phantom knock caused by their exhaust contacting the drivetrain or chassis. If the tune doesn't fix it, maybe that's something to look into.
 

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Tom,

Out of curiostiy, what would cause knock on a factory tuned car? (No mods Factory intake, exhaust etc). The ZX2 is prone to knock events on the factory tune, even with running premium fuel. I have logged this as well as others that have noticed this phenomenon. It may well be due to a factory tune, but if you switch PCM's and there are a plethora to choose from for the ZX2, the knock still persists.
 

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If it is detonation then lowering the timing is the only way , on the ZX2 depending on the code you have to adjust a few things in the tune for the knock sensor to work properly , this isnt the case with the ZX3

This is why canned tunes are worthless , even the factory does the one tune fits all and they have the timing to aggressive for this crap fuel we have

Tom
 
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