S-AFC II Knock reading all over the place suddenly??

[uberswede]

I'm still in the break-in stage on my 1g swap into my 97 Talon. I don't remember the S-AFC II ever reading anything for knock back when I had my 2g in it, but I could be wrong. I only ever really remember there being an occasional little blip, no higher than 2 or 3...

Anyways, like I said, still breaking in the fresh 1g swap, and I'm noticing some weird "knock" readings on the S-AFC II.

Sometimes I'll see next to nothing for a while, then sometimes I've seen the number blip up to as high as 55. This worries me, but at the same time, I have no idea where this wire is even hooked up to, if I have a knock sensor... Plus, the motor never seems to run/sound any different.

There have even been times where the knock reading is pretty high at idle, then when I'm driving around it's lower. This makes no sense to me.

Anyways, here are a couple videos showing some of the readings I've been getting lately...

YouTube - ‪Talon "Knock" reading?‬‏

YouTube - ‪Talon "knock" reading 2‬‏


And please, don't be asking any silly questions here. I know my gauges are bare at the moment... There are more important things being worked on. The S-AFC location is silly, but that's where it was when I bought the car. That will be moved shortly.


Baaaasically, should I be worrying about this sudden reading? I had a shop finish up the wiring for the 1g swap... Could they have hooked up the knock sensor?

The SAFC was in when I bought the car, so I really don't know where the knock sensor wire would be hooked up to... but a lot of the interior is loose right now, so if I had to trace out where the wire is hooked up, I could do that fairly easily.

I need to drive an hour out of town this weekend, and really want to know if this is safe to drive, or I should be taking my other car instead.

I should also add... Like in the first video, sometimes the number will sit closer to zero, but keep jumping up to random numbers...

Other times, like in the second video, the number will remain pretty steady around 16 or 17 or so... and will be 1 or 2 numbers higher if the A/C is on.

 

[4Lurker4]

If I remember correctly, the knock reading is only accurate on the 1gs. You do have a 1g engine so I take it wiring was done correctly, so should read it well. Could be phantom knock due to something loose somewhere from the engine swap.

 

[e_miller81]

Knock sensors can go bad and that could be an issue also.

 

[uberswede]

I talked to the shop briefly, and they said they don't remember hooking up a knock sensor, but they're going to look into it further.

They didn't touch any of the SAFC wiring though; don't know if that helps.

I suppose something COOOOULD be loose... What did you have in mind?

 

[JusMX141]

Taken from one of about ten threads on the topic which all provide nearly the same information- this post just gives the most in-depth description:

I'm not sure about a 1G but I have it hooked up on my 2G and it provides a numerical value, but the value is incorrect (alot higher than actual). The problem is that the SAFC II isn't calibrated for any particular vehicle's knock transducer output...so the method they provide you to set up the knock (rev engine to x rpm) isn't near accurate enough to properly calibrate the display output. It doesn't decode the signal as some would have you believe (the circuit only reads the output current/voltage, does not introduce or sync any voltage) so you can hook it up but it's more for show.

 

[uberswede]

So, more or less, these random numbers I'm seeing aren't particularly something to be worried about?

It's a brand new 1g with a built bottom end, drives beautifully, and I've barely even put 4psi through it yet.

 

[JusMX141]

We don't even have logging software for 2G's (aside from something like ECMLink) that accurately logs knock, so there's nothing an AFC is going to do for you.


BTW- in the first vid you linked, the preview pic from Youtube (before you even click the vid to watch it) seriously looks like a silhouette of Conan O'Brien. Anyone else see this?

 

[4Lurker4]

in the first vid you linked, the preview pic from Youtube (before you even click the vid to watch it) seriously looks like a silhouette of Conan O'Brien. Anyone else see this?

hehe

 

[uberswede]

Like I mentioned though, I'm now running a 1g swap...

Just to give you another example... I drove around for a while today, and the "knock" was basically at Zero the entire time.... About an hour or so later, the "knock" level was staying right around 20 at idle... Then it actually went DOWN considerably when I started driving it.... Even when pushing it a bit.

I'm thinking more and more that this readout im getting is basically bogus, and I should just ignore it entirely...


Ps. Conan ROCKS! So I'll take that as a compliment hahaha. Except I kept my beard, and he shaved his off.... Shame.

 

[steve]

Remember that the SAFC2 knock readings require training. If you didn't put in a 2G knock sensor in when you did the swap you have one problem with both the ECU and SAFC2. You'll need to retrain the SAFC with the new engine as well.

 

[uberswede]

I'll definitely try to get to re-training it this weekend if I can. I have the full SAFC2 manual somewheres... Just moved recently, so it might take some digging to find it.

But could the random numbers I'm getting REALLY be just a result of it needing to be retrained? I mean, here's just another example. It's almost sitting at zero all the time now, but just out of the blue the other day I got this reading... ‪Talon "knock" reading 3‬‏ - YouTube

Then, next time I start the car, it stays sitting at zero, with the occasional small blip. Driving habits are no different, nothing sounds different, all my other readings are exactly the same. It really just seems like something other than needing a re-training for the sensor. I'm not saying I don't believe you, or that what you're saying can't be true, it just seems odd to me. That's all.