Ok, so I finally got to log about 40 minutes worth of putzing around town. Only one half-assed WOT run (damned Chicago traffic).

Just got to examine the log files ... and ... I see knock counts

However, upon closer investigation, here are the trends that I am finding:

- ALL instances of knock activity are occuring at partial throttle
- knock counts are mostly occuring between 2400 and 3500 RPM (i.e. when I'm out of boost)
- some knock activity occurs when accelerating in this RPM range. Generally anywhere from 1 to 6 counts.
- much more pronounced knock activity occurs when I lift off the throttle below 4000 RPM. Anywhere from 5 to 20 counts.

I'm fairly sure that the knock counts during acceleration are being generated due to the fact that I no longer have balance shafts in my block. This was also evident last year when I was running a XEDE SMART system. We had to adjust the SMART tables to change the acceptable engine noise level at 3000 rpm.

The one WOT run (3800-5400 rpm, 3rd gear) I was able to perform today did not pull any timing and did not generate any knock counts.

However, I'm stumped as to why I'm getting knock counts when I'm lifting/reducing my throttle (going from 50% to 30% for example or lifting off completely).

Thoughts? Comments?

Please note: This is a heavily modified Evo ... ported head, AMS VSR intake, 65mm throttle body, AMS 50 trim kit, etc.

l8r)

 

That could be possible as far as the balance shafts, the most knock I have encountered was about 1-2, and that was a fluke because 30 min later same map, made a pull and they were not there anymore no changes made. If you logged 40 min and kept encountering knock at certain rpm ranges more than once then it is likely not a fluke.

 

Yeah, it's pretty consistant. It just doesn't make a lot of sense to me. Does anyone know if the accel enrichment also used for decel?

l8r)

 

Every now and then I get a knock in the same area also, usually at part throttle. Or if I have a half-assed shift it will knock. The only thing I can come up with is because of the clutch. I'm not sure if there is a lot more "noise" coming from the clutch setting off the knock sensor during shifting?

I heard that the knock sensor is located on #4 cylinder right under the intake manifold. Is there a way that it can be moved towards the center of the block say by #2 cylinder.

 

I occasionally see the same thing when lifting the throttle. I'm not accelerating so it doesn't bother me. You can toue out 100% of the part throttle knocking though, assuming its not 'false' knock like you mentioned from not having your balance shafts.

 

On my JDM GSR ECU running 3" exhaust and 22 PSI or more I get lift off knock. See my thread from yesterday in this forum. I was getting knock counts of 16 on lift. Clearly the ECU knows about it but doesn't bother about it, but when I can hear it in the cabin on occasion I felt I needed to tune it out. 4 degrees out from 120-220% load at 3000-4500 RPM did the trick. 2 degrees wasn't enough. This ECU does run +3 over the USDM IX though. Accel enrichment, lean spool settings, fuel map made no difference.

 

This may sound strange, but when I lift off, I thought I was getting (and reading) audible knock.. Turned out my 3" downpipe was hitting the crossbar and transmitting a noise right into the block.. Go figure eh?

 

Guys could you take a look at my log. I am getting some pretty heavy knock counts at 99% throttle. I know my dp hits the cross brace but I doubt this is the case here.

 

I just took a quick peek, and your max TPS value in that log is around 78%, not 99%. Most of your knock activity seems to occur at partial throttle and light decel (i.e. TPS going from 41% down into the 30s).

If your DP is hitting the crossbar, why not pad it temporarily and see if you still see the knock sums?

l8r)

 

subscribed...

 

Sorry posted the wrong file. Here is the one I was talking about. How bad do you think this really is? Dyno AFR at WOT was about 11.2 from 4.4k to 7k. I currently do not have a wideband of my own. Just got a tune last week. Thats where I am getting the AFR numbers from.

 

Wow, your intake temp is around 115 degrees! I think most of evos will knock bad with that kind of temperature with pump gas. I noticed perfect tune at 70F isn't going to work on +100F. The perfect tune without knock that I had before started knocking when I encounterd hot california desert weather. If you encounter like 115 degree, I think Even stock map is too aggresive for that kind of temperature. I would try to adjust air temp compensation table. so it will richen up a bit for the hot temperature.

 

What do you guys think of this my sample rate was 11Hz and if you multiply it with 18 knock counts you get 198Hz. What frequency do you think the exhaust resonates at?

 

Great call, the dyno tune was indoor with fans blowing on the open engine compartment. I'll bet the intake temp wasn't above 85deg. Unfortunatly I am locked out of the ECU. If I can get my lazy butt up early enough I may get a log when the temps are more like 80deg.

 

I experience the same, 2500-3500rpms, up to 36 count at part throttle, like 15%.