High Knock any ideas?

[j_biggz]

This is a 3rd gear pull on the freeway @20 psi. I'm using the local piss 91-2 octane premium. Got my A/F at around 11:1 but seeing a ton of knock. Looking for ideas for the reason. I have my balance shaft eliminated and poly mounts so maybe its phantom knock but I am unsure. Seems to run smooth.

 

[Justin_l_]

Check your timing yet? Knock sensor in good shape and tight?

 

[j_biggz]

Base timing is set at 0 but untill I install my 1g cas I cant change it. I have tried changing the setting in dsmlink to compensate for it but the knock increases. I haven't checked the knock sensor. From searching just now it looks like it will be a good time to check it. Could my octane be to low for that kind of boost? what about ignition like plug wires? Just trying to wrap my head around it.

 

[Justin_l_]

Octane shouldn't be an issue. I'm runnin 25psi on my 16g with 93 with no issues. I can't see the log from my phone so I'm not too much help. Check your sensor and report back.

 

[j_biggz]

I will check it tomorrow from under the car. I will verify its tight but what else should I look for? The motor has about 5-10k on rebuild but no idea on knock sensor. I would assume its stock. Any way to verify if I cant get a picture of it?

 

[way2fastlaser]

is this a built engine or stock ?

even so you could have a loose piston in rocking in the bore causing crazy knock

had it happen ...

 

[j_biggz]

Its a rebuilt engine. Pistons and rods but I haven't had the pan on to verify the rods but I know for a fact the pistons are wiseco. I have the paper work on the motor.
* just a thought, my tranny make some kind of loudish bearing noise when driving 3rd gear plus. Anyone think that could contribute to the 8* knock?

 

[jed344]

shouldn't the base timing be 5 deg?

 

[j_biggz]

That was my impression. I have it set there now and it still knocks. Not sure what the deal is. I haven't checked the knock sensor yet. Ill change it when I have the tranny out here pretty soon

 

[Dsmkauai]

What plugs are you running by chance. And about the trans what kind of noise like a bearing sound or clunk or what?

 

[j_biggz]

I'm running 7s and its bearing for sure. Its getting a shep stage 2 soon

 

[Dsmkauai]

Which 7's bpr or br?, and if it's a bearing could it just be a bad throw out bearing. How old is your current clutch?

 

[josh1095]

yea, i was gonna say, your timing is very conservative in that pull. there really is no reason for knock. its coming from somewhere else possibly, like you said.

 

[dsmcoder]

Check to see if your knock sensor is sticky or if black or brown goo is coming from it, that would mean it's on its last leg.

 

[CrawlinZX14]

Also check for things like exhaust leaks and such. Loose bolts can cause it too. I am getting much worse knock conditions in my 1g upwards of 30 counts, but its nothing to do with internal detonation. I have an exhaust leak at the mani, and we believe that is causing it. I have seen many instances where there are dozens of things that cause a knock sensor to read knock. Had a friend with a nasty lifter tick and kept throwing a knock for it. I had one car with a bad rod knock and no knock detection. Just make sure everything is tight that you can check, and go thru the process of elimination. I would start with checking for leaks, then start checking brackets and make sure they are all tight and not rattling around.

 

[allezgrand]

Is the AFR of 11:1 from a wideband or is it from your DSM Link estimate? If it's an estimate, there's a good chance that's not your actual AFR and you have a problem in your fuel or air system.

Have you pressure tested your intake, and how are your injectors? If there's a leak at your intake, the reading from your wideband would mean your knock probably doesn't have to do with predetonation, but if one injector isn't firing fully, you could be getting knock on one cylinder but your wideband would still be giving an AFR of 11:1 because the other injectors are compensating.

 

[92awdbird]

would a "Napa brand" be an issue? i got knock issues too. just thinking of the obvious.

 

[j_biggz]

To up date everyone instead of getting a new trans I am having the fwd removed and swapping it to awd. After showing a friend of mine the log and talking about my maf (#482 3g) he thinks that its my maf setting that are causing the knock. The a/f is an actual aem wideband. If you compare my a/f est to my actual a/f its way way off. So after I get the dsm back on the road we will be doing some playing with the maf comp table and seeing what we can make of it. I will verify that the knock sensor isn't in poor shape when we pull the trans out. Sorry for the long response but I have been pretty busy. Thanks everyone for the replies. As far as a napa brand knock sensor I wouldn't trust them unless it was OEM but that just me.

 

[WES_393]

To up date everyone instead of getting a new trans I am having the fwd removed and swapping it to awd. After showing a friend of mine the log and talking about my maf (#482 3g) he thinks that its my maf setting that are causing the knock. The a/f is an actual aem wideband. If you compare my a/f est to my actual a/f its way way off. So after I get the dsm back on the road we will be doing some playing with the maf comp table and seeing what we can make of it. I will verify that the knock sensor isn't in poor shape when we pull the trans out. Sorry for the long response but I have been pretty busy. Thanks everyone for the replies. As far as a napa brand knock sensor I wouldn't trust them unless it was OEM but that just me.

Mine was the same way. Snowborder suggested this link to me and it worked great.

maftcalibrationbywbo2 [ECMTuning - wiki]

You will basically adjust the MAF Comp settings until the A/F Est and AEM Wideband match. Then adjust the fuel using the sliders or fuel tables. I came to find out my AEM was telling me I was at 11.1:1 at WOT when I was actually pig rich and knocking as a result.

 

[j_biggz]

Very cool and thank you for the link. I will have to give that a shot when I get mobile again. I of course wont be able to set the injectors to stock being that I have FIC 1050s and that's what I have set in link with a dead time of around 400ish but they generally recommend about 300-350 according the the link forum. I just kind of guessed on the dead time. Thanks again for the link and I will report back with the details and another log after I can play with it some.

 

[DSMer541]

fwiw from my experience on 92 oct. I always seem to battle a little knock if I try to run more than 10.9:1 afr. my car seams to like about 10.6-10.8... may seam a little rich but its happier there.... I have tuned it around 11:1-11.2:1 on nice cold days without knock, but as soon as it warms up a little the knock comes back..... I think it has everything to do with our Oregon gas, the knock thresh-hold sux... the key to running any decent amout of boost on Oregon pump gas, is a GOOD large intercooler to keep intake temps down as much as possible and keep afr's conservative.... I run 26 psi on a E3-16G, 92 oct (w/ 10% ethenol), a ETS 3.5" intercooler, about 10.7-10.8 afr, 5*-7* timing during peak torque, 14*-15* timing at peak HP...I could probably lean it out just a little more and add another deg. of timing but you dont want to tune a street car to its edge, it wont like it...... hope that helps you a little...

 

[j_biggz]

Thanks for the info I will keep that in consideration when I am playing with the tune. I eventually plan on having it dyno tuned by English Racing up in Wa but until then I got to get it close. Ill shoot you an friend request since your in my neck of the woods.

 

[allezgrand]

Mine was the same way. Snowborder suggested this link to me and it worked great.

maftcalibrationbywbo2 [ECMTuning - wiki]

You will basically adjust the MAF Comp settings until the A/F Est and AEM Wideband match. Then adjust the fuel using the sliders or fuel tables. I came to find out my AEM was telling me I was at 11.1:1 at WOT when I was actually pig rich and knocking as a result.

I think Wes_393 was spot on explaining that you want the A/F Est to match your wideband reading. Tune it however you need to - it sounds like DSMer541 has a pretty good idea of what figures to use, but the bottom line is to make the A/F Est match wideband, then tune it to the edge of knock and back it off a couple degrees (if you want reliability). If you can't achieve the first part - you still have knock after making estimated and actual AFR match and you're conservative (11:1 or less), start looking for mechanical issues. There's no need to start making major physical changes and replacements if you haven't achieved the first part.