5 of knock....false KR? [Archive] - GrandAmGT.com Forum


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06-10-2004, 10:15 AM
So cruisin around today with a Tech 2, I'm getting a max of 5 of knock. First thing I did was add 5gal of 93 oct to the 2 or so gallons of 89 I had in there. Nothing changed. Still had a max of 5 at WOT. Does this sound like false KR? If so, for those who've had this problem too, what should I start looking at?

06-10-2004, 10:36 AM
In what gear? Plugs?

I got plenty of info for you lol - but I'm out the door to lunch in a sec. any more info you can provide about your setup would help.

06-10-2004, 11:12 AM
Alrighty. Just normal driving, I'd get no KR, occasionally 1. But the closer I get to WOT, the worse it gets. The plugs are week old stock Delco replacements, with MSD wires. Other than that, S&S headers, and SLP exhaust. My first thought was the headers/exhaust hanging around, but it looks like it's all got plenty of clearance. So I suppose it could be real knock, but why, I don't know.

The only other thing possibly worth mentioning is that I just retorqued my rockers since they were way loose. But then again, with them loose I only got 2 of KR.

06-10-2004, 11:14 AM
read this thread http://www.grandamgt.com/forum/showthread.php?t=25425&highlight=knock+retard

06-10-2004, 11:55 AM
Hmmm...so has anyone tried the Seafoam or BG stuff? They both sound like a good idea. Like Iceman, I can't visually see anything that might be banging around causing false knock.

Charles also mentioned that we'll get a little knock from the factory, which makes me wonder how bad it really is. Also, even though I know a AF guage isn't completely accurate, it does appear that I'm running a little leaner than normal. If that is the case, how can I fix that aside from buying an AFC or ICCU?

06-10-2004, 12:37 PM
As far as more gas, lol.. DHP should fix that :) I'm not sure how to richen it up without farting with the cals.

Seafoam, BG, or topend cleaner.. on my list to do... I've used BG stuff before, friend worked for em when I was in high school. Awesome products, well worth the $.

06-10-2004, 08:50 PM
ok, let me ask this differently. What could cause a lean condition? Incorrect MAF readings? Bad o2 sensor? Something else?

The MAF (stock) is reading about 3.9 gm/s at idle, I didn't think to look at WOT

The o2 is reading right, but it's 85k old, and from what I'm told, that's past is usual life expectancy.

06-10-2004, 08:57 PM
Yes on both accounts. I'm running a tad on the lean side as well, and see as much as 2 degrees of KR at times (although seldom). Monitor your primary O2 values; they should run between 910mV and 940mV at WOT. Also, look at your short-term fuel trims to see what kinda fuel deivery the PCM is commanding.

06-11-2004, 05:30 AM
ok, I'm going to run with the o2 sensor idea. Hopefully it gets here within a few days since I'm hitting the track next Friday.

Matt - I'll take a look at the STFT today if I get a chance. What kinda numbers should I be looking for?

06-11-2004, 06:06 AM
I know seth hasn't gotten around to this yet, but if you know its false KR, then you could also try sealing the threads on the knock sensor w/ some teflon tape. I know that's helped some of the f-body guys...

06-11-2004, 09:34 AM
^ Never would've thought of that. That's a nice, cheap solution.

06-14-2004, 09:14 AM
I've about had it with my car and the false knock.. Really piszes me off to no end. Ran a 15.9 this weekend, topped out about 13 degrees of KR through the whole run. The trans slipping the 1-2 shift doesn't help either. I've tried everything suggested here plus the expert advice of Chris and it's still stumping. I got a hold of a stock MAF with screen, I'm going to try to fit the stock airbox back in next week but I highly doubt it will fit in my engine bay any more :( . Gotta try changing the knock sensor too. I'd drive all over the country if I knew a person that could fix it lol

Ever see this? or something similar

It's really frustrating, the power is there, but can't get it to come out :(

06-14-2004, 12:32 PM
^ I'm there with ya. I'm installing a new o2 as soon as it gets here and will clean out the MAF today. I'm hitting the track this Friday, so hopefully whatever the problem is, it gets better.

06-14-2004, 12:36 PM

I'd be frustrated as hell too. I've looked over some of your scan results that you posted, and O2/IPW/MAFF values are all right where they should be. Have you perhaps tried logging for individual cylinder misfires? I'd look at the knock sensor as well.

06-14-2004, 12:39 PM
I stopped logging misfires because I was never seeing them, however I easily can.

I have the week off next week, while we are doing Pucci's heads (which by the way you all will be able to watch during the week, live :) ) , I'm going to play around with a new knock sensor, and as much back to stock air box as I can (I have electrical stuff in the way right now, that may not be possible at all). Everything else looks right just when the pedal hits the floor, the KR goes through the roof. minus the latest 1-2 transmission problem

I've done everything I've researched and I'm 99% sure it's false knock. If it doesn't go away, I'll just have to throw in the towel.

edit: Also, I posted in another thread, but I bent my EGR tube to hell when putting the headers in. It's not throwing any codes.. I'm sure it's not the cause because the KR was there before the headers and after.

06-17-2004, 12:20 PM
Well, good news for me.

New front o2 sensor + cleaned up MAF resistors = 0 KR.

And matt, because you asked - STFT @ WOT is 0%