wrd1972

iTrader: (12)

For the last several weeks I have been seeing this freakish and random knock retard on the Scanmaster. It seems to be at low load NON WOT conditions and has no real distinct pattern. It does not really appear at WOT and just seems to have come out of nowhere.

I am hoping for bad gas and the tank is nearly empty so some time tomorrow I will fill up at a different station.

Also when I was driving today at low load in 6th gear I felt a little bucking and it was in concert with some KR on the Scanmaster. I dont see how misfires can cause KR so I will assume the light bucking was from the timing being backed off when the sensor heard something. Also I dont think I have any misfires because the BLMs are all rather in check. Anytime I have had misfires, the BLMs go to Hell. FTR I also have the LT4 KM.

Any thoughts on what might be causing this mysterious random KR???

defaultexistence

iTrader: (11)

i get used to get some from the #8 primary vibrating on the frame... do you have an exhaust primary possibly touching something?

wrd1972

iTrader: (12)

That is the one primary that is the closest but at a glance, there is clearance. I will at it more closely.

n2oblkz

iTrader: (1)

Funny that you posted this because mine has been doing the exact same thing. The wife and I too the Z out this weekend and I noticed the bucking and the timting retard from my Scanmaster. It is right around two degrees of retard most of the time under light to moderate load in a higher gear and I get a little but of "bucking." The most timing retard that I saw was 4 degrees, but nothing under WOT? FYI, I recently had an AI cam installed and it's on a MadZ28 tune.

defaultexistence

iTrader: (11)

yes at a glance there could seem to be clearence ...like mine ,but put the motor under a load and the motor twists and my llp clones #8 would vibrate on the frame and the #1 on the steering link .. would then knock retard like .05-1.5 degrees

SS RRR

iTrader: (2)

The KS could be on its way out.

wrd1972

iTrader: (12)

Update:
I drove the car nearly empty and filled up at another station today and things got big time dramatically better.

I saw a big KR 1 mile from the station and then drove 75 miles without a single noted KR under all driving conditions. Obviously I either mistakingly pumped 87 octane weeks ago or the 92 octane was tainted. Again huge improvement.

Then later on, I then saw some KR out of nowhere at idle only with the motor hot and it was much hotter temps outside. All other driving conditions were completely free of KR including WOT. Just weird.

Hopefully the sensor is bad. I am going to replace it mid week and see.

killagt

iTrader: (3)

lol nice. Try alway fill up with shell. chevron, texaco, PB , exxon gas if you can.

wrd1972

iTrader: (12)

The questionable gas came from Shell. The gas in it now came from Speedway.

fex77k

iTrader: (2)

That has more to do with the station than the supplier.

wrd1972

iTrader: (12)

agreed

wrd1972

iTrader: (12)

Update.
Got a few more gallons of the believed to be tainted gas from the Shell station. Random KR remains.

I switched out the knock sensor with a spare one I had sitting in a junk box and so far it appears that all the random KR is gone. Maybe the other KS was bad. They both OHMd the exact same amount on the meter interesting enough but I want to wait for it to get back into the 90's outside so I can put some more miles on it.

Anyone ever see a bad KS?

fex77k

iTrader: (2)

I guess I am lucky there is a Sunoco station that has up to 104 on the pump right next to me.

ZFreie

Place near me has 110 leaded on pump, to bad its 8.50+ a gallon lol

I can vouch for bad gas at a few gas stations at least around southern NH where i live. This is before I had scanning software so i had to go by SOTP feel, and it was night and day. Car would start to take off hard and then pick up knock and fall on its face, put different gas in and problem went away.

Just to make sure it wasn't just a bad batch of gas I drove my car to empty on good gas, and tried a couple of the bad stations again. boom no power again. I'm now very very picky where i fill up.

My .02

SS RRR

iTrader: (2)

I had one start randomly acting up, pulling timing and making the car stumble while simply maintaining speed.

cadsmobile

I have an '93 LT1 in a Volvo 244 and have had DTC 43 most of the time I've had it running. I tried 2 different sensors from Napa and it never fixed the problem. I always had 5 volts at the connector and the sensor would show good resistance (~3800 ohms). Last week I replaced the KS with a 3900 ohm resistor and the DTC went away. I replaced KS this weekend with one from O Reillys and all in now well. Moral of the story, just because the resistance is good doesn't mean the sensor is good.

I hope now to finally get some good mileage and maybe pick up a few MPH at the track now that the PCM isn't pulling any timing!