frcefed98

iTrader: (16)

I've been battling a KR problem with my damn 98 I've been getting rediculous KR readings on my HPT 2.0 scanner ranging from 1-15degs of KR, but I can't hear any audible knock and neither can my friends or a local tuner. We pulled the plugs to check for any other signs of detonation but they looked excellent, nice and tan with no speckles of aluminum on the plugs.

The car does physically fall on its face during these KR events, but like I said above, no audible ping or knocking can be heard.

This only happens after the car is up to operating temp If the car is cold it runs normal

With KR up to 15degs, you'd think my head gaskets would be shot out. I have no coolant consumption at all. The coolant level is fine and hasn't needed to be refilled and is not contanminated with oil.

I'm at my wits end because we can't find the source of this problem. We've lowered timing, added fuel in the problem areas but it still happens.

Could a bad knock sensor or sensor harness be causing this? Any other areas that I need to look at? Any advice would be helpful.
Thanks,
Jeremy

horist

Is it setting any codes? Usually a bad knock sensor will set a code

Did this just start or you're not sure?

If there's a ton of valvetrain noise or if your headers/exhaust is banging it could cause false KR...

frcefed98

iTrader: (16)

Just started, only does it on a take off too? After you get past about 10-15mph it clears up and the car drives normal, until you stop and have to take off again?

Valvetrain is no more noisy than your normal LS1 set up with a set of heavy duty springs and cam. This valvetrain set up has been in the car for ~2 years with no prior incidents of massive KR.

Its just funny how the car will only do it after it gets past 178 degs temp wise on the scanner.

Bad ground? Leak before the O2's? Bad cam sensor? Bad crank sensor? Bad TPS sensor? Bad temp sensor? I'm at a loss and this is really pissing me off because its keeping me from the track with my new turbo set up.

MECHAM

iTrader: (4)

any updates?

frcefed98

iTrader: (16)

No Car is still sitting in the driveway I haven't tried to drive it since this happened. I don't want to hurt it. I'm waiting for a set of coil brackets too, so any day now and I'll be able to see if the 99+ knock sensors and knock sensor harness that I installed a few days ago, helped..

Thanks for asking tho. It seems like hesistation and things like this is a common occurance on the LS1 f bodies and even a ZO6 here lately. Also seems like no one ever comes up with a solution to this problem. From my searching here on tech it looks like 98s have an issue with this problem. Just don't know why it gets looked over so much.
J

Blackbird

it's a long shot but make sure your VE table is not really out whack.

back in the day before I knew anything about VE and tried some, lets say, "random" adjustments to it I would get crazy KR readings all over the place.

you could also have something else in your tune going crazy. try reverting back to a stock tune with the IFR changed to compensate for the injectors and see what happens.

frcefed98

iTrader: (16)

Sup heath ol Buddy. I reverted back to my tried and true blower tune, which was pretty dead on for a FI tune and didn't have this whacked out issue...and it made no difference, which confused me even more. It has to be a sensor, wire or even the PCM I'm at a major loss here. I guess if it comes down to it I can start with a stocker 98 file and start all over again.

I'll be glad when I get the coils and plug wires back in so I can see if the sensors/harness worked or helped, but i'm waiting on the coil brackets and wires to show up.

One of the connectors on the 98 knock sensor harness was cracked and barely on the sensor when we opened it up

J

ESR

iTrader: (7)

Im having your same problem on my blown car did you ever fix that. I can hit like 1 pound of boost and see 15 degrees of knock consistanly. I am throwing a knock sensor low voltage code though. i guess I ll have to change them out. I put one pound of boost with full meth spray and still saw 14 degrees of knock it has to be false knock. this is with a tune that usually was run under 16# of boost and Im still getting 14-15 degrees of knock. Did you ever solve your problem I guess Im getting the new sensors.

frcefed98

iTrader: (16)

I can't say if I did or not until I finish up my latest turbo project. I did swap out my knock sensors and harness for the upgraded units. I was able to run the car after the swap for about 15 minutes until one of my plugwires melted on my old turbo headers.

The car ran fine for those 15 minutes and it was up to temp before the short test drive.

So after messing with my old turbo set up I ditched all the hot parts and started new. All that i'm waiting on is for some fresh air tubing to route my airfilter to another place and its time to fire her up.
J