Low RPM KR

[97gpl36]

I finally found part of my PO171 problem by replacing my TB gasket.
UIM and rebuilt engine only have 4K miles.LTFT is back down to 2 and -3 at idle with A/C on,still have PO300 but I,m thinking the .531 lift Comp Cam has something to do with that.
After replacing knock sensors I am still getting some really wild KR,(up to 16*)that used to occur between 1800-2500 rpm,is now starting to induce KR at 1200 rpm. Dog bone mounts have been refreshed and there is plenty of room between sway bar and DP. Resonator,cat,and U-bend are gone.
I've been told the mufflers are not stopped up,but this issue will sometimes go away for a few stoplights then come back and stay a while.
Anyone have some fresh ideas on killing the KR?

[TLSheff]

Besides the comp cam and the exhaust work, what other mods do you have on this car???

just figure more info about the vehicle will help the brainiac's throw out some ideas.

[matt5112]

.531 with stock valve seals/retainers/heads?

If so, you might have oil consumption issues as well.

[97gpl36]

Heads and block were prepped by machine shop.Stock L36 block,heads were ported and fitted with the matching 105 LB springs,locks,retainers by Comp.
Comp Cams p-rods and lifters,264HR15 cam:.320/.320 Lift,.210/.220 Dur,115 LSA, NO u-bend,cat,or resonator.Ported LIM. fuel pump rewire,140 amp alt
Top swap next spring.

[matt5112]

Using your number of .320, your lift is .512, not .531.

Shouldnt have valve seal clearance issues.

More on topic, what fuel are you running?

Has the car been retuned since the work was done?

[darkhorizon]

I imagine this is a 96-97....

This is a common problem, and I have never been able to associate it with anything specific... raising knock floor and whatnot will not help much of anything... I end up having to disable knock detection for RPM's 3500 and lower.

Its a simple fix in the PCM, and will still give you knock detection at wide open. I would not run much more than 40 degrees of timing at cruise with this setup, and if you ever put regular octane fuel in you would have some problems.

[AjL227]

Dare I ask, have you gone wide open throttle since you've run the engine with the Comp camshaft? High load KR > low load KR

It is possible that this is more or less false knock, however those numbers seems to be excessively high.
Who tuned it?

[97gpl36]

Thanks guys,Matt5112 was right about the .512 lift.I entered the gross valve lift value from the cam card,still should be .512 with 1.6 ratio.I've been running midgrade (89) octane fuel,used to run regular before cam.Compression ratio shouldn't have changed much.I'm having to run stock PCM at the moment while my other is being tuned by backyard tuner guy,scary huh.I have seen 36.5*of timing at 78 MPH.It seems to run decent at WOT from a rolling start and highway speeds.

[AjL227]

Sounds like you need to either:
A. put 93+ octane in.
B. lower timing in the cells reporting KR/across
C. learn how to tune

What are you using to scan with?

[97gpl36]

Snap-On ETHOS
Had I known it would not change parameters I wouldn't have bought it.
Also is not compatible with windows vista on my craptop.

[darkhorizon]

Sounds like you need to either:
A. put 93+ octane in.
B. lower timing in the cells reporting KR/across
C. learn how to tune

What are you using to scan with?

quit cluttering up this thread with crap, you dont know what you are talking about.

[BillBoost37]

Maybe I missed something along the read. You say you have a cam and that is causing a multiple misfire code P0300. If P0300 is left enabled, doesn't that allow the pcm to induce KR in an effort to combat the misfires?

[darkhorizon]

The misfire code will not do much of anything... People have reported that disabling it will disable all misfire detection.

KR operates on another routine seperate from the misfire one.