I installed a lt1 scanmaster in june. Really cool instrument..Anyway i recently knoticed some knock retard under accelteration. Its gotten progressively worse. I have 0.0 - 0.2 at idle and about the same when crusing but when i hit they gas it will spike to 7.0 never more and often sitting at 7.0. I check my fuel pressure and it would drop after the fuel system was primed with the key in the "on" position. I checked for leaky injectors and they were fine. So i just put in a new fuel pump from racetronics and solved the problem also in hope that my knock would go away but it didn't. I have a lt4 km. I also popped off the valve covers and none of the rockers seem loose. I have new motor mounts new fuel filter, new fuel pressure regulator. My spark plugs are one step colder than stock. All summer i was reading 0.0 and the only thing i did this summer was changed out a thermostat because it was no longer opening all the way at the correct temp. I put 1 gallon of xylene in the tank with about an 1/16- an 1/8 of gas in with it with no noticeable change. What do i need to check next?

Thanks in advance you guys always give me good advice.

 

Have you checked the new motor mounts to make sure the bolts are tight? Is there any evidence that the headers are hitting on something like the steering shaft?

 

I'll check again tomarrow but i did a quick check when i was under the car installing the racetronix wire harness yesterday and everything seemed fine. I've never heard any banging from under the hood and i didn't see any dents or worn places on the headers.

 

Drove it again today seemed to only knock when accelerating or under load (goin up hill nd maintaining rpm). Also it takes a few minutes to start happening. For the first couple of minutes the knock retard stays at 0.0.

Also i still have the stock injectors. Is it time for bigger ones? Could this be my problem?

 

Well it really hard to tell. I bet alot of what you are seeing is spark being removed because it sensed knock during those same or near those same conditions before, especially if you are seeing retard while at light throttle/cruise and light acceleration.
There's one more key peice of equipment that you need to fully diagnose and that would be software like TunerCat or LT1Edit to see what your timing table looks like..may still be too much timing at certain places in the tune.

See this thread I had not long ago and my findings..now that I've lowered the timing in certain places by looking only at the knock counts and not the retard, I've driven over 100 miles with zero knock or retard. In some places in the timing table I'm a few degrees lower than stock but wot is still 3-5 higher.. But this is going to largely depend in cam/valve timing, SCR of the heads, cam itself, etc.
http://web.camaross.com/forums/showthread.php?t=546195

 

I thought that it could be too much timing in the tune but i've had the same tune all summer and the only things i did to my car was a new t-stat because my car was running too hot(it was broken) and an oil change and fuel filter. I looked around and coun't find the exaust rubbing against anything.

I might try some new valve covers mabye one of the rockers it slightly rubbing. I still have the stock ones that i cut the ribs out of.

Also...I have an intermittent code 22 at start up that will go away usually by the end of the driveway...?

 

Check the TPS sensor and find out why the voltage is below 0.20V at startup, setting the code. If the PCM is having trouble setting the baseline 0% TPP, it may be affecting the knock count and causing retard.

 

I get kr even@ idlewhen trans in neutral.I have code 36 and my opti has taken a dump and this has caused kr,hard starting,more % throttle when going uphill and timing all screwed up etc.I just bought theMSD opti which will be a big improvement as my factory opti was not vented,etc and i will get it installed next spring and hopefully my kr,drivability.will be better!

 

ok. I was getting a code 22 because my tps sensor was misaligned(most likely) or broken. I was getting .18v at start up at idle. I bought a new sensor and then it was .28v. I wanted a little more assurance so i drilled out the holes on the sensor and now it reads exactly .50v at idle. I was hopeing this would fix the knock but it didn't.It got rid of the code though. The knock seems to be getting slowly worse. Now i have .6 to .8 degrees at idle with occational jumps to 6.0 or so. When accelerating even lightly it jumps to or close to 7.0 degrees never more though. It seems to max out at 7.0. When i hold any rpm in neutral its 0.0 though???

 

Disconnect power from the ECM then reconnect and see if most of the retard is gone, and then drive around and see if it slowly returns to the extent where its retarding some almost always when accellerating.
Thats what mine was doing as described in the previous post, as if it was learning where the knock was.

 

I disconected the neg bat terminal after i installed the new tps sensor and the knock was the same as it was before. I doubt its a problem with the tune. It was fine all summer and i didn't change anything. Also the Xylene i added to the fuel would have killed any knock that came from too much timing. Or at least it should have. Which would mean i'm looking for false knock. I donno if i can't find anything i'll buy tuner cat or lt1 edit like you suggested and pull a few degrees of timing out over all and see if that makes it go away.

Tomarrow i'm going to get under the car and really look around for the exaust rubbing somewhere that i might have missed before, and do the knock sensor tests that are on shoebox's website just to rule things out.

 

I can't say with 100% certainty that disconnecting the power would reset it, I was reflashing mine so much. I know reflashing it caused it to go away..and then it would gradually come back..that is taking the timing out with no knock counts. After a reflash, I could go several miles with no retrad, then after the first occurrence of knock counts increasing, the retard would get more and more and eventually be taking out timing at almost anytime the pedal was pressed.
Once you get TC or LT1Edit and try a few flashes see if you have the same phenomenon...but eventually taking out timing at those places getting knock counts cured mine.

 

I think i found the problem. My passenger side header is rubbing in one of two places. it looks really close to this u shaped AC tube just under the primary closest to the front. It also might be rubbing on the cradle.

When i installed my headers i needed new motor mounts to get the clearance to slide them in. When i first installed them everything had plenty of clearance. I guess they slowly compressed over the last two years. I'm going to put a shim under the passesnger side motor mount and i think that'll fix the problem because i can't imagine my motor mounts being dead after only two years

 

That will do it. Might want to try a poly mount on just one side. Putting a poly mount on the driver side will keep the motor from torquing over and the headers hitting something too, and with it only on one side the vibrations will not be very noticable, or none at all with a stock idling cam.

 

yeah its a poly mount. I might just put in a new one.I donno. PITA. Thanks for the help anyway