6spd

okay i been have this problem with knock retard it happens at about 3800-4000 rpms it retards no more than 5 degrees i put the ez link on it today in closed loop rev it to just 3000 rpms and i'm getting the same knock retard this is a on going problem i'm having no codes fuel pressure does not drop timing is 6 btdc everything is new from sensors to tuneup i can't drive it because of the bad weather it seemed to get better as the car got hotter but not much i really don't know what to do with this anymore when you drive the car at the noted rpms you can feel a power loss it really sucks because the car wants to go?????????????????????? what else could it be???

devilfish

ge could be anything!
Something hitting the frame?
ANything that can make a "knocking" kind of sound.
My hedman headers triggerd the knock censor due to hitting the frame.

Pull a plug an look for tiny dark spots on them, that can indicate detonation.
Do you get spark retard during WOT?

6spd

yes it starts at 3800rpms i did pull the plugs and i have light brown spots on them it's like one light brown spot on all the plugs??????

devilfish

No thats not it. You should look for tiny black spots, often more then one.
Does it pull timing when you hit the pedal then fades out, or do you have a 5 degree retard all the way from 3800 to max rpm?


[Modified by devilfish, 8:47 PM 1/18/2004]

6spd

okay thats good it runs mint till 3800rpm then it pulls timing out

65Z01

Back the base timing off by 2-4 deg and repeat the test.

This will tell you if it's realy knocks or some mechanical issue.

6spd

i was told to do that to retard it and see what happens if it fixs the problem what could be wrong the prom??? i did touch the progs a few times on the prom they say it can damage it but no codes and if this timing retard don't fix it what else to look for????????

devilfish

:iagree:

Start with this. Then we take the next step.
What software do you use to log?

6spd

the only thing i have is the ez link scanner.

65Z01

Well if timing retard effects the knock counts you are getting true ping and we need to consider what could be the possible causes.

BTW, what is the O2 sensor readings on your scanner when you go to high RPM? Does the BLM cell number switch to #15 with a value of 128?

6spd

the blm cell is 4 the o2 sensor is around 800-875 thats at around 3500. it has to be something with my prom or ecm when the car was idleing in my garage and i reved it to 3000 rpm it started to retard but no higher than 3 degrees now there isn't even a load on the engine this doesn't make sense. a couple of times itook out the chip i touched the prom pins now i know i shouldn't have. is it possiable that my prom is losing memory. ??????????????

JAKE

I feel his best bet is to check this with the engine under load, not sitting.

The ECM won't switch to PE mode until he floors the throttle and the TPS registers 4 volts or more.

Just winging the throttle with the trans in Park may be giving false info that may or may not exist with the engine under load and travelling down the road.

Just my thoughts.

Jake

C4Crazy787

6spd,
As per our IM conversation I re-torqued my knock sensors to 12-14 ft lb, nojoy. Same 8* max KR. mine starts about 4000rpm. I'm starting to wonder if this is not normal, I was reading in my How to Tune n Mod Chevy FI,

Quote: Because a slight amount fo ping is to be considered normal on applications equipped with ESC system, a reading of four or so should not be interpreted as a problem. pg. 103.

I'm going to start another thread- Knock Retard Normal???, to see that the forum has to say about it.

I was able to record a new peak RPM 2 5950.


:seeya

6spd

okay well it's good to hear that some is normal i'm getting no more than 5 degrees of retard but why is it happening at 3800 rpms you can feel the performance loss and it is supposed to make peak power at 4500-4800 rpm i'm dying out at 3800 thats were it starts????????????????

GusBustamanteJr

Absolutely, in park, you are not really doing yourself anygood.
I also get that problem, I have searched the forum, and many others have come before us with the same issue. Once you have checked everything, all you can do is back off base timing. It wont hurt anything, as the ECM will advance as necessary, its the same exact thing as taking out of your tune. I put 114 octane in mine, and all the knock went away. With 93 I get about the same thing as you. I was told by Jesse to back off 1* at a time until it goes away. I thought my headers and roller rockers were causing it, I even bought a new knock sensor. I will just back off the timing as smarter people than me, have told me to do. Do a search for "knock" before you post a new topic, you will have enough reading material for the evening, when you finish that and get bored, search for "SR vs.MR" That will entertain you till 05'!