_Endless_

i thought i have a bad tank of gas so i change it and the knock went away considerably but it is still there. whenever i'm in 1st gear and accelerating from a stop or from an incline with the a/c on, the engine will knock a bit. the weather is a bit warm but it also knocks at night as well but not as often as in the day. what could be wrong?

by the way, the car(2000 SiR) is turbo running the vafc hack at .54 bar. the ignition timing was set at stock 16 degrees then i used the jacobs boost timing master to retard 5 degrees from stock and about 2 degrees when boost comes in. so i don't get why i'm knocking when the a/c is on. if the a/c is off, it does knock during acceleration but very very seldom. could it be something serious? i'm using the highest octane gas from where i live. could it be worn clutch?

any help will be appreciated.

ahobbs

This is just a guess but maybe the a/c adds a little stress on the engine and that may cause knock...that's a new one for me i would like to know as well.

_Endless_

bump for the morning crew.

will a rich mixture from running the hack cause knocking also?

glagola1

Your ignition is too advanced. When your putting a load on the engine the piston speed is lowered and it reaches tdc later and your spark is lighting too soon. Under no load the ignition advance is fine because the piston/ engine is not slowing down as much between the power strokes.

Retard until the knock goes away or rebuild later.

Pengo

wait, why did you retard 5 degrees off stock? i thought u would want to keep it closer to stock when it not in boost and retard only under boost.

twkdCD595

you can retard the timing while not under boost, it just makes the car feel a tad more responce sluggish.

Pengo

yea i know it can be retarded, but that's what i'm saying, why sacrifice the fuel efficiency and response by retarding when not even in boost. the point of a boost timing control would be so u can retain the cars performance when still in vacuum and then actively retard while in boost. this seems to defeat the purpose by retarding that much while out of boost

mos

He's running an afc. He doesn't have a choice.

Going up an incline or running your a/c will increase the load on your engine like glagola said. Thats why there is a difference under those conditions.

blackANESE

iTrader: (2)

The AFC hack also advances timing quite a bit.

yellowhonda88

Just a side note, I though my car was doing the same thing a while back. I took the shortest route....I replaced the a/c clutch bearing, and it solved the problem. When that bearing goes back, under load, it makes the same "marbles rolling around a tin can" noise. Just thought i would chime in with another opinion.

Brett

GreddySi99

I also noticed this when I went to the vafc hack. I had to retard 3 degress at the dist to make it stop that ****

incognitoracerr

I agree with yellowhonda...i am more than sure its not the engine...i had the same problem but mine was really loud...my a/c compressor went bad because of the boost...after a while boost kills it so I had no choice but to cut the a/c belt and ta-da the damn thing stopped making noise...so it could be the a/c compressor...try cutting the belt...its one cheap way to go

psileepR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by _Endless_ &raquo;</TD></TR><TR><TD CLASS="quote">i thought i have a bad tank of gas so i change it and the knock went away considerably but it is still there. whenever i'm in 1st gear and accelerating from a stop or from an incline with the a/c on, the engine will knock a bit. the weather is a bit warm but it also knocks at night as well but not as often as in the day. what could be wrong?

by the way, the car(2000 SiR) is turbo running the vafc hack at .54 bar. the ignition timing was set at stock 16 degrees then i used the jacobs boost timing master to retard 5 degrees from stock and about 2 degrees when boost comes in. so i don't get why i'm knocking when the a/c is on. if the a/c is off, it does knock during acceleration but very very seldom. could it be something serious? i'm using the highest octane gas from where i live. could it be worn clutch?

any help will be appreciated.</TD></TR></TABLE>

wow i thought i was the only one i pretty much have the same problem... knocks a lil off a light, just regular driving. Knocks a lil when at part throttle boosting but doesnt knock at WOT.

I was told that the hack and our ecus advance the timing a lot under load at part throttle conditions. More than at WOT and regular driving. so i think that has a big thing to do with it.

My clutch too is worn ... almost 100k miles on it... but i doubt thats it.

psileepR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by _Endless_ &raquo;</TD></TR><TR><TD CLASS="quote">bump for the morning crew.

will a rich mixture from running the hack cause knocking also?</TD></TR></TABLE>

id also like to know of an overly rich mixture can cause knocking.

_Endless_

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Pengo &raquo;</TD></TR><TR><TD CLASS="quote">yea i know it can be retarded, but that's what i'm saying, why sacrifice the fuel efficiency and response by retarding when not even in boost. the point of a boost timing control would be so u can retain the cars performance when still in vacuum and then actively retard while in boost. this seems to defeat the purpose by retarding that much while out of boost</TD></TR></TABLE>

i'm running the vafc hack that's why i had to retard timing even when i'm not in boost coz the hack advances ignition timing even when not in boost.

right now, if i'll be accelerating from an incline i turn off my a/c just to prevent it from knocking. i'll look into the a/c thing and i'm going to check my static timing again to see if it's in stock spec then retard further with the timing controller.