Burst Knock and 98 pcms?...
04-29-2009, 11:31 PM
#1
TECH Addict
Thread Starter
iTrader: (41)
Join Date: Jun 2005
Location: Jefferson City, MO
Posts: 2,329
Likes: 0
Received 0 Likes
on
0 Posts
Burst Knock and 98 pcms?... Can anyone explain to me whats up with the Burst Knock on 98 pcms? Someone told me that I am yet again screwed by the 98cm because you cant do anything about burst knock if it starts to drag you down?... Please tell me I am misinformed.. 
04-30-2009, 10:38 AM
#2
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes
on
6 Posts
From what I've seen (mostly on '99-up F-bodies)
the burst knock on our cars is safely out of the
way. Trucks have it set up really bad (for sporty
performance; meant for towing fuel economy).
But the main knock retard problem on '98s is not
burst knock (predictive), it's a poor knock sensor
design that ages badly and gives false knock
retard (reactive to engine noises, or just always
bugging). That wants sensor replacement with
the updated one that went on '99-up models.
You can scan for the various spark retard sub-
components (KR, burst knock, IAT, ECT, ...) and
determine which one is pulling the timing. That
will tell you whether it's replace-the-sensor, or
some other thing.
Burst knock is only seen on rapid throttle opening
where you get a big "air step". Or if the threshold
is too low (like on trucks), maybe on 1st gear,
fast RPM-rise will trigger the retard and sap out
the acceleration. But knock sensor problems are
more commonly about 4000RPM and don't need a
throttle transition to show up.
the burst knock on our cars is safely out of the
way. Trucks have it set up really bad (for sporty
performance; meant for towing fuel economy).
But the main knock retard problem on '98s is not
burst knock (predictive), it's a poor knock sensor
design that ages badly and gives false knock
retard (reactive to engine noises, or just always
bugging). That wants sensor replacement with
the updated one that went on '99-up models.
You can scan for the various spark retard sub-
components (KR, burst knock, IAT, ECT, ...) and
determine which one is pulling the timing. That
will tell you whether it's replace-the-sensor, or
some other thing.
Burst knock is only seen on rapid throttle opening
where you get a big "air step". Or if the threshold
is too low (like on trucks), maybe on 1st gear,
fast RPM-rise will trigger the retard and sap out
the acceleration. But knock sensor problems are
more commonly about 4000RPM and don't need a
throttle transition to show up.
