Upgrade the ECS Module 1985-1989 Corvettes

The \’85-\’89 L98 uses an Electronic Spark Control
(ECS) module to listen to the Knock Sensor and report ping to the ECM (on
\’90-\’96 Corvette motors the ECM listenes directly to the Knock
Sensor). When the ECM detects knock counts it pulls timing till no knock
is reported and then gradually increases timing to the current
Even with base timing at +6deg and running the
stock MemCal chip, my \’88 L98 was plagued with false knock counts under
WOT operation (seen on my AutoXray scan tool). These were causing timing
to be pulled, which I felt was hurting 1/4mi
When I discussed this issue with Gordon
Kilebrew, at Corvettes at Carlisle 2001, he told me to replace my stock
ECS module with the upgraded unit:
After doing this upgrade a short WOT run
on the highway showed no knock counts on my AutoXray.
testing at the local drag strip showed an improvement in trap speed of
about 1 mph. No other changes had been made and trap speed data was
normalized for weather conditions to provide a valid comparison with prior
time slip data.
Equipment Safety
This upgrade is safe for the
motor since the ECM checks the ECS module occasionally by advancing timing
till a knock count is registered; if no knock, the ECM would record a code
43. Just to be sure all was well, I advanced my base timing to about
+12deg and made a WOT run on the highway; 7 knock counts had registered on
my AutoXray.