Potential source of knock issues?
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,469
Likes: 6
From: Winchester Ontario
Potential source of knock issues?
Hi, I've been tracking down knock problems, false and probably real. I just read this (I'll cut and paste it here) and a little lightbulb went off above my head. Could this be a source of problems?
Taken from tunercat.com website.
My ECM has a long blue module (Memcal) but no EPROM. What do I do?
The EPROM's fro these ECM's are located in the Memcal. (You can see the EPROM through one of the holes in the top of the Memcal.) To gain access to the EPROM, carefully remove the blue (sometimes its tan) plastic cover. The Memcal's generally also contain the 'limp-home mode' resistor network and some knock sensor signal conditioning circuitry. There are several ways to work with these Memcals.
A while back I had somebody tinker with my chip but never really finished with it. Could the knock sensor circuitry have been damaged there causing some problems?
Taken from tunercat.com website.
My ECM has a long blue module (Memcal) but no EPROM. What do I do?
The EPROM's fro these ECM's are located in the Memcal. (You can see the EPROM through one of the holes in the top of the Memcal.) To gain access to the EPROM, carefully remove the blue (sometimes its tan) plastic cover. The Memcal's generally also contain the 'limp-home mode' resistor network and some knock sensor signal conditioning circuitry. There are several ways to work with these Memcals.
A while back I had somebody tinker with my chip but never really finished with it. Could the knock sensor circuitry have been damaged there causing some problems?
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Here's what I think.
The knock is caused by either mechanical sounds the sensor is picking up, an overly sensitive ESC module, lean A/F ratio, fuel pressure dropping off, too hot a plug or actual detonation due to high CR.
The mechanical sounds could be from the valve train or piston to wall (slap), etc.
You can try backing off the initial timing to see if it's the timing advance curve causing it. If backing off on the initial lead cures it then it's the timing advance causing it.
There's a less sensitive ESC module you can try. It's recommended for my 86, I got mine from GMPARTSDIRECT.COM Part # 16038331.
Jake
The knock is caused by either mechanical sounds the sensor is picking up, an overly sensitive ESC module, lean A/F ratio, fuel pressure dropping off, too hot a plug or actual detonation due to high CR.
The mechanical sounds could be from the valve train or piston to wall (slap), etc.
You can try backing off the initial timing to see if it's the timing advance curve causing it. If backing off on the initial lead cures it then it's the timing advance causing it.
There's a less sensitive ESC module you can try. It's recommended for my 86, I got mine from GMPARTSDIRECT.COM Part # 16038331.
Jake
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
The '89 was built with the updated ESC Module. It will always advance timing until it knocks and then pull 4 or 5 degrees the first time it approaches WOT - that's how it works. What are the specific issues? How many miles? Any modifications?
