valve rattle 94 automatic lt1 car
Thread Starter
Racer
Joined: Jul 2006
Posts: 327
Likes: 1
From: Trenton Ga
valve rattle 94 automatic lt1 car
my car is getting a lot of valve rattle at lower rpm's like the timing is to high. last month i found out i had water getting into the gas due to the gas cap area drain being plugged. i have replaced the fuel filter and ran ab out 3 tanks of gas through it. the car has 95 thousand miles on it. thanks for the help 
also the check engine light is still off. Thanks for the help
also the check engine light is still off. Thanks for the help
Last edited by byedan; Oct 5, 2007 at 07:23 PM.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Timing on your 94 is controlled by the ECM using input from the knock sensors, very unusual that the system would not work. I suggest checking for codes and repairing any that may be present using the FSM.
The service manual may also have a diagnostic chart for spark knock symptoms when no code is present, a few possibilities would be engine mechanical issues that can sound like spark knock, exhaust leaks or lifter noise for example.
An overheating engine can also cause such symptoms as well as a failure of the EGR system, good luck.
The service manual may also have a diagnostic chart for spark knock symptoms when no code is present, a few possibilities would be engine mechanical issues that can sound like spark knock, exhaust leaks or lifter noise for example.
An overheating engine can also cause such symptoms as well as a failure of the EGR system, good luck.
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
Knock
Could be bad knock sensors (or loose wires); they're way down on the block, just above the oil pan where the coolant drain plugs used to be.
Also the knock module could be flakey. There was a thread about unplugging and replugging the module into the PCM (to 'refresh' the connection) several months ago, but I couldn't find it. Later years the PCM was called the ECM. Did run across an interesting thread by searching for 'knock module'
http://forums.corvetteforum.com/show...t=knock+module
There are lots of threads under that search. A 'knock sensor' would show a bunch too.
Good luck.
Also the knock module could be flakey. There was a thread about unplugging and replugging the module into the PCM (to 'refresh' the connection) several months ago, but I couldn't find it. Later years the PCM was called the ECM. Did run across an interesting thread by searching for 'knock module'
http://forums.corvetteforum.com/show...t=knock+module
There are lots of threads under that search. A 'knock sensor' would show a bunch too.
Good luck.
Thread Starter
Racer
Joined: Jul 2006
Posts: 327
Likes: 1
From: Trenton Ga
could this be caused by a optispark that is going out, i do not have a check engine light on. or does the problem have to be on the knock sensor side, like i said the car is doing this around 2000 rpm. put the throttle to the floor it clears up
