Detonation
Thread Starter
Team Owner
Joined: Oct 2003
Posts: 21,465
Likes: 114
From: Hillsboro OR
Detonation
On my '88, at WOT, and only above about 4500 RPM, it detonates really hard. I've never heard a car ping this bad before. It does not ping under any other condition (lugging it, etc.) and again, it only happens above 4500 RPM. And in any gear (4+3). It has just started doing this. Timing is correct and it still does it on a second tank of (92 octane) gas. Any ideas?
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
We need to go back to square one.
Had you changed anything just before this started?
Are you getting any error codes?
Are you able to monitor fuel pressure by installing a gauge with a long hose taped to the windshield?
Are you able to connect a data logger to capture the numbers? Remember, it's all about the numbers.
I don't believe in jumping right in and begin changing parts - fuel filter/pump/ignition, etc. Let's first try to diagnose the cause, then, if necessary, change part(s).
Jake
Had you changed anything just before this started?
Are you getting any error codes?
Are you able to monitor fuel pressure by installing a gauge with a long hose taped to the windshield?
Are you able to connect a data logger to capture the numbers? Remember, it's all about the numbers.
I don't believe in jumping right in and begin changing parts - fuel filter/pump/ignition, etc. Let's first try to diagnose the cause, then, if necessary, change part(s).
Jake
If you are hearing knock, there is something else going on.
Thread Starter
Team Owner
Joined: Oct 2003
Posts: 21,465
Likes: 114
From: Hillsboro OR
Jake,
I haven't changed anything. It pretty much all of a sudden started doing this.
No error codes (no check engine light, etc. are displayed on the dash).
I don't have a fuel pressure gauge that will read high enough for FI.
Nor do I have a data logger.......
I haven't changed anything. It pretty much all of a sudden started doing this.
No error codes (no check engine light, etc. are displayed on the dash).
I don't have a fuel pressure gauge that will read high enough for FI.
Nor do I have a data logger.......
Instructor
Joined: Jul 2004
Posts: 118
Likes: 0
From: Smithfield Va.
My '90 started doing the same thing recently. Knocks like it's coming apart at WOT. Mainly when it gets hot but anytime it feels like it seemingly. It just started one day during a bad rainstorm. i replaced the EGR valve and computer...still does it. I'd like to hear any suggestions also.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by 88Z51
I don't have a fuel pressure gauge that will read high enough for FI.
Step 2.) Follow Jakes advice.
RACE ON!!!
